[Jfmoore79]

I have been chasing some increased fuel trims happening at low to moderate RPM. Ted Jannetty has pointed me towards a vacuum/boost leak or issue with the MAF sensor. I took all the Procharger charge and intercooling pipe apart to ensure tight connection and removed and cleaned the MAF sensor. I’m going to do some logs without the front bumper in case I have to pull it all apart again so speed and gear will be low. What trim numbers should be in the normal range at idle and low rpm?

[JANNETTYRACING]

Originally Posted by Jfmoore79

I have been chasing some increased fuel trims happening at low to moderate RPM. Ted Jannetty has pointed me towards a vacuum/boost leak or issue with the MAF sensor. I took all the Procharger charge and intercooling pipe apart to ensure tight connection and removed and cleaned the MAF sensor. I’m going to do some logs without the front bumper in case I have to pull it all apart again so speed and gear will be low. What trim numbers should be in the normal range at idle and low rpm?

I am always happy to answer your questions.

Fuel trims should be negative between -1-3%

We had that then all of a sudden the next log was Plus 10-15% which indicates some sort of air leak in the PCV, catch can, intake etc.

You said you found a vacuum line off but there was no difference on the next log so that indicates a bigger problem.

Ted.

[Jfmoore79]

I smoke tested the system and found it to roll out of the bypass/surge valve. Not sure if that is to be expected or not? I suspected the intake but could find no leaks by that test. In the old days you could spray some brake cleaner at each intake port and see if idle or sound changed. Is that still effective on modern cars? I could also bypass the catch can system and see if that solves the issue which will be my next option.

[JANNETTYRACING]

Originally Posted by Jfmoore79

I smoke tested the system and found it to roll out of the bypass/surge valve. Not sure if that is to be expected or not? I suspected the intake but could find no leaks by that test. In the old days you could spray some brake cleaner at each intake port and see if idle or sound changed. Is that still effective on modern cars? I could also bypass the catch can system and see if that solves the issue which will be my next option.

No it is not an effective way to check with fuel injection.

[Jfmoore79]

Should the gasket on the bypass valve be pushed out this much? I cant remember what it looked like before installation.

[Jfmoore79]

Originally Posted by JANNETTYRACING

No it is not an effective way to check with fuel injection.

Thanks Ted, I was pretty sure that was a no no.

[JANNETTYRACING]

Originally Posted by Jfmoore79

Should the gasket on the bypass valve be pushed out this much? I cant remember what it looked like before installation.

Looks about right but you can test it with a vacuum pump and see if it holds or leaks.

[Jfmoore79]

Originally Posted by JANNETTYRACING

Looks about right but you can test it with a vacuum pump and see if it holds or leaks.

Will do. I want to lean toward the catch can being the problem but since it has been on since the supercharger was installed I’m looking to something more severe. Should I pull the intake and see if a gasket/o-ring is torn or blown?

[JANNETTYRACING]

Originally Posted by Jfmoore79

Will do. I want to lean toward the catch can being the problem but since it has been on since the supercharger was installed I’m looking to something more severe. Should I pull the intake and see if a gasket/o-ring is torn or blown?

Best way to test,

Fabricate a cap for the supercharger inlet, pressurize with compressor 15 psi you will find leaks you never thought possible.

[Jfmoore79]

Like this but with a fitting to add air? Maybe use a pvc cap?

[Jfmoore79]

Or probably this

[JANNETTYRACING]

Originally Posted by Jfmoore79

Or probably this

Exactly

[Jfmoore79]

I think Ill have to make one since the most common sizes are 3.5” and 4” and the inlet size of the Procharger is 3.75

[Dysan911]

Of course it's out of stock at the moment but maybe you can locate one.

https://www.ebay.com/itm/3-5-To-3-75...-/312401911237

This is the coupler I used. One end fits the inlet on the supercharger and the 3.5in end was a common size that I could find a PVC Pipe endcap at a local hardware store to hose clamp in the inner diameter. Drill a hole at the endcap and pop in a rubber tire valve. Voila!.