Forge BPV and knock

[spec2k5]

I tried to search, but can never find what I am looking for. I have an 07 MS3 and just installed a Forge BPV. I also have a Mazdaspeed CAI. This is my first turbo car and my first car that I have modded. After installing the Forge, I have noticed I am having knock. I noticed it going to 2.1, but might have been a little higher. Is this a problem? does this have anything to do with the Forge? I did not notice knock before I installed the forge. I am running blue spring with 2 shims.

 

[chief_wiggum]

The CAI is your only other mod?

I found that for my car (SRI/TIP) that yellow +1 shim worked better. I initially started with blue no shims, but then went to yellow +1. According to Forge's website, the yellow spring is the one designed for our stock boost range. You might try swapping out the blue +2 for yellow + a shim or two and see if that changes your knock. In case you haven't, I'd also reset the ecu.

good luck.

 

[08cosmic3]

For stock set up Forge recommends the blue spring, with intake add 1 shim. I would start with blue only. Knock at low rpm while cruising is common on this car. Where you don't want knock is under heavy boost and high rpm. The spring info on Forge"s web site is incorrect for our car, so says Patty at Forge.

 

[spec2k5]

The CAI is your only other mod?

I found that for my car (SRI/TIP) that yellow +1 shim worked better. I initially started with blue no shims, but then went to yellow +1. According to Forge's website, the yellow spring is the one designed for our stock boost range. You might try swapping out the blue +2 for yellow + a shim or two and see if that changes your knock. In case you haven't, I'd also reset the ecu.

good luck.

Thanks for the response. I went ahead and tried the yellow plus 1 shim and the knock was even worse. I saw 3.2 at 15 psi. I will try blue plus 1 tomorrow and see if that is better. Thanks again.

 

[spec2k5]

For stock set up Forge recommends the blue spring, with intake add 1 shim. I would start with blue only. Knock at low rpm while cruising is common on this car. Where you don't want knock is under heavy boost and high rpm. The spring info on Forge"s web site is incorrect for our car, so says Patty at Forge.

What knock is considered not safe for this car?

 

[coyfish]

NEver heard of a bpv causing knock . . .

 

[spec2k5]

NEver heard of a bpv causing knock . . .

Me either. Maybe the car has been doing it this whole time and I never really noticed. I guess I just decided to check it today for some reason.

 

[PCspeed3]

Does your CAI have an airflow straightner? If not you should get one, clean your MAF and reset you ECU. Then see how she blows.

 

[spec2k5]

Does your CAI have an airflow straightner? If not you should get one, clean your MAF and reset you ECU. Then see how she blows.

Yeah, I have an airflow straightener in the CAI. I will reset the ECU since I changed it and see what happens and then clean the MAF. I am starting to think I have always had knock, but never paid attention before.

 

[coyfish]

Are you using the right gas ???

How many miles on your car??

 

[spec2k5]

Only use 93 octane and the car has 48,000 miles

 

[coyfish]

maybe you need new plugs ?