PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

New motor, strange first log.

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Old Jul 1, 2011 | 07:56 PM
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Default New motor, strange first log.

To start off it is a 383 stroker, Pat G custom 238/246 cam, FAST intake, TFS 215 heads, lucas 42.5# injectors. Running SD, MAF deleted.


Used RTV (not an entire tubes worth, possibly too little) and new grommet on the MAP and resealed the FAST with a new rope seal and rtv after porting (removed the wedge in the intake runners) and new FAST port seals and throttle body seal.

First thing i noticed was the car was alot rough than it should be above 1500rpm. While checking the log i noticed MAP kpa was at 94 no matter what the throttle angle or rpm of the motor. Could the MAP be loose and leaking enough in the FAST or could i have an intake leak i need to deal with?

The other question i solved myself, was seeing only 3 degrees of timing but researched and found that without the MAF, the pcm only uses the low octane timing table.

Everything else seemed normal, A/F was between 14.8-13.5 depending on throttle angle and o2's were switching when engine got to temp.
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Old Jul 1, 2011 | 08:46 PM
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Are you getting any codes for the MAP sensor? What tuning software are you using? This is how I seal the MAP sensor. It works perfect with no leaks.

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Old Jul 1, 2011 | 09:31 PM
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No codes, no SES light, thats the weird part. Tuning with HP Tuners v2.22. Might try that idea out for holding the MAP down.

Might the MAP also be broken?

Being at 94 kpa would be nearly zero vacuum (big leak) and i definately had the brake pedal sink to the floor when starting each time, showing that there obviously is vacuum to the booster.
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Old Jul 1, 2011 | 10:44 PM
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i bet your map sensor is bad, i doubt it would idle with a huge vacuum leak. check the wiring and the sensor.
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Old Jul 2, 2011 | 06:13 AM
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Appreciate the help guys, tore the intake off this morning and found out the ground wire for the MAP was just sitting there outside of the back of the connector. Looks like i got to get a new pigtail now. Glad it wasn't the FAST!
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