KR Situation

[mechguy]

03 GTP with mods per my sig + 104 plugs. 103k miles. All data given below per aeroforce, no wideband. No DTCs are present.


While cruising the car is perfect, fuel economy is normal, and the car was great prior to mods.

Seeing a lot of KR under even moderate acceleration, or more or less anytime MAP is more than 2 PSI. KR builds fast even at 1/2 throttle with boost, so I let off immediately upon seeing that. Cmdd AF is still 14.7 though I think, and timing drops to about 14*.

In 2nd gear at 3000 RPM, moderate acceleration, shows no KR yet but is giving off a noise like a cross between a dog chattering its teeth and somebody holding a big paper flapping in a strong wind. I quickly let off. Not SC coupler noise.


Long trim bank 1 fluctuates positive and negative a few numbers, averages zeroish during cruise.


O2 mV under cruise is anywhere from 80 to 900 during cruise, if you even care.

False knock possibility: IIRC sway bar was a good 1.5" from the DP. O2 was about 0.5" from firewall insulation, and the wires have not sheared off so I don't think it touches. You can remove and install an O2 without budging the DP.

Have been in and out of hospitals for 2 months with little time to tinker, which is why I created a thread for help. Many threads like this, but very few OP's post their solution.

Checking plugs would the first thing I do, so what else?

[mechguy]

Also, no misfires recorded.

[matt5112]

I had this issue when having my top swap tuned for the first time.

it was the ICM.

However we saw some misfires.

[Dtrick22]

I don't know a whole lot about tuning, but as far as the noise goes it could be your cat going out. (If you have one) Mine is rattling like you describe under light throttle

[mechguy]

I don't know a whole lot about tuning, but as far as the noise goes it could be your cat going out. (If you have one) Mine is rattling like you describe under light throttle

Forgot to mention catalytic is deleted.

[mechguy]

I had this issue when having my top swap tuned for the first time.

it was the ICM.

However we saw some misfires.

Thanks, I'll have to try an ICM. Would an L36 ICM be the same, anybody?

[matt5112]

yeah.

I got my replacement from an L36.

And the other couple i grabbed from the yard were all from L36's.

[Bio248]

the sound you are describing sounds like detonation, but if you werent seeing KR it leads me to believe you're crazy. i always like to say that detonation sounds like popcorn and if you can hear it there is a lot.

however, when were you doing this? was the car up to temp (the knock sensors dont even turn on until 160*)? when the car knocks, is your TCC locked up?

[mechguy]

the sound you are describing sounds like detonation, but if you werent seeing KR it leads me to believe you're crazy. i always like to say that detonation sounds like popcorn and if you can hear it there is a lot.

however, when were you doing this? was the car up to temp (the knock sensors dont even turn on until 160*)? when the car knocks, is your TCC locked up?

I do all my evaluations when the engine is at operating temp. And yes, in any gear when my RPM reaches 2800, TCC unlocked, I hear the popcorn noise. The gauge shows zero KR at that time.

I see KR by accelerating moderately with the TCC locked. Or from bypassing the popcorn phase and using boost.

Again, no recorded misfires, and I cruise 100 miles per day lately.

[Bio248]

you sure its not just the sound of your intake gulping in air before you get to boost where the blower whine drowns it out? if your knock sensors are working and youre not seeing KR then you shouldnt be detonating.

[mechguy]

Bio, please. One thing that comes to mind is that it could be the stock SD header flex. But I thought most people noticed that ticking at idle.


Matt: Did replacing your ICM cure both the KR and the tick-popcorn noise?

How much time to replace an ICM?

[Bio248]

ticking normally is heard until light to medium throttle.

[mechguy]

If it is header ticking, the whole game changes. Then I simply have a knock monster to deal with. No unassociated repairs such as ICM needed.

[matt5112]

without being there its difficult to diagnose.

When my ICM was bad it started missing after 2 psi, and kr resulted.

Swap ICM, (picked up a few for $5 a piece) and it ran fine.

[SlowNA06]

Bet's on vac leak.
Also, clean your MAF and make sure it's plugged all the way in.

[mechguy]

Bet's on vac leak.
Also, clean your MAF and make sure it's plugged all the way in.

Cleaned the MAF sensor and checked for vac leaks but found none. Still, as continuous improvement I will want to be replacing vac hoses and elbows. Also checked a couple plugs and they are in new condn, but maybe a touch cold. Double checked that plug wire routing is not interfering with other wiring.

Anyway, no improvement yet. Next step will be to try a little race gas or toluene to know for sure if it is false or real KR.

[98gtp]

Checking a couple plugs is no good, as you may have a faulty / bad plug. I did in ~ 10000 km with iridiums, cracked porcelain. When I first got the car it did the same thing (as well as all cars I testdrove) ended up replacing the plugs 3 months later when the code finally triggered, and what a difference in performance.

[blueguy]

What heat range plug?

Too cold of a plug can cause a misfire...but I doubt it would cause KR.

[01gpgt01]

sounds like a tune issue and an exhaust leak. If the leaks close enough to the rear 02 it can toss it off. Would be helpful to see a scan

[mechguy]

Also checked for exhaust leaks and found none, although those may be difficult to detect.

As the in the first post, they are A104 plugs. For straight highway driving or driving without boost, those are cold plugs. So when the problem gets fixed they should be OK. They are brand new and showing no recorded misfires, but yeah, maybe I'll toss the old ones in for a try.

And if the tune is too aggressive we will find out when I try VP100.