Well, i was having some hesitation problems with my car and I couldn't solve the problem so I began digging up info at work. I found this bulletin for 90-92 V6 F bodies and it seems to have solved my problem or at least improved it. I've been having injector problems also and I thought it was causing my problem. The hesitation problem is 99% gone so I'm hoping this solved it.

Anyways read this:

Bulletin #92-191-6E

Cold start stall/ Hesitation/ Idle roll and upshift sag

Model and Year:1990-92 F-body with 3.1L engine

Condition: Some customers may experience Cold Start Stall and/or Hesitation, Idle Roll and/or 1-2 Upshift Sag with their 1990-92 F car.

Cause: System and component variability and electromagnetic interference.

Correction: If any of the subject conditions are found, complete the following procedure:

1. Perform diagnostics, per Section 6E of the Service Manual. Make any adjustments as required, or replace any defective parts associated with the above conditions. (THIS REFERS TO THE GM SERVICE MANUAL. IF ANY OF YOU ARE EXPERIENCING THESE PROBLEMS JUST ASK AND I WILL POST THE DIAGNOSTIC CHART IN SECTION 6E)

Important: The customer should avoid the use of high octane fuels as they do not increase performance.

2. Replace the High Energy Ignition Module with a new P/N 16140039, and install a new Mem-Cal (PROM) from the table using the Service Manual and attached procedure.


PROM ID--------------Part Number-----------Description

AZTY 1331 ----------16171406 ----------Memcal(Federal-Auto Trans)
AZTX 1321 ----------16171410 ---------Memcal(Calif- Auto Trans)
BAWX 6651 --------16176864 ------- Memcal (50 State- Man. Trans)


A. Pull the underhood ECM continuous power fuse or disconnect the battery for 1 minute.

B. Remove existing PROM(memcal) and install a new service PROM per the latest service procedure.

C. Restore the battery power and place A/C controls in the "OFF" position.

D. Firmly apply the parking brake and block the drive wheels. Start the engine, and shift the transmission into "Drive".

E. Allow the engine to run until the engine cooling fan has cycled once, or a maximum of 10 minutes.

F. Turn the ignition to the 'OFF' position for at least 5 seconds.

G. Start the engine, and shift the transmission into "Drive".

H. Allow the engine to run for at least 5 minutes.


3. If the installation of the new parts does not eliminate the drivabilty conditions, then the ECM harness and the electrical harness(near the coil bracket) should be inspected for chafing and repaired as required.

 

very interesting. my car has never stalled....but what would idle roll or shift sag feel like? i am not quite sure what that means.

 

To be honest, I don't know what the Idle Roll/ Upshift sag is exactly. But if you're having hesitation or cold start stall problems, don't rule this out.

 

My 2.8 does the same thing, among countless other things that drive me crazy every day. Wonder if it would help w/ the 2.8 too?

 

My car has the cold start stall ill crank it it will start then die and it wil crank and crank and crak finaly it starts. can u put the page in the book up so i can look at it so eomore

 

I'll bring the book home tomorrow. I think it has a section for troubleshooting( it should have a cold start stall section) and the rest is DTC schematics.

 

HUUUMMM... My '92 RS gives me funny problems when it's cold. I usaly let it warm for 3 - 5 min, but for the first 2 or 3 blocks It will stall when I shift into first gear. At first I thought I wasn't clutching correctly, but after a couple of blocks it doesn't happen. Is this bulliten only for 3.1's with an auto trany? How do you get a hold of the TSB's?

 

No no, this is for ALL 90-92 V6's. Auto or 5 speed. If you look at the PROM's i listed, 1 is for a Federal Automatic, 1 is for a California Automatic, and 1 is for 50-state Manual Trans.

I have access to the TSB's at work. I just happen to run across this one while I was checking for updated PROM's in our computer's database.

 

If I wanted to get a hold of a copy of the TSB's can I get them through the dealer? I have a whole list TSB's I want to get a hold. I found a list at www.alldata.com, but they want you to get a yearly subcription. I don't want every one they list, but I think there is some thign 12 -15 that I have interest in (I don't experience all the probs just some) I don't want to get a yearly subcription for some thing I'm going to use once. Fortunetly the TSB you posted is one of the ones I was looking for.

I do the fix and see if it helps.

 

You might be able to get them from a dealer. If you have the Bulletin numbers and your car year I can look them up.

 

Well, I have the GM service manual with me, so here are the HARD START Possible Causes:

DEFINTION: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately dies.

CHECK:
--TPS for sticking or binding or for high TPS voltage with the throttle closed. Closed TPS should read below.98 volts.

--High resistance in coolant temperature sensor. When cold, the coolant temperature sensor and the Intake Air Temp. sensor should read relatively close. (A scan tool would be valuble in this situation... )

--Fuel Pressure. FP should rise immediately to approx. 40-45 psi when the ignition is turned on. FP should not drop below about 38 psi.

--EGR operation. Be sure the valve seats properly and is not stuck open.

--Ignition system. Check for bare and shorted out wires and check for proper spark output with a spark tester on the end of a plug wire. If the ign. system is unable to produce 25,000 volts, the spark tester will not fire.

--IAC operation. Check IAC connections and check IAC passages for carbon buildup.

--Check spark plugs for wetness, cracks, improper gap, burned electrodes, or heavy deposits.



Some of these things might be hard to test without the proper tools. If all these check out, THEN I would consider replacing the PROM and ign. module with the updated part numbers. In my case, I had tested EVERYTHING and they all checked out OK. The PROM update was my last resort and it worked.

 

GOOD FIND, Dan!! Maybe you could submit that TSB as a tech article? I like how the 1-2 upshift sag is associated with the ignition module and the PROM chip- especially since the computer doesn't control the 90-92 transmissions. Apparently the weak ignition was killing the upshift.

Sounds like a good time to get that Holley ignition module #891-103, eh? (Or the Accel one, whatever part # that is...)

 

Just replaced my HEI module and WOW! What a differnce. It really helped out the hesitation problem. Also about 2-3 days ago the car started doing this wierd thing. When I would come to a stop the idle would drop down to about 400-500 and back up to normal and then drop again, and keep doing it for about 2-3 times, then stay at normal idle. Since I just replaced the HEI Module, it doesnt do it anymore. Thank for posting that CALICAMARO RS!!!

~Josh~

 

my car does that how much was the hei module??? and how hard was it to do

 

Well, I got my from AutoZone and it was about $40 I think it was. It wasnt hard to do. Fortunatly I have small hands. It is a tight fit in there. You take off the cap. Then there are two little bolts holding down the module, take those off. Then there is three plugs total. Disconnect them. Put new one on attach the plugs, insert little bolts. Put the cap back on and thats it. It took me about 20 minutes. To me well with it. I guess I could have gotten one from Summit or something. I believe Holly makes and aftermarket one but it was annoying me to much.

~Josh~

 

I own a 1990 3.1L Camaro. My car sometimes while in motion, say just a normal speed of like 30 or something, it would sometimes lag a little if I press the gas. I don't mean like SLAM the gas, but just like press it to accelerate a little bit. Is this what you guys are talking about? Would this HEI Module that is spoken of solve my problems? This weekend I'm replacing my fuel filter, thinking perhaps that will help. When I replaced my spark plugs and wires that helped a little as well I believe. Thanks in advance!!

Mark

 

Ignition Ignition Ignition system, thats the whole problem with these Camaros, the Ignition coil is located next to the EGR pipe and gets the sh*t cooked out of it, the coil becomes weak and sometimes fails but most of the time just gets weaker and weaker and weaker, you replace it but it just starts all over, you end up with stalls, HARD SHIFTS, glowing coil in the dark, poor gas milage, and lots of hesitation.

I brought a brand new MSD stock replacement coil and RElocated mine next to the fan relays, FIXED ALL MY PROBLEMS, I thought I had a trany going, GUESS WHAT, tranny shifts like a dream now. HESITATION whats that... no more for me. Gas Milage, its way UP!!! And as for glowing coils in the dark, NOPE, no more loss to ground from coil break down.

 

Ever since the winter started, my car has been shaking and rumbling in the morning when i turn it on. It goes away when i drive it for a few but it ticks me off. I just had a tune up and it helped a little. I think the cold weather from over night is chillin up the wires. I never experienced this in the summer.

DJ

 

Check your motor mounts. Also, if it's misfiring, generally a cold start misfire is caused by clogged/sticking injectors.

 

This is the thread iv been looking for for the last 2 years, "Idle roll and upshift sag" is the terminoligy i have been trying to describe but im not that articulate and as im from the uk some of our terminoligy is totaly different to yours so its hard to explain some things.
iv had this hesitation and what felt like a loose tranny or lash in the drivetrain somewhere but i was convinced it was nonthing that was loose rather a ecm fault or sensor, iv changed loads of sensors and will be doing some more stuff in the next couple of weeks like fuel filter(i know i know this should have been the first thing to change) also changing the icm,pickup coil and ign coil,

so if these dont work..... where can i get this new ecm as im in the uk, do you know of anywhere i can get it shipped over?
thanks again its good to know im not far from curing my problem.(was about to give up and go carb'd 350).

Nick

 

I realize this thread is 4 years old, and this may not get read, but I just had to add be sure to use the heat-transfer grease supplied with the new module. I cleaned the entire mounting plate, the vents were plugged with grease.

Bob

 

Wow, I almost didn't believe my eyes when I saw I got an e-mail from this thread.... I agree with TealRS looking back and remembering, good point!

 

Yep, probably a shock, from a 4 year old thread!! Actually, Rexer found it

I just re-read your post, did you ever solve the problem? Do you still even have the car? Did the fix seem the last, or did the problem come back?

Thanks,

Bob

 

Yes im interested in knowing if the problems were solved. Im only having this issues when the engine is hot so i will begin looking at the ignition stuff a little bit closer.

 

wow why to got thread diving im going to try to tomorrow

 

It was me, actually, and I seriously think this should be a sticky, what, with all of these ignition related problems occuring lately on the late ThirdGens? I also hope someone finds a way to get rid of these problems as I don't want to be doing 70 down Rt 90 and have the car shut off again when I redo the harness swap.

 

This thread seems to pop up about every 4 years, I guess the problem is still out there!!

I never had it shut off when running, except when I replaced the coil, and the plug-in retainers were (still are) broken off, so plug wouldn't stay in. A zip tie wrapped around the plug fixed that problem.

The BIGGEST issue I had was the hesitation when first starting out. This is a manual transmission, and every time you shift, and step on the gas, it would hesitate (or "sag").

Changing ALL the ignition components (I mean ALL) didn't really address this problem. Changing all the sensors didn't either. I pulled the heads, had them vacuum checked, all OK. Checked for vacuum leaks, drove car without brake booster, vacuum accessories connected, no change. One issue I had was the timing mark not being correct. I changed the timing chain, and just for kicks I dummied up the cover to see if the timing mark lined up with the 0 degree mark when it was at TDC. It did not!!! The indicator is adjustable, and it was moved all the way back, so timing was advanced about 10 degrees. You need a security torx bit to loosen the bolts. You can see in the photos the clean area, that's where the indicator was. This position is correct.

To check yours without trying to get a TDC indicator inside the #1 plug (it's behind the alternator and air pump), pull off the harmonic balancer bolt and washer and locate the keyway. This lines up with the #1 journal, and needs to be 30 degrees left of center. There are four bolts holding the pulley on, one of them is lined up with the keyway. Park your car on level ground, replace the two bolts on the sides (with the keyway pointing straight up) with longer bolts. Put a level across these two, and get it level. Now your timing mark should be 30 degrees after TDC. At this point, you can use a degree wheel, or figure the circumference of the balancer, divide that by 12 (30 degrees is one twelfth of 360 degrees), put two lines that far apart on a length of masking tape, and stick it on the balancer with one of the lines at the 0 degree mark on the timing indicator. The other line should be at the mark on the balancer. I forget the exact diameter of the balancer, but you can measure it, and multiply by pi (3.1416). Or just measure the pulley, and stick the tape on the pulley. I replaced my harmonic balancer just in case it had moved, but it was fine.

That's ONE possibility.

This helped some, but still hesitating. I tweaked the PROM to give more "pump shot". This made the most difference. It still hesitates some, especially coming off a long deceleration (say coming to a stop sign), then when you start off again, it will sag some. Before, it would "catch" late, and chirp the tires. The PROM for the manual transmission is no longer available, I bought one of the last three left in the country about four years ago. You can get the one for the automatic, and get it tweaked. You have to find someone who can install an erasable IC in your PROM and reprogram it. I would advise keeping at least one stock PROM, so buy one to play with. Not many people have the data for V6s but it's out there.

If anyone wants, I can recommend someone in Livermore, CA. who does have the data for the V6 (I had to buy it).

See you in 4 years.........

-Bob

 

The thing with mine is that I have an 87, and I have the factory harness which runs the 3.1 DAILY and LONG DISTANCE (400+ miles) without any problem of any form (except for a very slow IAC response). Put the 3.1 harness in and everything's peachy for about 3 weeks. Then something happens where it will stall at random stopping, going, whatever. I wanted the newer harness just for that reason (it's newer), and because I would rather pay LESS to replace the MAP which doesn't go out often anyways than I have to for my MAF that fails every so often.

It's got to be something in the harness I bought... Which is why I'll be replacing it when the replacement shows up.

 

Maybe this is what I'm experiencing. Driving around I tap the throttle and notice a very slight almost hiccup. New plugs, wires, plugs, filters and fuel pump. So maybe the harness or the coil overheating. Gonna try to move the coil later this week.

 

hmm, when my 1991 3.1 is Cold (first start in the morning) it starts like new. idles very smooth. but if i rev it up it shakes and sputters... then comes back to smooth regular idle. i can drive it, and it takes off no problem runs excellent. just hates a cold rev, which doesn't bother me because i dont rev it up when its cold. once its been running for 10 minutes i can shut it off and it will rev fine..

after reading this thread, is this one of the issues? Cold start hesitation? i get 22mpg city with it. past 6 months ive got a New Coil, Injectors, fuel pump, plugs/wires, dist. cap/rotor, and the ICM a year ago. I use this car everyday it has 212K miles on it. the motor was replaced in 2002. mileage is unknown on the motor. but it was replaced. doesnt smoke and it goes pretty good for a 3.1. ive been replacing parts just to do it.... i dont know the entire history of the car and its parts. so Why wouldn't I?