reduced engine power after 3bar install

[9secVette]

You will have the 103 and sometimes 102 codes present. that is necessary for the Speed density...

You should get some codes when the reduced engine power appears. You might be getting a p0106 which is a map sensor codes.. please resport the codes you get.

Thanks for the quick response!
Just the p0102 and p0068, I am assuming it's the p0068 that is causing the issue. This is in an 04 Vette, I have raised the tables I have listed a few posts up. Can you think of anything I can be missing? Keep in mind the car was fine with a few less pounds of boost, 12-raised to 15.5. on a 427 engine.


Thanks for the help

[DrX]

There is a disagreement between the SD calculated and MAF airflows.
Assuming correct MAF sensor calibration and MAP sensor scalar value, could the MAF be still active but maxed out, or not fully disabled?


DTC P0068

Circuit Description

The powertrain control module (PCM) uses the throttle position (TP), barometric pressure (BARO), intake air temperature (IAT), and engine RPM in order to calculate the predicted mass airflow rate. The PCM compares the predicted mass air flow (MAF) value to the actual mass airflow value and the speed density calculation in order to verify the proper throttle operation. If the PCM detects that the difference between the actual air flow (MAF) and the speed density calculated air flow is greater than expected, DTC P0068 sets.

[ringram]

Did this get sorted out?
Got a similar issue here.

[9secVette]

Did this get sorted out?
Got a similar issue here.

No not yet, Thanks DRX!

The maf has been removed and the operating system has been installed for 3 bar map s/d use. I have also tried a two bar map and scaled it for both 2 and 3 bar each time. Maf has been set to max value also. I'm not sure what else I could be missing here, but I'm sure it's just one simple thing. A friend of mine is going to pull the program with HP tuners, according to him they have a section where he can raise the minimum rpm to set the p0068 code to 8149. I looked all through EFI and could not find that. I am going to meet up with him this week, I'll post up how it went. If anyone knows where this can be found in EFI please let me know.

thanks!

[DrX]

What is your B0120 set to? Try maxing it out as you have no MAF anyway. Looks like that was the only change I made when I was having this problem.

[9secVette]

What is your B0120 set to? Try maxing it out as you have no MAF anyway. Looks like that was the only change I made when I was having this problem.

Thanks again DrX,
I checked B0120 table, I got all excited because it was at 8888.1 and max is 12,xxxx. I maxed the table but have the same results.
Since this is an RPM based table it seams odd that max is 12k, but maybe this is the table my friend with HP was talking about?
the operating system I using is 12587603--04073003, which show to be a match. I'm really at a loss, anyone please!!

btw, this was with the two bar in place, I am technically just over that at 16lbs, I have had a three bar in there (both scaled) but was told that might be the problem so I switched it. Am I correct that if the two bar is maxed it will still work fine just not show the pcm the additional lb of boost, or can that be a problem I introduced on top of the B0120 problem?

Thanks

[DrX]

I checked B0120 table, I got all excited because it was at 8888.1 and max is 12,xxxx. I maxed the table but have the same results.

8888 should have been good enough. Don't think you will be revving that high. Must be another issue.

[9secVette]

8888 should have been good enough. Don't think you will be revving that high. Must be another issue.

Thanks anyway

Anyone? can someone maybe look at the file? pleeaase

[joecar]

Post your .tun file in this thread (go Post Reply, and then go Manage Attachments, browse to your file, and upload it);

there's quite a few people here that will view it.

[9secVette]

This is the file prior to raising the B0120 table, it is now maxed, there are some minor idle issues that I have not bothered fixing yet till this problem was taken care of, but any help would be greatly apprieciated.

I guess while your looking, I noticed when the car starts cold, it runs for a few seconds then dies, this will happen several times and then it's fine. Thanks again for your time.