Schocki

Hi guys,
Just wanted to share my experience with John Speak to get my 928 running smooth again.
My GTS has 173000 km's on the clock and started to have some driveability issues. The car starts rough when cold for a couple of seconds and idle was never really smooth. I emailed John and he always replied to me within minutes when timing between Texas and GB was not an issue.
He gave me tons of advice and free hints how to pinpoint the problem and do the necessary repairs. I never played with the fuel injection system on my car and that is what we found and I assume other older 928's have similar issues.

1. I checked all the gounding points and found that the "master" ground connecting for the LH-ECU to the engine block had some high resistance issues.
The factory soldered all the wires into the connector but there was some serious corrosion over the years.
2. John offerded me instantly to send me a rebuilt MAF to try if it improves the idle issues. If that was not solving parts of the problem he would give me the money back and I only pay the shipping. Excellent! John found out later after he received my old MAF that it was 2% out of tolerance and this caused the engine to run about 10% to lean all the time.
3. The biggest issue however was the LH-ECU! John's ECU tester had some serius issues with my cars computer. The actuator test that activates and tests the injection valves, idle stabilizer, flappy and other ECU controlled components refused to work correctly! The test always started and stopped at step #2 (idle stabilizer test). The stabilizer moved and the tester was unable to get the ECU to continue. ONLY when the idle stabilizer pin was disconnected from the computer by means of a small piece of tape the test ran through.

The idle adaptation also refused to work correctly and never completed itself no matter what John and I tried. Again after tons of advices and many emails John send me a "loaner" ECU to see if the tester or the computer was faulty. The only thing that I was stuck with at that point was the shipping if the new ECU didn't solve any of the problems.
Turned out that my ECU was dying the well known "slow death" with the new computer all the previous issues were history. If you have never done an idle adaptation on your car... do it. It is unbeliveable how much smoother the engine idles afterwards! (John still tries to find the gremlin in my old ECU)

4. The last issue was and still is the cold start my car idles at very low sub idle RPM for about 5 seconds or dies on the 1st start attempt. It immediatly runs fine when I turn the key the second time! We found that the idle stabilizer is most likely faulty although it seems to work when it is checked with the actuator test function.
When the car is started after it sat for a long time and I wait until it stabilizes a nornal idle RPM (after 10 sec). I can shut it down and let it sit for hours, it will start up with no problem!!! The idle stabilizer has no shut or open position when it's not energized. It simply stays at the position when the engine was shut down. The air demand on a cold engine is higher then on a warm engine. When the engine is stopped after it was warmed up the stabilizer sits in the nearly closed position. My stabilizer must be sticking initially and it takes the ECU a couple of inputs before it opens up. Afterwards everything is fine.

The plan will be to get this fixed during the summer and the manifold and valve covers powdercoated. I will post a follow on what I will finally find...

Why do I write this all? If you have any issues with your fuel injection don't waste your time by playing with it!!! Talk to John he will save you a lot of time and frustration and you learn a lot for free!!! If you never worked with the ECU tester, try it! It is amazing what it can do for you!
Thanks John!

Z

If it's doing that, it's sticking. There's a spring or something inside of it that normally closes it when there's no power going to it. If you've got one off of the car, you can look inside the air passageway you can see the rotating cylindrical piece that adjusts the air opening. If you turn it towards the open position, it'll spring back towards the closed position if it's working correctly. When you take your's off and look in there, chances are that you'll see that the rotating piece is dirty or gummy. Spray something like WD-40 or carburetor cleaner in there and move that piece back and forth, and it'll clean it out and probably free it up so that it moves very easily. Whether you replace it or just clean it is up to you. I've just cleaned and reinstalled a couple of them and they've been working great ever since.

I have to agree with your comments on John Speake and the level of support and service he provides. As you mentioned, he's always very good about and prompt with his communication and in providing information.

Schocki

Tried the trick already with WD-40 and carb cleaner and nothing worked. If you say that it closes why does the car start after it ran for a couple of seconds even after hours? Any ideas?

Z

I wasn't refering to the trick of just spraying the WD-40 or carburetor cleaner into the hose. I had the idle stabilzers that I cleaned like I mentioned off the car and in my hand. I sprayed directly onto the dirty rotating piece inside of it, turned it by hand, and flushed out the dirt with the spray. They rotate very freely, and spring back to towards the closed position instantly, after any dirt in there is flushed out.

I'd guess that you're probably right when you say that your idle stabilizer is sticking initially. When it's completely cold it's more likely to be sticking more as well.

drnick

i can tell you that john is a nice bloke in person too! no affiliation with his business other than having one of his rebuilt MAF in my 86. not long after getting the SE i called john for advice and he offered for me to bring the car around to his house and take a look which we did. most helpful and knowlegable with an ability to explain some of the electrical gubbins as we went along.

Peter F

I was in contact with John before buying my GT and he was really helpful.
Gave very quick answers to my questions and showed a deep knowledge.
Will for sure use his services when my MAF and ECU needs to be rebuilt.
This seems to be needed sooner or later on our cars.
Have recommended people on the local Porsche Club to use his service, and they have been very pleased.
Also very impressed by his diagnosis tool he developed for a fragment of the cost for the original hammer.



/Peter

Schocki

I used the cleaner initially and then used the actuator test to make it move while I sprayed more cleaner into the hose. I can't visually confirm that the valve is not gummed up anymore when installed obviously.
I also thought about a slow vacuum leak but I can still move the HVAC actuators after the car sat overnight with the ignition on before I crank the engine. Any ideas?

Tony

Ok. Question.

I know it slams shut when power is off, but how does it open?

Does it slowly rotate open....

or..

does it cycle open and close rapidly almost pulsating and regulating the air by pulse lengths?

Lagavulin

John Speake:

John Speake

Bu**er, I wondered why my ears were burning...

It was great working through these issues with you Schocki. I'll let you know what I find on your old ECU - when I have time to check it thoroughly.

Although the ISV is spring loaded, a faulty one "may" not spring back as it should ?

Regards