HELLO:

I've got 3.1 V6 with throttle body and automatic tranny.

It runs like a dawg, idles rough and the idle goes up and down and it wants to quit if you don't ride the accelerator. It used to do this only occassionally, then it only did it when it was cold, but now it does it all the time. Now, once I get going down the highway, it runs fairly good and their has never been a problem with shifting, so I assume the TV cable and/or adjustment is okay.

This is what I did to try to fix it (but it only got worse):

New wires, plugs, cap and rotor. Replace the TPS (throttle position sensor),the EGR valve, PCV valve, all with GM replacement parts. I put a new fuel filter on it also.

I bought one of those cheap code readers, but I lost the direction on how to use it, any tips? I know the system goes through the same code twice at first (to let you know it's working) and then it does the code for the prob, any suggestions/tips on that would be also appreciated.

I'd like to fix this myself and have always gotten good advice from this board, thanks in advance!!!

PAT

 

Sounds like a bad IAC valve.

Once its replaced (get gm, I went thru 3 aftermarkets), you will have to do whats called "idle learn procedure". Search under my screen name, and IAC in the gen engine tech, and it will pull up the process as I had to do this to mine 6-9 months ago

Does the check engine light come on?

You dont need a reader. Just a paperclip and a haynes/chiltons repair manual to read and understand the codes.

 

What's the details on that Dale? You mention that when ever this problem occurs. A few times I sent people to your thread as I remember it as being strange for just the 3.1 But I have found ever regulars in this forum will says it BS. They never had to do that, bla bla bla it BS and so on....

I'm not saying anything [ cause I don't know either way.]
but they stat the idle learn is BS???


I have never mentioned it again form the **** poor responses I got when mentioning your thread and the 3.1 idle learn.


TekViper
Nixion1

have both said it was BS, they own 3.1s

They said the car stalled once but then would idle fine.
They never had to do any idle learn.

I'm not saying anything [ cause I don't know either way.]

 

When I say I have a cheap code reader, it's just a plastic thing that fits over and shorts the two terminals (same thing the paper clip does) and soforth. I know you short the terminals, with the key off, turn the key on, then watch the check engine light. Now I have a book with the codes, but doesn't it blink the same code twice and then it blinks the prob code. Am I on the right track?
I did this once before in another vehicle, but my over middle-aged mind is getting weak and I can't remember the procedure.

I'd like to do this before purchasing the IAC and am in the process of researching your thread on the IAC/Idle Learn Procedure, if I can find it.

thanks!
PAT

 

I have only done the idle learn once as I got tired of doing the process. It did seem to occasionally help it idle smoother.

If you dont want to do it, dont. I havent on my last few. After installing my l32, and all new goodies, I will do again.

when you first short the system out to get blinking light, it will blink code 12 first (almost always, if not, you have other problems). Then it will blink whatever problem.

Also, forgot to mention. clean the tip of the IAC with old tooth brush and carb cleaner. Spray carb cleaner in hole and with rag on small pinky, wiggle around in hole and clean it. See if this helps before new IAC.

 

sorry, it wasnt IAC, it was idle learn


https://www.thirdgen.org/techbb2/sho...ght=idle+learn

 

DALE:

AHA, I got my cheapass $3 WallyWorld code reader/book out and read the instructions (which I had forgotten there were any...) and did what it said. It said that all codes would be displayed 3x's and I got code #44 and this is what the book says about it:

ECM CODE#44 - Lean exhaust indication - oxygen (O2) sensor voltage stays low after one or two minutes of engine run (Left sensor ondual sensor engines).

This is what it said about resetting the ECM and the rough idle:

To reset the ECM and clear the computer memory, remove ECM fuse for at least 5 minutes. The ECM computer will then be reset. Replace the ECM fuse. This clearing of the (ECM) computer memory will cause a rough idle and the "idle information" will be restored after driving up to 40 miles.

I am going to replace the O2 sensor, but I will clean the IAC too and possibly check the charcoil canister too (from another post).

PAT

PS I'm crossing my fingers.......

 

good job.

DO NOT GET THE O2 remover tool, it sucks. Get a boxed ended 3/4 wrench and some pb blaster. Squirt blaster on, let sit a while, then use wrech and BFH.

 

I think a 7/8 flarenut/line wrench would work a little better on an O2 sensor than a 3/4 boxed........

 

Is it 7/8? I might be wrong on size.

however, the o2 sensor remover tool sucks.

 

hmm mine started doing this today

 

There are some cars where the O2 sensor tool is neccesary. The thirdgen V6 is not one of them. And yes it is 7/8ths.

 

I've Had that EXACT same problem with my 2.8 since I bought the car. I've been ALL trough the motor, I still have the crappy idle and code 44. None of my coworkers could find the cause either....If you find out let me know. Not that it will matter much...that's why I'm going 3.4L

 

It might not be throwing a code, but I would also check the MAP sensor (or whatever it is you 3.1L guys have to measure the air coming into the engine). It sounds to me as though the ECM is not getting a reading of some sort and is trying to cut the fuel supply (too much air in the engine maybe?) giving the O2 sensor reason to set a lean mixture code.

Or, there is my famous line:
CHECK YOUR VACUUM LINES!

 

i think i just got some bad gas cuz its acting like it doesnt have any when i full throttle it its skips a beat every now and then and weve looked the engine over grrr

:lala:

 

Also check the fuel filter. Your probelm also sounds like a clogged or backwards filter since you said that.

 

found the poblem one of the wires on my airbox came loose

 

I completely agree. That slit they put in the side of the socket allows the socket to "expand", and if the oxy sensor's in there tight, the socket flexes.

I had always used a regular socket for the job until my dad bought an oxy sensor socket. Tried the socket out- it jammed itself on my oxy sensor b/c the socket spread open. It took forever to get off; then, I just used a regular socket. (Just cut the wire off the oxy sensor, Or, break the back of the oxy sensor off so only the nut remains at the y-pipe.)

 

Well here's where I'm at:

1: new cap/rotor/wires/plugs
2: new fuel filter
3: new oxygen sensor (used a torch to get this baby off, worked like a charm!)
4: had the MAP sensor checked, and it's okay
5: checked all vaccum lines, replaced the bad ones
6: new air-filter (also changed oil)
7: put some "water-remover" and fuel injector cleaner in and filled up with fresh gas (I commute 50 miles aday, so my gas doesn't have time to go bad)
8: adjusted timing to factory settings (my buddy did this and disconnected something under the dash first and reconnected after correcting the timing)
9: removed and installed new plugs again (even though the old ones were okay)
10: removed ECM fuse (overnite, probably overkill) and installed and drove 60 miles solid on the Interstate afterwards

It still won't start on first crank, sometimes on the 2nd, mostly on the third try. I have to ride the pedal to keep it running, but once it's warmed up, it actually runs and idles pretty good. On the interstate the darn thing will fly. At stop signs, the idle is good, but sometimes it gets choppy, then goes back to good. Sometimes it hesistates on takeoff, sometimes it doesn't.

Basically it's running alot better, but I don't like to have to crank it so much just to start it (don't want to wear out my new starter, as they're a pain to put in). It never has been one you could reach in and just turn the key to start, so what's new there.

I'm wondering if my ECM is going bad, maybe the fuel pump???

Anybody have any other suggestions???

Thanks for posts, all have been very helpful!!!

 

ALso forgot to mention that I replaced (with OEM) the
EGR valve and the TPS (Throttle Position Sensor) and
replaced the gasket between the intake and TBI unit.

PAT:hail:

 

YOu can have the ECM tested at Autozone. If it would stop snowing here I would have already gone and done so. Have your buddy or you grab a digital multimeter and check the voltage on the TPS. There is instructions on adjusting the TPC and idle air controller on the TGO main page. Also, check and clean the air passages inside the throttle body as they may be dirty with carbon from the EGR valve.

If you have to replace some vacuum lines, REPLACE THEM ALL! If some of the rubber ones are bad, chances are that others are too, and that won't cost much more than replacing the others did, and I have no idea why you wouldn't do it anyways. Also, don't forget the one going to the brake booster. It can become hard and after a lot of removing and replacing it, it just won't seal right any more because it is stretched and hardened in that position.

OKay, now, seeing as you don't have a cold start injector (unless the engine is actually a 2.8 mislabeled) I would check the o-rings around the injectors for damage. The part is at AZ (I don't recommend going there, but I have a part number since I bought my o-rings there) and is part number 800-9220.

Also, if the ECM trouble SES light gives you code 54, like mine does, first connect a 12 VDC fused power source between the top-right and lower-left connectors on the ALDL, in the driver's footwell. If the pump runs when you connect up this power source, the relay, pump, and wiring are still good, and that leaves one object that is bad: (I'm pausing for suspense) THE ECM. That is where I stand and have to have the replacement checked because it is not working at the moment.

 

Actually this was originally a 2.8 that I pulled, got a 3.1 and took the intake, exhaust manifolds, distributor off and replaced with the ones off the 2.8.

Therefore, it's a 3.1 short block with the 2.8 trimmings, if that makes any sense. Needed some HP, and this was the cheapest way for me to do it at the time.

thanks!!!:hail:

 

Does the intake still have the CSI (cold start injector, connected to the fuel rail by a white metal tube, located in the back of the lower intake manifold)? If it does, that could be clogged, inoperative, or disconnected.

 

Sorry, double post, but I forgot to add that NAPA sells a kit that cleans the injectors and does a much better job than any in-tank cleaner will any day of the week. Because the engine runs using this cleaner ONLY as the fuel when you have connected it up to the schrader valve on the top of the fuel rail and disconnected the fuel pump, the engine used the contents of the can od cleaner to run on and cleans the injectors better. Or you could go to a local Monroe Auto Service and have this done for $50.

(And I didn't feel like using the edit button this time. Sorry guys.)

 

which injectors did you put in it?

How long does it have to sit between times to make it have problems starting? Every time, even when warm, or only after it sits? Reason asking is your idea of fuel problem is possible. Have you checked the pressure at the rail?

What color is your spark at the plugs?

 

I went ahead and redid this post (should have done this on the first post), but I'm getting senile...

Here is the whole basket of apples:

I got a 3.1L engine out of a 90's camaro that was totaled, but the engine still ran and only had 40k on it. I then pulled the 2.8L out of my '88 GMC 4x4 and removed the TBI, intake and exhaust manifolds, the oil pan and pickup and did the same to the 3.1L. I was left with the 3.1L long block and put the stuff I took off of the 2.8L and bolted it on the 3.1L long block and this bolted right back into the GMC truck, just like factory.

So yes Maverick, you're probably right about the newer 2.8L not having TBI. But that's not the case here.

If it sits and gets cold (more than a couple of hrs), then it's hard to start, if it's still warm, it fires right up.

As far as rebuilding or replacing, I'll go with what is cheaper and easier anyday.

THANKS!

 

To answer your question, yes, the injectors can be rebuilt. Is it cheap? NO. You are better off going out to the auto parts store and buying a new set which will cost half of what you will spend on rebuilding the injectors you have.

Edit: Okay, now that you stated that the engine is not originally from an F-body, I have retracted the statement that was originally in this space.

If you do a search on Yahoo for injector rebuilding in the automotive section, you will come across a place that does so exclusively and outlines their process in a lengthy brochure. Their rebuilt injectors run about one and a half times and much as do the newer injectors from GM or the ones at auto parts stores.

Okay, also in edit: I take the above paragraph back... the injectors that LinderTech rebuilds are for sale for $24.95 each and this is their site:

http://www.lindertech.com/reconinj.htm

I hope everyone in this thread bookmarks this site. Their injectors are cheap! They also stock Bosch injectors (at twice as much money as regular auto parts ones) that have a lifetime warranty!

 

ok, so this is a TBI engine in an s10?

A 1994 Camaro would be a 3.4, not a 3.1. When doing this on a tbi engine, you are required to do 1 of 2 things..

1. Installed TB and Throttle cable from a 4.3l engine, and port the intake.

2. Bump up the fuel pressure on the 2.8 tbi.


since this is s-10 tbi, might I suggest you register at s-series.org, and have them people explain it a little better then me.

 

Man this is a hard thread to follow.

But a tip on the O2 removal. It helps if the car is hot when you change it/ break it lose. You can get burnt but it breaks lose much easier hot. A day or two before the change Id start spraying it down with crap.

Then either with the car warm or heat the fitting with a propane torch and it should come lose easy.

Might need to cut the wire off the old one too.

 

Good tips, Gumby! Here's one more; I always add a TON of extra anti-sieze to the threads so the thing comes out easier for me next time. But don't get ANY anti-sieze on the sensor end... don't get any on the "bulb" that pokes into the exhaust, and definately don't get any inside the bulb's slits. If you get any on there by accident, wipe wipe wipe it clean with toothpicks and/or towels. The anti-sieze can contaminate the oxy sensor and it won't be as effective.

But this whole system is tbi, in a truck, then? That kills about all of my suggestions for MPFI cars... but I can say this- buy a $40 fuel pressure gauge and check the system out. Uh... actually... wait... if this is TBI you'll need a special gauge that'll cost a bit more. Comes with an extra hose; there's no schraeder valve on the tbi systems, the extra hose splices into the feed hose at the tbi unit and gives you a "tee" to put the gauge into. F/P is low if I recall, on tbi... 14-18 psi?

 

Don't you just love a wild goose chase. pjd1959, you should have come clean on the very first post. As it is the TBI injector(s) are too small and the ECM calibration is way off.

Best bet is to get the ECM from whatever car you got the engine from and swap that in along with the entire induction setup you took off the the new engine. Most likely will need a PFI fuel pump swapped in too. Then it will run correctly.

Yes, I got your PM.

RBob.

 

rbob, he doesnt need to run that ecm/injection system. He needs to up the pressure if it is a 3.1. If its a 3.4, he needs to drop a TB off similer year 4.3, and pull/bore the intake to match the blade size.

This is what they do on the s10 boards.

 

Like I said in an earlier post, I should made my complete problem detailed from the beginning, .........SORRY! This 3.1 long block came out of a 90's camaro and it is a 3.1L, with the 2.8L trimmings.

Up the fuel pressure, how does one do that........?

thanks :hail:


PS...I'll check the S10 boards in the future for this particular vehicle, thanks for the link!!!

 

Ok we have an 88 2.8 TBI that spun a bearing.

He took the short block from a 90 3.1 and put all the 2.8 sutff on it.

So its a 3.1 with 2.8 parts.

All the 2.8 parts are original for the truck, it just has a 90 3.1 block/cam/heads/crank/rods/pistons



I question the TBI, by 88 it should be MPFI.

 

See, problem is, that setup has nothing to do with our cars. Your "2.8 trimmings" are from a TBI truck, and our v6's aren't Throttle Body Injection, they're Multi-Port Injection- very similar to the V8 TPI's. We have one injector per cylinder, and the 2.8 MPFI systems have an extra cold start injector. So there's really nothing that our motors have in common with yours, besides the engine block itself.

Gumby, they put MPFI into S10's?

 

pjd1959, that site has a link in the 6/60 forum that tells you how to make your stock TB adjustable. Takes a bolt, tap, drill etc.

One of the members themselfs figured out how to do it.

 

I don't know but don't know why they wouldn't. TBI sucks.

I guess GM does funny things at times.

I think he needs to convert to MPFI and get it over with.

 

no mpfi was ever factory installed on a s-series untill the 4.3 vortech.

I actually like tbi more then mpfi myself.

pjd1959, heres the site you need.

http://members.shaw.ca/betterthanyou/fpr/fpr.htm

 

Thats a nifty job. Better than others I have seen. One import site I saw had a jige you made out of pipe to crush the stock regulator 1/4in at a time to rasie it 12psi a crush.

 

UHMMMMMM>>>>>

You guys know your stuff here............, and I appreciate the info alot... and apologize for the crapshoot on the first post (again).

I figure now since fuel pressure is of concern and probably the culprit of my problem. I'm going to check to see if the diaphragm in the stock regulator is screw'd up first. I'm also going to put a fuel pressure guage on the line and see what I get there also.
If the diaphragm is screw'd, I'll replace it and check the tension of the spring also. I know from working on Holley carbs, if the pump diaphragm is screw'd, it can cause of problems and can easily be fixed. So I'll go the simple route 1st. I know that I could probably put a stiffer spring in and/or modify the existing one, but that's not really curing the problem and I like to things right, even if it involves some overkill.

If that doesn't work I'll go with the info on the link (that Dale posted) and go with either those options or the options that are listed on the same site at thisURL:
http://members.shaw.ca/betterthanyou...ine%20swap.htm

Now this link is part of the other link, and the guy suggests here, just changing the injectors........, check it out. Now this would be alot easier, and it might be better also. S-Series.org has a post on that subject also at this URL:
http://forums.s-series.org/viewtopic.php?t=237


And yet another good link for info on this.....damn:
http://forums.s-series.org/viewtopic.php?t=26470

and another REAL good one:
http://www.goingfaster.com/spo/tbi.html

My only other concern is with the cold start problem and if modifying the fuel pressure and/or injectors will take care of that.

You guys have really helped me here, this board really kicks!:hail: