20 PSI Feels like 5 PSI, What the heck!!!

[guyd_15]

The boost gauge indicates 20 psi, but the car doesn't push you back in the seat, well just barely. The car is an 88 CSXT, 2.2, G valves on the swingvalve actuator and MAP sensor. Loosened the MAP sensor G valve, boost drops to 15 PSI, car still feels sluggish. Checked the intercooler hoses no obvious leaks. I don't believe it's a bad boost gauge because we run both the factory and an Autometer and at 20 PSI indicated by the Autometer the factory gauge gets pinned.
Thanks,
Guy Douglas

[cordes]

The boost gauge indicates 20 psi, but the car doesn't push you back in the seat, well just barely. The car is an 88 CSXT, 2.2, G valves on the swingvalve actuator and MAP sensor. Loosened the MAP sensor G valve, boost drops to 15 PSI, car still feels sluggish. Checked the intercooler hoses no obvious leaks. I don't believe it's a bad boost gauge because we run both the factory and an Autometer and at 20 PSI indicated by the Autometer the factory gauge gets pinned.
Thanks,
Guy Douglas


Perhaps it is pulling timing like it's nobodys buisiness.

[guyd_15]

How can I check to see if timing is being pulled? I don't have a scanner, is there another method?

[guyd_15]

Some more description
I'll check the base timing tomorrow. I don't believe it's the timing though. The engine pulls over 15" of vacuum at idle and has good throttle response through out the rpm range. The boost gauge is connected to the vacuum block. We have a full tank of 93 octane. The ignition system factory coil, new Magnecor wires, new Champion RN9YC lugs, new distributor cap and rotor. Not a hint of ignition problem, no break up under high boost pressure. A/F readings by Dawes indicated a lean condition at 15 psi so we turned the first additional injector on at 14 psi, we have another secondary injector ready.
Guy

[cordes]

What cam are you running? that vac would be low unless you are running a more wild cam than stock turbo or TBI cams which could in turn indicate base timing is off.

I am unaware of any way to see if timing is being pulled other than a scanner.

[Una]

A custom cal can be made to flash the check engine light when timing is being pulled..But at that point, you still need a scanner to see if it's 1degree or 20degrees of timing being pulled... Too rich can make the car fall on it's face.. Does the car accellerate better at 12psi than 20?

[turbovanman²]

What kind of turbo and intercooler. I know my larger turbo is slow with my small intercooler, and my track times back that up.

[3nglenn]

I wouldn't think adjusting the G-valve on the Map would affect your boost level itself, just the cut-off/shut down point. I would take the valve out of the MAP line for now and just use the G-valve for the waste gate and see what happens and go from there (back it down of course to start). I use a diode in my MAP circuit with no problems to 15 psi with a G-valve holding it steady there on the waste-gate (88 T2). Might want to check the intercooler itself for leaks. But if your showing 20 psi on your gauge it doesn't seem like leaks are a problem...Good luck and keep us posted. G.P. :thumb:

[supercrackerbox]

I second the pulling timing idea, or possibly a heavy exhaust restriction. What are you doing for fuel at these boost levels? Have you pulled the spark plugs and looked for signs of detonation?

[turbovanman²]

Might want to check the intercooler itself for leaks. But if your showing 20 psi on your gauge it doesn't seem like leaks are a problem...Good luck and keep us posted. G.P. :thumb:

You'd be suprised. I dynoed my van it hit 25ish psi of boost, I thought, Hmmmmmm, thats low. I had to do some work on it in the next few days and saw the ripped IC hose. Boy, did it run harder when I fixed it, :thumb:

[cordes]

You'd be suprised. I dynoed my van it hit 25ish psi of boost, I thought, Hmmmmmm, thats low. I had to do some work on it in the next few days and saw the ripped IC hose. Boy, did it run harder when I fixed it, :thumb:

+1, you would be suprised at what leaks you have in your system some times.

You can make a leak tester for really cheap. I think mine cost about 2 bucks tops.

[Russ Jerome]

Cam timing or ignition retard due to knock.

Boost is boost in manifold, if it were leaking that
bad you would never see 20psi on gauge.

[Russ Jerome]

No mention of 3-bar or big injectors, I know what
20psi in a stock car sounds like driving under a
bridge as WOT with window open ;)

[jre97]

Might be a stupid question but is your clutch slipping? I'd think you'd notice the smell of burnt clutch though.

[3nglenn]

Uh, not stupid at all-good point! My Spirit did just the same thing. Lot's of boost but not much motivation. Worth looking into... G.P.

[cordes]

Might be a stupid question but is your clutch slipping? I'd think you'd notice the smell of burnt clutch though.

I have had that happen in both my cars now. When you notice the tach shoot up like it is nobodies buisiness, but the speedo does not move, it is a pretty good sign that your clutch is slipping.

[guyd_15]

I didn't get to check much last night, I'll be out there again tonite. We did pull the G-Valve out of the actuator line the car felt slightly better at 7 lbs. As far as clutch slippage, when we jump on the gas in third the tach rises steadily with out a jump.
Simon,
We switched the Mitsu for a stock T3 garrett. Intercooler is made of 2 stock cores.
Russ,
Fuel system is 33 lb injectors with two Saab cold start injectors.
Cordes,
I'll put together some type of pressure tester tonite.

You guys are probably right about a timing issue. I'm going to double check tonite.
Thanks for the help,
Guy