Yep, probably would be 2000 miles.... LOL

Apparently, the modules are all the same. I found out that the one I bought was a "PV" ..... perfect value, meaning economy. So maybe it is inferior, I don't know. I was going to change it this morning, but it is so hot right now, I think I'll wait for the weekend.

The GM bulletin said to replace the PROM (which you have already), and the module with part# 16140039, which crosses to the Delco D1943A. So I'm assuming that the original GM stock item was inferior. So how many of these replacements are duplicates of the older, inferior one, or duplicates of the newer superior one? That's why I am replacing mine with the Delco, just to be sure.

Another thought: the PROM for the automatic trans may work better, because it doesn't have to provide for a cleaner "decel" between shifts....... but the shift light comes on when the converter is supposed to lock.

Anyway, I would be anxious to know if the new icm helps

 

YAY we made it on to page 2 lol.

i will let you know what happens with the icm mate, il change it when i pick up my car on my next day off( i do 6 on 3 off 24hr call out)

think im gona have a nightmare getting the dizzy out though , dont know how im gona get that bolt out.

Nick

 

A long extension and a universal (wobbly) will do it. I think it's a 15mm? My plate (where the icm mounts) was covered with grease, don't know if someone else smeared that heat transfer stuff all over, but the vents were plugged. A good cleaning won't hurt.

If you have never taken that out before, REPLACE THE O-RING on the shaft. It is subject to oil pressure, and if it is old, it will definitely leak. It won't leak right away, it will surprise you. Don't use a standard O-ring, either, it is a thicker than standard one. Go to a GM dealer (or supplier) and get one. I replaced mine with a standard one, it seemed OK, didn't leak when I checked for leaks. I left a trail of oil all the way to work. Almost lost all the oil in about 25 miles.

I'm not going to pull the dizzy, think I can do it on the car, but you are replacing the pickup also, and that O-ring is probably due...... They can start leaking at any time.

 

This is a really good thread. I have the same problem with my car and im sure there are many others out there. I see a ton of third gen f-bods chugging along here in cali. I'm glad there are some 3.1 guys in here that can relate to this problem and acutally care about getting it fixed. keep it up guys.

-Jess

 

Welcome to the forum! Yep, this seems to be a common problem, is yours REAL bad, or just moderately bad? How bad do you want to fix it? As you can see, we have done a lot to little or no avail.

Seems like the PROM change was the single item that made the biggest difference in mine, but Rexer already had the new PROM, so.......

Good Luck

 

I took out the ECM and checked the PROM and it was the right one. ever since i got my car it's been knocking really bad, and i thought it was an exhaust leak or something. I got my exhaust checked up and it was fine, so im thinking the knocking is coming from my valvetrain. The timing is correct, its set at 10 deg. btdc. Maybe the hesitation is coming from a bad rocker arm, or broken valve or something??

 

Since I am the owner of a v6 as well,and yes..I too have or say had the familiar hesistation.I just replaced the pick-up which I ohmed the old-new one and found about a 5 ohm difference.I replaced the control module 1943a and the Air temp and coolant temp sensors(OEM stuff)...and when I replaced the coolant sensor I broke that vacuum line that runs from the fuel reg.and branches off to the divertor valve at the back of the air pump.So I decided to check it(divertor) and the **** thing didnt hold no vacuum so I just ran the line to the fuel reg. and Hesistation was gone..very very slight but not enough to complain about it.It runs excellent.I cant say what fixed it but am leaning towards the divertor valve.My question to you guys would be if the valve is plugged off(vaccum line) what would the direction of air flow be going?stuck in upstream or downstream?..If its stuck in upstream would the O2 pick it up as lean and dump fuel?..Block Learn was 128..which is normal.So I am assuming its stuck in downstream to the CAT.ANybody have info on how it operates?

 

Well, the Air Management Valve, is where the vacuum line goes, at least it does on mine. There seems to be different hose routing schemes for different emission requirements. Mine has no "gulp" valve, no diverter valve, the AIR pump only pumps air to the converter (CAT). I've been told this is just for cooling, as during some rich conditions, it can overheat. You have the automatic, which uses a completely different AIR system than the 5 Spd, plus mine is a California car, but I don't think it is much different from the 49 state version, because it is a manual trans. There is also an electical connection to the valve, so the computer controls it, too, not just vacuum.

My AMV also didn't hold vacuum when I sucked on it, and I thought it was bad, so I replaced it. This is a $180 part. I tried plugging the line first, didn't help the hesitation. The new one didn't hold vacuum when I sucked on it, seems you have to apply vacuum (a lot) to get it to work. I put a vacuum gauge in the line, started it, squeezed off the vacuum source, the gauge held steady. There is a check valve in the line to the converter, that is only $20, it was stuck, and I replaced that.

When you replaced all these parts, did you disconnect the battery? When you reconnected it, the hesitation was gone, right? Has it slowly started to come back? Also, you would not notice it as much with an automatic, as we do with a stick shift, it gets pretty aggravating having that happen EVERY SHIFT

The air temp sensor on mine is located in the air filter housing, not in the plenum as the service manual says. It is the old exposed bulb type that I read somewhere is only used on 85's. The air temp sensor used on later models is supposed to be the same as the coolant sensor. I did a resistance check, it seems to be working, though.

 

You know, I thought of that, maybe air is getting past the valves, or a leaking valve is allowing air to back up into the intake, so the first air flowing back in is not fueled. Also, when I had the exhaust manifolds off, the back cylinders had a white deposit over the soot, maybe those two are running lean, and fooling the O2? I had many exhaust leaks which I have fixed, that stopped the backfire (muffler explosion) I was getting on downhill engine braking. The heads were vacuum checked, and came back OK......

The next thing the GM bulletin says to replace is the ICM with updated part #16140039, which crosses over to Delco D1943A. Rock Auto (.com) has them for 49.99. It's cooled off today, I'm going to replace mine now.

 

When I replaced my pick-up/module and coolant and air temp sensors I didnt clear the computer.I did noticed that when I start my car up for the first time in the morning it idles high and then comes to a set idle.It never did it before.My Air Temp is also in the cleaner....I did check mine before I removed them and they checked out okay but replaced them anyway cause of the mileage on the car.It hesistates a bit in Open Loop but is gone in closed.I picked up a scanner and was going to watch the O2 volts to see if that would shed some light,on the AMV function.If your saying it takes a lot vacuum for that AMV to operate then if you have already replaced the things I have and still have a hesistation then inside the motor could very well be a starting point.How about a worn cam lobes?...a broken spring you couldnt miss hearing that.
If you have weak valve springs..then that would be something.A vacuum check would solve that?Has anyone checked it?Whats the rec.vacuum reading for these engines?

 

Hmmmm weak valve springs, thats a possibility. I think I'm pulling about 15" of vacuum just off idle, at least thats what the ported vacuum was above idle. I will check again.

There didn't seem to be any badly worn cam lobes that I can remember, I had the heads off, I think I would have noticed when I adjusted the valves. We didn't do a valve job when the heads were off, just extracted some broken exhaust studs, and vacuum checked them.

Do you know for a fact that you have an AMV? As I said, automatic equipped cars have different AIR plumbing than manual cars. The service manual shows a diverter valve, and air tubes going to the exhaust manifold, mine has none of that. Is the air temp sensor the same part number as the coolant temp sensor? I may replace mine just for the heck of it, the coolant temp sensor is new.

I changed the module today, man, you really do have to let it re-learn as the book says: idle until the cooling fan cycles (about 20 min), then shut off for 5 min., then idle again for 5 min. It seems to be running better, but time will tell, the computer usually takes a couple of days to fine tune the mixture, usually toward the lean side, then the hesitation gets worse.

Can anyone decipher the code stamped in white numerals/letters on the top of the ICM? Is a date code? (e.g. 369 5L09)

From what I hear, the fast idle when you first start is normal, the ECM finds the desired idle by adjusting the IAC valve.

 

Good thing you are replacing the pickup coil as well, I remembered the connector that plugs into the ICM gets brittle, and the keeper will probably snap off when you unplug it.

As far as the GP/Sorensen parts, I don't know if they use GM "rejects" or not. The PV KEM ICM I had in there says GM right on it, and it looks like a GM part. I'm just wondering if it is old stock they bought up cheap, and are reselling it. If that is the case, then it could have been outdated.

These are the numbers stamped in white letters on top of the three modules I have (had):
The original one I removed: 039 0H10
The KEM "perfect value": 369 2H19
The Delco D1943A: 369 5L09

The screws that mount the icm were badly rusted, don't know if they are supposed to ground the mount holes, but I cleaned them off (had to use a small file on the underside of the head), and used new serrated lockwashers. I didn't do that the first time, don't know if it is important. Tried to get new screws at the hardware store, but they are #6-40. The finest thread they had in a #6 was 6-32, so I saved the old ones.

 

Mine has always done what you describe, but not completely gone in closed loop, just better. But sometimes even in closed loop it'll sneak in and surprise you, for instance when you are trying to beat someone off the line it'll sag right when you don't want it to

Have you tried my little test? Start it up (cold or warm), put it in gear (you have automatic), let it idle down the road, then step on it. Should be no hesitation at all. Now stop, and accelerate again. I'll bet you notice a sag this time. Stop and shut off engine. Restart it and do it again, should have same results....... My question is, WHY is the first acceleration perfect (I mean PERFECT), and any further acceleration attempts have that annoying sag?

Unless the automatic (being always under load) prevents the engine from "coasting" you should get the same results. I'd be interested in knowing how this works in an automatic, would you try this, and let us know your results? Maybe after trying this a few times, make a run keeping it in first gear, and see if it hesitates then. I have a feeling the manual trans compounds this problem. Thanks for the info.......

 

I just checked out my AMV set up and I only see a tube running to the manifold not to the cat or at the cat.I still have the hose plugged up and havent tried to re-hook it to see if the hesistation comes back.
I will try your test tomorrow on the way to work cause if something happens it gives me an excuse not to go.I read in the Technical Service Bulletins that this computer takes 40 plus key starts to relearn once power was lost.I also know that everytime you turn the key on the computer looks at the TPS sensor voltage and if its within it range it will self zero.I also checked my TPS via-scanner and couldnt get it over 4 volts at WOT.I replaced it and same thing unless I really mashed the throttle pedal into the firewall and I got 3.90.I was thinking maybe the cable stretched?..I have read it should go to at least 4.50 volts.??
Another thing the Air Temp and coolant temp are not the same I had to order one for a 92 cause the place I ordered it from didnt have one listed for a 90 so I told him just order one for the same engine just 92.It looked just like the one I had so I installed it.I checked mine before pulling and they checked okay,and then rechecked the new ones.The old ones were within 1-2 degrees of each other and the new ones were about 8 degree difference?
I almost forgot ..I checked my engine vacuum at the MAP via-scanner and it read 26 inches I havent actually hooked a gauge to the motor itself ,but if your getting 15 inches that seems kinda low?..dont have a performance cam do you?.

 

Yeah, I knew it took a long time to re-learn everything, 'cuz it seems to run differently every time I start it...... LOL. Yes, the hesitation is creeping back.

The line running to the cat is from the pump itself, it is pumping air into the cat to cool it (or perhaps to aid in burning HC). At least that is my setup. I actually replaced the AMV for two reasons, 1, I couldn't hold a vacuum by sucking on the hose, and, 2, I was getting backfire through the muffler on downhill coasting. I don't think either of those things were affected by replacing the valve, but at least it's new. The only reason the air pump is even on my car is to pump air to the cat........

26" of vacuum sounds awful high, I haven't seen any engine pull much more than 20". You are reading it off the MAP with a scan tool, I am using a vacuum gauge in a vacuum line. I just checked to see if I was getting ported vacuum to the canister, not really checking the vacuum reading, but I will check the manifold vacuum next time I get to it, and let you know the reading. Maybe the MAP sensor on yours is reading too much vacuum and leaning the mix? I have a new MAP sensor in mine, never used a scan tool on it myself.

 

I could be wrong on the vacuum reading ,thats why I want to check it with a gauge on the motor itself.The MAP is brand new AC DELCO..I 'll get back to ya tomorrow.

 

So I thought I get back to you guys ..I took the maro this morning to work and did the little test ,but I didnt stop and restart it ...I got about a mile or two from the house and came to stop and gave it some juice and like you said it didnt respond...(lagged I would say) the first light I stopped at it was good, but after that lagging stop it didnt do it again,so your right once in awhile it wont be responsive.The only thing I can say is ...I would have to hook up the scanner and road test it and hope I can see something odd on sensor values when it does it.On the way home it ran great ,but I dont romp on it at every stop..plus it was raining and even one wheel wonder like to slip and slide.

 

Thanks for getting back, and trying the test. With a stick shift it does it ALL the time, you don't have to romp on it to make it hesitate. Even just mildly punching it makes it "sag". Would still like to know what vacuum reading you get, I haven't checked mine yet, worked a 14 hour day........

 

Havent checked my vacuum either..I can see why that would be a pain for you stick shift guys.I would hate that..I will see if I can get time today and check it out my vacuum readings.

 

iv just worked out exactly what idle roll is and thats whats wrong with my car, so hopfully the icm will sort that, im tempted to just do that first and then think about pulling the dizzy. i think the reason its like a bucking bronco on idle roll is the computer cant work out what it wants to do, fuel it or not fuel it , have you noticed if your coming to a set of lights that if you come off the gas and start to slow, then start braking and put the clutch down the engine revs up to 2000 or so and doesnt come down till your nearly stopped? thats what mine is doing and im convinced its because of this idle roll.

Nick

 

Guys i was just searching around on google when i found this, its on a bike forum but read it, does what they are saying ring any bells?

RiderForums.com Community - off-idle abruptness

incidently they are on about the motorbike i own but dont have this problem with it. they go on about fuel mixture and transmision slack and i also heard mention of egr hmmm i feel im a little bit closer now.

Nick
----------
also found this , its for a ford scorpio (uk car) but look

88-05-12 IDLE ROLL - 2.9L EFI - Throttle plate modification and EEC IV processor on vehicles built before 9/1/87

sounds like the tsb for our cars a bit.

infact look at this list

89-25-06 HESITATION - 2.9L - EFI - During acceleration from idle after cold start-up
88-24-05 HESITATION - During acceleration - Improper idle "hard stop" adjustment
88-24-06 HESITATION - During acceleration - Sludge in throttle body
89-16-05 HESITATION - During acceleration - Sludge in throttle body
93-24-08 HESITATION/STALL - During acceleration or deceleration
88-26-07 IDLE - Rough - 2.9 EFI - Engines with less than 500 miles
93-14-04 IDLE - Rough - Engine coolant does not reach normal operating temperature
93-24-08 IDLE - Rough - Engine coolant does not reach normal operating temperature
89-24-04 IDLE - Rough - Replacement Air By-pass Valve inoperative
88-05-12 IDLE ROLL - 2.9L EFI - Throttle plate modification and EEC IV processor on vehicles built before 9/1/87

 

can my cars ecm be remapped? i may just take it to a shop with a rolling road and get them to remap it . from what iv found so far i think this would be the only soluton.
----------
just a thought, on the 2.8's they have an adjustable tps,hmmmm how about elongating the holes in ours so we can adjust it? or would the computer just compensate the adjustment? just running ideas.

 

Just pulled the icm out and the numbers on it are as follows.

on the top it has in white digits.... 039 2A31
underneath on the metal bit it has ...... 039 3436

mean anything? is it the old crap one?

im gona fit this gp sorensen one and let you know what happens.

Nick

 

Fitted the icm, made no difference. **** this pos v6. im looking for a v8 with a carb lol

Nick

 

Yes I did have that problem, but can't remember how I fixed it, I think when I did the injectors, 'cuz it would buck at low speed in the higher gears. I could not turn a corner in 4th gear, and accelerate out of it, it would jerk, and buck. The new injectors smoothed that out, but that's when I first noticed the hesitation. I installed a set from an 88 2.8, and thought they were wrong, so switched them for the right ones. Still hesitated. It was REALLY bad when I got the wrong performance chip from Summit. They sent me one for a V8, when I installed it, the speedo did not work, the idle was at 2000. Drove it to work one day, and when I slowed down to where the engine was below 2000, it would buck like crazy.

 

I'm thinking the same thing....... the new PROM helped even when cold and still in open loop. <u>DIY Fuel-Injection Tools:</u><br>Created by an EFI enthusiast for EFI enthusiasts like you! : Moates.Net is a site devoted to this.

No, the adjustable TPS makes no difference. The computer reads the setting every start and self-zeros to that value.

A "rolling road"? Is that what we call a "treadmill" here? LOL

 

Well, if the 039 is an indication, it may very well be the old one. What did the GP have on it? Does it have the GM emblem on it? If neither, it is not made by (or for) GM. Even the KEM unit I had was a GM. Seems as though the 369 may be a later version, as for the last 4 characters, I'm thinking it's a date code?

 

I'm really perplexed by this, but I can't do much altering here, I have to smog it every two years. The best I could do is a 305 or 350, but up to 1991 emission levels.

I'm going to pursue the re-mapping idea. There is a guy in Livermore (about 30 miles from me) who is a member of moates.net. He said he needs to download the profile for my particular car and modify from there. He actually solders a different ic chip into the PROM. I'm hesitant about ruining the stock PROM, but I have two spares (one from the shop meant for an automatic, and the original ARPL). I wanted to try a few more things, and I think I've done about everything else.

Good luck, mate

 

Yep, it reads a steady 15 at idle. When I rev it up, it stays about the same, on decel, it goes to 17, no jumping needle, steady readings always. I used the manifold vacuum going to the regulator, and AMV, I have a tee in the line. If I "goose" the throttle, it doesn't drop much, but the RPM goes up a bit, after sagging.

 

Interesting site, there, the riderforums.

As you recall, I got results when I squeezed off the return line, giving the injectors 60psi. But, as the computer learned the values, it compensated for my attempts at enrichening the mixture. I removed the clamp after a day or so, and it REALLY hestitated, worse than with the old PROM. It slowly learned the new values, and the hesitation was better by the time I got home. The moral: The computer will not allow a rich mixture, so therefore, the computer needs to be re-programmed.

This must be an inherent design flaw, as I had a 94 Ford Explorer (well my daughter had it), and it never hesitated. It had MAF, some say that is better, because it lets the computer know exactly how much air is getting in, not using a set of default values based on fixed air flow rates.

Good luck, all

BTW, I did adjust the hard idle stop, maybe this is a factor? But I've re-adjusted it so many times, and still unsatisfactory results

 

The computer will not allow a rich mixture, so therefore, the computer needs to be re-programmed.



I am going to have to agree with you on that one..I havent bothered checking my vacuum and probably not going to find anything different then you did.If it was a vacuum problem it would be there all the time not just once in awhile.If you look into this please let us know.What I want to know is what would they tweek in the computer to remove this hesitation problem?

Have anyone possibly looked into worn throttle shaft bushings?..I remember someone I know talk about it being a problem back in the time.I know I can feel some play in the shaft if I manually move it?..any thoughts?

 

Yeah the throttle shaft bushings can be a vacuum leak source, and I thought a sticking point when pushing the pedal. Got mine re-bushed, still hesitates. On carbs, it can be a major vacuum leak.

I thought of the O2 sensor, too, so I asked TPI Parts what they thought, here is their answer:

Item_Description: O2 Sensor
Comments: This more a tech support Q. What would the advantage of a heated O2 sensor be? I have a hesitation when accelerating, and I'm wondering if the O2 is showing too rich so the ecm cuts the fuel? Would a heated O2 solve this?

Answer:

A heated O2 sensor will allow you to have a more accurate reading if you
have installed headers on your vehicle. Headers usually more the oxygen
sensor further down the exhaust stream, where the exhaust temp is cooler.
The exhaust must be atleast 600 degrees at the sensor for the sensor to read accurately. A heated O2 sensor heats itself, which helps raise the
temperature quicker, and keeps it reading accurate.

I've never seen an O2 sensor fail and read rich, they always read lean when they go bad. More than likely, your O2 is indicating a problem with
something else, not a bad O2.
-------------------------------------------------------------------------------------

I'm not sure exactly how you would tweak the computer, it is a steep learning curve when you get into DIY prom burning.

You can check out www.moates.net and see.......

 

Heres something else which strikes me as odd ,I have access to TSB(technical service bulletins)at work and the only thing it has on this, has already be discussed in another thread.What doesnt make sense is if this was a big problem... as it is now for us v6 owners why wasnt it a problem back then and have more complaints about it in the TSB's?They just say replace ignition module and update the Prom.People have done that and still have the hesistation.My boss used to work at the dealership during the time of production of these cars and agreed of the common problems with the engines but he didnt really give me a solution of what they found.

 

A couple of things, a silicone poisoned O2 sensor reports rich. It will cause the fuel trims to move down (removing fuel) to the point the engine shuts off. Silicone based sealers (RTV) are the common cause of sensor poisoning.

For those running a 3.1L and auto transmission, have you done an idle learn? If the battery has been disconnected this procedure should be done. Otherwise the engine just doesn't run right. It will eventually, takes a couple of weeks of daily driving to straighten out.

The acceleration enrichment (pump shot) on these engines is lame, real bad. The ECM doesn't have any MAP related AE, it is all TPS based. Even at that the INTegrator makes up for a lot of leaness. The calibration folks also increased the VE table to make up for the lame AE routine.

Last but not least: the injectors. The 3.1's use the Multec injector, which are terrible. And, they are now 14 -16 years old. Within the past month or so a couple of people here replaced them with great results. I recommend a Bosch replacement. A direct replacement can be found on Ford 1986 2.9L, 3.0L cars. Have a gray top with the number E67C-9F593-AB on them. The 1986 5.0L SEFI ran the same basic injector with the number E67E-9F593-BB on them (also a gray top).

RBob.

 

A heated O2 sensor will allow you to have a more accurate reading if you
have installed headers on your vehicle. Headers usually more the oxygen
sensor further down the exhaust stream, where the exhaust temp is cooler.
The exhaust must be atleast 600 degrees at the sensor for the sensor to read accurately. A heated O2 sensor heats itself, which helps raise the
temperature quicker, and keeps it reading accurate.

I just did a road test on my v6 ,I did a good 5 -7 mile stretch of cruisin,and then back about 5-7 miles in town.I had my scanner hooked up paying attention to O2 volts.I came back home and turned off the car not really noticing anything out of the ordinary via-readings.I let the car sit for no more then 30 seconds and started it up again and after it started it went into open loop ...what the *&%$ the O2 should of been hot enough by then?.is the O2 positioned to far from the exhaust heat?..is it possible that being too far from the heat that it could create a hesistation?

 

Interesting, i did change the o2 sensor for a new delco one. may be time to borrow my mates infa red laser thermometre thingie, and check this out. may have to think about moving the o2 sensor to a hotter location. sounds feasable. is there a way to check if im in open or closed loop mode without a scanner?, so does your auto car do all this bucking? im not sure i have the same problem as you guys after somone mentioned getting new injectors. il try that and then get back on it if the problem is still there.


Nick

 

[quote=Rexer]Interesting, i did change the o2 sensor for a new delco one. may be time to borrow my mates infa red laser thermometre thingie, and check this out. may have to think about moving the o2 sensor to a hotter location. sounds feasable. is there a way to check if im in open or closed loop mode without a scanner?, so does your auto car do all this bucking? im not sure i have the same problem as you guys after somone mentioned getting new injectors. il try that and then get back on it if the problem is still there

I was thinking the O2 position is too far away from the fumes to stay heated.I am hoping someone would shed some light on the wiring for a heated O2.Hopefully wont have to tweak the computer for this application?My car doesnt do the bucking,but of course I dont let off the gas everytime I shift so its possible thats where you manual guys are getting problems.I dont know how you can find out if your in O/L or C/L without a scanner.I didnt see any constant lean condition during my test run...so I ant sure about the injector replace..but I wont rule it out.

 

I have looked into a wiring diagram for the heated O2 on a three wire connector... one runs to a switched ignition source.Another runs to a good ground either engine or chassis and the other is to the original wire.I wonder if anybody has done this procedure on the third gen's yet and what sort of results did it produce.I also looked into some of the results of my road test and most people say its normal for it to pop back into open loop,at a idle and drop to no reading or 000 volts,but going to 800-900mv when it isnt running has got to be wrong.Unless an injector is leaking and the exhaust valve is open?I already replaced my injectors for the sake of age.I can't see that whats causing my readings ,plus I read in another post that they had similar readings with a bosch O2.If I dont get a reply, I will look into the O2 swap.

 

Well..I have looked into many things and have came to the conclusion that a heated O2 will help it get into C/L quicker but will it solve a hesistation..I dont think it will... it will just create a more accurate reading for the ECM.I think RBob is correct.The AE tables are weak and either remapping these areas or running a better set of injectors would be the way.Possibly both?Otherwise you have to live with it or sell it.I still plan on replacing the O2 ...to a heated one.You can get more life out of a heated one then a one wire O2,that is also a plus.

 

I saw your post in the "3.4 injectors in a 3.1" topic, thanks for posting here, too

I did replace the injectors with the same old GM gray and black ones, I'm assuming they are the Multec ones. Do you think the newer Bosch replacements would fix this problem? You also mention the VE tables, is that addressed by burning a PROM? You say the integrator makes up for a lot of the leaness, is that a PROM function, also? I have been considering burning a new PROM, or burning a piggyback, at least.

I'll try the injectors before delving into the world of PROM burning, you say the injectors for an 86 Ford 2.9L or 3.0L would work? They are the same as an 86 Ford 5.0L? Maybe I should stick with one made for an engine closer to my size? (3.1)

As I stated before, the problem seems to be only with accelerating after the engine has been in "decel" mode, but now that I haven't reset the ECM in a while, and I am getting close to the 40+ key starts, it seems to be learning to do it (hesitate) on the very first accel, too.

The service bulletin posted 4 years ago by CaliCamaroRS says the replacement PROM to be a BAWX 6651. The one I got from the dealer in Visalia was in an opened 16176864 box, but the actual PROM reads BAWX 6865, could this make a difference?

BTW, I removed all traces of silicone, and replaced to O2 (the third one this car has had), no difference

 

Well..is this dedication or what...I just spent most of my 4th of July making a by-pass wire for the VATS system.Never know when it will come in handy.After robbing the power supply from an ol'Sony tv for its resistor..and two trips to Radio Shack..I finally finished.
ANyhow..I was told by some people not to even mess with a heated O2,and maybe look into a aftermarket PROM,but here again a slightly over stock PROM from what people say is nothing more then timing advanced and dont waste your money.So back into the burning prom mode.My question would be what would you alter the VE tables or the PE tables to achieve that off idle hesistation?.About a week ago I by-passed the heated throttle body and it seemes to help some.Maybe the heat is messing with the TPS sensor...I live in the desert so de-icing is like the Dinosaurs..

 

The "performance chips" you get from Summit (and others) do not directly replace your existing PROM, they mount between the PROM and the ECM. Your PROM goes sideways on top of the chip, so it will fit. They change the fuel delivery, and timing, but do nothing under 1500 RPM, so I've been told by tech support at JET performance.

I thought the heated throttle body was part of my problem, too, but not because of too much heat, but too little, causing icing. I don't think this is the case in mine, nor yours. The coolant only circulates through the very bottom of the body, not completely around it. The little cover plate you see down there is the extent of the coolant contact.

I don't think the O2 is the cause, as this occurs in open loop, when the O2 is not operating. When it goes to closed loop, the condition improves, but is still there. Whether the ECM uses the O2 to set the default values for closed loop is my thought, but I don't know enough about it to really be sure. I still don't know what VE tables are, or INTegrators (see RBob's post)

 

I dont know about you ,but this is beginning to be a pain..VE stands for volumetric efficiency..and intergrator is a memory register both play an important part of the off idle acceleration in the PROM.VE ..is a table in which you can alter inside the PROM values and the Integrator is helpful tool if you own a scanner to see if the ECM is changing the injector pulse width.I am not an expert in the computer tables and values...been reading/searching on it though.This site has some good info on beginning PROM burning.I found you can buy the tools for it ,but when it comes to altering certain tables/values then I would be lost.I have been considering purchasing an aftermarket PROM ,but like you said will it solve the off idle symptom?So its appears like you have only a few choices..find a company or someone that will burn you a PROM...buy the equipment to do it yourself and try and learn..or maybe swap the injectors for an upgraded version and hope it helps.My car isnt too bad I can live with it like it is,but would like to see them manual guys sort this out and never get to that ...oh the hell with it ,I am selling the car..

 

The INTegrator (or INT) is the short term fuel trim. This changes in response to the O2 sensor value, and moves quickly. If you observe the ALDL serial stream the INT increases rapidly as one rolls into the throttle. An INT value above 128 is adding fuel. It will actually go into the 160+ range. Which is 25% additional fuel (160 / 128).

This helps cover the lean AE, but does not eliminate the lag. Getting into PROM burning will help. As there are parameters that can be adjusted to help. Along with fixing some other issues.

RBob.

 

I agree with the pain part....

I think we may have to become experts at computer tables to see this all the way through......

I wrote letters to the Linder site, and got responses such as: the bosch injectors don't short out like the multec ones do, or, did you check the resistance when they are hot..... These are rebuilt units, I don't think they are defective, at least, not yet. Besides, if everybody is having problems, including those with fresh injectors, somthing else is wrong.

I read RBob's response a few times, and one thing still sticks with me. Why is the very first press on the gas smooth, and all others rough? The O2 is not even working when it first starts up, so no info for VE tables or INT actions. The only difference would be that the vacuum spiked during the decel time, maybe the signal to the ECM cuts fuel? I know the ECM will cut fuel completely during long coasting periods, supposedly to keep the cat from overheating. My vacuum reads 15" at idle, up to 17" on decel (just while revving in neutral). If there is a way to limit the vacuum to the MAP to 15" maybe it would not go to coast conditions. Or limit the voltage to never show vacuum higher than what it is at idle.

Another person who burns PROMs said maybe it is going into cruise mode, that would make sense. Maybe burn the PROM to not allow cruise mode right away, if that is what is happening.

More than likely, this is an emissions issue and cannot legally be overwritten (or overridden), hence the lack of info on this subject. I think it is just another one of those things Detroit has shoved down our throats, saying that's the price you pay for clean air...... I drove a 94 Ford Explorer (V6 also) to work a few times, and was expecting the familiar hesitation when I left the first stop sign from the house, but guess what, it wasn't there!!! What do they have that we don't? Maybe those bosch injectors RBob is talking about?

Rexer has no emission requirements in England, it would not affect him if he altered it. I do think, Rexer, that new injectors would benefit you. Yours sounds the way mine did when I had the extremely rich running injectors in it. My cat plugged up, but you don't have one, so you would not urgently need to fix it, as I did. Can you run your engine in 4th gear (or any gear) down to say, 700 RPM without any bucking or jerking? Then accelerate from that low RPM? Mine would not even run below 1000 RPM until I changed injectors. I changed the ICM then, too, as it burned up when the cat plugged up Come to think of it, I turned the idle screw down then, too......

Well, that's my story, and I'm stickin' to it..........

 

Well, I ordered a bunch of new stuff, including accel injectors, which are backordered, and won't ship at least until Jul 20. I got and installed NGK G-Power Platinum spark plugs, but while removing the wires, one came apart at the plug, these are 8mo. old AC Delco!! I got a new coil too, an MSD Blaster, and the coil wire had been broken at the dizzy cap, so had been arcing. Since then I have ordered a set of Taylor wires, and accel cap & rotor.

Already it seems quieter, think the arcing was part of that LOL.

Holley makes an adjustable FPR with ALL the internal components, and a large coined **** to adjust it with, much better than the JET item I returned. I haven't installed that yet, waiting for the injectors, so I don't have to pull the manifold twice

I'll keep you all posted on how each item affects the car. I think I'll start out with the stock pressure setting, so I can see if the injectors are making a difference.

 

Yeah,I already done the full tune-up..The only thing I didnt replace was the distributor housing itself.Module/pick-up/coil/wires/cap/rotor/plugs.I had no choice they were all original 129K miles on them.. the plugs.. the center electrode was gone.I am thinking of going to a better plug something that will last longer then stock cause of that famous #2 plug..what a F"in pain.It wasnt the plug that was bad, it was trying to get the wire back on.Hard to tell if it clipped on the plug or not.

What size injectors did you order?Where from?

When I did my injectors the idiots in this town kept giving me the gaskets for a FWD 3100 ..I was so pissed I finally got them through the dealer for 12 bucks,had to keep the package cause if I ever went back in there I would be right back in the same boat I was.

 

Yeah, that plug is a bear, actually that is #1, the first one on the right. The V6 is numbered differently. Look at the heads, the right side is forward, the numbering applies the the rod bearings. I took off the AIR check valve for access, and still don't know if it really clipped on, and the alternator bracket is too hard to get to the bolts, unless you go in from underneath the car. Be careful not to drop a wrench on the starter wire............

I got the accel injectors from Summit, the stock replacement 15 lb/hr, no computer mods req.

http://store.summitracing.com/egnsea...115+4294870746

These are not in stock, backordered, expected in Jul 20......

 

Sorry..your right #2 ...had a brain fart...and let us know when you get them accels in..I am really curious to see how they do.You are driving it now before you get the injectors in right?.reason I ask then you can determine if there was a increase in performance from the swap.

 

Yep, I'm not going to disconnect the battery, either. It takes so long to re-learn, you can't really make any serious comparisons. I'll let you know.