Tonytheturbo

Last night just installed the new spring, went for test drive and just when I felt the car was about to literally take flight then BAM, I lost all boost while my head almost hit the steering wheel. After some research I'm assuming the cause is the boost pressure switch located on the IC. Can anyone else comment on this problem? My car is a completely stock 1991 C2 Turbo with about 70,000 miles on it. I'm in southern MD and it was about 41 degrees last night when I attempted my run.

Mike Andrews

That's exactly what happened.

You have done one of two things. You have managed put the wastegate in a bind (or tore the diaphragm) when you installed the spring or do not have the pressure pipe hocked back up to the wastegate properly.

I guess there are other things that could have happened but that's where I would start.

Staffan

I don't agree, think the cut out switch was activated, very common when you install a 1 bar spring.

First of all I think you should get a proper boost gauge so that you know what kind of boost you have, you could kill your engine in no time with to much boost.

Second you need to deal with your cut out switch.
There are a number of ways to deal with this:
1. Get a new stock cut out switch they tend to get "soft" over time, but it might not solve your problem

2. Get an adjustable cut-out switch, search this forum and you will find information on what's available and at what pressure it should activate

3. Relocate the cut out switch so that it reads manifold pressure instead of pressure inside the intercooler, perhaps in combination with 2., this is what I will do, currently waiting for delivery of my adjustable switch

4. Ground the wire connected to the cut out switch, VERY VERY BAD idea, adjustable pressure switch is cheaper every day of the week compared to an engine rebuild

5. Get a 0.9 bar spring instead

6. Get an EBC (Electronic Boost Controller), I have one, works great, running 0.85 on the track

Flachbau

What cut off switch is that? Are you talking about the rev limiter?

Tonytheturbo

Replaced pressure switch (OEM Part) went for test run and I now have full boost and an extremly fast car, boy what a difference! Thanks for all the help. See you all on the 23rd.

VinnyC

Since the thread is already going, is the 1 BAR spring a "safe" mod or is it asking for trouble? Without any tunning of air/fuel etc. is the mod dangerous on a stock motor?

Now that tonytheturbo replace the pressure switch, it is likely it will happen again?

Sameer

1 bar is safe with a healthy engine, good fuel, adequate cooling-additional oil cooler.
The 964 turbo S 3.3 and the flachbau comes from the factory at 0.9 bar of boost. Now is the factory going to offer you a 0.9 bar spring if 1 bar is not safe? Dont forget these cars dont leave the factory after being put thru a lot of stress during their research and developement. 1 bar is fine with the correct elements mentioned above in my first sentence.

Staffan

It's the fuel cut-out switch, located to the right of the boost pressure sender (and you know where that one is ) at the back of the intercooler. It grounds the fuel pump as long as the pressure isn't too high. I think it's calibrated to activate between 1.1 - 1.4 bar. If activated it shuts down the fuel pumps.

You can really feel when the fuel cuts out, teeth marks in the steering wheel kind of thing, very different feeling from when the rev limiter kicks in.

Staffan

Great stuff!

Lexlyf

Where in Southern MD are you located?

Tonytheturbo

Lexlyf, I'm in Charles County in a small town by the name of LaPlata. Most people have heard of Waldorf which is about 8 miles north of me.

Lexlyf

OK. Very familiar...Waldorf, LaPlata, Port Tobacco. I'm closer to 495/ 5 on the PG County side by AAFB.

Tonytheturbo

I work at AAFB and for a minute there I thought I had the only 965 in Southern MD, by the way Lexlyf nice ride! When do you drive it and are you going to the big swap meet this month?

Lexlyf

I am seriously contemplating going. If I do, it will be a "day trip" for me. As for my ride, thank you for the complement, but it is actually an '86 911 turbo with 964/5 90's body updates down to the mirrors. It even has a G50-5 speed transplant. I hope that doesn't "ban" me.

It's one of the "items of interest" that caused me to fly to Seattle & drive the damn thing back across country to here in Maryland. It has really been an adjustment period for me b/c the car itself attracts way too much attention. Sometimes even the negative type from bodine (aka feds, federal"ies", 5-0, po po, State Po, Park Po, Johnny Law, jump out boys, the jump out squad, police, etc.; I think you get the point lol!).

At any rate, I'm suppose to get my car back from Curry's in Chantilly, VA on Monday (rear trailing arm & rear wheel bearing replacement). We should link up in your neck of the woods, as I love Southern Maryland. The roads are smooth and the view is even more beautiful. I'm contemplating building a house down there or on the Eastern Shore.

Hit me up one day.
markensmith@comcast.net

Woodster

If car is totally stock, doesn't additional boost create alot more heat and not alot more
power?? My point is that you are not getting full benefit, you NEED headers, no cat and
low restriction mufflers otherwise you are not accomplishing much. Remember H.P. is
never cheap. just my $.02 worth (since I tried all these things).mk