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View Full Version : Boost goes to 1-2 psi above 2200 RPM??



96turboSuburban
01-06-2005, 06:21
Now that I have gauges for boost and egt I can see that almost no matter the load or condition my boost goes down to 1-2 psi above 2200 rpm. I have a new fsd/fsd cooler from JK and the JK boost controller and have stayed with the vacuum actuated wastegate. I have the boost turned 2 turns clockwise and it gives me approx. 13-15 psi at max. but as soon as I hit the 'magic' 2000 rpm she backs right down to near 1 psi. Is this a function of the main computer to back psi almost completely off at 2200 rpm??? :confused:
Thanks for the help!
I'm fairly new to modifying my sub.
Todd

JohnC
01-06-2005, 08:58
Originally posted by 96turboSuburban:
...as soon as I hit the 'magic' 2000 rpm she backs right down to near 1 psi... Sounds like the PCM is detecting too much boost and dumping the wastegate. Below 2000 RPM the PCM does not control boost. If you're seeing that much boost below 2000 RPM, something is amiss. Make sure the wastegate is not frozen shut and that the solenoid is plumbed correctly. Also, the solenoids used to be a common part to fail, but seems not so much any more.

(on further consideration, unlikely the wastegate is frozen if it drops at 2000...)

MTTwister
01-06-2005, 11:16
You might try screwing up the Boost fooler, so the PCM doesn't see the excessive boost above 2000. Just count your turns, so you can return to 'normal'. I have my homemade fooler set to 2000 Ohms.

96turboSuburban
01-06-2005, 19:46
Thanks Guys!
On furthur inspection I have in fact found that she will boost up to 12-13 above 2200 rpm when cold only, as soon as everything heats up to operating temps, she dumps most all boost above 2200 under moderate to heavy throttle pressure.
I'll try suggestions on boost screw and let you know!
Todd