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Speed Junkie
 
Join Date: Jul 2004
Location: MI
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1989 930 runs rough above 2000 rpm

Ok, I got the engine running using the jumper wire with the yellow relay. However, when the engine gets up to operating temperature, it runs very rough above 2000 rpm. During the test drive it started to lung/stall as if I were to step on and off the gas quickly and make a back-fire sound. I checked the linkage to the throttle and everything looks good. Any thoughts on where I might start looking?
Old 06-27-2010, 06:36 PM
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start with the basics,,
timing, are all cylinders firing ?
fuel ( AFR ration ? sounds like it's running rich)
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Old 06-27-2010, 07:39 PM
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Speed Junkie
 
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I think it is running rich. How can I check and adjust accordingly?
Old 06-27-2010, 07:49 PM
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Quote:
Originally Posted by 9dreizig View Post
start with the basics,,
timing, are all cylinders firing ?
fuel ( AFR ration ? sounds like it's running rich)
+1^^^^ And after that all checks out, you should also verify that your fuel control pressures are correct. It takes a specialized gauge setup, but really quite simple to check.

While you're poking around back there, you may want to verify that all your intercooler seals and turbo pipes/hoses aren't leaking. One of the possible things that can cause your symptoms is a simple air leak someplace prior to the throttle body....quite common for the o-rings from the up-pipe from the turbo and/or the o-rings for the intercooler connections to tear or dislodge. Air will leak out at those points and cause a very rich mixture, getting more and more pronounced as you step on the gas. And as a matter of course, check all vacuum hoses as well. 90% of the time it's something so basic and obvious.

After 6 years of storage, I'm wondering on the general condition of the fuel system. Might be all gummed up inside? I would say to run some fuel injector cleaner in your tank, but I'm not sure if it will disolve real serious varnish. Did you put in a new fuel filter since taking her out of storage? Do you know for certain that both of your fuel pumps are running?
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Last edited by mark houghton; 06-27-2010 at 08:09 PM..
Old 06-27-2010, 08:01 PM
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Speed Junkie
 
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The fuel head was rebuilt and modified by Imagine Auto, 4 years ago and sat in a plastic bag until I installed it 3 weeks ago. The fuel filter hasn't been replaced and is 6 years old. Both fuel pumps are running and I am running fresh 93 octane. I replaced hoses and o-rings with new ones and checked for leaks prior to install. I've got all 6 cylinders firing with plenty spark. Is there a way to adjust the fuel mixture? I do believe that it's running rich, especially with the modified fuel head?
Old 06-27-2010, 08:39 PM
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Your fuel head was rebuilt and modified by CISFLOWTECH for Imagine Auto and as far as I know they were all set to flow 20% over stock unless you asked for something different.
Now you go directly to CIS Flowtech for fuel head work.

Brian Leask's adjustable warm up regulator to adjust the mixture better and a vacuum solenoid in the boost hose going to the WUR operated by an rpm switch will get it running real good. Adjustable 930 WUR Website

There are other electronic add ons for the control pressure circut that have been found to work too.
Old 06-27-2010, 09:50 PM
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Speed Junkie
 
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Are these devices that I have to run in order to get the engine running correctly?
Old 06-28-2010, 04:09 AM
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Speed Junkie
 
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The reason I ask is that I have a spare stock fuel head that I could run until I can afford to buy any additional devices. And hopefully get me on the road for this weekend.
Old 06-28-2010, 04:20 AM
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If you haven't had your car re-tuned after having the fuel head built to flow 20% more fuel as Jim mentioned, then I would think you're kinda shooting in the dark. At this point I would say an adjustable WUR is probably a must. You can go digital, or you can go with a modified/adjustable WUR per Brian Leask for about half the cost of digital.

Yes, you could right now start messing with your base mixture adjustments via the adjustment on the fuel head itself, but that won't give you the tuning needed across all conditions of running. Plus, I would be reluctant to mess with the mixture there until you first have a means of knowing what your AFR's are doing (a wide band AFR monitoring system, or your basic tail-pipe emissions/CO tester at a minimum). Or, if you're good at it, then tune by ear at idle. I guess you could slap on your spare "stock" fuel head to get you going and to confirm that the issue is indeed with your new fuel head.
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Old 06-28-2010, 05:55 AM
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