What is happening?? CL rough idle, in OL lean only after WOT with boost!

[keith Goosen]

What is happening?? CL rough idle, in OL lean only after WOT with boost!
Background:
2005 TJ 4.0 6-speed with turbo upgrade. Using HPT has been a challenge due to the limited support for the NGC3 PCM (no custom OS). So far things have been a constant tuning process for 2 years, since there is always something needing a small change, as I live in the Canadian Rocky Mountains.

Parts:
.63 T3T4 Turbo, intercooler, cooler spark plugs, 2Bar MAP (SRT Neon #MP124), 36#@stock pressure 58psi injectors (Ford 4L8E-A4A, 4L8Z9F593AA, CM5088), PCV to manifold, headers, AEM WB, HPtuners package, BOV, 35mm WG, (IAT sensor left to upgrade to the manifold vs intake pipe).

Issue:
A couple of weeks ago i started having an interesting and random rough idle, only after driving for a while. To be clear, driving mostly without boost, or very minimal amount. At a stop, the RPM would drop real low, and stay low, but then the engine would try to save it, and would, it could idle after 10 seconds of chaos. The WB gauge would ping real rich, then real lean. VCM Scanner data would show all kinds of messed up data, but made sense. The big thing that was captured, was watching the WB AFR start to climb, and climb everywhere. The PCM was just pour fuel to keep it all running. With all this, I have no issues driving it, and low or high speed, power is always there.

Investigation:
1. I gave the Jeep a look over with a fine tooth comb, and my first find was a loose ground collection point located on the engine block by the oil filter (SWEET), but issue continued.

2. Due to the location of my new exhaust run, I found the Crank sensor somewhat melted, so I purchased a new Crank and Cam sensor (were original), issue continued.

3. Checked over all electrical, and tested the entire power distribution block, no issues found.

4. Pulled the spark plugs, looked good, and adjusted the gap while I was there. (Coil pack is only 1 year old). Issue continued.

5. Checked all vacuum lines, pulled one, idle RPM increased, good not an issue.

6. I looked at the Idle control motor, original and dirty, so I replaced it, issue continued.

7. Did a VCM Scan for electrical, inj timing/PW/DC, spark, MAP, IAT, etc. Added a Baro PID and chart, and noticed an odd and maybe normal, but seemed wrong to me. The Baro chart showed the pressure at KOEO 102.3kpa (normal and matched weather), it record 102.3 from 20-100 as I drove around. When I went WOT and into boost, the baro reading would follow/match all that was above 100kpa, but then carry and rewrite all below 100-20 with 149kpa, like it was stuck, and as I mentioned, the PCM would start increasing the fuel to all cells including idle. I thought this meant the MAP sensor was bad, and replaced it with another company that was available at the time, BWD EC7033. The baro data was the same and issue continued.

8. Wanted a better look, so I disabled the O2 sensors to run OL. This brought a nice surprise, I had to completely remapped my VE table for the better (minus 10-15) and the engine ran better, got snotty in a way, but when I go WOT/boost, issue STOPPED, idle was a little rough, but idled. What I noticed now, I will do a light drive for a while, the VE data is on the rich side a little, but when I go WOT/boost and return to the normal drive, it all leans out again. The WB will read about .93 pre-boost, and 1.03-1.07 post boost. If I stop and turn off the engine, restart the engine 10 seconds later, all will be back to normal again, running on the rich side.

Why is it doing this?? My guess is, this is happening in the background when the O2 sensors are enabled, and compensating for the lean fuel by adding fuel constantly?.


9. Throughout this, I noticed that my oil pan was leaking oil and other little messes. I had to upgrade my crankcase venting issue from a CCV to open atmosphere, to a PCV manifold vacuum system, thinking and seeing that crankcase pressure may be playing a part in this all of a sudden.

10. I also ordered a new fuel pump assembly too, and will replace that soon, but I have no issues with RPM and speed or fuel demand, so this isn't an issue, right??

Thoughts:
I ask the tuning community to look over my files and offer any feedback to assist me with this?
I am not a pro, and know I might be missing something in the scan, or experience with an issue like this. Like I said, I have been running this tune for 2 years, and this is the first time I see Baro sticking, and lean fuel only after WOT, but resets to normal after turning the key off?. I would like to get my O2 sensors enabled again, as I live and play in the mountains and need the PCM to aid..

I know that turning Baro learning off will stall the engine when I get near 100kpa. I have edited the learning delta, but haven't tried it yet, since I need the O2 sensors enabled.

Has anyone logged baro before? Is this a normal operation in a log?

I am tempted to replace the MAP for another company and see if its just an issue with this brand.

Let me know if you, thanks in advance.

[HaasExp]

Do you have a log where you disabled baro learn showing the engine "stalling" when you get near 100kPa?

Problem with baro learn and boost is that it will update the baro value to the highest pressure read by the sensor and therefore it will incorrectly "scale" the pressure ratio used for the VE tables. On your log "with boost" the PR never rises above 1. This is to be expected since PR = MAP/baro and the baro always creeps up and somewhat follows the MAP as its continually being updated. On restart the learnt baro value will be wiped and just take on the atmospheric value again.

[keith Goosen]

Do you have a log where you disabled baro learn showing the engine "stalling" when you get near 100kPa?

Problem with baro learn and boost is that it will update the baro value to the highest pressure read by the sensor and therefore it will incorrectly "scale" the pressure ratio used for the VE tables. On your log "with boost" the PR never rises above 1. This is to be expected since PR = MAP/baro and the baro always creeps up and somewhat follows the MAP as its continually being updated. On restart the learnt baro value will be wiped and just take on the atmospheric value again.

Thanks for looking at my issue.
Yes, I have attached the scan, with baro learn disabled. The engine stalls.

[keith Goosen]

Here is an interesting thing.
I edited the baro learn max delta from the stock 1.7v-2.4v scale, to .90volt for all rpm.
The first p1 file shows the baro relearning, it scales up then at some point scales down...this seems perfect, as the WB AFR was nice around 1.00.
The second file p2 shows it staying up and does not relearn... the difference in p1 vs p2 is just a "stop record" followed by "start record", i did not stop driving or restart the engine. What is happening??

[keith Goosen]

Update to this confusing issue here.. The BARO will intermittently relearn..

https://forum.hptuners.com/showthrea...485#post653485

[HaasExp]

Thanks for looking at my issue.
Yes, I have attached the scan, with baro learn disabled. The engine stalls.

That is really strange. The engine is stalling out because the inj PW stays at 0ms and doesnt even try to recover until its too late.
Have you tried disabling you DFCO?

[keith Goosen]

That is really strange. The engine is stalling out because the inj PW stays at 0ms and doesnt even try to recover until its too late.
Have you tried disabling you DFCO?

I have not, but I am willing to try it.

Thanks for the suggestion.

[Ryandunkel]

Was this issue resolved? My fully built 6.4l is having extremely similar symptoms.