Is it even possible that I had KR values as high as 80-90?

[Langning]

I bought a ScanGauge II 3-in-1 scanner for my 2001 3.8 GT for a couple months now. One of user-programmable gauges displays "KR (in degree)". I started noticing that KR value fluctuates from 0-80 (even 90s in a few occassions) whenever my car is traveling on inclines while I am giving gas. As soon as my foot is off the gas pedal, the value goes down to zero. I am seeing (less frequently) double-digit KR on accerlerations on level surface too. I don't notice of any driveability issue, trouble code, or hearing any strange engine noise other than my mileage is 22-25mpg vs 24-26 a few years back.

I tried switching from regular Mobil to Mobil 91 (no difference), then Shell 91 (slightly lower KR values) and I am using regular Shell now.

So today I swapped out Autolite AP606 plugs with Autolite APP605 (3 hours job ) and took a test drive. Same result and the KR shoots up as I gave it gas. As far I can tell, my car runs fine!

I don't have a second GM car with ODBCII (VPW protocol) to test my ScanGauge scanner with; my other GM car is of CAN protocol which the custom gauge uses different parameters... So my question is it even possilble to have high KR values like mines? Or is it just a false/incorrect reading by my scanner?

I really like this tool http://www.scangauge.com/support/xgauge.shtml. However, the high KR readout is really bugging me the last 2 months.

[tblake]

hmmm, are you running regular gas right now? Should always be running premium 91 or higher octane in a GTP. Do you have any modifications?

Might want to doublecheck the heat range numbers on the plgs you installed. I thought that the higher number, the colder the plug with autolite plugs. But I'm not sure.

Rich, Bob, GTPDad????

[BNaylor]

Wow! Now that is whacko! The KR figures he is getting doesn't sound right. You'd have driveability issues with that much KR. Since it is a GT N/A 3800 I wouldn't worry about it unless it can be confirmed with a program like Autotap or a scan gauge like the Aeroforce which are accurate based on my experiences.

Probably the scan tool being used.

[Langning]

I have a 3800 GT and 87 octane is the correct gas. AP606 is the correct plug for my engine. Before the AP606, the car came with Delco 41-921.

Today I put in APP605 (replaces Delco 41-919,41-910) which according to the posts here, is colder and should help lowering KR.

Because the way ScanGauge works by having the user entering sets of parameters, I can't be sure if the parameters provided by ScanGauge people is correct. ie. the parameters for ODBII/CANSF protocol don't work wity my wife's 05 Chevy Equinox. I want to know if the scanner is giving me false readout.

[Langning]

Originally Posted by BNaylor

Probably the scan tool being used.

Thanks, I will ignore it for now.

[GTPpower]

So you get kr values of 80-90??

If you do, something isn't right. The PCM limits kr to I think 25*......or maybe it's 20. I don't remember for sure, but it's way less that what you have.

Do you have a link to the scan gauge you bought?

[richtazz]

check for catalytic converter blockage. The added backpressure can throw KR values out of whack when using a generic scan tool. If your car has under 120k miles on it, the cat could be covered under a GM extended warranty due to known problems with 01-02 cats. This would also explain your loss in fuel mileage and the readings being worse under acceleration than when off the gas.

[Langning]

The cat. convertor was changed once under warranty in 2005. Shortly after, I received the letter that the warranty coverage has been extended to 120,000 miles. And as of yesterday, my car has 114,622 miles on it.

To compound the problem, my local Pontiac dealership closed and it is not easy to go other Pontiac dealerships due to child-care and work-commute... Do you think I can have my Chevy dealership perform the warranty work should my cat. convertor be the culprit?

CONVERTER, OXIDATION CATALYTIC - REPLACE
07/19/2005
Your GMGoodwrench Dealer
47,895
$0.00

[BNaylor]

The readings he is getting are impossible. With the 80-90 degrees there would be big time driveability issues for anyone that has experienced hi KR especially with GTPs with boost mods or done any competent level of testing with known accurate products like Autotap or the Aeroforce scan gauge. The engine will stumble and it will feel like a severe misfire or engine cutting off. For very degree of KR it takes .8 seconds recovery time. So as an example 15 degrees KR would require 12 seconds for the ignition timing to be restored to pre KR levels. Do the math with 80-90 degrees.

Try a scan tool capable of accurately reading out KR that works first before jumping off the cliff.

[Langning]

I found a post on another forum that other ScanGuageII users are having the same problem. So my KR value may have been only as high as 8.0 to 9.0 degrees. Most of the time, the readout is between 15 to 60 or (1.5 to 6.0 factoring in the missing decimal).

I know with a scan tool sometimes it swill be 33 and actually need to read 3.3. Sometimes the GM stuff will leave a decimal place out there. 33* of KR is non sense. hellbent has had some experience with those stupid capacitor spark plugs and they will show KR with it idling and start pulling timing before you even tough the pedal.

http://www.ls9gto.com/forums/showthread.php?p=3489974

[richtazz]

It's obvious the readings are not actual KR, (but the missing decimal point theory makes sense and puts these readings back to believable), again due to the generic scan tool not jiving with the PCM. I should have started my post with that.

I doubt the cat is the issue again, as the problem arose from the maker of the OEM cats for the years 01-02, and the new converter is of an improved design.

[BNaylor]

Originally Posted by Langning

I found a post on another forum that other ScanGuageII users are having the same problem. So my KR value may have been only as high as 8.0 to 9.0 degrees. Most of the time, the readout is between 15 to 60 or (1.5 to 6.0 factoring in the missing decimal).

http://www.ls9gto.com/forums/showthread.php?p=3489974

I don't think that is right either. I've never seen KR that high on any normally aspirated 3800. Different story if you have a GTP with SC pulley mods. I never got that much (9 degrees?) even with a 3.0 pulley.

Of course there are different categories of KR and when it occurs. Burst, shift, etc. Hypothetically, lets say the up to 9 degrees is correct and therefore a bonifide problem. Maybe you have a knock sensor issue or the KR module in the PCM module has gone South. Maybe it is a false knock. But I find even 9 degrees hard to believe unless you are experiencing driveability issues.

[Langning]

On my commute home after work I was going 65-70 on left lane when a van was closing behind me. The spot at the highway was at 5% uphill when I gave it a bit more gas to get out of the way. My KR display shot up to 102 and I could feel the engine "studder". I immediately removed my foot off the padel, the KR went back down to zero (within 1 second) and "shaking" sensation went away. Did I just experience "Knock"?

I drove the rest of way w/ the slower traffic (at 65 and no hard accerration) and made it home no problem. I felt the engine was slightly louder (but can't be certain), it could be just my head no thinking straight.