KR at WOT after intake

**hensleya1** · 08-20-2013

Just as the title of the thread says - I'm running a '99 GTP with 210k which (had) zero degrees of KR at WOT until I built and installed an open cone intake. After that, I got 2-4 degrees at WOT above ~4k, which was not solved by installing a downpipe. Adding a bottle of 104+ octane booster didn't do anything to reduce KR, either.

No DTC's except for P0140 (rear O2 sensor that I pulled when installing the downpipe), and I just put in new spark plugs and wires.

Video: Accelerating up the onramp - YouTube

The gizmo up front is a Linear Logic scangauge which is showing (on the right side) AFR and KR.

I guess I should be asking if this is false knock? I'm really itching to do a pulley drop.

**Bio248** · 08-20-2013

the octane booster didn't add any octane so that was a waste of money.

was the weather different on the days where you noticed more/less knock?

**comatoast** · 08-20-2013

That 104 booster is garbage. As is most octane booster. Your not at 104 anything. I'd be surprised if you added 1 point to your system. ( 93 pump with booster would be 94 octane ). If you have access to race gas, add a few ( 3 gallons) , then fill up with pump ( 91-93 ) more than likely it will go away.

Also how hot was it ( ambient temp ) when you run an open cone the intake temps tend to shoot up real quick. Which would lead to kr as well.

Even on a 99 I would suggest headers before any pulley drop. And even after headers I'd only drop to a 3.5 max.

**hensleya1** · 08-20-2013

That's the goal I was hoping to achieve with the octane booster - add a point or two and see if it reduced the KR, so I could at least diagnose the problem. I have access to race gas and can give it a shot, but at $6 a gallon it isn't a permanent solution. I'll have to see if it changes anything, though, and report back.

Ambient temps were in the low 60's. Ambient temp has little or no relation to the amount of KR I'm getting - I've seen it on cool nights and blazing hot days in roughly the same amount - always 2-4*.

**Bio248** · 08-20-2013

well, something has changed. what kind of HAI did you go to? do you still have a MAF screen?

**hensleya1** · 08-20-2013

Originally Posted by Bio248

well, something has changed. what kind of HAI did you go to? do you still have a MAF screen?

Bio248--

Changed the stock box to this guy:

The MAF screen is still there. The MAF sensor was replaced about a month ago (about 2 weeks before I put the intake on).

A thought: Could the intake cause the system to run too lean? (I'm already seeing AFR at 11 at WOT though?)

**comatoast** · 08-20-2013

The intake/ air setup does change the aircoming in but 4* seems a bit much. The tune would dial in the Afr and maf, but it still deems a bit much. Pit a 3.6 on, or until then put 3 gallons of race gas in. At the very least you will find out if its false kr or not, and more than likely will really like the results. My setup is pretty stock. Overkill PCM, no cat no res, 605s 180* stat and a shift kit. Even on stock pulley I see kr. I add some 110 to it and its all gone plus its never boggy, throttle response is great and it really does seem to make the car run better.

**hensleya1** · 08-20-2013

Originally Posted by comatoast

The intake/ air setup does change the aircoming in but 4* seems a bit much. The tune would dial in the Afr and maf, but it still deems a bit much. Pit a 3.6 on, or until then put 3 gallons of race gas in. At the very least you will find out if its false kr or not, and more than likely will really like the results. My setup is pretty stock. Overkill PCM, no cat no res, 605s 180* stat and a shift kit. Even on stock pulley I see kr. I add some 110 to it and its all gone plus its never boggy, throttle response is great and it really does seem to make the car run better.

comatoast--

Currently on the stock pulley and stock tune. Are you saying that a canned tune (dhp, Intense, etc.) would dial in the MAF/AFR better and reduce/eliminate the KR?

**blueguy** · 08-20-2013

Still have a U-bend?

Bringing in more air.

Still can't get rid of it.

Go have an exhaust shop hack that out...bet that would solve the KR...or a downpipe in general...3"...

**hensleya1** · 08-20-2013

Originally Posted by blueguy

Still have a U-bend?

Bringing in more air.

Still can't get rid of it.

Go have an exhaust shop hack that out...bet that would solve the KR...or a downpipe in general...3"...

blueguy--

That's why I'm confounded-- I installed a 3'' downpipe and it made no difference in KR.

**blueguy** · 08-20-2013

I don't read details, hah. Flip the dog bone mounts?

Are the lower mounts shot causing contact between the downpipe and sway bar? Also, just toss the front of the box out...the PCM will sit on the fender and not move...did that on both my cars. If you're worried about that then you can get a Blazer/S10 PCM tray...they bolt right in.

**comatoast** · 08-20-2013

Originally Posted by hensleya1

comatoast--

Currently on the stock pulley and stock tune. Are you saying that a canned tune (dhp, Intense, etc.) would dial in the MAF/AFR better and reduce/eliminate the KR?

My intense tune sucked. My overkill PCM is much better and is probably the best IMO.. In the same scenario, same gas, same weather same temps my overkill PCM cut my kr in half. I would usually see 5-6* kr with stock PCM now I barely see more than 2* ever. If I do see more its usually crap 91 gas that causes it, as we only have one station here with 93.

So to answer your question. Yes a canned tune PCM will help performance and reduce kr, but will not kill it all. I don't think will ( overkill ) touches the maf tables unless you have him tune for a cam, I/c, or other major mod. Fuel tables are left untouched as well I believe.

**matt5112** · 08-20-2013

04-07 cars aren't a fair comparison because the PCM commands overly aggressive timing.

If better fuel doesn't help the knock, then mods won't. Likely there is something else wrong that is causing the PCM to believe there is knock. See Blue's post for more.

**comatoast** · 08-20-2013

Regardless. Add 3-4 gallons of 105+ race gas. You should not see one tenth of a degree of kr.

**blueguy** · 08-20-2013

Not practical though.

Band-aiding isn't the best option either.

**spazzz** · 08-20-2013

Isn't the front of the old air box more of a heat trap after the cone install? I would think it would stop a good chunk of incoming air.

**TLSheff** · 08-20-2013

I wish I had access to race gas. Closest track is about 60-75 miles away. Unless I can mix in jet fuel? We have a airport with fueling station for them...
would that work? haha

I have a similar issue on mine, stock pulley, intake, SD Headers, DHP1.0 but still seeing 4-5* KR. Need to drive around and see about a 93 station, most I've seen local are only running 91 and none of them work better than the other for getting rid of the KR.

**Iceman6669** · 08-20-2013

I am going to agree with Blue and Matt... I think there is prolly another issue somewhere that is causeing KR. I run a very similar intake but without the bend... I even had my tuner check the MAF frequency to make sure my MAF numbers were not skewed and they were fine. I dare say it has little to nothing to do with the intake.. But like said about remove all the stock airbox for better/cooler air flowing to the filter..

**hensleya1** · 08-20-2013

Originally Posted by Iceman6669

I am going to agree with Blue and Matt... I think there is prolly another issue somewhere that is causeing KR. I run a very similar intake but without the bend... I even had my tuner check the MAF frequency to make sure my MAF numbers were not skewed and they were fine. I dare say it has little to nothing to do with the intake.. But like said about remove all the stock airbox for better/cooler air flowing to the filter..

Iceman66969--

I tried searching for this but came up with nothing - exactly how is the other half of the stock air box removed? I couldn't figure it out for the life of me (and if I can pull it off, I'll add a larger filter at some point).