Engine question
 

Hi everybody;
I've got a '79 930 with a modified engine - rebuilt with 3.4 pistons, SC cams, Kokeln turbo and intercooler, BB exhaust etc.
The car did not even run 1k miles before I bought it and I like it more everyday.
What worries me is a strange behaviour under partial throttle when on boost.

The engine starts skipping and jerking as if it would hit the rev limiter on and off with a frequency approximately twice a second. When I floor the throttle it goes fast and strong.

It seems to be happening more easily when going uphill - I think.

Is it normal? I think not. Bad fuel delivery? starvation? I don't know.

Could you guys give me your thoughts?

Thanks,

Sounds like either a boost leak or ignition issue. I'll bet you have a leaking o ring at the IC.

Welcome to the forum!

If you really want to get some answers and establish dialogues, you MUST FIRST post some pictures of the car and engine bay. FYI, that's rule #1 here for new members.

Sorry, I did not know this rule. Here are some pictures:


http://forums.pelicanparts.com/uploa...1347743822.jpg
http://forums.pelicanparts.com/uploa...1347743839.jpg
http://forums.pelicanparts.com/uploa...1347743851.jpg
http://forums.pelicanparts.com/uploa...1347743871.jpg
http://forums.pelicanparts.com/uploa...1347743888.jpg
http://forums.pelicanparts.com/uploa...1347743906.jpg

I am very impressed with the knowledge you guys have. I am a car enthusiast doing as much DIY as possible for me, but I am totally unfamiliar with the turbocharging and this is my first turbo; I just enjoy immensly the way this car drives and how directly responsive it is (no turbo lag to talk about really).

Please help me with my problem.

PS Let me add I have an enhanced Fuel Distributor from Fuel Injection Corp. in Livermore, CA part # 810027, whatever it means.

Nice car!

For me, it sounds like a fuel issue, too lean I suggest. Get an AFR meter and check, good help for diagnosis...

Yes, I suspect leaness at miniumum throttle. Mine has always had this issue - AFR off scale at 16 under light throttle. When you give it a bootful you get a fuel dump, which cures it - but bit hard to drive between lights like that :-).
This opens up a heap of discussion issues - like what fuel system, what WUR, are the settings right etc.
Alan