p1514 and no reason

[tazinhawaii]

** REPOST FROM FORCED INDUCTION SECTION **

OK, I've read all the other posts and made sure everything in my tune was setup right. Here's my setup... C5R 427 with twin PTS T-64 turbo's, 95# injectors, 90mm TB, AFR 225's, etc. (listed in my sig below). I've got road runner and have been tuning for a while. I'm going MAFless because at ~8psi, the MAF was maxxed out and caused some severe tuning issues. I've got everything setup for SD tuning. I've set the following tables as high as they will go (max values). C3003, C2911, C6101, C6102. The problem is it keeps popping a code 1514 and going into reduced power mode at about 7-8 psi boost. I tried disabling p1514 in the diagnostics area, but all that does is cause the code not to come up, but the car still goes into reduced power.... I'm trying to increase my boost VE table values to try and fix this, but I've had no success so far. Am I missing something? Are there any PID's I can log to see what the computer thinks airflow is by MAP and speed density?

Also, for some reason I'm not getting any LTFT's now. I can't believe that everything in the LTFT table would be 0.0 except cold idle and WOT (both around -2%).

I'm attaching a log of this event (happens around frame 460) and my current tune file....

ANY help would be appreciated.
Derrick

[GMPX]

Hi Derrick, not sure about the P1514, seems you changed the correct table, maybe some of the other tuners of boosted C5's could help.

As for the LTFT, you won't get them with Custom OS3, this OS was designed so the PCM did not end up messing with your tuning. You can still have STFT, but not long.
Having said that, with the VE dialed in right there is really no need for LTFT, I know my own car will run at idle / part throttle in open loop at 14.6:1 rocks solid with no need for any fuel trims. However, STFT's are worth keeping if you don't have any means of tuning yourself (eg a customer).

Cheers,
Ross

[C3vette75]

I notice that your Boost VE Table for 105 kPa column has different values than the Main VE Table for the 105 kPa column. I don't know if this is part of your problem but I believe they should be the same.

[tazinhawaii]

C3vette,
Nice catch, but it still didn't solve the problem.

All,
With the MAF disabled, what airflows does the PCM use to do this comparison?? It seems like this p1514 would be disabled all together if the MAF was inoperable. I did another log today with every airflow type PID selected so that I could to try and see a problem. P1514 happens around frame 680.

This sucks since other than this, the car is running really good in "everyday grandma driving" situations. Also, the LTFT's were working before I just went to a SD tune. Now they show up in the log files,, but the table when I click on the 'fuel pump' icon of the scan tool comes up with all 0.0's in all cells (except cold idle and WOT).

Well, Thanks for any help or suggestions. If anyone else may have a tune file for a setup similar to mine, I'm always willing to look at yours and see if there are any differences that may help me...

Thanks,
Derrick

[C3vette75]

Derrick
When you set up your COS, did you follow the guidelines of http://68.178.219.18/tutorials/PDF/Custom%20OS%20Upgrade%20Tutorial.pdf for installing a Custom Operating System? When I went through your file, I noticed that a few things are different, for example it recommends setting Table B4205 to max of 140, yours is around 34 this in degrees C, which is 284 and 93.2 degrees F respectively. Also on page 19 of 21 of the pdf or page 17 if you print it out there is a note which states that Long term fuel trims will not work when using the B3647 or B3649 calibrations. I went through your calibration and changed it according to the pdf. Here it is but check it out real good if you decide to try it.
1527
Let us if this helps.
Joe

[tazinhawaii]

I actually did that the other day. But the damn 1514 still comes up. How frustrating. the tables that worked for everyone else (C6101 and C2911 I think those were the numbers) just aren't doing it for me.

Does anyone know what PID I can log to see what the PCM thinks airflow is using TP, BARO, MAP, and RPM? I'm not sure what to compare with the speed density air flow PID in order to figure out why the PCM thinks there's such a large difference.

Derrick

[joecar]

More info that may help (post #6): showthread.php?t=5029 (http://forum.efilive.com/showthread.php?t=5029)

[Turbo595t]

Derrick,

Just to verify, that that maf is off the car or do you still have it on for the air temp sensor?

Brian

[tazinhawaii]

The maf is still on the car, just disabled via the tune. I do have the P0103 code.

Derrick

[Turbo595t]

The maf is still on the car, just disabled via the tune. I do have the P0103 code.

Derrick

Hello Derrick,

I found this on another site.


"Check dynamic airflow.

If you are over 2.32 g/cyl you will get a 1514 no matter what you do to the 1514 table.

Drop your IFR and VE table by an equivelent amount (say 10 or 20%) and that will drop the dynamic airflow. If you still bang the limiter, go another 10%.

I have had the same problem on a 427 with a ProCharger F1R. I was getting a 1514 at 4000 RPM. It has 750cc RC injectors so my original IFR table started at 83 lbs/hr."

So then I checked your g/cyl on your log and it hit 2.45 when you had the issue (see attached pic).

I think it has to do with reaching the internal limits of what the pcm is programed to calculate, also when I loaded your file it said some of values were out of range on the boost ve, either way this would be worth a start.

Let me know how it goes,

Good Luck

[tazinhawaii]

OUTSTANDING!!! I will try that.

Thus far I have switched to the '02 COS3 op system (from the 2001 years system) with no change and have foved C6101 up and down with no real change. I have also fixed all the other problems (i.e. the out of range issues). I also noticed it would always cut out around the same airflow and RPM. And it just so happens it's usually 2.32 g/cyl.

I will try this tonight. Thank you again.

Derrick

[C3vette75]

What RPM does it happen at?

[Turbo595t]

What RPM does it happen at?

See the picture in my post 10.

[C3vette75]

Brian
I know yours was around 4000 RPM. I was wondering if Derrick's was occuring near the same RPM. Table B0120 has a value of 4000 RPM and it states, if engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder. No updates are made to the airflow correction factor. I know the the MAF is supposed to be disabled but what if you change this value to 5000 or more.
Will the reduced power occur at the new value?
Joe

[Turbo595t]

Brian
I know yours was around 4000 RPM. I was wondering if Derrick's was occuring near the same RPM. Table B0120 has a value of 4000 RPM and it states, if engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder. No updates are made to the airflow correction factor. I know the the MAF is supposed to be disabled but what if you change this value to 5000 or more.
Will the reduced power occur at the new value?
Joe

Joe,
Please re-read my post 10. The part in quotes came from something I found on another site. The picture I posted came from the scan log that Derrick posted and is from his car.

[tazinhawaii]

Yes, mine did occur around 4000 RPM, but I already changed that value to 8000RPM to see if it had any effect. It didn't. I reduced the VE tables and IFR's but now I need to go get some gas to try and see if it worked. But I'm in the middle of my son's B-day party now (hiding in the computer room since it's all my wife's hen crackling friends here for it)....

Derrick

[tazinhawaii]

That's what I said as I left off the throttle after hitting 100+ MPH in mere seconds. :banana:

OK, there are a bunch of people who post about p1514 codes when going forced induction. Mosst solve it by increasing the C6101 table apparently. But here's the kicker. Apparently the PCM can't handle calculated cylinder airflow greater than 2.32 g/cyl. That ALSO pops a P1514. Thanks GM for not putting that into the service manual. I knocked the VE tables WAYY down and the IFR table as well. Took the car out and it runs like a CHAMP. Only 8 psi right now while I get everything dialed in for that level. Then I'll slowly bring it up to 18 psi (which is what I built the motor to run at - 8.6:1 CR).

[Turbo595t]

That's what I said as I left off the throttle after hitting 100+ MPH in mere seconds. :banana:

OK, there are a bunch of people who post about p1514 codes when going forced induction. Mosst solve it by increasing the C6101 table apparently. But here's the kicker. Apparently the PCM can't handle calculated cylinder airflow greater than 2.32 g/cyl. That ALSO pops a P1514. Thanks GM for not putting that into the service manual. I knocked the VE tables WAYY down and the IFR table as well. Took the car out and it runs like a CHAMP. Only 8 psi right now while I get everything dialed in for that level. Then I'll slowly bring it up to 18 psi (which is what I built the motor to run at - 8.6:1 CR).

Derrick,
That is great, thanks for testing it. I got a project coming up that knowing this works, I won't run into this problem.

Brian