Single mom here who 's son's 1991 bonneville continues to randomly shutoff while driving .the problem started with just inability to start the engine, it would roll over but took forever to start. This would happen occasionally and as months went by problem continued . Took it to pep boys and no problem found, Now it has progressed to randomly shutting off while driving (radio still on but engine shuts off) unable to restart but turning over and then it will start again and may have no problems for days and then here we go again. Shuts off on highway..unable to start it for a good 15 mins and then all of a sudden it starts and runs fine..Son says he also has notice while driving and coming to a stop the RPM's were at 1600 and this also occurs randomly as well . Took it back to pep boys and they replace a part they said was stuck and causing the RPM's to be so high. Car was doing ok for a couple of days and now SAME PROBLEM...RPM's were high ..shut off while driving, rolls over but won't start up right away and then we get it started and it runs ok. Pep Boys have it again and say they can't find a problem...What should I do?...Pep boys didn't fix the problem , can't find a problem and I'm out probably $ 400.00 for nothin...I need some good advice..I'm frustrated I know nothing and my 18 year old son is ready to pull his hair out.. Please help

There are a few possibilites. Faulty crankshaft position sensor, corroded battery cable ends/connections, PCM problem... intermittant high idle kinda makes me lean toward the PCM for some reason. Can you try pulling codes? All you need is a paperclip.

Codes:

viewtopic.php?f=51&t=1624

How to get them:

viewtopic.php?f=51&t=8689

Pepboys probably replaced the idle air control valve, by the sounds of it. Not a difficult job.

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WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

I would stop taking the car to Pep Boys first. Do you have any other reputable mechanics in town?

This sounds very similar to a failing ignition control module. If you have a local auto salvage yard, send your son down there, and he's looking for this:


http://www.pontiacbonnevilleclub.com/fo ... =44&t=1684

It's the coils and ignition control module from a 93+ 3800, doesn't matter whether it's from a Bonneville or anything else. If it's not a pull-your-part yard then he'll have to tell them that. Shouldn't cost more than $30, and if your son is even remotely mechanically inclined and has a few tools he can probably replace it himself in your driveway/the street, etc. This will also make the car a little more efficient and improve the throttle response.

Tools needed will be a 1/4" Drive ratchet, a small extension, a 5.5 mm socket, a 7 mm socket and a 10 MM socket, I believe. He can get those just about anywhere if you don't have them, they don't need to be anything special.

It'll be a good learning experience for him to get a little dirty and greasy under the hood.

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Bye Bye:

RIP sandrock

well ..first thank you for quick response..pep boys have it now....and I'm definitely going to go pick it up today...we can do the paper clip for codes but would pep boys have done that already?...should we do it ourselves anyway...also sounds like the ignition control module would be inexpensive part to replace ...I know my son could replace that..one of his friends has a local mechanic he uses and we could take it there...just wondering where to start..how much to replace that crank sensor?...and if its a faulty PCM how much to replace it?...I know we can visually check the battery cable ends but if it was that why would the radio still be on when the engine shut off?..Does that rule out the battery? Expense wise what would you replace first or can we rule out the sensor or PCM some way before replacing it?

A used PCM can probably be had from a junk yard pretty cheap. It's hiding above the front passenger's feet behind the hush panel.

A crank sensor (you'd only want a new one) is $60-80, I think. A few hours labor to replace.

If the cable ends are corroded (or loose, even), enough current for accessories can pass, but not enough for the car to run.

It would be nice to diagnose before buying parts that might not be the issue.

Does car temp have any effect on the symptoms?

_________________

WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

Pep Boys may have read the codes. Ask them if they did and what codes came up and if they cleared them. Otherwise it will probably throw a code when it happens again.

The major thing is corrosion internal to the battery cables. The insulation on the wire needs to be cut back a little to visually inspect the cable. If it's corroded or black, replace it.

The only way to truly rule out the PCM and crank sensor are to replace them, but lets not jump the gun here.

Where are you located? Maybe someone here is in your area or at least knows someone in the area who can recommend a mechanic.

_________________
Bye Bye:

RIP sandrock

thats a good question..the temp that is...when the issue first started the car would just not start up right away in the mornings and it would take a few tries of reving the engine with brake applied to hold the start . I drove it to work several weeks ago and noticed after I had started it it was at high Rpm's..they replaced that valve I believe and no problem until this week with the high RPM's again and random shut offs... I'll ask pep boys about the codes and then definitely check those cables...and then see about taking it to a local mechanic...I still want to figure out a way to get my money back from pep boys cause after 3 trips the original problem is still there and I spent alot of money all ready with no results

You may have to write Pep-boys money off as what I like to call "stupid tax" Im not saying you are stupid but they arent known for their great mechanical skills in general. Learn your lesson about them and never go back. Follow the advice here there are alot of people here with alot of knowledge. PCM and Ignition coils are the things I would be checking. You can bring your coils and module to AUTOZONE or Advance Auto and have them tested. Gotta get lucky at those places too and find someone who knows what they are doing!! They just test the coils with a meter so you could do that at home too. Maybe its time for a Haynes service manual. That would give you the basics you need.

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1989 Pontiac Firebird Formula 350
2004 Saturn Ion 3 Quad Coupe

Have your son disconnect the battery, let it rest for a minute or two... The reconnect and check to see if there are any codes... Do not start the car, just simply check to see if any codes pop up for no reason..

When you first go to start the car does it buck and miss like crazy while trying to run..?

I too would like to know what codes they pulled from the ECM... ECM failures on these cars is common, when a lot goes wrong all at once and the driveability gets erratic the ECM a lot of the time can be the culprit.. But lets not go that far yet...

The Crank sensor can also be another culprit, but I am thinking this is not the case as the car will start... If its bad enough the car will not start at all..

Also like stated the ICM( Ignition Control Module ) can also be having issues, but not quite like the ones you are describing...


You did a pretty good job of describing what has been going on... If there is anything else you can think of, or you may remember... As well as anything Pep Boys did trying to repair the car I would love to know...

For the most part, even an old 91 Bonneville will be ultra reliable... I think the problem is simple, pep boys is not looking in the right place at all...

ok so we took the car to another shop recommened by one of my son's friends...pep boys told me they checked the battery voltage thru the cables and it's fine and if the radio was running when the engine was dead unlikely it was a battery problem) he pointed to the coils coming away from the battery when he said this.. they checked the fuel pressure and its fine..it would not crank for them last night turned over but no start and they just rolled into the shop..said they got a misfire code but not sure what it was????...who knows if they are telling the truth or not.. they also told me unlikely an ignition coil cause when it starts fine it's running well ... it does not run erratic..sometimes running at high rpm's randomly but not buckin or missing..they replaced the idle control valve which they said they saw sticking (whatever) money lost for a problem still not solved... It started and ran perfect on the way to the the shop we took it to tonight..we got lucky enough not to need a tow .. and it did not shut off at all this time while driving it there...so here we go and see what this shop tells us..the mechanic there said getting these codes is tricky?..and something about if its the ignition module things could get expensive..he did say it could be the sensor or faulty PCM ..I'll let you guys know after I get a call back to see what they come up with and will concur with thsi board befor I let them do anything...thanks so so much for ALL your advice

Getting the codes is the opposite of tricky. Like I said, all you need is a paper clip, as any mechanic probably knows. Or a cheap scanner will do the trick too. A working used ignition module should be cheap too. And extremely easy to replace.

I forget, how important is the cam sensor to a pre-92?

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WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

The cam sensor on a 91 will act just like the 92... some of the 88-89's were a little more pissy iirc..

The Cam sensor is used only as a #1 Top Dead Center reference so that the can can run in Sequential Fuel Injection mode... Even if the sensor is not there or failed, the car will still start and run, the SES will light.. And you will have degraded performance..

an ignition control module seems to be the problem...replacing it today..fingers crossed..thankd for all your great advice!

Hopefully you found the issue. What led you there?

_________________

WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights

FYI, if Pep Boys told you there was a misfire code, they're either idiots (they are) or lying. The 91 pcm cannot report misfires.

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For anyone who encounters this problem...
Mine was randomly starting...it seemed to not want to start unless I left the key in for a minute or so.
Sometimes it would start up right away, sometimes it wouldn't. The died a few times without warning.

It ended up being dirty (carboned) contacts in the ignition switch. Once the contacts were cleaned, everything was great.
It starts every time, and stays on.