Custom OS 3bar problem (need the experts)

[QUICKSILVER2002]

I'm running the custom OS 02030003.tun on a 2002 c5 m6 and there seems to be some type of problem as soon as it hits the boost VE table.

I put in a 2bar map and followed all the stuff in the tutorial. Car is running fine and I was working on part throttle VE stuff.

I slowly rolled into it and as soon as the reading hits 105kpa the motor cuts and it goes into reduced power mode.

The only DTCs set were for the MAF and service traction control system. I still have the MAF on the car, but fail frequency and all that are set.

I pretty much know what I'm doing, but this is my first time to try the custom OS. I noticed the Predicted MAP tables. Could that be it?

It acts just like a car would act with ETC predicted airflow table not setup correctly (p1514), but I have that scaled way up and got no code.

Any ideas?

[Dirk Diggler]

For the benefit of others here, I've been talking with Nitro via Email and he sent me the tun file and log file from he's current setup.
Nitro had set the MAP and Boost VE table up fine, but what I saw from the log file was as soon as MAP hit about 110 - 115 kPa the timing dropped from about 17 to -7 and less. That is why this thing was falling over under boost.

So, luckily I can run these PCM's up on the bench :)
So once I flashed in the tun I needed to see what was causing this massive timing reduction, of course it was torque managment, actually, transmission torque mnagement was pulling about 20degrees of timing out (GM.EST_XMSN_DMA).
The easy fix is to zero table {B1902} and set {B6619} & {B6620} to max.
Problem solved, now it holds the timing steady all the way upto 285kPa.
I'll Email you the changed file Nitro and let us know how it goes.

Cheers,
Ross

[QUICKSILVER2002]

Thanks for the info, but I don't think that is the problem I have.

The log shows plenty of spark.

This car was actually tuned and running good with a MAF for a long time, so all the basic stuff like that has been set.

This is some type of PCM fault or rationality test being hit.

[dfe1]

You may well have a problem with the values in the predicted airflow table (C6101) or the Max predicted air flow (C6102). It may be that the values exceed those in the table when you get into boost. I had a similar problem when I first started experimenting with a 1 bar custom OS. The values logged were considerably higher than I expected, given what they were with the MAF running the show. Don't forget that you can get into boost at less than wide open throttle. You should be abe to log GM.CYLAIR_DMA and see what the values are when the engine dies. Then bump the entries in the predicted air tables as required.

[GMPX]

I am not going to make a habit of this but send your tune and a log file to ross@efilive.com and I'll take a look. There might be a few gotchas we need to include in the tutorial (like the timing one).

Cheers,
Ross

[QUICKSILVER2002]

Ross,

Before I waste your time, let me log some more data and play a bit with the c6101 (predicted airflow table).

I had that table adjusted and working fine with the MAF hooked up (and even playing around in SD with a stock sensor). I checked it today just to verify the values were in range, but I forgot that it was displayed in milligrams per cylinder. I was thinking g/sec when I looked at it and knew there was no way I was hitting those values. Looking at it with mg/cyl in mind, I can see where it could be my problem.

I just went back and looked at my log and I was on the borderline of the values in that table. I did not get p1514 set, but I remember not getting it set one other time also.

It is too late to wake the neighbors with my obnoxiously loud car, so I will give it another try in the morning.

[VortechC5]

Quicksilver,

Once you figure out what the issue is please post the fix.

I just got my 2bar sensor and will be converting to the same custom OS that you are using. Like you I have a stock OS based tune that works fine and will use that as my basis for my custom OS tune.

[QUICKSILVER2002]

Ok, feel like the boy who cried wolf here :oops:

It was the predicted airflow table. I should have known better. I have messed with that table many times, but forgot that I was basically starting over here and needed to max it out while setting the base tune.

My advice to others would be to set it to max values while doing the base tune. Then go back and put sane values in (max logged + 20%).

I’ll have to admit that I saw another post about crazy stuff with the 2002 3bar and immediately jumped to conclusions. I would normally have done more through troubleshooting before posting.