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86 944 turbo boost issues

Old 06-11-2018, 09:47 PM
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jagdhund
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Default 86 944 turbo boost issues

So I drove my stock 86 turbo 1200 miles from IN to CO. It got extremely hot from the trip and with about 100 miles to go I had a sudden loss of boost pressure/"pull" while flooring it in third to pass someone.

Currently the whole car seems much slower in low RPM's. It takes about 10 seconds for any boost to build while flooring it in first gear (could be the altitude though). Once reaching 3000 rpm it quickly builds boost like normal (and sounds normal) but then quickly stops at about 1 bar and never gains anymore boost. I seem to recall it going past 2 bar (on the OEM gauge BTW) before.

I had planned on doing a lindsey racing 300 kit after the trip anyways but I would hate to still have this problem after all the new parts.

Could I get some help as to how to try and start diagnosing this? I didn't quite understand what was being talked about in threads I searched with similar issues so I thought it would be better to start my own thread.
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Old 06-12-2018, 11:47 AM
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Dash01
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If you're still in CO, the density altitude difference will play a part in lost power, in addition to whatever else may be at issue.
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Old 06-12-2018, 12:47 PM
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Dan Martinic
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Originally Posted by jagdhund View Post
So I drove my stock 86 turbo 1200 miles from IN to CO. It got extremely hot from the trip
Hmm.. I've taken my 951 on long trips and never had it radically change temperature by the end. This doesn't sound right. How do you know it got extremely hot? Did the temp needle suddenly show a higher than usual reading?

Anyway, one winter I had this odd problem of boost suddenly cutting out (ie. dropping to 1 bar on dash guage which is effectively no boost). It also did this if the engine was wet like after a hose down.

I changed the distributor cap and haven't had the same symptom since
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Old 06-12-2018, 07:19 PM
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Is the acceleration smooth, but slow, or is there signs of misfire?
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Old 06-15-2018, 07:38 PM
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jagdhund
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Originally Posted by Dan Martinic View Post
Hmm.. I've taken my 951 on long trips and never had it radically change temperature by the end. This doesn't sound right. How do you know it got extremely hot? Did the temp needle suddenly show a higher than usual reading?

Anyway, one winter I had this odd problem of boost suddenly cutting out (ie. dropping to 1 bar on dash guage which is effectively no boost). It also did this if the engine was wet like after a hose down.

I changed the distributor cap and haven't had the same symptom since
I would check oil at every fuel stop and the dip stick (including the plastic) was too hot to touch. The coolant temp never showed over temp but I've never had the engine bay that hot.
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Old 06-15-2018, 07:39 PM
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Originally Posted by Tedro951 View Post
Is the acceleration smooth, but slow, or is there signs of misfire?
It is still smooth but very slow and very low boost. no misfires.
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Old 06-15-2018, 08:12 PM
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Check for a collapsed exhaust manifold or crossover pipe.
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Old 06-15-2018, 09:23 PM
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Cycling Valve, or sometime parts companies call it the timed valve... Vice Grip the Wastegate hose. If you get all sorts of boost with the vice grips odds are the cycling valve just failed...
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Old 06-16-2018, 12:23 AM
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shortyboy
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Check intercooler hoses for leaks or vacuum lines for leaks
​ Pretty common for these age of cars. Also, Wastegate might have tear in diaphragm..
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