Knock issues

[HawkZ28]

I've been doing some scans to work on the timing in my tune, and I am getting KR at oddball times. Tune is done w/87 octane, HO table copied over LO table. 05 Colorado 3.5.

Basically, if I am holding a steady speed or coasting, and then give it gas to maintain speed or accelerate (hard or just to keep speed), sometimes I get .5-5* of KR.

In my logs, I noticed that I also get it at gear change- right when it hits the next gear, I get about the same.

Lastly, I noticed that when my MAP begins to ramp up or ramp down- gradual or otherwise, even when cruising on flat interstate.

I drained the tank down and filled up w/ 91. Knock retard is still there, just not quite as extreme or plentiful. Feels lazier w/ the 91, too. I don't plan on running 91 all the time- costs too much for the miles I drive annually.

Any ideas? Should I start w/ switching to the OE LO table values, and add timing until I hit KR, and then back off 2* or so? Or am I looking to adjust the wrong thing?

[HawkZ28]

Figured it out, in case somebody needs help in the future. I did what Russ K said to do in this thread:

http://www.hptuners.com/forum/showth...d+decay+attack

Desensitizing the knock sensor helped w/ the weird places I was getting KR at. I maxed out retard decay, zero'd out burst knock, and halved the base retard.

[jackedupcanyon]

If I can ask a favor, scan misfires with the stock settings and again with the Russ K settings mentioned above and let me know what you come up with.

Thanks,

[HawkZ28]

Here you go- this is 1/2 of my drive home running 87 octane again, and the Russ K settings.

[jackedupcanyon]

Did not see that you were scanning misfires in any of the files above.

[HawkZ28]

My bad, thought I had it logged already in the scanner.

Here's one w/ the Russ K settings. I'll log one w/out the Russ K settings tomorrow and post it up.

Also, this was taken after the truck had already been driven aroud town, and the intake track was still hot from sitting. Made a quick run to the gas station, and logged on the way home. You can see the IAT's lower as the log goes on.

It seemed like I got a couple hits while the IAT's were up, but they went away as they came down.

The KR in frames 694 to 774 are while I was climbing a big hill in 4th gear, converter locked. I expected it as I've been adding to the spark, and subtracting KR as I encounter it.

[HawkZ28]

Here's the latest w/ no Russ K settings.

[jackedupcanyon]

Thanks! Looks like these trucks misfire quite a bit also. Looked like you had more at the beginning of the scan but decreased towards the end. Probably relearning the knock sensor settings. Like my truck, it also appears the majority of your misfires are on decel (hard to tell because you are logging history versus current). Think I am experiencing more misfire because of the extra strain I have put on the truck with the double lifts and larger tires. I also seem to get some misfire when the truck hits a rough part of the road, maybe because of the stiffer suspension??? I need to double check my wiring, coil packs and actual spark plug connections to verify a solid connection. Also need to work on my transients........where I can in this limited PCM. Just trying to eliminate all misfires if possible. Thanks again for help.

[HawkZ28]

Yeah, I adusted that in my config and histos with my latest. It seems that I had more misfires w/ the stock settings.

I don't have anything other than the stock suspension, but my tires are cranked up to 40psi. I wonder if maybe the boots need to be replaced on the middle 3 cylinders. It seems that 2-4 are the worst. 0 to none in 1 and 5. Anyway, I know a mechanic that told me it's always a good idea to replace the spark boots when you do the plugs. I'm running Denso Iridiums that have about 20k on them now. I also need to double check my exhaust and make sure nothing has loosened since I installed it- I've heard of things hitting the exhaust tripping the sensor.

Either way, at least it's not a huge problem, and under accel. Let's hope we get some transient controls (and more transmissioncontrols) in the next release!

Thanks for helping me out, too!

[jackedupcanyon]

I know a mechanic that told me it's always a good idea to replace the spark boots when you do the plugs.

I hate the idea of replacing the coil packs the way they are priced. Maybe your mechanic friend can get you a good price on them. Not throwing any codes so it cant be that bad right now. I also need to inspect my current intake and work on my custom intake. If the price is right I would change them in a heartbeat if I knew they either were or most likely the major reason for the problem.

Let's hope we get some transient controls (and more transmissioncontrols) in the next release!

Good luck with that. Our platform is the red headed stepchild that no one likes and is not in any demand. An additional anything in the tuning software for our trucks would be great but I am not sure how much more HPT can give us on these limited PCMs.

[HawkZ28]

I hate the idea of replacing the coil packs the way they are priced. Maybe your mechanic friend can get you a good price on them. Not throwing any codes so it cant be that bad right now.

Not the coil pack itself, the coil boot-this piece

http://www.rockauto.com/catalog/moreinfo.php?pk=1323634

Sometimes they're listed as a coil boot, other times as a plug boot

I was thinking too- if the injectors are way off from the factory- not matched at all, and you get a couple from the bottom of the flow spectrum, and 3 from the top....the ones that aren't flowing as much could be causing a lean misfire. Do you have a cylinder(s) that always misfire, and one or 3 that don't.

[jackedupcanyon]

Will have to check out the boots then. Not sure how much those will run. Do not think the injectors would be that far off from the factory. Still no codes. Seems to be just about evenly spread between cylinders. If any, 5 may be the least likely to see a misfire. Will have to go back and check the logs. I am still playing with shift points for the larger tires to prevent the chugging and bogging from jumping to a higher gear to soon. I think this is also playing a part in the misfires.

[jackedupcanyon]

0-ohm resistance:

http://www.carparts.com/autoparts/It...52610913931279

[HawkZ28]

Mongo LIKES! I wish that you'd of posted that about 2 weeks ago....that would have been the perfect fathers day present for my fiance and/or daughter to get me LOL!

I assumed aside from a turbo/sc, I had all the aftermarket mods covered. Now I have to buy one more thing .

Also, FYI, I noticed that when I was logging to get my KR in line yesterday, my logs in the afternoon- ambient was 92-94*, IATs ranged 94/96* highway, 100-130* in town, and engine temps of 196-207 w/ a/c running, I got signifigantly more KR, and it seemed MF's too, compared to the a.m. with 75* ambient, 78-79* IATs.

Obviously all the added heat isn't helping, but I wonder if I'm running a tad lean for the summer temps/humidity. It seems like my MAF/LTFT and STFT have jumped postive a bit- changing the filter this weekend to see if it helps. I'm thinking I'm going to go back to my MAF and tune for more of a consistant negative STFT value since I had it ranging -2 to +2 in SD.

[HawkZ28]

Quick followup- I've noticed that my results are almost identical after I 'wash and rinse' the spark table w/ my KR results.

My current tune, I added 7* across the board. Logged 1/2 my drive home, and subtracted the + kr values from both tables (both were HO +7*). Loaded the tune, reset trims, and logged back to town. Repeated at my first the process at my first stop. Drove home through town, looked at KR + values, and they are almost the same, so in some cells, I will have removed almost 15* of timing. I really think that it's false now.

I haven't even so much as heard real knock aside from one time when the converter was locked, 4th gear, 40mph climbing a slight grade. Replacing one of my clamps this weekend on the exhuast- wondering if that isn't a cause of all the KR too- it's as tight as it can go, but I still have almost a 270* leak around the joint- switching from a band to good ol guilitine style until I can get it welded.

Also, my misfires are (I think) due to my trans settings somehow- it won't release the gear in decel, and doesn't release the gear until about 900-1000 rpm, and the 'dashpot' doesn't catch it until it dips down to 400-500 rpm. I've noticed I get a misfire everytime then, as well as when I get deep into DFCO and locked into gear.

[jackedupcanyon]

With out a WB, the changes are not instantaneous! Have to give the truck time to relearn and adjust for the changes. Rule of thumb seems to be about 100 miles but go longer if you can and vary your driving conditions. Going this route will (should anyway) take you a very long time. Without a WB you are just wasting your time.

Yea, most of my misfires seem to be in decel. Will have to look closer at gear changes and release points. I think the DFCO settings on my truck were set to never engage. will probably make sure they are disengaged for at least a while. Not sure if I will ever turn back on. The 33s tend to help to slow the truck down.

[HawkZ28]

I'll have to try once a day then- my commute is 54 miles one way if all I do is go to the 'oriface'. I'll just continue to vary the crap out of my speed, gears, and TP/load. WB is out for a while- at least until mama is off maternity leave.

Makes you wonder why our I5's have this bad habit of missing on decel- design or programming (now that we're tuning/modded) flaw that we don't have access to.

[jackedupcanyon]

I would try to make changes every other day or maybe every 3rd if you can stand to wait that long. The more time you give the truck to learn and settle in - the better.