Boost leak..All suggestions welcome...PLEASE!!!

[1SIK930]

I'm having a problem with boost leak. I have a 1.0 bar spring in the wastegate, yet I step on the gas pedal and the boost peaks to .8(highest .9) then, while still fully on the gas pedal, I watch as the boost needle starts to drop off. I've changed all the o-rings on the I/C, I've checked the hose leading to the wastegate, and still nothing has fixed it yet. All suggestions welcome, it's driving me crazy!!!!!!

[WERK I]

What turbocharger and muffler system is in the car? Is there a catalytic converter on the car as well?

[1SIK930]

K27-7006, not sure which muffler, but no cat. When I bought the car a couple of months ago, it boosted fine. The only thing I've messed with on the engine is adjusting the timing so it would pass smog. It was way off. I adjusted it with a timing light and followed the directions on the engine lid. I put all the hoses back on the distributor.

[WERK I]

Stock ignition or aftermarket?
What was the timing before and after?

[1SIK930]

Stock ignition. Where the timing was supposed to be 26 degrees btdc it was 14

[WERK I]

To pass smog (what state?) a lot of people, myself included, had to adjust the idle mixture screw down (more lean) to pass smog. Unfortunately, this also leans out the top end. Once the car passes smog, the idle mixture is cranked up and up goes the richness. Idle mixture wasn't touched?
What year of 930 is the car?

[1SIK930]

CA. For smog I have a cat that attaches to the turbo, for the sniffer. But they also check to see if the timing is right. They will not pass it if the timing is that far off. Any suggestions on where to start looking for my boost leak?

[cole930]

J,

Your car is a 83 euro, timing should be 29* at 4000 rpm. (vacuum hose disconnected)

Wastegate springs are seldom dead on with an original wastegate. Wastegate seat could be seating badly and therefore bleeding off some boost, diaphram could be pinched lo leaking.

Check for leaks by spraying started fluid around any hoses, Oring joints in the boost and intake system from the fuel head to the wastegate.. You do this with the engine running and if there is a leak the idle will speed up for a few seconds from sucking in the starter fluid.

Cole

[1SIK930]

It's an '87, US car. I'll try the starting fluid trick. I just hope it's something that leaks without pressure. Any other suggestions? Before I open the hood, I'd like to have a list of things to try. Thanks

[WERK I]

The reason I asked all the questions about the exhaust is that excessive back pressure will cause the symptoms you just described. One guy on the board found he had a loss of boost because his cat disintegrated and clogged up his muffler.
It would be nice to know what is stock regarding the engine and what is not. We know you have a different turbocharger (k-27 7006) and stock ignition. It always helpful to diagnose a problem if we know more about the patient.
Also, I'm a firm believer in "cause and effect". The last thing you did to the engine was change the ignition timing......that would be the first I area I would check.

Put your hand over the output of the wastegate and see if you can feel any exhaust pressure.

[1SIK930]

It's got a 3.5L Andial conversion, twin plug heads, bigger cams, Andial I/C. I only know what I was told by the previous owner. I can only confirm what I can see externally. I don't know the details on the internal. I know it has stock headers, ignition(other than twin plugged heads), and fueling(other that an Andial fuel enrichment switch). I don't know what brand the muffler is, but I know there's no cat. If you need to know any more, I will answer with best of my knowledge. I've worked on a lot of turbo charged rice rocket cars, this German car is new to me. But I'm learning a lot as I go. I also put a K&N filter on the intake, but that was after I started having boost problems.

[WERK I]

Sounds like a very nice engine. One last question, I promise.
Is the distributor a twin-distributor setup (like the Porsche 964 engine) or is it a single-cap, 12 lead distributor? Andial usually recurved their distributors, with their advance curve, with or without vacuum or boost retard.
Do you have any pics of the ignition, engine, wastegate setup?

[1SIK930]

It's a single cap with 12 wires. It has 2 vac lines coming off of the distributor. These are the only pics I have of the engine bay



These pics were taken before I replaced the rubber mounts on the I/C and the o-rings. Could my decel valve cause boost leak?

[WERK I]

If there are two lines coming off the distributor, one may be for boost retard and the other for vacuum advance. Could it be you got the two lines mixed up when reattaching to the distributor after setting the timing?

[RarlyL8]

Nice engine!
I'd put the timing back where it was and observe. Could be that your distributor has been modified or your timing marks are off.

[mooney265]

What is the "breather line/filter" on the driver side connected to?

[JFairman]

vent hose from the origonal turbo sump tank that went to the origonal air filter housing in that spot.. most likely.

[mooney265]

Originally Posted by JFairman

vent hose from the origonal turbo sump tank that went to the origonal air filter housing in that spot.. most likely.

I don't have a vent hose on my turbo sump tank? Just an oil feed in [from top] and oil line out of the bottom/side...???

Should I have one? Where would it be connected?

[mooney265]

I was talking about this line... BTW... So, you're saying this is connected to the Turbo Sump somehow?

[JFairman]

yeah i know.. if you don't have a vent line then you don't have the origonal sump tank, or if you do have the oem turbo sump tank it's been capped off or you havn't found it yet.