Hi -

I've been troubleshooting this for the last month or so and been reading all posts on possible causes. I put in a new Petris Optispark last November and since then the car was running great. One day I noticed a bit of a rough idle while stopped in drive (gear) - auto trans- . Didn't pay too much attention to it and it got worse. Ran a data log and it showed my left O2 sensor wasn't responding correctly. I replaced it with another Denso - both left and right have Denzo's. Now datalog shows both are functioning correctly. Looked @ all plugs on the affected side - left side - they all looked good but the stopped in drive rough idle continues. When I start the car cold it runs great in open loop till it goes into closed loop @ 140 -160 coolant temp per datalog. At stops in idle it idles rough. I turn off the car and restart it - datalog (dl) shows it's now back in open loop and it now runs rough in open loop when stopped in drive as well as when it goes back into closed loop. I'm thinking it is some sort of heat soaking issue so I had the original ICM (I had changed it out with a new AC Delco - used the thermal paste and all - previously when troubleshooting another issue about a year ago) rough idle still there. I cleaned the MAF sensor and tested it while plugged in and unplugged - rough idle remains. Traced all vacuum lines - no leaks. no plug wires arcing (checked @ night). DL shows fans turning on @ 226 deg and the 2nd one @ I think it was 237 deg. Also swapped in a different coil wire with no success.

I'm thinking it can't be plug wires - I'm not certain if those can be heat soaked when the dl shows coolant is @ only 140 - 160 deg. I can grab another set of those and try swapping them (I currently have a 8mm ceramic boot set on). The only other component I have not touched is the coil and the opti. Called Petris, who I got the opti from last Nov, in short they said symptoms don't sound like the opti but he had a family emergency and will be getting back to me shortly. Am i missing something obvious?

I have a couple datalogs but can't seem to find how to attach them - weird - I know I have in the past. Thx in advance for any solid ideas
Anything else here I may be missing that could cause this rough idle in drive once out of the cold start open loop (happens in open and closed loop after engine is warm and restarted)?

Thx, Rick

 

Ok I found the advanced option to attach DLs

 

I'm backed up with a lot of these requests, Gets more complicated because I am having trouble with a less than satisfactory recent eye surgery, and it's very difficult to stare at tiny numbers on a bright screen for any length of time. May take a while. Maybe someone else could jump in here.

 

Injuneer - Sorry to hear about the eye surgery not working out as well as expected. Hopefully there is something that can be done to fix it?

 

What’s the difference between the two data logs, so I know which one to start with? A cold start through closed loop, plus some drive time in closed loop is most useful.

I don’t know if you have seen this previously - post #2

https://www.camaroz28.com/forums/com...-guide-886891/

 

Oh man - now that I read it I remember reading it a couple years ago. I'll run another log this evening with the 4 minute warm up period @ the beginning. I have a new log from today where I ran it with the O2 sensors disconnected to make it stay in open loop just to be sure the issue happens in drive @ idle open loop. I ran this dl before you refreshed my memory on the standard DL procedure. The only thing I didn't do was the 4 minute warm up with this DL.

This attached log is all in open loop
@ 12:16:11(line 988) thru 12:16:37 (line 1053) I was stopped while the car was in drive and the rough idle issue was happening.
Line 1731 thru the end - line 1820 - I was in park and the engine was idling and it was idling rough - this is in park.

The other interesting thing about this DL is it shows a DTC code "16". I saw this 16 - low res failure- a couple other times in other logs I ran within the last month but the car never died like it did in the past (with the previous optispark) when code 16 would show up. Am I jumping to conclusions thinking this opti's optic sensor is the problem here? Maybe this low res failure is leading to complete failure. I'll have to do some research to see what else could cause a 16 code other than the opti.

Just an FYI - I installed a new opti wire harness when I installed this latest optispark.
Thx for any help or input on this. I'll run another log once the car cools all the way off with the O2 sensors plugged back in.

 

If the engine is running, DTC 16 has to be a stored code. It isn’t unusual for the code to set at startup (cranking) if the PCM doesn’t see the low res pulse immediately. If it was an active code the engine won’t run because the PCM shuts down the fuel.

 

Thanks for that explanation. That makes sense as to how this DTC 16 is showing up. I assumed it was stored but didn’t know exactly how it was tripped without any of the normally associated behavior like stalling out and not startling. I’d be pretty psyched if this was not an Opti issue.

I’m going to clear the 16 code and run a new DL this morning using the standard procedure outlined in your referenced post as soon as i get back from an early apt this am.

Thx again. The assistance is greatly appreciated.

 

DTC 16 only sets for one reason. The PCM counts high resolution pulses, and if it sees a certain number of those without seeing a low res pulse, it sets the code.

 

Hi Injuneer,
Ran a new DL this morning according to your guidelines. Saw the rough idle @ the following lines/ timestamps:
Line / Time stamp
2160 10:10:00 Idling in drive car stopped
3583 10:12:59 Idling in drive car stopped
4457 10:14:49 Idling in drive car stopped
5726 10:17:30 Idling in drive car stopped
7101 10:20:24 idle - NOT in Drive - - in PARK

Did 2 WOT hits from a rolling start - was going about 25 mph on the 1st one and it down shifted and just lit up the rear end - I never really beat on her so this was the 1st time I ever experienced that. I didn't know she had it in her. The second WOT hit was from a 40 mph roll and was more realistic - didn't break the rear end loose.
Thx again!

 

Just an update. After going thru the data log several times I'm not seeing anything that is jumping out @ me - I'm no expert by any means just didn't find anything. I've confirmed the rough idle while in drive and stopped happens in both open and closed loop. The only time it does not happen is during the 1st start of a cold startup before the engine compartment warms up. 3 minutes of summer driving and coming to a stop and the rough idle starts again so I'm thinking this is a heat soak issue. I first bought a cheap Opti and swapped it in - that didn't solve the issue which means the Petris Opti I installed in Jan of this year is good and I'm glad to see this is the case. Petris builds a really nice spline drive Opti which has the Opti II ventilation system built into it plus they send you all the hardware needed to make the changes needed to install it. The other part I swapped was the coil with a new Delphi coil. Neither change fixed the issue. I'm going to try a new set of plug wires and I'll inspect all the plugs while doing this although I've never heard of 2 year old Accel ceramic boot / 8mm plug wires succumbing to heat soaking. Like probably everyone here I've seen wirers get fried when resting on the headers but visual inspection of the set I'm going to swap out shows no exterior signs of melting or burning. If the plugs are all carboned up I'll clean 'em and reinstall them ( already checked the left bank a couple weeks ago so I'll be inspecting the right bank) - they are the Iradium NKG's that are recommended by several folks on the forum here and are only a year old.

I've checked for arching when the engine is showing the issue @ night and don't see any. I swapped the ICM out with the original, pulled the MAF sensor, swapped the O2 sensors after replacing one that went bad due to this rich/rough idle, cleaned the throttle body, cleaned the IAC airways, looked for vacuum leaks with carb cleaner using carb/intake cleaner and inspected the air intake system. After these trouble shooting steps, I have yet to find the issue.


Anyone ever hear of the injectors becoming heat soaked and not working correctly when hot?

Thx - Rick

 

Sorry, but I have not looked at your latest log. I'll try t get to it ASAP, But my eye surgery was not successful (still healing) and staring at a computer screen can be painful. I'm way backed up on helping people out.

 

OK.... downloaded the file, ,and set it up for review. It's a huge file, because you have an excellent scan rate, about 8 frames per second. makes the file larger, but also improves the resolution of the data and makes it more usable. Also good that you followed the guidelines. I think they are fairly clear, but an amazing number of people don't seem to understand them, and create files that are almost useless.

In your file, I was able to break it down to four discrete sections - open loop, closed loop idle, closed loop driving, and a second final closed loop idle. Did see a couple possible problem areas just looking at max, average and min readings in each section of the file - appears some cells in the closed loop/drive portion have very low long term fuel corrections, pulling out a lot of fuel. There is at least one place where there is 12-deg of knock retard, and at WOT the TPS volts are only 3.84 (although the PCM does interpret that as 100%). I'll see if those are real problems when I dig into the details.

As noted, might take a whole. Just wanted you to know I downloaded it, set it up for review, and the file looks like its very useful.

 

Injuneer,
I swapped out the plug wires last night and after 2 test drives it look like the issue has been resolved. Sorry for any time you spent on this - I appreciate you looking @ it - I owe you one. I inspected the wires about 3 weeks ago and they all looked good just as they did when I pulled them yesterday and replaced them with a set of 7mm Delphi brand. One of them (Accel Ceramic boot 8mm set) must be defective and stops letting spark thru when it reaches a certain temp.

Rick