My car was running great in fact better than ever which to any veteran f-body guy means lookout something is going to break.

I took off from a light and wound out 1st and 2nd then into 5th coasting to the next light. Then the car lost about 1/3 of it's power and shakes pretty bad.

If I give it gas it will make up to about 5000rpms which is 1000 low and it sure doesn't get there very fast. I replaced my EGR this morning and the car ran great for about 15 minutes, seemd to have recovered about 90% of it's power then it started to shake again. It makes like it wants to stall at under 2000 rpms and the driveline starts bucking back and forth. The injectors all read the same on the multi-meter. I took the cap and rotor out to inpect and they are ok.

It doesn't sound exactly like a cylinder is misfiring, it feels and sounds like the system is either retarding or advancing the timing so much (trying to compensate for who knows what ?) that the engine barely makes any power at all.

Plugs and plug wires are all less than 10k old. Same for O2 sensor. Same for ignition module.

A n y i d e a s ????

thx,
RP.

 

my guesses
1)Loose connections
2)vac leak
3)faulty EGR valve

also one thing to check is the ceramic coated connector on the EGR valve..The wire or cceramic might be broken..Its sold separately by GM..


Daz

 

It may not be at all the same thing, but when mine was running bad, it turned out to be a brand new coil wire that was the problem.
Sounds exactly like the way it was running.
If I leave the old 7mm wire on, it runs find. If I put the new 8mm on, it runs s**ty.
I'm replacing the coil this week, to see if thats the problem.
I also replaced the EGR thinking that was it.
Just a thought.

 

Could it be a fuel pump, or fuel pressure? My car did almost the same thing, even though my engine is carbed, and it turned out that dirt had found its way into the carb. So it turned out to be a fuel delivery problem. It's just a thought....

 

Hey guys thx for the help.

I have tried it with and without the Jacobs system on the car. Makes no difference it still shakes -- although it runs noticeably better with the Jacobs system but then that is what the Jacobs system is supposed to do so I am not surprised at that.

I did replace the EGR what a freaking pain to do had to disassemble 1/2 the TPI to get at one bolt. The car ran great until it started to get hot at running temp at which point the problem showed up again. I don't think it was EGR related so too bad I blew $80 on the EGR.

The ignition wires, cap & rotor are recent. I gave it a good check this aftyernoon looking for anything that is not where it is supposed to be. COuldn't find anything. I am wondering if my ignition module went bad again cause this feels kinda like that last summer I had to replace it as well. What a pain.

I think it is getting gas atleast the injectors all read the same. I am going to spray some TB cleaner on the base manifold to see if the gaskets are leaking ? It it revs up then I have that kind of problem otherwise it is going into the shop Monday to get checked out at $100 GM per hour what a freaking pain.

I'll keep yah posted.
RP.

 

Almost forgot to mention -- I am not getting any codes. The ECm thinks everything is just fine.

RP.

 

I'm having intermittant problems with my knock sensor(code 43) and that is exactly what happened to me the other day. the timming advanced or retatrded so much I had zero power and limped home.The next morning it was better, or at least drivable. So far its running as normal for my car,i've had a bad miss for a year now and I can't seem to fix it. Maybe its my knock sensor goin south, i don't have the coin to fix it right now.I incerted a 3.9k resistor inline from the knock sensor, this is supposed to limit the knock counts, so far so good(no new codes)I have been laid off so playing another round of "Lets repalce a sensor"is not in the cards. Funny thing is that the day before the computer set the code 43 my car was also running real good.

 

Sounds like a fuel delivery issue or a timing issue. The best way to make sure it isn't a fuel issue is to get readings on your o2 sensor and make sure its at spec, I don't have the normal idle values off the top of my head but the key is to look at idle and WOT numbers to make sure the readings aren't screaming lean all the time.

If it does turn out to be fuel, you have some possibilities injectors, delivery or pump. Just because an injector is firing doesn't mean its actually firing something. Delivery entails the fuel lines ensuring no blockages are there and that the fuel filter is not blocked. I've had an issue prior that my filter was clogged and gave similar results and no codes tossed. Basically struggles to idle or stalls and peak rpm is lower. Twice I noted such occurences for my car but from 2 separate causes. Once was a clogged filter and the other is the last issue which is fuel pump. Unlike yours, mine died one day and could not start. A few months later I managed to get it started with some creative wiring and it had a hard time idleing and was cut off from 4k rpm. (yes my daily driver sat from Jan to March this year when gas was at its cheapest lol)

For your sake I hope its just a fuel filter. Change that if it hasn't been done in oh say a few years since depending on the gas you buy, it could be clogged. Pumps are a pain in the *** to replace for any thirdgen and I would not recommend doing it yourself unless you enjoy cussing a lot at your car.

Timing is another thing that can produce the same results, but I have a hard time explaining the idle issue if its timing since a)its ecm controlled and usually does not advance at idle and certainly has no retard at idle. A vacuum leak would cause an erratic idle, but would not create the sensation that it wanted to stall. Just basically a crazy idle that's too high or fluctuates. You can usually feel the difference b/w a "want to stall" fluctuate and a "I have no friggin clue what to idle at" fluctuate. Trust your insticts as you diagnose, test the suggestions that are passed to you from everyone and hope one of them is true and its an easy fix.

Oh yeah, if any of the above is wrong, there will be NO code. A code is only triggered when a sensor or commanded item is not working.

 

It sounds sort of like what my lil jimmy suddenly started to do in the middle of last winter (in the passing lane of the QEW no less). When it was good and hot it started shaking violently and wanting to die when I was on the gas, but it idled well. I reset the timing, no help (although it was a mile out. I can suggest one shop you should not go to for a tune up...). New wires, no help. New cap/rotor, that did it. It hasn't had another problem, aside from it's recent e-test failure.

If all else fails then replace the cap/rotor. It's cheap enough to be worth a shot.

 

I know your getting lots of possibilities as to what the problem is,( and there all possible ) but it seems coincedential that it started shortly after your new ignition system. Could be way out in left field here, but maybe something to look into.
Also, have you tried disconnecting the EGR and taking it for a drive.

 

Try another MAP sensor. Try using the coolant spray for electronics.. and cool down the base of the distributor when the car runs crappy. This will tell you that there is a bad module.

 

Last year I had bad injectors and a bad distributor. That in fact is the condition I bought the car in which may give you an idea of why I got it so cheap. I spent $500 at GM all diagnostic hours to find out I had a bad distributor collector and some bad injectors. Altogether they made for one aweful experience driving. But I got it fixed and the car ran great afterwards.

The O2 sensor has 2000kms on it.

So here is what happened this morning:

Started the car and it idled reasonably well, 725rpms smooth as glass. Took it for a drive and it made good power running normally still not at operating temperature. Part throttle good, WOT good to over 5500rpms.

ABout 10 minutes into the drive I stopped and the idle was crap and the engine ran like it had bad spark. No power, or like I had lost 100hp. It was not chugging like a cylinder is missing, rather like the timing was so retarded or advanced that it cannot make power ?

It had a hunting idle not the driven kind like a IAC gone bad rather like it was persistantly recovering from a stall event.

I am leaning towards the ignition module again ? Oh yeah the injectors read 12.2 volts and I can't get a resistance reading off them multi-meter is to hard to figure out.

The car exhibits the same behaviour wityh or without the Jacobs attached -- runs better with Jacobs I'd have to say.

thx,
RP.

 

16th owner

The EGR is new I replaced it yesterday trying to find out if that was the problem. Throwing parts at it.

thx,
RP.

 

Well the o2 is new so that's good, but the idle is fighting back like its from a stall event, so you are still at 2 possibilities spark or fuel. You're either not getting fuel in when you need it, or not getting spark when you need it.

Trace the system for the ignition... check plugs, then wires, then distributor cap/rotor, then coil wire, coil etc...

Trace the fuel... injectors, fuel lines, filter, pump....

Something along the line is faulty here its just a matter of figuring out which is the weak link. I'll check with the old man about ignition systems and when putting in a aftermarket which items also have to be changed to go with the new ignition else would fail otherwise to see if that's the case. The resistance of the injectors is key to figuring out if the injectors are bad, gm stock ones have a history of going bad.

 

I think the engine is getting fuel. I let it cool down for an hour and took it out again. If it felt like it lost 100hp earlier today then now it feels like it is down about 50hp. Pretty subjective I know.

I guess I will have to drop it off at GM tomorrow and get ready to be hosed by their $100 per hour diagnostic fees. Worse part is no one on the shop floor understands TPIs very well so I get some apprentice who is 'learning his way' at my expense. No kidding it took them 4 hours last year to find out I had some bad injectors and I think I had to suggest the test ? They thought my bad injectors was a bad O2 sensor so I paid $200 to find out that it was not.

I took my ignition module out and had it tested at the Parts Source this morning. It passed the test even after 15 tries (I was trying to get it VERY hot) it still passed.

A Closed Loop question -- if you run the car in closed loop then turn it off for an hour and the temp goes down but the engine is not cold then you start it again does it automatically go into closed loop again even though you may be below the temp for closed loop duty cycle ?

I know the car runs great in the morning, cold, until it goes to closed loop, running temp, then runs garbage. So it must be a sensor issue ?

It will help alot if I can tell GM what not to look for, saves me alot of money in diagnostics.

thx for the help guys,
RP.

 

Yeah GM techs are pretty useless... I brought mine in after I "thought" I failed an e-test... put in new o2 sensor... adjusted injectors... found out it just wasn't hot enough when tested.. hey my first test all those years ago, how would I know then?

Bastards made me buy a new sensor... and get injectors adjusted cost $300 mostly labor dammit...

Closed loop occurs under these conditions.

Temp is above 40C or 140F I believe
Car has been operational for a certain amount of time.

During open loop the ecm dumps a rich amount of fuel into the system, not too rich, but a rich condition nonetheless to warm up the car essentially. If ignition works ok here when cold, then ignition may be ok since they only factor that changes when in closed loop is that fuel is metered via sensor readings.

Closed loop sensors take over and fuel is metered according to need. So either a sensor is messed or fuel delievery is still an issue.

When a pump is going to die, under high pressure it'll have a hard time working. Under closed loop injectors are only firing when necessary, so pressure builds and forces the return of fuel via the return line creating the 50psi normal reading. Under open loop, the injectors are firing fast and consistent, thus pressure is less on the pump since it's focused on the 8 injectors as outlet and the return line sees little.

I've gone through this before with my pump. Basically the only way to get the engine to run was not at idle. Make the low pressure generated by the pump focused completely on the injectors thus adequate fuel delivery to keep it running.

I hope I'm making some sense as to why the pump/delivery line can still be at fault.

 

This is the problem I've been having for over a year now, as soon as the car warms up boom bad idle, or after the myriad of new parts Ive thrown at it an annoying and intermittant miss.Lets see, i've replaced the egr,egr solenoid,cap,rotor wires,complete new distributor,new injectors,new o2sensor, new coil,new plugs, and the list is still growing. I even swapped out my ECM for one from a junkyard and the problem persisted.I hope you get to the bottom of this without spending as much as I have.

 

Hmm... A nasty vacuum leak perhaps? Just a thought. You could grab some carb cleaner and go hunting for leaks just in case.

It still sounds just like my lil Jimmy when his cap went bad, although that was only when it was bitterly cold outside. It did get worse and worse though until it was barely driveable.

 

This could be way off the wall, but are you running the Taylor wires with a stock GM coil? Just asking, cause I can't get away with it. I also get an intermittant miss.
I need to run the stock coil wire for the car to run good. Don't know if it's a faulty coil or so I've been told ( by GM techs ) that there coils need the resistance of the small wire. I'm installing an MSD coil this week to see if I can run the 8mm wire.

 

originally posted by 16th owner
"This could be way off the wall, but are you running the Taylor wires with a stock GM coil? Just asking, cause I can't get away with it. I also get an intermittant miss. "

I'll have to give that a try. Thanx for the tip.

 

palric... find a MAP sensor off any GM car, and plug it in, don't even mount it... see if it solves the rough idle and power loss problem. Heck, come here, I have a spare one on the Grand AM.

Anyway.... when you figure it out... let us know what it was.

Oh... there is a a guy at the dealer in my town that knows his **** with TPI's. Maybe give them a shot... Gillespie Pontiac and Buick in Welland.

I htink I am going to buy a Diagnostic computer and start diagnosing these bad TPI motors, and make some money.. LOL..

 

Obviously this is a heat-related issue, therefore I might suggest:

Dist. cap ionization or moisture buildup- too much heat under the cap can cause ionization and give you all sorts of grief. Trapped moisture can do this as well. If you have an old dist. cap laying around- drill a couple of holes in the sides (well away from any terminals) for venting and see what happens.

ECM goes into closed loop operation once warm, and although there is no code being generated- a faulty 02 sensor will not generate a code unless it falls outside it's normal range- the problem being that while it's not outside it's normal operating range, it may still be a full .5 volts off where it should be and causing major issues with A/F mixture.

Also- a single bad ignition wire could cause this type of problem- you've obviously checked them and not found a short/burn through- but maybe switching one wire at a time with an old one might be worth the time/effort just to be sure.

I wouldn't look for an obscure, complex problem until these have been disproven/eliminated.

 

For some reason my multi-meter would not read my injectors in the scale I needed so off to GM I went to get a $98 per hour diagnosis.

Here are my injector readings by cylinder location:

1) 1.5
2) 17.0
3) 7.1
4) 16.9
5) 11.8
6) 16.8
7) 10.2
8) 17.0

You may notice the odd bank or driver's side, is all low. This would worry me (bad harness ?) but last time the other bank was the culprit so I think it is just random Multec injector'itis.

It's been my experience that anything under 16.5 is loss of driveability and anything under 10 the car runs like absolute crap.

These injectors were a replacement set I bought off the board, $50 so I really don't care that they are dead and dying $$$ wise. Just hate to have to pull the freaking rail again. What a hassle.

Hey everyone THX A TON FOR THE HELP. When your car is dead it really matters having the support from you guys !!!

adious,
RP.

 

I have 22lb injectors you can borrow..I might be missing one though..Just to see if its really the problem...

Daz

 

hey Daz a generous offer thank you very much ! I have 19lb injectors though -- and if yours worked I wouldn't want to give them back (ha,ha ).

Hey are they for sale ?

RP.

 

It should work...Im selling it for $100 or you can just borrow it..Only reason I yanked it is because it wasnt big enough for my application..Im using 30lb SVO injectors now..Since Ford rates their injectors at a lower pressure it actually flows more like 34 lbs..No more pinging above 4500 RPM now

Daz

 

Why don't you get some Accel Injectors Palric?

 

I was thinking about it but the cost in is pretty high with border and all that. Of course even that is low compared to the GM price.

RP.

 

My motor pings alot right now. I thought it was something with the timing but what did I know ? Bad injectors again.

Do you know what year your 22lb'ers are from ? What make ?

thx,
RP.

 

1987..Bosch

Daz

 

Check your PM.

 

You should be able to get Accel injectors at a canadian parts store

 

Daz, what have you got under the hood of that IROC? I know you've got a SuperRam but what else have you got?