Engine going lean for no apparent reason

[Flytrap]

I have been pledged with what seems to be a dead spot between 2,5000rpm and 3,500rpm. This happens under normal driving conditions at a very low throttle position. It happens accelerating away from a stop or rounding a turn normally, as I said at a very low throttle. The commanded AFR stays at 14.7 (my AEM WB reading between 14.0 & 15.5) then at that throttle pressure, for no reason goes up to commanding 16.34 (on the WB as high as 17.0). Basically it seems to be starving itself for some reason. I've talked to BennyHHR and others about this issue but, no one seems to know why this is happening. I've attached my tune, config file, & one of the log files where this seems to be happening. The commanded AFR goes up to 16.34 at frame 2099 in the scan file. Any help would be appreciated.

[Julex]

I didn't take a look yet, but have you changed anything, I don't have a 2.4 config file to compare it to.

Also Set DFCO and CFCO to as high as possible so they won't enter into that and try and see if that helps.

Also what you should really do is click status bits in the scanner, and add groups, and add all the status bits you can, cause that could tell you if something like DFCO. Then scan and add it on here. Good luck.

[redhotjamedjimi]

you are at a ltft threshold at 3000 rpm at 65 map. So maybe play with them see if thats the problem. and your 1st gear rpm limit torque vs rpm delta vs gear is low in 1st whatever the hell that does.

[REDFOCZ]

you are at a ltft threshold at 3000 rpm at 65 map. So maybe play with them see if thats the problem. besides that tune seems fine.

how would you go about doing this?

[redhotjamedjimi]

i personally leave ltft on but that tune doesnt use them above .04 tps so i dont know whether it would matter. raising all the numbers wouldnt hurt to see it replicate. i think it have more to do with the torque control in 1st gear. if it only happens accelerating from a stop.

[Bill@HPTuners]

I believe its a catalyst test running if im not mistaken, we are going to try and add the parameters needed to turn off this test.

[Flytrap]

I believe its a catalyst test running if im not mistaken, we are going to try and add the parameters needed to turn off this test.

Thanks Bill that seems to make scents. I'll wait for your reply.

[Flytrap]

I found on the VCM Editor where to disable the Catalyst Test. Engine Diag. < General < Catalyst < Catalyst Test. I disabled it, wrote the tune to the car and tested. The attached log file is the unfortunate result. There are 4 spots I noted (frame 731, 1771, 1956, & 3003) were it would just out of know where jump to 16.34 commanded AFR. This time it was almost like turning the ignition key to off. The WB would read between 17.0 and 18.0. This one is a real head scratcher. Tune, scan, & cfg. are attached. Just dunno...

Thanks,

[Flytrap]

Well... This evening I decided to go back to the stock tune to verify whether or not the problem was related to a mechanical issue with the car or a software issue with the tune. After flashing the ECM and then making 3 long runs, it turns out that it was something in the tune that is causing the problem. With the stock tune, the car lost all it's zip but, the mid range dead spot is totally gone. The commanded AFR didn't budge off 14.7 the whole time. Now to figure out what in the tune caused this problem.

[BennyHHR]

I had looked at his earlier scans, and this random lean condition appears to pop out of nowhere. I can see no reason for this to happen and have never seen this on any scans of my LE5 / E67, nor a number of others. Even compared his tune to others and nothing was apparent that would cause this. I believe that some "hiccup" occurred, either with the ECM or HPT.

John, since going back to your stock tune seems to have cured it, can I suggest trying this: Start with your stock tune and gradually modify it piece by piece to bring it back to the tune you've worked out. Log each change to see if the condition comes back. If it does, you should (hopefully not!) get an indication of what change caused it.

[Flytrap]

I had looked at his earlier scans, and this random lean condition appears to pop out of nowhere. I can see no reason for this to happen and have never seen this on any scans of my LE5 / E67, nor a number of others. Even compared his tune to others and nothing was apparent that would cause this. I believe that some "hiccup" occurred, either with the ECM or HPT.

John, since going back to your stock tune seems to have cured it, can I suggest trying this: Start with your stock tune and gradually modify it piece by piece to bring it back to the tune you've worked out. Log each change to see if the condition comes back. If it does, you should (hopefully not!) get an indication of what change caused it.

I fixed it!!! It is very strange to understand what actually cured the problem. As I stated earlier I went back to the stock tune and it ran good (without any tune) no lag or mid range dead spot. Since I don't have any CATs the 6 codes I turned off on Bank1 Sensor2 tripped the MIL light. I went and turned them off (with NO OTHER CHANGES) to read "No Error Reported". After this I made another scan and BOO YEAH up comes the 16.34 commanded AFR AGAIN. I decided at that point to reset the DTCs to read "NO MIL LIGHT" instead of "No Error Reported" and unbelievable as it seems that fixed the problem. After that I re-initiated the original modded tune but then changed the codes to read "No MIL Light" and now every thing works the way it should, no dead spot, no bogging, no nothing, it runs perfectly. I am a very happy camper... and so now the NX Wet Kit goes on this weekend.

[BennyHHR]

Wow!! Glad you finally found it! Didn't know you were running w/o cat or had disabled the DTCs.

To HPT: When comparing files, any changes to the DTCs do not show up in a tune comparison. While John's issue still doesn't make sense, the ability to see ALL changes would help anyone trying to troubleshoot an issue.

[Flytrap]

Wow!! Glad you finally found it! Didn't know you were running w/o cat or had disabled the DTCs.

To HPT: When comparing files, any changes to the DTCs do not show up in a tune comparison. While John's issue still doesn't make sense, the ability to see ALL changes would help anyone trying to troubleshoot an issue.

Sure... I told you all that in our very first phone conversation. You even mentioned how you were an environmentalist and didn't approve of running without a CAT.

The thing that really shocked me is that just telling these 6 codes "Not to Report an Error" would cause a change in a tune to the point were it would actually effect the AFR and overall performance of the car. That's a real weird one if you ask me. Bottom line is that it's fixed and hopefully this will be useful information that anyone else can benefit from if a similar problem arises.

[BennyHHR]

Sure... I told you all that in our very first phone conversation. You even mentioned how you were an environmentalist and didn't approve of running without a CAT.

The thing that really shocked me is that just telling these 6 codes "Not to Report an Error" would cause a change in a tune to the point were it would actually effect the AFR and overall performance of the car. That's a real weird one if you ask me. Bottom line is that it's fixed and hopefully this will be useful information that anyone else can benefit from if a similar problem arises.

Forgot about the cat... That was a while back and just another sign of the onset of "oldtimer's" disease! Not an "environmentalist", just don't believe that the miniscule gain of running catless is worth the pollution.

Thanks for posting the solution, though. I'm sure it will benefit someone else down the road.

Now, just for shits and grins... Add the status bit for A/C clutch to your config. Compare the actual status to what your modified settings are. Dang if I can figure that one out!?!

[Bill@HPTuners]

Wow!! Glad you finally found it! Didn't know you were running w/o cat or had disabled the DTCs.

To HPT: When comparing files, any changes to the DTCs do not show up in a tune comparison. While John's issue still doesn't make sense, the ability to see ALL changes would help anyone trying to troubleshoot an issue.

Go to the DTC window & the changes are very apparent since they are color coded. They just won't show up in the comparison window.

[Bill@HPTuners]

Which reminds me Flytrap could you please post your stock file so I can see what codes you modified & how.

Thanks
Bill

[Flytrap]

Which reminds me Flytrap could you please post your stock file so I can see what codes you modified & how.

Thanks
Bill

Sure Bill... The codes in question are P0036, P0054, P0138, P0141, P0420, and P2A01. As I mentioned earlier setting them to "No Error Reported" is what caused the problem so I reset all six to "No MIL Light" and this cured the issue. I've been driving the car for a day and a half and it is definitely fixed. I can't believe I waited for a month and a half to get enough energy to fix this. It's like driving a new car. The stock tune is attached.

[BennyHHR]

Go to the DTC window & the changes are very apparent since they are color coded. They just won't show up in the comparison window.

Yeh, Bill, but my problem is that I'm always in a hurry! The Compare... View Comparison Log has always been the quick way to look where the differences are without having to open each window / tab and look for the color coding indicating a change. Any changes to the DTC settings will NOT show in the Comparison Log. What else is not there?

Anyway, learned something.

[Bill@HPTuners]

What else is not there?

Thats all that im aware of.

[Dyno Dan]

I've been fighting this for a very long time on my turbocharged TBSS, so I'm excited to change the calibration and get this sorted out. I'll report back once I can flash in the cal and do a few drive cycles.

Thanks for the tip!!.......and thanks to Bill for pointing me to this thread.