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Just picked up my dream car....a 1991 Porsche 928 S4 in Black....a project and didn't pick it up...it got flat beded to my work. But it's ok....I'm a project type of car guy. It doesn't run...it starts and idles for a few seconds but if I let go of the accelerator it stalls...if I accelerate it stalls. Please let me know where to start looking.
I should add the car hasn't been driven and almost 2 years. I put a new battery and filled the gas tank half way.
First thing to worry about is the timing belt and water pump. If you don't know when they were last changed, think very seriously about changing them right away. If the belt snaps, your valves crash into the pistons. Also, making sure the fuel lines under the hood have been replaced at some time is important. A "Carbecue" is a really, really bad thing. There's a pretty recent thread on one (page 2 IIRC).
For the stalling condition, the first place I'd look would be the MAF. Or the O2 sensor. Or the ISV. Or all your vacuum lines. Or the fuel injectors. Or a bunch of other stuff.
And you need to post pics. You really need to post pics. Yes, we all know what a black 91 looks like.
We don't care. We want to see yours.
If there are no fuel leaks (test by jumpering the fuel pump relay position), for now I'd leave the fuel lines well enough alone. Easier to do them at the same time as taking the intake manifold and fuel rails apart, at which point you can replace all the hoses, o-rings etc. on the fuel system at the same time.
As for whether it needs TBWP - they all do, but before just taking it apart, you should be diagnosing why the car fails to proceed.
TO be sure about the timing belt, take the belt covers off and check tension and inspect the cam gears for wear - if you have a receipt showing last timing belt job, the belt is ok (no cracks, esp at the base of the teeth), and the gears aren't too worn, I'd just continue to diagnose and not worry about undertaking major work until the car runs.
First test I'd do with the symptoms you describe, is unplug the MAF and see if there's any change in behaviour. I suspect not - at which point you need a rebuilt MAF.
While you've got the battery disconnected to unplug the MAF, also check your throttle position sensor is working and that the idle contact switch in it is closing properly (can measure it with an ohm-meter at the LH plug). If not, it may need a cable adjustment so it closes properly when the throttle is released gently.
Another first thing to check is the flex plate clamp position.
Many discussions of this here. It is a known fail point, the load can cause an engine to stall at idle.
The best part is, it doesn't cost anything to check it yourself.
as to the stall problem, one of the easier things to check are the multitude of vacuum lines in and around the engine. These are the cause of more idle issues and related running issues than anything else. Do the cheap easy stuff first, like check all vacuum line connections (search is your friend for diagrams), and clean all ground points to a nice and shiney state - especially at the underside passenger side of engine to engine bay, and back by the battery box. Check your ground strap too. Once all of that checks out - all free by the way, then start with the other stuff mentioned to chase the problem, like the maf and throttle position sensor, ISV valve, etc.
Congrats!
Mine also a 91.
Good luck on the project. Hope she'll turn out to be as sharp as any.
Your car looks awesome! First 928 I've seen that aftermarket wheels really look the part. Do you happen to have any more photos? What are the specs on the wheel/tire/suspension combo?
Your car looks awesome! First 928 I've seen that aftermarket wheels really look the part. Do you happen to have any more photos? What are the specs on the wheel/tire/suspension combo?
+1 I thought the same thing that's a great looking 928! Nicely done
(New 928 owner Welcome Aboard! )
'89 928S4 GP White/Black
'80 911SC Targa Black/Tan (new owner picking up on 9/18/15)
Thank you guys! Awesome stuff. I own (well....I take care of) a 1987 BMW 535is that I know inside and out. I'm restoring a 1974 Alfa Romeo Berlina that I'm doing everything from metal replacement to engine rebuilding, but this 928 intimidates me....I guess that's why this project is so exiting for me. Not to mention the 928 has always been my all time favorite sports car! And certainly my favorite Porsche...go figure!
This is my 928....just after delivery and not yet cleaned!
Fellow 929 owners...this is what's happening. I put a new battery and filled the gas tank almost to half....the car had been parked without starting for over 2 years. It is a new key recently made by Porsche. I start the car and it fires up but only idles for less than a minute. If I try to accelerate the engine dies; just like when I let go of the peddle it also dies. I have to keep my foot on the peddle with slight pressure for the car to stay on idle at 500 to 1000 RPM. I do get a heavy gas smell.
Got my Shop Manual and I'm learning everyday about my 928. If you tell me where to go or what to do I'll find my way there.
Thank you so much for all your comments. I hope to give back and contribute to the forum just like I'm taking from it.
09-15-2015, 07:12 PM
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