Hi all,
We ran into an annoying issue. After replacement of the clutch master and slave on a 1986 2.8 (4 speed), the car will stall (when warmed up) when pressing the clutch in. It will idle fine in neutral and even stall in neutral once the clutch is pressed. The car does not have to be moving to make this happen. It will also stall when it is coming to a stop.
Any ideas as to where to start looking?
Dave

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1987 GT (my toy-see above), 1987 GT (daily driver), 1986 SE with a VW VR6, certified master technician/shop owner
www.njautobahn.com

clutch safety switch miswiring?
there is also a switch for the cruize control on the clutch.

we didn't mess with the clutch switch or pedal. The car does not have cruise control.

seized throwout bearing? thats a mighty seize tho....

does it sound like the motor is loaded down to a stall - or it is a spark/fuel shut off stall?

quote Originally posted by Pyrthian: seized throwout bearing? thats a mighty seize tho.... does it sound like the motor is loaded down to a stall - or it is a spark/fuel shut off stall?

It will stall even in neutral, which makes me believe there is no way the clutch is grabbing to stall the engine. If the car is at a stop light in neitral, it is fine. If you press in the clutch (in neutral), the engine will start to bog and try to catch itself, but it will eventually stall. I'm wondering if the IAC has any signals from the clutch switch. The german cars I am familiar with have a clutch switch that will prevent stalling on the fly by wire cars.
Dave

well, I suppose a elimination test would be: unplug the clutch switch(es). this will eliminate any electrical/wiring possibilites.

unplug them, and see if the porblem goes away. if so - it is wiring - if not - it is mechanical.

I would have to suggest checking the wiring around the clutch arm and slave push rod. See if they are hitting and shorting any wires in that area. They only wires I can think of though would be the o2 sensor or the grounds that attach to the bell housing bolt

I vote for the clutch switch / neutral safety switch, etc. Sounds electrical to me.

bmwguru....how cold is it in NJ??

I had this happen to me when it was very cold out. Once I pulled in the clutch for the first time...the engine would stall. Once I did it again the engine sorta loped down again, but the engine didn't stall. Once the car was warmed up, the car was fine. This was on my old 86 GT.

Just a thought....

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fierogt28

88 GT, loaded, 5-speed

I dont think it would be your clutch switch, it only interupts the starter circuit. and the fact it stalls in neutral, I agree that its not the T/O bearing or clutch issue. But I cant think of anything else that could cause your problem, Some help I am....Im Lost !!


Gotta be a connection that got knocked loose somewhere

Thanks for the input guys. I think we tracked it down. I'll post up the answer once I am certain
Dave

Okay, im curious !.........................................

Back to the basics. The car has an inoperative oil pressure gauge. When the clutch is pressed in, the rpms drop just low enough so that oil pressure is too low to keep the fuel pump relay activated. We added 2.5 quarts of oil to bring it into spec and problem is solved.
I love puzzles.
Dave

Wow, I would have never went there...... No Low Oil perssure light?

quote Originally posted by bmwguru: Back to the basics. The car has an inoperative oil pressure gauge. When the clutch is pressed in, the rpms drop just low enough so that oil pressure is too low to keep the fuel pump relay activated. We added 2.5 quarts of oil to bring it into spec and problem is solved. I love puzzles. Dave

It needs the fuel pump relay problem repaired then. The relay is activated by the ecm only. The switch in the OP sender runs parallel to the relay and is only a backup for when the relay fails to activate the fuel pump. Does the fuel pump prime for 2 seconds when the key is turned on? If not swap the relays on the firewall and see it changes anything. If the OP sender continues to carry the full electrical load of the FP it will eventually fuse internally and keep the fuel pump running continually after the engine is shut down.

[This message has been edited by 2farnorth (edited 01-26-2009).]

quote Originally posted by bmwguru: Back to the basics. The car has an inoperative oil pressure gauge. When the clutch is pressed in, the rpms drop just low enough so that oil pressure is too low to keep the fuel pump relay activated. We added 2.5 quarts of oil to bring it into spec and problem is solved. I love puzzles. Dave

So anotherwords...the oil level was really low?? (by 2.5 quarts)

Nice to hear that the problem is solved.

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fierogt28

88 GT, loaded, 5-speed

quote Originally posted by fierogt28: So anotherwords...the oil level was really low?? (by 2.5 quarts) Nice to hear that the problem is solved.

Yes...and since there are no leaks and the oil was changed recently, it might be time to start tracking down where the oil went.

yep, it was an interesting test, kept Dave and I thinking all day. And for 2farnorth, the fuel pump does prime and shut off with the key on engine off.

Shawn

quote Originally posted by shawnhalolush: . And for 2farnorth, the fuel pump does prime and shut off with the key on engine off. Shawn

Then the solution doesn't make any sense to me. If the fuel system was working normally, loss of oil pressure would not shut it down. The original system isn't designed that way.

You are correct 2farnorth. I didn't understand the the "fix" either. A couple of days went by and then the problem came back. I replaced the Oil Pressure Switch to be safe since it seemed original. The problem remains along with my gauge now reading no pressure at idle! While driving, the pressure doesn't raise above 40. I don't trust the gauge at all. Now for more in depth info. The problem seems to happen while traveling on the highway (stopping at lights). This has me thinking My egr block off plate. Since my fiero spends 90% of its time on traveling on highways, and I blocked off my egr (tube was broken) without adjusting any parameters in the ecu. I have been driving this way for about 2500 miles. Could this be finally effecting my engine in this way?

Shawn

I don't think it would be caused by the EGR being blocked off. My 86 went 2.5 years with no EGR and ran pretty good until it soun a bearing - due to low oil and a heavy footed teenager! I has to be something electrical. I had an Oldsmobile 88 once that every once in awhile, wen you hit the brakes, the car would die. Hit the ignition switch and it would fire right back up, hit the brakes and it would die - like you turned the switch off. After months of tracing and trouble shooting, I found that the idnition switch was to blame. I had a rather large set of keys at the time and the weight of the keys hanging on the ignition switch caused the switch to go haywire. What finally got me to look at the switch was that the car never did it when my Wife drove the car. She had 3 keys - ignition, door and house key. With the weight of my keys - I'd hit the brake, the keys would swing and tweak the switch just right and click - car off. One day I took the ignition key off the ring cause I wanted to leave the car running in the sub freezing temps. Drove it to work, all overtown that afternoon and for the next 5 days - no problem. The minute I put all the keys back on, click - car off. The light bulb came on in my head. Replaced the switch and put another 150k on the car and never had the problem again.

It's got to be electrical!

While I worked at a Ford dealership, I saw that problem quite a few times. It would happen with girls a lot since they like to have those big key chains. Being electrical wouldn't surprise me, but given the circumstances in which it happens, I'm at a loss for what it could be. It doesn't seem like a TPS, MAP, IAC problem....ignition module, cold start switch, and all there temp sensor, sender, and switch are new.

Shawn

A VW 1.8t swap would correct this.....and I know you want to do it!

It doesn't do it unless the clutch is depressed, or did I miss something there? That stinks of mechanical to me, but I'm having a hard time with a physical theory. I suppose you could be shorting a wire up around the pedal, got anything hanging around loose under there? It didn't do it before the new clutch install?, so that sets me to eyeballing that area.

[This message has been edited by weaselbeak (edited 02-06-2009).]

Ok. A little background info: the day I discovered I was 2.5 qts low, the motor started ticking really bad(typical for a car with almost no oil) when I topped the oil up, the ticking went away after about 30 miles. It came back the following day and has been ticking ever since. I figured I'd throw a new set of lifters in and rock the car for as long as I could. Flash forward to last night, I spent the night looking through wiring diagrams to see how the engine controls work. Today was a little slow at work so i brought my fiero in the shop to continue looking at it. I first wanted to settle my oil pressure gauge concern. I did this by pulling the OP switch and putting a mechanical OP gauge in place an running the car. My car is running at 5-10 psi at warm idle! I'm pretty sure that this is the problem. I decided to drop the 5w30 and put some 10w40 in to see if the pressure changes. The 5w30, which was only a week old, came out looking like it was in there for years and very sparkly. My conclusion: the motor is toast, I'm returning the lifters and looking for a new motor. I can't catch a break with cars. That motor has given more grief in my 2500 mi ownership than any of the 13 other cars that I've owned.

Shawn

Grief is automatic with only 1 1/2 quarts of oil in it. It would need to be about 50% STP to get that oil pressure gauge up to a decent level. Did that once on an old 318 Dodge coming home from Florida.

Your crank probably has some end play and when you press in the clutch it pushes the crank and puts it in a bind. Might have a bent crank or simply worn through the thrust bearing.

When you yank the motor do a teardown and see what you find.

So now I am a little confused. Is the Fiero Oil Pressure sensor and Fuel pump relay supposed to work in conjunction? Meaning, if your oil pressure drops too low will the fuel pump cut off? Today, after driving my 86 with new motor in it about 70 miles, as I came off the interstate, the oil pressure gage (factory) dropped low enough that the light came on. The car did not die and when I checked the manual gage, at idle I had 25 psi. The way I understand it is that the car should die if your OP light comes on! Or am I wrong?

Pat

The OPS is kinda like a back up. if the relay fails, the op can keep power to the pump as long as it has pressure. 25 psi sounds low to me. According to Alldata, the idle spec should be 35-40ish. I'm not entirely sure why my car still dies when the clutch is depressed. I'm certain that my oil problem is the culprit but as far as explaining it, I can't. If someone has any insight, I would love to hear it

Shawn

quote Originally posted by shawnhalolush: The OPS is kinda like a back up. if the relay fails, the op can keep power to the pump as long as it has pressure. 25 psi sounds low to me. According to Alldata, the idle spec should be 35-40ish. I'm not entirely sure why my car still dies when the clutch is depressed. I'm certain that my oil problem is the culprit but as far as explaining it, I can't. If someone has any insight, I would love to hear it Shawn

The way it's supposed to work is the OPS fuel pump back up switch comes on at 4 PSI oil pressure. That way if the relay fails you can start and run you car to the shop to get the relay replaced. But if the relay is working the OPS should never come into play.

[This message has been edited by 2farnorth (edited 02-07-2009).]

Well to make sure, I have a spare 2.8 you can borrow and try out to see if the stalling goes away. Maybe even lease it with a $1 buyout at the end.
Dave