I really hate to come here and ask for help with a junk pontiac. Its my 1000$ beater work car that i drive in the winter to keep the salt off my 300D.

Ive been driving my 83 300D, RUST FREE, awesome condition, ON SALTED ROADS. For the love of god i have to get this thing fixed so i can put my baby back in the garage! Its breaking my heart to get salt on her!


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1996 Bonneville SE 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!

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Clint. 1983 300D turbo, 150k
http://www.youtube.com/clintard

Sound very much like a ground Issue. Try to find the other end of the ground connection to the car take it off and wire brush it. Or you could put another ground on . Just make sure it is to bare metal then cover with die electric grease. Hope this helped.

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86 300SDL. 250,xxx on #14 Head. One eye always on temp gauge.. Cruising towards 300K

I would add a second ground too. Actually two more, one to the engine and one to the body.

Faulty grounds can be a real paint to diagnose. They can lead to everything from the car stalling to random lights and accessories operating...

__________________
"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
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'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
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'92 Subaru
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The usual culprits been eliminated altogether? How are the plugs, wires and distributor cap if it has that? If not, how are the coil packs? How is the fuel filter?

I would get a known GOOD spark plug and pull plug wires one at a time when it is running. You must get a good blue flame. This checks for spark

Next thing to check is fuel. I am not sure but I would THINK that you could hook up a fuel pressure gauge and see what the pressure is. Consult a book to find out what the running pressure is. If you had a L98 engine I could tell you more but I am sure you are not running such an engine. When you shut it off, if the pressure drops rapidly, it could be the fuel pressure regulator or less likely, the injectors leaking. Crimp off the return rubber hose and see if it drops. If it doesn't, it is the regulator. While we are on fuel, I am not sure if there is crud in the tank clogging up the sock filter.

Get a scantool and see what the IAC counts are. It could be that the Idle Air Control solenoid is shot or the IAC passages are clogged.

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Make sure you don't have oil or grease on the belt and that its properly tensioned on the new alternator. Just because it doesn't squeal doesn't mean its not slipping.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I had a '94 Bonneville for five years ending in late 1998. This engine has three coil packs each servicing two cylinders. IIRC, the voltage regulator is part of the alternator, which means that it should have been replaced with the alternator. Not that it rules out the possibility that the new regulator is bad. I also seem to recall Schrader valves on the fuel rails, facilitating a fuel pressure evaluation.

It's been my experience that IAC valves that are viable in warm weather can act up as the temperature drops, so Aklim may be onto something.

I would first clean up the grounds, as a 14-year-old salt belt car is certainly a candidate for corrosion in those areas. I wouldn't ignore interior and underhood fuse boxes and relay blocks as corrosion-related culprits either.

THIS might help

If he had an L98 engine I would say he should hook up a scanner and see if he gets about 20 counts but I would THINK that the principle should be the same. That is how I adjust minimum idle since my system is so "non stock". If his passages are clogged up, it could be an issue since the IAC might be commanded to close up but the carbon there might still allow air to go thru and it could be turning lean.

Also another thing that makes me wonder is this. If it acts up when the engine is warm, wouldn't that mean it is acting up in closed loop? IOW, it cannot compensate. Maybe the O2 sensor is lazy?

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Sounds like you are running out of juice at low RPM and it is stalling.

Which means:
a)alternator
b)battery
or c)ground/wiring

Can you get someone to do a charging system test for you? It isn't expensive and rules out the possibility of bad alternators/batteries. I know they are both new, but they can be bad (bad battery cell, alternator, etc.)

Once you have the results of the charging test and it passes, then start looking at the belt (does it slip?) and checking heavy ground wires.

As a check for shorts between two ground points, hook up a jumper cable onto each point (clean paint off the metal first so you make a good connection)

If the car runs perfectly with the jumper cable hooked up, you have a bad ground connection OR maybe the ground wire itself is bad. They can flex inside the insulator and crack. Still look good, but they are bad.

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'83 300SD 335,000km (207k) mi SOLD
'87 560SL 163,000km (101k mi) SOLD
'86 300SDL 356,000km (220k mi) SOLD
'92 500SEL 250,000km (155k mi) SOLD
'90 300SL 140,000km (87k mi) SOLD
'01 S430 260,000km (161k mi) SOLD
'03 SL500 167,000km (104k mi) SOLD
'07 S550 4MATIC 235,000km (146k mi) SOLD
'07 GL320 CDI 4MATIC 348,000km (215k mi)
'13 GL350 BlueTec 4MATIC 170,000km (105k mi)
'14 SL550 72,000km (43k mi)

Just to jump in here...

I once had a Dodge Omni that did this same thing. Being pressed for time I took it to a old guy that rebuilt alternators, generators and starters in his shop. These used to be called Generator shops and there might be one near you.

Anyway, he started it, let it die, and said I needed a new grounding strap. This was a flat naked wire that ran from the block to the body. He took mine out and it was burned almost in two.

The new strap fixed it.

I asked him what caused this and he just said it would take all day to explain it and if he was fixing or talking he charged $35 an hour, so I still don't know why this took place.

All I know is I never had the problem again.

As said, IAC, or TPS, EGR. Or gummed up throttle body.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Not ruling out other issue's, but looking at electrical problems.

Check the main battery cables, usually right at the battery connectors, the copper rots out. Between the battery fumes and salt the cable is crusty, sometimes under the rubber coating.

Do check bothe ends, and agree with disconnecting the grounds, cleaning the connector and putting it back together.

Do let us know what finally is the solution.

Don't let the electrical issue cloud your thinking, It's probably something simple and stupid (the voice of experience).

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KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.

Im sorry i took so long to get back on here and update this!!

Yes i have a check engine light on.

Earlier this year, the fuel pump went out. It was a real bear getting the gas tank down let me tell ya! Sheesh. You have to take an exhaust pipe down to get the tank out. Strap bolts were rusty just spun. I got sick of messing with it so i torched them bastards out. I know, not smart when right next to a fuel tank! LOL. I didnt burn myself to death tho and i got the tank out. Put a new fuel pump in it, rigged some strap bolts and put the tank back up. Car started and ran so i was proud of myself. My girlfriend went to get it and drive it home, and im not ****ting you, she drove it 5 feet and one of the O-rings on the plastic fuel hoses blew out and start pissing gas everywhere so it stalled. DAMN IT. I found a similar O ring and tried to make it work, but it would only last a few miles and they would blow out again. I figured the plastic fuel line was warped or something. Bought 2 new fuel hoses and put them on. Drove the car 10 feet this time and it stalled again! I could hear the fuel pump running but NO fuel pressure.

Had to take the damn gas tank down AGAIN, and when i took the sending unit off the get to the pump, i snapped the damn hard line on the sending unit! The gasket between sending unit and fuel pump had blown out.

Got a new sending unit and its a different design so i had to figure out how to rewire some **** to make it work. Put the pump on it and noticed it just didnt seem right. It had a little play between the sending unit and the fuel pump where they meet. Theres a gasket between them. It seemed like enough pressure to keep that gasket sealed so i put it all back together, put the gas tank back up and strapped it in. Drove the car for about 20 miles and it stalls AGAIN. That bastard gasket between sending unit and fuel pump had blown out again.

This time im absolutely FURIOUS. I took the tank down again, took out the sending unit and fuel pump and brought it up to the parts store. Not autozone but a reputable parts store in our small town who sell OEM stuff. They gave me the wrong damn fuel pump from the beginning! I guess they gave me the pump for an SSEI supercharged bonneville and it is just SLIGHTLY different so that explains why it didnt feel as snug against the sending unit as it should be.

So, i get the right fuel pump, put it all back together, put the tank back up and she had perfect fuel pressure. Car has ran perfect ever since that whole ***** of an ordeal!

These things have a sealed fuel system. If you forget to screw your gas cap back on, youll get a check engine light. The check engine light has been on in this thing since i bought it, but the only code it showed was the one for the gas cap being off. There are tiny pin holes in the top of the tank itself so its not perfectly sealed and unless i replace the gas tank the light will stay on. I can live with that. My grandpa is a retired GM mechanic and told me stories about how they would pressure test the fuel systems with nitrogen or some kind of gas that would show up under UV light to find them pinholes and seal them. Screw all that ill just live with check engine light stuck on.



UPDATE on the stalling issue. Im 90% sure it is fixed now.

I went back to the parts store and had them bench test the alternator i turned in for core, and it was indeed bad. So i didnt waste my money on alternator and battery etc.

I spent a day chasing wires and checking for bad grounds. I ran a big fat ground wire from battery to a mounting bolt for the alternator and it didnt help. It would still stall.


After alternator and battery and fixing the cables up it stays rock solid 12 volts off, 14 volts on now even at idle. When it stalls the volt gauge stopped dropping before it stalled but the sum***** is STILL STALLING.

I cleaned the grounds under the coil packs and they werent very bad. Still stalling at idle etc.

I thought the serpentine belt was slipping, so i changed that. That resolved the ticking noise i was talking about but the car would still stall.

After a bunch of reading next i decided to check and see if the IAC, intake air control valve was dirty and clean it. I took it out and cleaned it. It was filthy. This actually made the thing stall worse.

Somehow in the process of taking the IAC off and cleaning it, i broke a vaccum hose down by the vaccum modulator for the transmission and didnt realize i had done it, so the thing wont shift until 4000 rpm's and is reving up to 3500 when started. I thought i fried the computer or something.

Changed all the vacuum lines and fixed the shifting/revving when started. But still stalling.

I took the IAC out again and with the IAC in my hand, i was gonna test and see if it was working. Told her to cycle the key on, then start it. She cycled it on, then back off, and the damn plunger in the IAC jumped out and i lost the spring.

Paid 50$ for a new IAC valve, put it in, thinking this HAS to be the problem. Started it up and ran it down the street and it starts dying again, worse than ever before. I just kept driving it all over town, letting it idle, hitting stops signs etc and it finally cut the **** out.

I think when installing a new IAC the computer needs some time to learn and adjust things for it to work. Tonight i drove the car for about an hour, in town, stop and go, hitting every stop sign and turn i could and i couldnt get it to stall out. The idle drops down and gets rough like its going to die out but so far it hasnt died.

SO, i guess the motor in the IAC valve got lazy on me.


If it starts acting up again. Im done messing with it. Im going to just adjust the idle speed up a tad and live with it.

__________________
---------------------------
Clint. 1983 300D turbo, 150k
http://www.youtube.com/clintard

You're right about the learning curve for an IAC. When I replaced one in a Ford Expedition, the service manual recommended letting the vehicle idle for 30 minutes.

Next time you deal with a stall at idle issue with a GM, clean the IAC and then disconnect the battery for a few minutes. Reconnect, start it and it'll run like crap for a few miles, then smooth out and figure out how to run itself.
Also, if it has a MAF in the intake tube, clean it and make sure the rubber intake tube doesn't have any leaks.

You DON'T test the IAC that way. You cannot do it right. If you must, you should read up the test procedure. I would have taken the IAC housing off and watch it move if that was the way I wanted to do it. A lot of your work seems to be of the "shotgun" approach. You need to do it systematically. Get a shop manual.

There is some learning but not that much provided it is adjusted closely. 2 ways on an L98. First way is to extend it out to max (read you manual) and set the idle speed for a certain number and then reconnect the IAC wires. Another way is to do it by IAC counts. I favor the 2nd method.

This is why people like carburetors. They don't know or understand what is going on and they do it the old school way. You DON'T do it that way. The ECM will compensate. There is a command idle number set by the program in the ECM. What you are doing is forcing it out of range. Well, fine. It works at this set of conditions. When the window changes, well, here we go again.

Get yourself a shop manual and a scanner. Or you can throw money, parts and time at it until you finally hit he answer.

__________________
01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow