Jason928

Took the car up the road last night (2 minute drive) to get dinner, everything was fine. Came back to the car and all of a sudden it won't hold an idle, the throttle has to be held down to keep the car running. It seems to be running fine, except that it is very difficult because as soon as you let go of the gas, it stalls..
This is a 1985 Auto

Any thoughts would be appreciated, haven't looked at it much yet.

Jason

Snowball the 81 white 928

1. airflow sensor
2. fuel pressure
3. clogged injector(s)
4. throttle body gaskets and o-ring

it could be anything, what have you done to the engine lately?

<img src="graemlins/icon107.gif" border="0" alt="[icon107]" />

Jason928

Well I was looking at my shop manuals and it suggested looking towards the temperature sensor. I checked it, it appears to be shot, but after poking at it a bit, I tried firing the car up...runs fine now... .

Ill stll replace the temperature sensor but for now its looking good

Bernie

Hi Jason,

It is very possible that your idle stabilizer is going south on you.
At the front of the engine, just under the fender brace, is a round black cap. Under this cap is a series of sockets at 11, 1 and 6 o'clock. Your connector might have been spun but look at the connector so that it lines up with what I have said. Take a piece of wire and jump sockets at 1 and 6 o'clock. This will bypass the idle stabilizer. If the car stalls out when you do this, your stabilizer is probably ok and you can look elsewhere for your problem. If there is no change at all with the idle, you may have found your culprit. To be sure, try dropping the idle screw on the throttle body low enough so that the car should stall. The stabilizer will keep it running if it functions properly - did on mine anyway. As soon as you jump those sockets, the engine should drop like a stone. This actually confirms that the stabilzer "is" working.

Greggg

Hey Jason. My 87 auto just did the same thing during speed testing. After a quick 0-60 run the car wouldn't idle. I limped it home just like you, checked the temp connectors, went out again it was fine. another run it wouldn't idle correctly, back home again. I was playing with the throttle cables earlier and figured out that my throttle plate cable was too tight. The plate wasn't closing all the way. You may not have played with the cables but if your throttle plate is sticking you would have the same problem. This could easily be caused by debris or your linkage might need a lube. I also read on jagereng.com that he uses some penetrating fluid(can't recall the brand) and injects it into a vac hose that routes to the idle solenoid. Hope this helps! <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Jason928

As a matter of fact I was playing with the throttle cables..I will have to check this.

Also may give the throttle stabilizer a check.

A few days have now passed though and the problem hasnt come back, so far so good.

Thanks for the input!

Greggg

Hey Jason, I just lubed my idle stab with penet. oil, let it sit for 4 hrs. This helped calm down some off idle stumble. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Greggg

hey Jason, found another item that helped. I had read that after modifiying the car in any way to unhook the battery so the computer could reset. My voltage was a little down on the dash so I decided I would clean all the contact points also. This made a markable improvement in idle quility for me and now I'm showing 13volts on the dash instead of 11.5. <img src="graemlins/yltype.gif" border="0" alt="[typing]" />

WallyP

From an earlier post:
"It is very possible that your idle stabilizer is going south on you. At the front of the engine, just under the fender brace, is a round black cap. Under this cap is a series of sockets at 11, 1 and 6 o'clock.
Your connector might have been spun but look at the connector so that it lines up with what I have said. Take a piece of wire and jump sockets at 1 and 6 o'clock. This will bypass the idle stabilizer. If the car stalls out when you do this, your stabilizer is probably ok and you
can look elsewhere for your problem. If there is no change at all with the idle, you may have found your culprit. To be sure, try dropping the
idle screw on the throttle body low enough so that the car should stall. The stabilizer will keep it running if it functions properly - did on
mine anyway. As soon as you jump those sockets, the engine should drop like a stone. This actually confirms that the stabilzer "is" working."


There are a couple of comments here that are easy to misinterpret.

Shorting the pins in the socket at the top front of the engine should indeed kill the effect of the idle stabilizer. At this point, with the engine warm, A/C off, you adjust the idle screw to specification with the stabilizer disabled, then remove the jumper to reactivate the stabilizer.

The function of the idle stabilizer is to hold the specified idle when cold, when the A/C is on, etc. The engine SHOULD CONTINUE to idle with the stabilizer disabled.

Big Dave

Greggg:

Did your idle issue occur before or after you fiddled with the throttle cable? I noticed last night and this morning that my shark doesn't want to hold an idle very well.... Then, as I drive, I am noticing that the idle seems to be a bit on the high side, like the throttle isn't being released as much as it should when I lift my foot from the pedal.

I'd sure like to know the answer before I start trying to figure out what else the culprit may be. I have first hand knowledge of the sticky throttle.....I had an adventure in April when my throttle got stuck in the wide-open position and I nearly had to change my shorts. A few squirts of WD-40 did the trick that time, but this feels different. Maybe the throttle plate is sticky...but not "sticking".

Greggg

Hey Dave! Your adjustment is easy. On the cable going to the throttle body there is a large black plastic adjustment nut which you can turn by hand. If you want, call me and come over I'll help. <img src="graemlins/oops.gif" border="0" alt="[oops]" />

Big Dave

Greggg:

Does my situation sound exactly like what you were experiencing?

Is that adjustment nut out in the open or down in the intake manifold area? Why would my car suddenly start acting this way after being fine since the cable adjustment last Monday? <img src="confused.gif" border="0">

Greggg

Yeah, mine has been acting weird also. I think the cars spirit has been disturbed!? The adjustment is located in the front with the other cables. <img src="graemlins/yltype.gif" border="0" alt="[typing]" />

Greggg

Quick update; after adjusting your throttle cables,check them again when engine is hot. Mine and Big Daves needed a little readjustment which we are guessing caused our earlier idle problems. More to follow... <img src="graemlins/yltype.gif" border="0" alt="[typing]" />

Big Dave

Gregg:

Thanks again for the free wrenching on the throttle cable. It doesn't appear to be idling too high when hot.

BUT....I'm still not able to hold an idle when the 928 is cold. Given the possibilities listed above and the fact that we heard that nice, loud HISSSING sound from my in/under my intake, I'm guessing that I have a throttle body gasket or O-ring problem.

I sure hope the HISSS and the idle problem are related.

Thoughts? Suggestions? Anyone? Bueller?