boosting at idle

Tbirdsc Colonel

Registered User
After a hard accel if I let it back down to idle the engine will start boosting up to 5 psi and the engine seems like its going to die, then it will kick up to about 1500 and bounce between 300 and 1500 for a while until it dies (boost remains between 0-5psi). Then it starts back up agian no problem at all. Could this be the Tps or Iac sensors
 
no boost

you should have no boost at idle ...it would seem your bypass valve is stuck closed ...check vacume line to the diafram[spelling]..on the bypass valve ...if not the case could be plugged exhaust from bad cats ..creating way too much back pressure...it's not electrical....dave
 
Thanks Im going to try to get a video of what my gauges do. I htought it might be the bypass but when it was idling normal I pulled the bypass butterfly manually and it didnt even move the boost gauge. which i thought it would. I am going to try to get the video on by this evening.
Thank you please check back I need some advice, no one around here has any idea
 
No my mods are

Aluminum jackshaft Pulley
Under Drive Pullies
Aluminum Driveshaft
Centerforce 2 clutch
Ripper shifter
3.27 Gears
Zr intake
73mm Maf
70mm Tb
Mp Plenum
S port Superchager
3/4 Raised top
5% OD
Mp Fmic
Intercooler sprayer
Ic fan
Magnecore 8.5mm Wires
Be Cool aluminum radiator
2-2.5 3.5 2-2.5 exhaust
Magneflow 2.5" in 3" out
Dynomax muffs
Headers midlength
High flow cats
255lph fuel pump
ac DELETE
condensor removed
 
Could Be just gauge problem

This happened on mine that the boost gauge would stick. The hose Ford used on these is a very small , "hard" plastic tube. Mine had gotten clogged with some oil that I assume was coming from the EGR circuit.

I replaced the entire hose with I believe 3/16 fuel line hose and have not had any issues since. Taking the dash out is a bit of a job if you've never done it before so allow yourself about 3 hours for this job. (To remove the dash, you have to loosen the two bolts that hold the steering column "up").

To see if this is the problem, try removing the hose connection on the engine intake for the boost gauge. It is located on the driver's side close to the firewall.

Good luck.
 
Thanks but thats not it, I tried unplugging a few different vacuum line and it made no differances. It idles fine most of the time, just after it goes into boost its like somethign sticks once and a while. After that it idles down really hard and eventually will die. I took a video today of what happens, but the boost does not go positive in this video but it has before. Is it possible for the IAC to stick open or closed? I hope to have the video on tonight but at latest tomarrow.
 
video added

This is what happens after a hard accel. I pushed the clutch and just let it idle down, that is the engine recovering itself
 
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I guess the file is to big. I you think that seeing the video of what the gauges do please let me know and I will email the video to you or if someone could host the video that would be awesome as well. Headski12@aol.com
 
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The only way that boost can go positive is with a restriction. I would consider a clogged exhaust by way of bad converters. Just a suggestion. The idle and gauge issue may be just coincidence.
 
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