Installed a boost gauge on a recently purchased '94. I'm getting more of a 10-8-14 pattern. I know solenoid/actuator issues can cause some interesting boost patterns. Does anyone have any ideas or have had a similiar problems yourself?

Thanks for any and all help.

 

Did you take the pill out?

 

Yup - no wastegate pill most likely.

Is the car stock?

 

What exhaust system does it have?

 

I was under the impression that removing the pills lowers boost?

 

Completely stock, engine and exhaust.

Thanks for the quick replies.

 

No pills will give you 7 psi essentially running off spring pressure. Check both lines that have the pills in them from your WQ and prespooler. If 1 side is torn before or after the pills it will cause boost spikes as well as cause the car to lag and get louder so to speak.

 

If your car is a 100% stock, it should be hitting fuel cut at 12psi. It does sounds like boost spike to me. Do 94+ have restrictive nipples vs pills?

 

Your impression is right.

While the pills limit the pressure to the actuators, the ECU also controls boost by cycling the WG and Precontrol solenoids. So, if you remove the pills and cap the lines going to the solenoids you should have rock bottom boost.

I would suggest 1/4" fuel hose with a bolt clamped in the end rather than vacuum caps for capping the lines. Vac caps will rupture and then you've got overboost again. You can also insert a ball bearing into the solenoid soft lines with dish soap.

Precontrol effectively controls your boost pretransition and the wastegate controls it after. So if your pretransition boost is fine, then it could be the wastegate lines, actuator, or solenoid.

 

That's what I thought, but I have been told by some fd vets that in lower gears the stock ECU can not cut fuel fast enough to keep up with pressure. I have also experienced the exact thing my self. Fuel cut in 4th/5th gears only. Scary!

 

You are right - brain working backwards today!

My stock was boosting to 13 psi when I bought it for no reason that I could spot. I had to use a larger than stock pill to control it. You should get a boost controller before driving again. A cheap manual one will do.

 

14PSI blew my motor on a stockish setup

watch out