Turbo16v

I just picked up a 1986 951 with 43,000 original miles. The car has good maintanence history with reciepts for timing belt, clutch, etc. Drove it for a few days and boost seemed a bit weak. Now it is not building any boost at all. Also recently had computers replaced. I tried swaping computers but that didn't change the situation. Thinking the wastegate could be stuck open. Is that common on these cars?? The car sounds like it has an exhaust leak but no visual signs. If it was exhaust leak related, It woudld have to be massive to blead off enough velocity to not spool the turbo. I check most of the vacume lines and connectors. everything seems in order. Any ideas on what to trouble shoot are greatly appreciated. I really don't feel like pulling the turbo.

skene

It's a very common thing for the stock wastegate to go bad. Actually, few of them aren't bad by now. Most people replace theirs with a tial wastegate, lindsey racing wastegate, or some other more modern thing. If you're not getting any boost at all though, it might be something else. I'll let more qualified people answer that one.

jacklet

where are you located in pa

Turbo16v

I'm in NE PA.

chris951

My wastegate is crap, it is shimmed and will only push 14psi without anything to control the boost. I want a tial bad!

Ahmet

I think the wastegates are suprisingly reliable. If you're getting a 'no boost' situation, it's not likely to be the wastegate from my experience. How does the car run otherwise, is it misfiring?
Ahmet

Turbo16v

I have a tial with SFR adaptors that I can try on this car but I wanted some advice before I pull it apart.

KLR

I agree with Ahmet -- they wear out (i.e., don't hold more than 10psi of boost and leak while building boost), but don't usually fail. If you are getting no boost whatsoever, perhaps the cycling valve is forcing the car into limp home mode?

Regardless, it would be wise to replace the wastegate and all vacuum hoses with one of the kits (lindsey, myswiss, etc.). I'd also suggest deleting the cycling valve when doing this and slipping in a reliaboost or similar. All of this stuff is crucial to proper operation of the car and is probably way past due on even a limited use car after 20 years.

special tool

I have said this many times here.
The 951 wastegate is one of the worst wastegate designs of any car EVER.
It was designed as a safety valve and to insure that the 951 was slower than the 930.
If you put a decent wastegate on a stock 951 and change the software, you have a car that dances on the face of a contemporary 930, and then dances with it's wife.
Evidence suggests very strongly.

jerome951

Turbo16V,
There 2 very easy tests to determine if your wastegate is stuck open and/or leaking.

First, with a cold engine, start the car and let it idle and feel hot the wastegate dump pipe heats compared to the main exhaust. If it gets hot rather quickly, the wastegate is stuck or leaking badly.

If you can't tell from the first test that the wastegate is OK, clamp the hose between the cycling valve and wategate and drive the car. Be careful as the boost may spike to pretty high levels. If you're able to make boost, your wastegate is fine.

Although the wastegate design isn't the greatest ever, it is fairly reliable. I would think that a 43K mile gate is OK.

pa944red

I would check all the hoses and clamps on the intercooler piping. It was one of those clamps that was the cause of my car only building 8-10 lbs of boost. Tightened that clamp up and checked all the others one and now I'm seeing the 18 lbs I have my boost controller set at.

How far NE in PA are you?

Tom

Turbo16v

[QUOTE=jerome951]Turbo16V,
clamp the hose between the cycling valve and wategate and drive the car. Be careful as the boost may spike to pretty high levels. If you're able to make boost, your wastegate is fine.
QUOTE]

Where is the cycling valve located? Are you refering to the recirculating (i.e. blowoff) valve? I have been told that the factory bosch ones are known to leak.



Tom, I am located about 20 minutes south of Wilkes Barre/Scranton area. I live near Hazleton if that helps. It's 2hrs West of NYC and 1.5 hours North of Philly.

Turbo16v

To answer some of the other questions, other than the boost issue, the car runs fine. Just runs like a N/A 944. I wasn't leaning toward a vacume issue because the idle is normal. I figured something is bleeding off boost. Either wastegate, relief(blowoff) valve, or hopefully not bad turbo. Will these cars exhibit a normal idle with a large vacume leak?

jerome951

No, it's not the blowoff valve, though those can leak as well.

The cycling valve is located under the intake near the back. You should be able to see a vacuum line running out from under the intake down to the top of the wastegate. This is the line you want to clamp

jacklet

i'm in wind gap in sranton about twice a month ditch the fact. wg and put the tial in if you had it, do a venturi delete check ur diverter valve