Alright, I'm trying to help my brother get his car running half decent here. He's running a '165 and apyp, $6E. I'm not sure what is going on here but...bit status for O2 ready says ready when it is warmed up and in closed loop, but learn function stays at 'disabled'.

Also, O2 sensor reads around 700-800mV at idle, 1 crosscount in the period of....well I removed the time variable from the excel sheet printout, but lets say its a couple thousand samples. One crosscount the whole time, but the blms and int dont' change (well, int changes once to 127). Otherwise they stay at 128 the whole time.

I've got another datalog where the blms do change, as well as int, when the O2 reads in the 800mV, engine warmed up again to normal. Seems to me like sometimes they will change sometimes they wont at all. When they do change they seem to be consistent with how its running (for instance they go to 108 when they do change).

Whats going on, anyone have any ideas? I have the log if anyone wants to view it.

 

If there are no 02 Crosscounts and the 02 vlotage is pretty constant then very likely the 02 Sensor is bad.

I had one die a couple of weeks ago that behaved in that manner.
However, I DID get an error code and the Check Sys light illuminated.

Do you have any error codes or stored codes?

My quess would be the 02 or the ECM.

 

Well, first off I was under the impression that the O2 sensor created a crosscount when it switched 'over' or 'under' the threshold voltage specified in the calibration (what is it like 562mV or something). So I can see how it may not create crosscounts. But with it reading 7xxmV, now I'd think that at least the INTs would start going down, but they don't.

The only error code he gets consistently is a code 51 PROM error, which is always on. But we know that the code on the emulator is working because the PROM ID while datalogging is consistent with the one we uploaded, and changes to the emulator affect how it runs. So we still do not know why it gets a code 51. I thought maybe it had to do with the checksum being incorrect but we've tried using TunerPro with 'disable checksum by..." on and off.

 

Error Code 51:

PROM not properly installed in the ECM.

Faulty PROM.

Faulty ECM.

 

HMM.. maybe you are in open loop at idle that would explain the 128 BLM and no cross counts. Your O2 sensor may not be getting hot enough at idle.

 

Well the flag for closed loop is set when it is supposed to go CL, up so I think it is going closed loop.

I would hate to think that the ECM is faulty, but the PROM (emulator cable-chip) is seated as well as the adapter so that may be a possibility. I wonder if that would have anything to do with why it runs inconsistently. For example, idles fine, rev it and hold it at a certain rpm, let off and it will drop back down and idle erratically sometimes, sometimes it will be ok again.

??

I may have him invest in another ECM just to eliminate that possibility.

 

I am no longer getting a code 51 PROM error but i am still having the other issues. BLM and INT dont change in closed loop they consistantly stay at 128 unless i hit the gas, they go to say 118 until i let off the gas and instead of slowly changing the blm and int show 128 again. Also im not sure why the learn is showing disabled either?? As far as O2 sensor reading ill get a few crosscounts for a short period of time and then they will stop and keep repeating this process. Not sure if this has to do with the ecm or not but the idel is horrible too. Sometimes it will idle halfway decent and most of the time the idle varies up and down a hundred rpms. Another thing, went out today and started right up, backed onto the road and stalled, tried to start it and it took about a minite or two of cranking to finally start. Sometimes it runs decent and sometimes it runs like crap. Something isnt right and this whole tunning thing is turning out to be nothing but a pain. Any help would be appreciated!!!

 

Does your car have headers? If so are they ceramic coated?

 

Yes and yes.

 

Looking through the logs, I have noticed there will be times where the O2 will be reading rich for a long time then jump down to like 50 something mV, or something extremely low like that then jump back up which creates a crosscount but that doesnt seem right. Would this be the O2 cooling off really quick?

 

No, this doesn't seem right. What brand of O2 sensor are you using?

 

well im currently using a bosch part # 12014. I put in my old o2 sensor tonight which worked when i took it out and got missed results. The crosscounts would change fast for awhile then just stop and stay there or change very slowly. The O2 sensor was reading anywhere from 0 mV to 900 mV.

 

If you have long tube headers you'll need to install a heated o2 sensor.

 

I know the bosch O2 sensors don't work very well for tuning. You can't tell a difference, but to the computer it makes a difference. Appearently the bosch will flatline, sort of like the 0mV you mentioned. I know this is bad.

To me, it sounds like the O2 sensor is not staying hot enough and is giving you incorrect readings. Read this post and see if any of it sounds like yours. I can't realy be of much more help..

Link: https://www.thirdgen.org/techbb2/sho...hreadid=291181