Newbie here Sportin a 91 3.1 rs. A ride I have had for some time now.

I got it for $400 6 years ago. Let my Son drive it for about a year and a half. His first car. He had issues with it and gave up on it.

Saw some serious maintenance woes. I have it back now. I gotta say This Is a nice ride.
I loved driving it and I will again. Plans' ? Hmm well ?? I have been eyeballing the hybrid postings.
I wont entertain the idea of dropping a 8 in her. I like my 6. Plus I am enjoying tinkering.

Fixes and Mods
replaced Idle control motor (ICM)
TPS
re-installed 02 sensor
re-set timing back to factory 10*
re-installed air intake duct (was missing )
patched together a "severely" botched exhaust (cat was cleared out and then looks like the rest must have high centered or struck something?
fixed short in the steering column
found a nice aftermarket rear sway bar no name stamped on it so I'll get the calipers out when I install it. planning on installing soon.
took out sagging headliner

Issues and problems

Someone drilled out the idle adjustment cap and has been messing with the factory setting. (looks like they bent the strike plate for it also)

factory tachometer is faulty ( it works it just reads 6200 @ low idle (700 rpm from hand held unit) anyone know how I can fix this??

surging idle seems much better now that timing has been adjusted.

engine stalls under load. It ran but still stalled and or overheated at stop signs until I adjusted the timing. Now It wont drive unless in re-learn mode. in re learn mode it runs like a beast. good throttle response ,nice idle, clean acceleration/deceleration. But as soon as 20 min are up she stalls and wont run under load until I unhook the battery wait for a few min then hook up and go.

I have read most of the boards here regarding tuneups and repairs. I am used to old time tuning. Not this electronic witchcraft. So I get a lil lost at times.

Anyone have an idea where to start?


update: fine tuned timing and idle. Was still a little rough and hard starting ran relearn and smoothed things out.

took a nice long drive. 120 miles

New problem cruising at 70 mph running good .. then stumble lagg no throttle. Like I'm running out of fuel.
Drop to neutral pull over. She dies . try to start while coasting. starts but wont idle. let it set for a few moments try again.
start up rough idle. smooths out and off we go.
did it three times.
thought it could be bad fuel or clogged injectors I ran SEA FOAM seems to have smoothed things out.
But I hit the power to the window with the fan on and she died.

So Short ?? Bad alternator? or injectors where the heck do I start??

 

I would set everything back to factory setttings. Have AZ or Checker check your alternator and charging system. The stumbling at speed sounds like a mixture issue. Make sure all of your sensors (MAP, MAF etc) are good. Makes sure your fuel pump/filter are good. Make sure your injectors are good. You can find out how to check them here on the board.

The tach sounds like it went bad. You can get them on ebay pretty easily or check the classifieds here for one.

I hope this gives you a place to start.

 

I am having the same issues. I can be crusing and it will just die. I hit the gas a few times and it will fire back up. Here lately I have had to pull over and turn the switch off and then wait a few seconds and then start it back up. Its funny though b/c I drove from Charlotte NC to Norfolk VA and I had no problem. Drive it around town and thats when it does it. Checked pump, injectors and all is fine. I know I need to change the fuel filter and plan on doing that tomorrow so we will see. But let me know what you come up with.

Derick

 

Ugh... ok here we go again. I dislike helping people diagnose their problems because I usually don't get the info I need without being there and it ends up inconclusive because people don't report back what fixed it. But I enjoy a challenge and feel obligated to share knowledge. So here's the first question- what are your check engine light codes? Jumper pins a & b on the aldl connector with a paperclip and turn the key to the 'on' position (engine not running) and write down the 'check engine' light flashes.

 

Try a different Ignition Coil. My car would do crazy things sometimes, It would be fine then it would stumble, backfire though the intake, stall, tach did weird things sometimes, idle horribly. I would have to pull over for like 5 minutes and it would be fine again for days. I changed it out for a junkyard Accel SuperCoil and I haven't had problems since. It also never gave and codes except 12... the one it reads when you have no tach signal.. like when the cars not running.

 

Setting the idle is a cinch. Disconnect the IAC. Start the car. Turn the screw(its usually a torx) in or out until the idle hits 400 RPM. Shut off the car. Reconnect the IAC. Clear the ECM as a code will be set. Do idle relearn. As for fixing the tach, do a search here for the tach fix. There is a resistor that goes bad and needs replaced or just get a junkyard tach. As for your issues, first order of business is to pull any codes that might be in the ECM. This is always your first starting point. This being a 91 car its more than likely speed density, so I would suspect a vacuum leak or a bad MAP sensor if it stalls under load. A bad coolant temp sensor will play hell with how your engine runs as well. The base timing is 10* BTDC is that where you set it at? Also a bad O2 sensor will make your car a complete turd. But without knowing any codes that might be present, we can only speculate as to what might be the cause. Acouple of other things to add. Do you have an odor of gasoline when you walk around the front of the car? If the answer is yes, then your charcoal canister is hosed. It will fill up with fuel and dump raw gas into the engine and make it run like crap. These are justa few things off the top of my head.

 

You need to jumper pins A & B on the aldl for 30secs with the key in the on position then unplug the iac and turn the key off to close the IAC pintle before you set min air. There's alot of guesses with little info so far. Baddadido if you're still there start with the codes.

 

Ok so here we go again.

My 91 rs STILL wants to stall. I have been posting in the ECM boards and I'm back.

So updates on the fixes I have completed to try and find this ghost.

I have replaced these items

fuel pump, fuel filter,fuel injectors, fuel pressure regulator, IAC, TPS, MAT, O2 sensors,
Distributor, Dist cap,Rotor, Plugs, wires, All vacuum lines, electric fan,
Took it to a diagnostic shop and they could not find any thing wrong,
Said it was possibly the ECM. And wanted $380.00 plus $140.00 to install.
I gave them a difiative NO!
Auto zone has them for 20 bucks If I do need to replace it do I need to purchase a
prom chip with that?

But I dont think ist the ECM, I just dont see how the ECM could have such sporatic issues. The car runs fine at speed on the HWY or around town.
The stalling happens at any time.
It reacts the same wether I'm going 80 or 8 mph.
And no worries about me dropping off the boards I enjoy working on and posting my proggress. It's become personal now.

 

Well, I'm sure I already told you that there is a TSB regarding problems in the ignition wiring that will cause the engine to cut out whenever it wants. Let me guess, it stalls, you pull over for a minute and shut everything off, and then you fire it again just fine after about a minute or so? That's caused by some resistance problem somewhere in the harness. Especially since you eliminated the other 2 culprits: the pickup coil and the ignition module in the distributor. You can try replacing the ECM, but I can almost guarantee that won't help.

A member not too long ago took his car to the dealer and got a replacement engine harness out of it... Doubt you'd get the same, but you could try to take it to a dealer and mention the TSB. I'd have to do some searching to find the bulletin number, though.

:edit: Read this thread: https://www.thirdgen.org/forums/v6/8...-you-have.html

 

Hi maverick. Thanks for the info. I don't remember reading your post on that.
thanks for the link
I'm not to sure that's my problem I will check into it. But here's the deal.
While its cold everything seems to run fine.

Any more of this crap and I'm just gonna install a 3.4 full harness and all.
Getting tired o this. I just wanna get this thing running so I can do my mods.
I am starting day shift soon so I will have to find a reliable shop.
or search for a harness. I guess I could find a new harness and shield it with some copper tape? move the coil to the fire wall. Finish the cold intake hood I have started.

I have most of the parts I need for the 3400 head swap. Do you think I should just pick up a short block and move ahead with my plans??

 

Problem with the 3.4 is that only one year used a programmable ECM that didn't use the SFI fuel injection setup (93). You can try to find a stock 2.8 harness and make it backwards compatible, but that would also be more trouble than it's worth.

Definitely get the short block and build up a hybrid 3400... Good for about 80 horsepower.

 

Why are you planning on swapping motors & harnesses when you still haven't figured out your stalling issue? It could be something as simple as a loose battery cable. Any codes!? You may have one set in memory even if the maintenance light isn't on.

 

Hey thanks for keeping an eye on my thread.
Well here's the deal. I was planing on a 3400 top end swap and turbo next year.
I have had the car for some time and it has unfortunately become my main source of transportation. So this issue has to be resolved I have been throwing money and time at it and STILL no resolution. My next thought is screw it ! yank it all and get what I want. The motor has some miles on it the electronics are having issues and the wiring I am unsure of.
The way I see it I could purchase a rebuilt 3.4 short block. $300.00
I have most of what I need for the top end.
materials for the headers $200.00
A dynamic EBL p4 ECM unit $520.00
wiring harness ???
be about as much as I put into it right now.

I'm frustrated because I normally work on old school motors
diagnosis was easy AIR , FUEL, FIRE.
THIS makes no sense to me. To much can go wrong between point A and point B.
I will get the problem solved no doubt about it. One way or another.
This project will be completed.

 

Its been my experience that people on these forums aren't looking for a logical, cheap fix - seems like everyone would much rather swap in another problem.

 

Thanks for the concern guy's
I am looking for the fix. Believe me.
I will fix it. I came to this forum because I found most of the individuals helpful, informative, knowledgeable, professional and sincere.
I am a fair mechanic a decent fabricator and well rounded in automotive knowledge. I do not profess to be professional.
What I am trying to do is learn as much as I can. Aint my first rodeo.I do find this problem interesting enough to carry on until I fix it. I know its something small that I have missed.
I will revisit all of my sensors and run through the grounds and connections.
It's been my experience that most people don't know when the horse is dead.

 

Mav yeah up here in this area I found a 3400 complete 60k on it for 300.00 harness and all.
I have got to get this problem resolved so I know where I can focus my attention. fabbing in prep for mods. Or electrical.
when all is said and done. If I have a problem I want to be able to rule out mechanical or electrical.