JE928Sx4.

Did a swap of an LH computer into my 88S4 that has ben stalling and running rich. Started like a champ with no stalling, but I'm guessing from the smell and the soot that now comes out the tail pipe it's running even futher to the rich side now. I'm guesing I've got a bad computer and something else.

This sucks.

heinrich

JE, maybe she's just puking all that pent-up soot from all the coughing?

JE928Sx4.

That would be nice, but I don't thnk so. The smell of raw gas in the exhaust is stronger now than before.

John Speake

Was it a known good LH you swapped in?

JE928Sx4.

It was supposed to be and has been used for testing on other cars. The car ran better in many ways, just more rich (which it was previously doing along with some stalling) to the point of producing soot in the exhaust which it wasn't doing before (the exhaust cloud was more grey than black and no soot with the old computer).

Thanks for your advise John, and thanks for lending Jon Holdsworth one of your rebuilt MAFs for his demo at last years Frenzy. By the way, I can swap out a known good one of those. Do you think I should give that a try?

heinrich

Being no expert I suggest trying a battery disconnect for a while. Then try the replacement MAF.

JE928Sx4.

I'll give that a shot, I have to borrow it from my buddy I just sold the 86.5 to.

Drewster67

Contact Rich Andrade, for all your LH controller needs, at www.electronikrepair.com or send him a PM - Rich9928p. He has it going on with controller repairs -
Quotes Taken from his website:

Common symptoms of a failing LH injection module:

- (Porsche only) Fuel injection valves click when the ignition turned is on and engine is not running
- Engine will not run at idle
- Air-fuel mixture is too rich (this can damage catalytic converters)
- No fuel pump operation, but the fuel pump operates when its relay is jumpered
- The engine will not rev higher than 3000 RPM
- A/T cars: no idle speed regulation when switching between drive gears and neutral or park
- Engine will not start, spark plugs are dry and the ignition system


Thanks

JE928Sx4.

Thanks Drewster,

I've already spoken to Rich who is a friend of mine from our both attending Euro 928 the last two years. If I can positively identify that my computer requires a rebuild, he will be doing it.

John Speake

JE,
MAFs can develop a thermal problem that means the mixture gets richer and richer the longer and harder the car is driven.

It's a design fault that Bosch corrected eventually.

The O2 loop circuits are also part of the dreaded "tile" in the LH ECU, so this is a strong possibility as well.

I assume this car is a recent acquisition, so there is quite a bit of checking to do ? You know, the usual Temp sensor 2, O2 sensor ?

JE928Sx4.

Yes it is new to me and so is the S4 model and these pro9blems. So I have alot of schooling to do and little time to do it in.

Drewster67

Cool - Rich and I hang out at the track quite a bit, your definitely in good hands.