Replacing the CPS and troubleshooting starting issue, 1985 Porsche 928 S Euro

Trying to figure out a starting issue that only occurs when the engine is warm.

[@cobras034]

I had a US 86.5 with the 32v engine. Always had this intermittent hot start issue on mine, where it would kinda fall flat on its face without giving it a little gas after starting when the engine was warm. Honestly I never troubleshooted the problem since the car was a charm besides this, and well was even more of a pain to diagnose than your Euro model. This issue never left me stranded either so I just lived with its quirks. Love your videos!

[@OCDHAUS]

Mr. Stallone, thanks for taking the time to comment, I know you’re a busy individual. Yeah, I might stop troubleshooting it at this point and come back to this issue later, Rennlist has given me a couple places to look into, but my gut tells me it’s got something to do with the LH-Jetronic module. I think the previous owner either replaced it or something, because there’s handwritten labels on it. At the very least I know he mucked with it. Nonetheless, I just increased the idle by half a turn and I think that’s improved it somewhat. Seriously though, thanks for taking the time to comment, I appreciate it.

[@peterschmidt1453]

There is the Idle Control Valve which may be the issue. I haven't changed out mine on the 87 S4, but it's under the air filter / throttle body area too. It's under $100 (non-genuine) on most sites i've seen it on.

[@OCDHAUS]

Thanks Peter, I think I more or less fixed it with the replacement of the fuel pressure regulators and dampers. I show it in a subsequent video.

[@mcr1photo]

MAF or fuel filter? Just a guess. Shot in the dark. Good luck.

[@OCDHAUS]

I’ve recently replaced the MAF, but haven’t consider the fuel filter. I’ll look into it, thanks Michael.

[@gazfish]

You didn’t loosen or tighten the clamp around the MAF when you took the airbox off, maybe you just skipped that in the video.

[@OCDHAUS]

I did, they’re just short clips in the video. Thanks for checking though.

[@928smnporsche3]

Have you gone thru all of the electrical grounds and cleaned them? IIRC on my ‘85 US model there were 10 of them. Some not so easy to reach. Not familiar enough to say how many the Euro has.

[@OCDHAUS]

Yes, I did that long time ago when I was troubleshooting an electrical issue. Thanks for checking though...