Can you guys help me figure out a car problem?

Id sure appreciate it. This problem is driving me freakin nuts!

1996 Pontiac Bonneville SE (non supercharged) with 195k on the clock. Having electrical issue.

When coming to a stop sign, making a slow turn, or sometimes just idling in park or neutral the car will stall out. It only does this when the car is somewhat warmed up. Never when its completely cold. Before it stalls, the voltage gauge drops down into the red then it dies, BUT if you give it gas it will come out of it and the gauge goes right back up to 14. Never have a problem restarting the car and it cranks really fast even when acting up. I suppose im losing enough power somehow that the fuel pump slows down and the lack of fuel pressure causes it to stall. Ill also not that the headlights dim, the blower slows down, together at the same time so i think that eliminates it being 1 power source from sucking too many amps.

I checked the battery terminals, cleaned them, and installed new bolts. They are clean and tight now.

I had alternator tested, they said it was bad so i put a new ac delco alternator on. I sure wish i would have taken it off and had it bench tested, might have saved some money but oh well.

I bought a brand new battery and installed it.

Shortly after the alternator install, it was acting fine for a while but then started doing it again.

Bear with me here,

There is a repetitive clicking noise coming from somewhere around the serp belt that increases with engine speed. It sounds exactly like a lifter. I took the belt off and started the car, and the sound went away. I suspected it was the idler pulley. It spun freely but felt a little gritty so i changed it but im still get the noise. I took a long screwdriver and listened to all the accessories, and thought it was coming from the alternator but new alternator didnt fix it. Hope its not the water pump because i felt around on all the pulleys and the only one that had any play whatsoever was the water pump and just a tiny tiny amount.

I haven't changed the belt yet but i dont think its slipping. It never squeals and ive watched it as the car died several times and it dosnt seem to be slipping at all. Also, the spring in the tensioner is still extremely strong and isnt locked up.





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Could this be a bad ground connection at the frame or somewhere else?

Im not a very good mechanic, so i apologize if this makes no sense. I dont really feel like crawling around under the car in the slushy frozen winter that is Illinois right now. The new battery i got has top and side posts. So to test for a bad ground causing this, could i hook a negative terminal up to the top post on neg side of battery, and then run that to a bolt somewhere on the engine? Would doing that eliminate if its a grounding issue?


Im scratching my head like crazy over this one. I really appreciate any help i can get. Thank you!

Hope this will solve the ptoblem,
I've seen simular symptoms when the air idle controle circuit/motor has failed or gotten really dirty.
Good luck.
Lew

EGR? Dirty thfottle body?

If everything is dimming out and the voltage is dropping quite low, then one of two things is happening.

1) Temporary short. I doubt this especially if fuses aren't popping and everything else (electrical) is working.

2) Huge voltage drop (high resistance) in a primary circuit. This can be caused by a lot of things. I've seen IGNITION switches do this. Fusible links can be culprits. I'd pay close attention to any and all POSITIVE cabling that comes directly from the BATT POS terminal and any of the branches from there. You're lookng for bad, dirty and otherwise defective connections, wires and terminals.

If you don't find anything obvious on the POSITIVE side, go looking for bad GROUNDs. Usually, there are enough grounds in the system to compensate for the UNIVERSAL voltage drop you're seeing, but you never know.

If you can, try separating the harness at non-critical spots and see if things improve. (Be wary of necessary circuits, little things like brake lights, horn etc.)

Good luck!

Those things would explain the stalling but not the dimming of the lights and slowing of the blower motor. Even if the engine slowed down, the battery should carry the lights, blower and voltage for quite awhile.

The problem is electrical......somewhere.

Is your voltage regulator an integral part of the alternator assembly on your vehicle? If not, then this is the next place I would look.

The fact that the issue seems to be related to temperature sounds like something electrical getting hot and shorting out. In that you are not blowing fuses would lead me to believe it is in the power delivery system, prior to the fuse box.

Thanks a lot. I will take the IAC sensor off and clean it today. I figure if anything it has to be dirty, if its bad it wouldnt idle for shit right? It idled for 45 minutes today without a hitch but when i took off down the road to drop kid off at daycare it started dying again.

Ill also run that ground and see what happens.

Gotta warm up my balls first though, been up half the night dicking with it. I think my bag is literally a frozen mass!

Thanks for the help!

the only problem is when you harvest the brake? if you disconnect the brake switch signals, the problem go away? If you disconnect the pipe to the vacuum booster, which will, or maybe power brake vacuum sucks the air? and therefore fall speed? I propose to make 2 test - disconnect switch stop light (next to the brake pedal enough to remove 1 wire. any.) see what happens. and the second step-test leak air
vacuum brake booster. but. it's advice on the Russian car sorry

check the weight very easily. need to start the engine and a voltmeter to measure the voltage between the motor and terminal *-* there should not be a strain. then turn on the light and measure again. and then to measure the body and motor. and minus the battery and the body ...

шульц. said:

the only problem is when you harvest the brake? if you disconnect the brake switch signals, the problem go away? If you disconnect the pipe to the vacuum booster, which will, or maybe power brake vacuum sucks the air? and therefore fall speed? I propose to make 2 test - disconnect switch stop light (next to the brake pedal enough to remove 1 wire. any.) see what happens. and the second step-test leak air
vacuum brake booster. but. it's advice on the Russian car sorry

Click to expand...

Thanks for the reply. I had thought about it being something to do with the brakes BUT it dosnt do it only when the brakes are applied. For instance, i can go out and start it up and let idle until completely warm, sometimes it will die, sometimes it wont. It will also die if your just coasting around a parking lot with rpm's at idle sometimes.

Really sucks when your pulling into a parking spot and lose power steering. Bout killed me an old lady because of it

clintard said:

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Click to expand...

to take pliers long lips. .. put readily available when the engine is running poorly - pliers rubber pipe clamp amplifier. watch-work motor smoothly or not ...

I am not a mechanic either, but thinking out loud: when you take a slow turn, the power steering pump puts a load on the engine that is supposed to be at idle or near idle ( i.e. cannot accept excess load ). This does not happen when you warm-up the engine because the idle at that moment is higher. When you depress the brakes, the lights represent a load on the engine too, that might cause it to stumble or cut-off. Try at idle to increase electric load by switching on different loads, like a/c, heater, blower, headlamps, fog lamps, etc... while monitoring the voltage at the gauge or at the battery using a voltmeter.
Good luck

Have you checked for a weak fuel pressure? I believe when a pump nears the end of it's useful life, it can cause issues at idle speeds and not necessarily at regular speed.

Not that I am a mechanic but I think that the engine dying is a symptom and not the actual problem.

The fact that the voltage drops way down with a new battery and new alternator in the system points toward something drawing a massive electrical load.

Even if you starve the engine for fuel or kill it, the electrical system will be carried on the battery and maintain the voltage at 12V.

I would bet that when the voltage drops down below some threshold (9V ?) the electrical systems in the car stop functioning correctly (ECU, fuel pump, etc...) and the car dies



When the engine dies, does the voltage come back to 12V or does it stay low?

WAAAAY too much information... :hmmm:

Anyway, try not to get bogged down on mechanical stuff. Folks are offering lots of advice that COULD be helpful except that you clearly mentioned a drop in voltage.

Stick with electrical troubleshooting and you'll get to the bottom of it.

Are there any error codes when checked with a scan tool?

i had a chevy s10 that did that all the time. it was a 91 with 200k+++++ miles. never died on me when it was cold, but once it got to operating temperature it wanted to die on me and shit.

took it to an exhaust shop and got a new exhaust and they replaced all the sensors for the air.

IDLED GREAT AND RAN LIKE NEW!!!! lol i couldnt believe it. best 150 bucks ever spent ever.

sold the car for more than i paid for it shortly after.

I got a 2004 Bonneville that has it's own electrical "issues" and have posted for answers here http://www.pontiacforum.com/pontiac/index.php? and the guys have been helpful.

Sorry I don't have any suggestions to help directly...............

I've had a lot of "lazy" idle speed motors on my fleet of Dodge vans over the years. They will test OK, but their reaction time is too slow to compensate for loads. It's one of the few sensors I keep on the shelf because of common need. I don't know if GM has a similar problem with those motors - I just started replacing Dodges with Chevy's. What if you dis-connect the idle speed motor when it's at a good idling speed ? The light will come on, but that's easy to reset & if it doesn't stall any more it may help you to prove that the motor is sluggish. I like to prove things with zero $$$ whenever possible...

Hi Rich,
Is that the air/idle control I mentioned in the second post????

Zackley Lew - I agree with you 100%. It's a known issue with Mopars, I'm just not sure about GM's.

Since you have a mid-90s GM car, it's pretty likely there's a plate somewhere under the hood that holds the 4 or 6 coil packs. Rather than a dedicated ground, the coils simply ground through their mounting to the plate, then to the body.

Over time the interface between the coil and plate corrodes and creates a weak/bad ground. I've known three GM cars that had weird electrical issues(one refused to start entirely) that this was the cause of. Remove all the coils, sandpaper the crap away, put it back together.