New guy w/serious idle issues

[James87]

I will start by saying I have only had HPT for a couple weeks now, so I apologize for my ignorance and will try to keep this brief.

I have a 5.3l/4l80e swapped GM squarebody I finished up a few months ago. I sent off the PCM to be tuned for the engine mods listed below.
From First start til now, I have been battling nasty random misfires (P0300), fouled spark plugs, and the exhaust reeks of fuel.

I replaced the plugs, plug wires, MAF, and O2 sensors with no change. I have also swapped injectors, and moved coil packs around with no change (Cylinders 2,3, and 6 are the main culprits).
If I hold RPM's to say 1400, it smooths out and my misfires disappear.

So in my wanting to get HPT for a while anyways, I decided to pull the trigger thinking this would be a great opportunity to get use to the scanner and help troubleshoot this truck.
I found the RussK Idle-airflow config and used this to log the truck at idle. Problem is, I don't quite understand what I am looking at or how the PCM is using this data to make other changes. It is very frustrating to look at the log knowing something isnt right, but not knowing what to do or how to proceed.

So, can someone take a quick look at this log and let me know what you, from a tuners perspective, see here? I feel like if I keep running the truck, something will break soon

Engine is a Gen III DBW LM7 with the following:
Isky cam 206/212 dur. @.050, 25X/26X lift, 112+4 LSA (-15° overlap)
799 heads stock with appropriate valvetrain for above cam
Longtube headers and 2.5" exhaust
CAI
Mail order tune


Thanks in advance for any help!

K10 BASE + DTC DELETE.hpt Idle-Airflow.cfg Idle-Air scan (high IAC).hpl

[leamangriffin]

wiring issues maybe? Not sure why the log isnt showing Long term and short term fuel trims or Intake air temperature, or 02 duty cycles. those things have a lot to do with diagnosing these problems... and Im not too sure about the drive by wire setups but why is it showing 16% throttle at idle? Are you holding the pedal down?

[mowton]

Gotta run out, but its not a 5.3 LM7 tune. Need to get with your mail order tune guy or download the correct tune to start. Try this updated ,cfg to get more data. The RussK will log your LTIT and STIT and develop the changes needed to be made to your Idle Desired air for non-moving (Adptive) idle. Check all wiring per above and the new log will shed more info on whats going on.

Idle-Airflow erm update.cfg

Will look more when I get back.

Ed M

[leamangriffin]

yeah definately need to get the tune sorted out. the tune in there now is for a 6.0 Also Maybe its just me but your target idle above 100degrees seems low for a cammed engine. the correct tune should fix your issues to be honest because the pinouts for a 6.0 Litre could be different than the 5.3L

[James87]

wiring issues maybe? Not sure why the log isnt showing Long term and short term fuel trims or Intake air temperature, or 02 duty cycles. those things have a lot to do with diagnosing these problems... and Im not too sure about the drive by wire setups but why is it showing 16% throttle at idle? Are you holding the pedal down?

I haven't ruled out a wiring problem yet. I was hoping to get a better handle on the scanner and use that to point me in the right direction of where a problem could be. I will probably start checking wiring this weekend. I have confirmed all my grounds are good though.
The 16% TPS was from a cold start. Once it warms up, it will drop to around 9 to 10%. I wasn't touching the throttle at all. Does that sound about normal for DBW? I was under the impression that it was. That being said however, I am starting to think I may have a bad throttlebody. I noticed in my log that the IAC counts were maxed @ 310 from first start to 175°F when I stopped the log regardless of what was desired.

mowton,
Thanks for the cfg! Once my little girl wakes up I will try to get a log for you. I have to go to work soon, and working between a 4 month olds nap schedule so time is limited lol.
The base cal is based on a 2500 silverado with a 6.0. I believe this was done because I am running a 4l80e and an odd PCM? That way engine and trans can be controlled? I could be very wrong on that though.

New log coming in a few, thanks guys!

[James87]

OK guys, the log is attached. So, before I did the log, I unplugged the battery because I read that that will reset all trims and I haven't tried that yet. The truck seems to idle better with a slight miss, but unfortunately I now have an audible metallic "chirp" that is very intermittent. I have never heard this before, but it does appear to be coming from a pulley. I also noticed the my B1S2 o2 is staying at around 450mv, That is Stoich correct? That is also a first, as it has been switching like normal in all my other logs. Could it be fouled? I have 2 brand new spare Denso o2's, so I may switch it out tomorrow.
I have to get to work, so I will respond to any suggestions tonight. Thanks guys!

[mowton]

I haven't ruled out a wiring problem yet. I was hoping to get a better handle on the scanner and use that to point me in the right direction of where a problem could be. I will probably start checking wiring this weekend. I have confirmed all my grounds are good though.
The 16% TPS was from a cold start. Once it warms up, it will drop to around 9 to 10%. I wasn't touching the throttle at all. Does that sound about normal for DBW? I was under the impression that it was. That being said however, I am starting to think I may have a bad throttlebody. I noticed in my log that the IAC counts were maxed @ 310 from first start to 175°F when I stopped the log regardless of what was desired.

On a DBW setup, there is no IAC. The Throttle Plate is controlled by the PCM which is why you see it is 16% at cold start and slowly closes to 9%. That is perfectly normal. I would ask that you check out the throttle plate to make sure there is no hole drilled in it though....just to be on the safe side. Don't worry about the IAC count.

Also, you need to perform the RussK scan from a cold start to temps reaching say 215-220. Your tune wont begin updating the LTIT until 176 F. If you are running a cooler thermostat, you could lower that value to say 140/150 F.

The O2 sensor has bit the ghost if it is just sitting at 450 mv. It should be toggling between 900 and 100mv.

Will review the logs next...

Ed M

[James87]

Thanks for the info Ed, I will check the throttle plate when I get home from work tonight. I dont recall seeing any when I took it off to clean it recently.
Is it typical for an o2 to just fail completely all at once? Just thinking out loud, but it definitely makes me want to confirm the wiring on that bank. Either way I have new spares so I'll switch it tomorrow and hopefully get a log up to those temps, but I may look into this chirp sound as is has me very nervous.

[James87]

Ed I just took a look at the log again and noticed it was B1S2 that was dead. I don't have downstream o2's so that explains why it reads as such. I Thought I was looking at B2S1 lol. Do you want this logged like that, or do you want me to change it to B2S1?

[mowton]

Ed I just took a look at the log again and noticed it was B1S2 that was dead. I don't have downstream o2's so that explains why it reads as such. I Thought I was looking at B2S1 lol. Do you want this logged like that, or do you want me to change it to B2S1?

James, my apologies, that was my bad. In my haste I picked the wrong PID and never verified it then sent you the bad .cfg. Yes, you want to log B2S1.....

Again, sorry.

Ed M

[James87]

No worries bud, I will have the log tomorrow. I just wasnt able to swing any extra time to mess with it today.