Problem: Backfiring 4-5 seconds after entering decelaration

[kevinhurley]

Problem:
Loud backfiring/popping from tailpipes upon decelaration, zero% TPS at 2500 to 1000 RPM's (1st - 3rd gear mostly).
After entering decelaration, popping and then loud backfiring occurs after 4-5 seconds then seems like fuel is cut, stays off until I add more fuel (EI;tapping gas pedal).

CAR: 2008 C6 Corvette base model, 29K miles, M6, Kooks 1-3/4" headers, catted mid pipes and x-pipe, Corsa Sport mufflers (2-1/2" inlet), K&N air filter.
Exhaust installed at E.S.P. in Sterling, MA.
Stock tune.
The backfiring started after installing new exhaust.

I own my own HP Tuners S/W and license.. I am familiar with HP Tuner S/W.

Also familiar with DFCO. Probably need to change some parameters in > Engine > fuel cutoff tab .

1)What is the solution to eliminating the terrible backfiring??

2)Can someone help with a solution?

Thank you,

Very Sad!
Kevin

[SultanHassanMasTuning]

data log whats going on and i am sure it will point you in the right direction

[kevinhurley]

Hi Sultan,

I was hoping someone could help me set up the parametrs for the "DFCO cutoff" Tab.
I would like the DFCO to Enable 1-2 seconds after entering decelaration....in other words i want to enter DFCO enable as sooner, this will stop the backfiring.

See attachment please.

thank you

[jcrumpley]

I had that same issue on my 2007 and my 2012 Corvette with headers and corsa sport exhaust. I fixed it by adjusting the entry and exit spark tables on the table you posted above. As I recall, all I did was change all cells of the exit and entry spark to all 10's. I'm sure there are better ways to do it, but that got rid of the annoying popping on mine in most all conditions.

[SultanHassanMasTuning]

attached pic looks like its disabled, compare a stock file and you will be good to go man

[gofastwclass]

Post a data log and the tune file.

[kevinhurley]

I had that same issue on my 2007 and my 2012 Corvette with headers and corsa sport exhaust. I fixed it by adjusting the entry and exit spark tables on the table you posted above. As I recall, all I did was change all cells of the exit and entry spark to all 10's. I'm sure there are better ways to do it, but that got rid of the annoying popping on mine in most all conditions.

Hi JC,

Could you show me some screen shots of the exit and entry tables as you had set.

TY

[kevinhurley]

Hi Go fast,

How would I get a data log?

TY

[edge04]

The DFCO is disabled in that pic.

But, you state "stock tune" however in the pic that looks like a tune for a 06 GTO??

[jcrumpley]

Ty,

I don't have access to my tune at work. From your comments though, particularly the part where you say, "how would I get a data log", it appears that you may not have read through the link below.

http://www.hptuners.com/forum/showth...iles-and-Demos

The stuff in that link will get you to the point of being able to get a log. Once you do, post the log and the actual tune from your car and you will get more assistance.

[kevinhurley]

Hi edge,

That is a screen shot of a different car, but this is how my stock tune is set on my C6.

still backfires!

[kevinhurley]

Hi JC,

I watched the video on stand alone data logging, seems I do not have the record buttons on my MPVI.

Please advise.

[kevinhurley]

hi JC,

I found different instructions on how to save datalog.

I will try this and upload a copy of my current tune file and the stand alone data logging file, (as suggested by go fast also).

thanks for all the help.

[kevinhurley]

hi JC,

I found different instructions on how to save datalog.

I will try this and upload a copy of my current tune file and the stand alone data logging file, (as suggested by go fast also).

thanks for all the help.

Hi All,

Seems I'm still learning!

My MPVI is not a PRO, so can't do logging...correct?

I'm still try different config's and sometimes think I have gotten closer to figuring out how to get the feel to cut with 0%TPS.

Today it seemed better...but then heard it backfire s..t. least I could do at this point is post a copy of my current tune.

TY

[GHuggins]

I had that same issue on my 2007 and my 2012 Corvette with headers and corsa sport exhaust. I fixed it by adjusting the entry and exit spark tables on the table you posted above. As I recall, all I did was change all cells of the exit and entry spark to all 10's. I'm sure there are better ways to do it, but that got rid of the annoying popping on mine in most all conditions.

Think he stated how to fix it here and also you should be able to datalog without the pro... Attached some pics with modified tables that I did to fix this same type of problem... You can go a lot lower on the crank ref entry spark tables if need be, but these settings will usually make a happy medium between having DFCO related fuel issue "going into and out of too much" and actually fixing the problem. May still notice an occassional pop though...

[GHuggins]

Then there's also a coast spark table that should be modified to correspond...

[schpenxel]

Hi All,

Seems I'm still learning!

My MPVI is not a PRO, so can't do logging...correct?

I'm still try different config's and sometimes think I have gotten closer to figuring out how to get the feel to cut with 0%TPS.

Today it seemed better...but then heard it backfire s..t. least I could do at this point is post a copy of my current tune.

TY

All interfaces can do logging.. Pro lets you log without having a laptop connected to it, and lets you connect external sensors like a fuel pressure sensor or wideband.

Those screenshots look like they're from a 2003 version of HP Tuners.

[kevinhurley]

Then there's also a coast spark table that should be modified to correspond...

Hi G,

Thank you very much, I was missing a few parameters including the exit/entry spark blend.

The backfiring is gone and I can hear the fuel shutoff after 3-4 seconds, it still gurgles and pops, but that's expected with straight thru exhaust (Kooks headers, catless and Corsa sports)...very happy!

I set everything per your attachments except the coast down spark.

Not sure which table to edit for coast down spark.

See attachment - HPTuners version 2.24.758

Please suggest me which table to edit.
Also, why can't I get it to shutoff immediately?... or 1-2 seconds. maybe I'm asking for to much :0)

[GHuggins]

Idle Spark Advance - Coastdown from your attached pic. I like having the couple seconds of delay just for the simple reason that sometimes dfco can reek havoc on in and out throttle drivers - You know the ones that none of us can really stand to ride with You can lower those entry spark tables way down to enter quicker and modify your speed settings to keep and get it into dfco at lower vehicle speeds. Wouldn't go any lower than 5 mph. 9 to 10 mph might even be pushing it.

You might also want to drop Bill an email and update to 2.25. Decent amount of tables have been added. Then make sure your setup as advanced under your edit tab. Sometimes causes tables to be hidden.

Hope this was what you were looking for.

[kevinhurley]

Idle Spark Advance - Coastdown from your attached pic. I like having the couple seconds of delay just for the simple reason that sometimes dfco can reek havoc on in and out throttle drivers - You know the ones that none of us can really stand to ride with You can lower those entry spark tables way down to enter quicker and modify your speed settings to keep and get it into dfco at lower vehicle speeds. Wouldn't go any lower than 5 mph. 9 to 10 mph might even be pushing it.

You might also want to drop Bill an email and update to 2.25. Decent amount of tables have been added. Then make sure your setup as advanced under your edit tab. Sometimes causes tables to be hidden.

Hope this was what you were looking for.

Hi G,

I will update to latest version later...TY.

You described my driving like the wife would!

See current tune attached.

I think I need to at least update speed table....and coast down.

thank you