evotino

My check engine light has been flashing (knock) in 4th or 5th when full boost kicks in. I filled up with Shell 93 and I'm wondering if they gave me some bad gas. Has anybody had this problem with Shell?

BTW, knock barely ever goes above 15 and boost is not spiking. It must be the gas. What's up with Shell?

j8

iTrader: (4)

I am no expert, but the cooler weather we have been seeing will make the car run a little leaner. You may need to remove some timing or add a little gas in the cells you are seeing knock. 15 is actually pretty low from my knowledge. Does not sound like much to worry about.

robertrinaustin

iTrader: (5)

Along ths same lines as Jason, what boost are you running and what are you using to control it?

evotino

When I said knock usually doesn't go above 15, I meant before I started seeing the CEL. I just got a new tank at Chevron and I'm having the same problem. In 4th or 5th gear, 2/3 or more throttle, and as boost peaks I get knock. The highest value I saw was over 100.

My boost is set at 1.5 and the highest peaks I'm recording are 1.55. I'm using the Apexi boost controller...the one that comes with the Power FC package.

j8

iTrader: (4)

That sounds like true knock. What RPM are you seeing knock? You most likely need to adjust those cells and reduce timing, add fuel, or you can lower your peak boost. Did you get it tuned professionally when it was installed?

evotino

I've had it for about a month now. It was dyno tuned by a local shop that does great work. I didn't have this problem until last week and I can't think of anything that changed, other than the temps.

As long as boost isn't spiking from the duty cycle being too high I thought I would be ok. Doesn't the PFC have intake temp correction?

j8

iTrader: (4)

Evotino,

I would just take the car back and have them check it out. I am sure it is the shop I know up your way. I am sure they would be more than happy to help you out. The temps outside can make a big difference in tuning. The Power FC to my knowledge does not have the ability to reduce timing when you hit knock, so you need to adjust timing from time to time as temps go down or you run more boost. Like I said I am not a expert, but I do run the Power FC on my car and have to make occasional adjustments to it.

evotino

Actually, I did change something which should help prevent knock. Last week I installed one step cooler Denso plugs.

j8

iTrader: (4)

Evotino,

The plugs are not going to do to much. Try runing your lower boost setting and see if the problem continues. It is most likely to much timing. I would personally take it back to my tuner to have it checked out. Just to be on the safe side.

Karash

iTrader: (6)

its your tune tbh...I know the stock tune for example will knock bad as its looking for high octane japanese gas.

evotino

Thanks guys. I'm calling him tomorrow and I'll let you know...

j8

iTrader: (4)

Good luck hopefully everything works out.

evotino

I'm going in Saturday morning. I'll get this worked out.

BTW, I just switched my stock tranny fluid to Motul and WOW what a difference in shifting! For those of you who haven't switched yet I definitely recommend it. The dreaded 1-2 shift is much smoother and easier to engage.

robertrinaustin

iTrader: (5)

The PFC does have intake and water temp correction. It can make timing adjustments for intake temps over 50 degrees and water temps over 85 degrees.

robertrinaustin

iTrader: (5)

Also, I forgot to add that you need to try to make note of what rpms the knock kicks in just in case the tuner can't get it to knock. Form your description, I would guess around 4000 rpm.