Overboost When Cold?

[Hi-psi]

I've had a boost bypass/overboot eliminator valve from Diesel Site on my truck for years.

When the ambient temp is warm outside and/or the truck is at normal operating temp, the truck will not overboost and defuel. 24-28psi no problem.

However, when it's cold (ambient temp mid 30's or lower) and/or the truck is not fully warmed up (within 10 mins of startup) it will overboost, defuel and set the SES light.

Is there something in the ECM which lowers the boost threshold (limit) for overboosting when the truck is under a certain operating temp or is it simply possible that when the air is cooler/more dense the boost is coming in so quick that the Diesel Site boost bypass valve just can't vent it off quick enough and the MAP is still seeing enough psi to set a normal overboost condition?

Trying to determine if it's just something I have to deal with, or if changing my boost bypass approach will correct the situation.

Thanks in advance.

[ttyR2]

Beats me. Mine won't make much boost until the temp gauge starts rising when it's cold out.

[OregonStroker]

EBPV could be the issue.

[Hi-psi]

Originally Posted by OregonStroker

EBPV could be the issue.

Negative. Not there. Removed/gutted.

[OregonStroker]

Thats a tough one. I think your prognosis of a denser charge could be the issue. Mechanical boost foolers are touchy. You may pop in a 4.7v Zener Diode. Works tremendously good. (IF you cant fix your mechanical fooler). Is there adjustment?

[Hi-psi]

Nah, no adjustment on the Diesel Site valve. It's essentially a spring loaded pop off valve.

May throw an adjustable one on there and see if it makes a difference.