I have a 2012 Coyote with a Whipple SC in my '33 Ford Roadster. The power tune is fine (623 RHP), but I have sharp, uneven backfiring during throttle closed decel. DFCO is enabled with stock settings. MBT tables are stock. I can eliminate backfiring during decel with slight throttle pressure. I'm uncertain how to even out or eliminate this condition. Any help will be appreciated. Joe
Same thing happens to me also my axle back blows up because of that
Attach your Tune to help you out , i think i have fix my issue with little playing in DFCO and Torque Management I’ll try in your tune if you send it
Neither one of you posted a tune. Can guess all day.
It’s okay , go to fuel >cutoff dfco > set Dfco to 0
Go to toque management > spark only tq > set DFSO to 1.00
Also Torque management > fuel cut TQ > set DFSO to 1.00
Try that and let me know
Of course I should have included the tune file. Sorry 'bout that. JoeOriginally Posted by Thatwhite5.0
ACD HotRod-3.hpt
attached the your tune after editing there's a lot of things need to be changed i just play around and change some of them
Thanks! I'll give it a try this afternoon and let you know how it goes. Joe
Wow! You made a lot of changes and most are way over my head. I just returned from a test drive and the backfire continues about as before. Any ideas? Thanks, Joe
Send the log please
Any particular parameters you need in the log?
Sorry for the delay in sending this. It's been raining here since our last communication. Attached is a short log file, with the car up to temp, showing the conditions during backfire. Thanks again for your help. Joe
33 Hot Rod 080722 1000.hpl
joegarner, that log could use some improvement. Observations:
- The polling rates are horribly slow so it's hard to see what's going on at all.
- For some reason, no data came through on many of the PIDs. Perhaps repoll for supported parameters and reconstruct the list.
- Any idea why the pedal is only going to 15% when you let off? This should be closer to 0%. Perhaps this is why it isn't entering DFSO mode - it doesn't know you let off the gas. Your driver demand table seems to only go down to 15% so this could be the cause.
- The fuel, torque, and spark source aren't working, which would help diagnose this. These sources get you looking in the right place to fix the problem.
- The fuel trims are going way high on deceleration. It's normal for them to be weird on decel (since your DFCO isn't working) but those seem rather far off still. Are your O2 sensors far from the exhaust outlets? Reversion on decel can cause strange readings. The PCM is responding by flogging it with fuel. Extra fuel and low timing on decel = major backfires.
If fixing all of the above doesn't help, then a last resort can be to increase MBT in the load/speed/mapped point where the problem is worst. But the initial goal, IMO, is to make it enter DFSO/DFCO. If there is no fuel then there is no backfires.
Hi engineermike, Thanks for your feedback. As you suggested, I repolled supported parameters and rebuilt the list. Much improved. I see that the pedal is going to 0% now. Fuel, torque and spark source are working. The O2 sensors are about 22" from the header flanges. I've attached a fresh log. Perhaps this one will provide better info. Thanks for your help. Joe
33 Hot Rod 080722 1430.hpl
Ok that is a much better log. I would look at the spark timing polling rate and change it to lowest as well though.
Your car still isn't entering DFCO. I looked at the parameters and they all match a gen1 stock settings exactly (I'm assuming this works on a gen1). The only thing I can think of is there is some sensor it needs to work but doesn't have, like OSS or VSS.
Fuel trims are strange on decel, but again this MIGHT just be the nature of non-DFCO deceleration. I'd compare the two sides closely because Bank 2 (driver's side) is showing super lean and the PCM is flogging it with fuel as a result. Bank 1 seems normal.
It's using Spark Torque Ratio to control torque on decel. As a result it's cutting timing to 12 deg. Go to table 33458 Spark Only Torque Ratio and change Dashpot to 1.0. I believe Dashpot is what is used on torque-based decel. That said, if I were you I would open up the 2011 copperhead file that came with VCM Suite and copy the entire 44776 table over into yours. Also, confirm your Fuel Cut Torque Ratio is all at 1.0.
I'll implement the changes you have suggested and let you know the result. I really appreciate the help.
You have me thinking about the possible missing sensor input causing it not to go into DFCO. I'm using an aftermarket tranny controller, but think that I have VSS going to the PCM, since I have speed indicated in the scan. Could I be wrong?
If oss is indicated in the log then that’s probably not the issue.
I think we can get it decelerating ok without dfco but it would drive me nuts until I had it working.
I'll check that off the possibilities. Thanks. It will be tomorrow before I'll have a chance to work on the car again. Fingers crossed. Joe
Hi Mike, I think we're on the right track. All of your recommendations have been implemented. The attached log shows the same backfire pattern early in the drive, but not in the latter period. ECT may be a factor in achieving DFCO. I'm also attaching the current tune. Thanks!
33 Hot Rod 080823 1000.hplACD HotRod-3 EMedited-1.hpt
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