Turbo tuning issues/questions

E Ray · 09-06-2002, 06:22 AM

OK, I have issues with the turbo, took it out a few weekends ago and I ran like a champ, a few days latter it started running crummy, sputtering off idle, hesitating in low/mid range, just kept getting worse and worse, over 4K to 7K runs like a rocket. The car is a ’78 euro 930, new motor 3500 miles, 964 cams, 7.5:1 comp, k2700 turbo, EBS valve job with racing springs, new cap rotor wires and new green dist wire, all new filters, tuned in January, and ran great. I have been trying to track down the problem and have been coming up empty. Have checked fuel pressures twice, all within spec, No apparent vac leaks, however the vac retard unit on the distributor has a very slow leak but it works, could this be the culprit? Are these vac units available (same as SC?) w/o buying a whole (euro) distributor? How do you get the old one out?

I’m thinking injectors next, but over 3-4k it wants to scream to 7k so its getting fuel, right? Bumped the mixture richer a bit but no change, was set for smog check at .01co but ran great then.

Ideas?

Thanks

Eric

Eric

dean · 09-06-2002, 01:27 PM

I doubt it is the vacume unit on the dist. I think that is a vacume retard for emissions. I think they all leak a little. Mine does.

Have you checked you cintrifigal adv.? If you have a factory manual, it has all the specs to check out your dist.

Those vac units are availble aftermarket for around $30

To remove the vac unit, remove dist., unscrew vac unit and pivot the pot up.

E Ray · 09-07-2002, 11:52 AM

Centrifical advance checks out, just checked it again.......this is driving me nuts everything seem to check out ant it runs great above 3K..........

Any othet Ideas?

Thanks

Eric

dean · 09-07-2002, 02:35 PM

One way to check for vacume leaks is with a vacume gauge. Have you done that? What are you pulling for vacume at idle?

E Ray · 09-07-2002, 03:56 PM

8.5"hg at idle, 850rpm, taken with a "t" in in the vac line to the distriburor, it jumps to 12-13"hg with tha vac retard diconected and the line pluged, approx 1100rpm...........

Played with mixture this afternoon.....no change lean to rich......Ideas?

Eric

dean · 09-07-2002, 04:29 PM

I think you have a vacume leak. That is not enough vacume. It should be more like 12" with the pot connected and 18" disconnected.
Do you know how to look for a leak?

E Ray · 09-07-2002, 05:21 PM

Oh yea, Vac leaks, its a way of life with the Mercedes.......I'll be all over it tomorow.....Thanks

Eric