DasRabe

Had a major scare in my new 951 today. Got on it in second gear and as soon as the boost spooled up (gauge read about 1.6 bar/4000 revs) the engine cuts out and the car jerks so hard it about sends me through the windshield. I let, off and power comes back on. In neutral the engine spins to red with no problems.

I first thought it was fuel related, but low fuel pressure should cause some stumbling first, right? So after browsing the forums on RL I'm now think it was the overboost protection cut off.

Does this sound right? Any suggestions on how to confim or correct this? Thanks.

'86 944 turbo

I would also like to know the problem.

'86 944 turbo

bump

zakk

Certainly sounds like the overboost protection. Do the normal, check hoses for leaks and such.

James86-951

What year is the car? The hose from the cycling valve was broken on my car and I would have the exact same problem on hard acceleration. (My boost guage pegged though.)

alpenweissisnice

This will sound crazy, but here goes: My car has only cut out once before like you describe. Came up on boost, cut out. I rolled on the boost again, cut out again. As the gas tank was almost empty, I filled the car up and the issue went away. It hasn't resurfaced since.

My thought was that the fuel pressure was compromised due to the tank being about empty, and the car cut out. I say this because anything other than WOT near redline I had no problem. I have since taken the same on ramp where the incident occured at the same WOT with no issues.

Was your car about empty?

'86 944 turbo

alpenweissisnice is the Hyperboost Recirculating Valve the same as Billet Diverter Valve?

alpenweissisnice

Yeah, the whole Blow Off Valve/Recirculating Valve/Diverter Valve thing gets funky with semantics. Here goes my cut at it: Blow Off valves vent excess pressure to the atmosphere (the loud PHHFFFTTttt you sometimes hear on certain turbocharged cars.) Recirculating valve and diverter valves do the same thing: they "recirculate" or "divert" excess pressue back into the intake system, thus helping keep the system pressurized under boost and not wasting pressue already manufacuted by the turbo. (Certainly, if the guru's out there feel I have this wrong - correct me! I'm still climbing the learning curve!)

The stock Bosch valve is known to fail, so many folks upgrade their valve as I have done. Got mine at <a href="http://www.stratmosphere.com" target="_blank">http://www.stratmosphere.com </a> but there are many other good valves. Perry951 made a list of 'em on a recent post; you might do a thread search...

MichelleJD

Mine did this on her maiden voyage to her new home. I looked down after getting on it (thought I was still in my n/a - how stupid of me ) and the rpm's were dropping from near 7000. I just figured it was the rev limiter keeping me from blowing the engine. The speedo was also on the way down from 80-90 mph. I was doing about 40 out of a toll booth trying to get around some idiot pushing me off to the edge of the road. It only took a couple of seconds to be well beyond the speed limit. Haven't done THAT again!

DasRabe

Thanks for the replies. I've done a preliminary check of the hoses and so far haven't come up with anything. The cycling vavle sounds like a possibility as well.

I'll give a run through this evening and let everyone know what I find.

BTW, the car is an '86 951.

led

It happened to a friend of mine in a supra. When he floored it, the fuel would go to the back of the tank (almost empty) and the pump would starve.

p.s. If it read 1.6bar on the stock gauge I believe it's actually .6bar of boost, 1bar == atmospheric pressure (on the stock gauge, no boost/no vac).

DasRabe

Thought I'd post a follow up in case anyone else was experiencing this problem....

After checking everything I could think of vacuum hoses, cycling valve, etc. I was getting really frustrated. Then coincidentally, I disconnected the battery to install a new CD player. Ever since, I have not had one problem, and the car pulls to about 1.8 BAR.

Must have reset the computer somehow. Go figure....