Strange Advance Issue - Tuning Forum

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Strange Advance Issue
Saturday, September 06, 2014 5:43 PM
I've noticed that the car seems to fall on it's face after shifting to the next gear at WOT. I took a log and after review it's clear that a lack of timing advance is the issue.

When I shift into the next gear and resume WOT the pcm is pushing less than half of the advance it should be for a second or two. This causes the obvious lack of power until it ramps back up and the car starts pulling again.

There's no knock retard or any other obvious reason for this, so what gives? A quick google search noted that DFCO could be the issue stating that the pcm pulls timing before fuel so even letting completely off for a split second can cause this. That being said, I find it hard to believe as I've never had this problem before and always had DFCO enabled.

I attached a picture of my PE spark advance table for reference, discuss..
Attachments
PE HO Advance.jpg (99k)



"In Oldskool we trust"

Re: Strange Advance Issue
Sunday, September 07, 2014 7:04 AM
Soo much more information is needed.

A true HPT log, copy of the tune etc..



FU Tuning



Re: Strange Advance Issue
Sunday, September 07, 2014 7:06 AM
Yep figured I'd just wait to see who was interested in taking a look. What's your email address John?



"In Oldskool we trust"
Re: Strange Advance Issue
Sunday, September 07, 2014 2:24 PM
jmhz2497@comcast.net



FU Tuning



Re: Strange Advance Issue
Sunday, September 07, 2014 2:44 PM
Email sent, thanks again.



"In Oldskool we trust"
Re: Strange Advance Issue
Sunday, September 07, 2014 10:08 PM
I would like to have a look too if you don't mind. Sparksdt@gmail.com



Re: Strange Advance Issue
Monday, September 08, 2014 4:28 AM
I'll look also.

You should have my email...






Re: Strange Advance Issue
Monday, September 08, 2014 4:34 AM
Sent to both. Thanks for taking a look guys..



"In Oldskool we trust"
Re: Strange Advance Issue
Monday, September 08, 2014 8:14 AM
Your injector duty cycle....kind of high at 93%.

Why is your VE off set so damn high?




Re: Strange Advance Issue
Monday, September 08, 2014 8:36 AM
-MD- Enforcer wrote:

Your injector duty cycle....kind of high at 93%.

Why is your VE off set so damn high?

And that's on 60s with ~60psi base fuel pressure. These things I cannot explain. This car has ALWAYS demanded a lot of fuel, even with the other motor on a bone stock s/c kit. Hell on a 3.1 with 75psi base fuel pressure I was still all but maxing out 42s.

VE offset is what it is. Oldskool had it at 70% but when I went to the 2.8 I found I was unable to add as much fuel as I needed so I had to bump it up. I've now added more meth so I could probably back it down to 75% but it doesn't seem worth the trouble.



"In Oldskool we trust"
Re: Strange Advance Issue
Monday, September 08, 2014 8:38 AM
I can also tell you that Trent is running a very similar setup with the 1 bar map and a 2.8. He told me his offset has settled in at 85%.



"In Oldskool we trust"

Re: Strange Advance Issue
Monday, September 08, 2014 9:30 AM
Didn't PJ get his VE offset back to normalish?





Re: Strange Advance Issue
Monday, September 08, 2014 9:32 AM
-MD- Enforcer wrote:

Didn't PJ get his VE offset back to normalish?

Not sure. He was doing all kinds of crazy stuff.



"In Oldskool we trust"
Re: Strange Advance Issue
Monday, September 08, 2014 12:01 PM
Mine does it with fresh tunes; or if i leave the battery disconencted for a period of time.

Drive it around a day or so and it stops. Of course mine lags a little more because of the size of the turbo; but thats nothing about 10-20% tps during shifts hasnt fixed .

Its never really concerned me too much; but also the tune isnt finished; so there may be something there that IS causing it.

my timing table is similar to that, but there is more advance in almost every cell.

iirc PJ used the injector constant to get the pulsewidth where he wanted it and drove the offset back down. Mine is only at 40 or 50 with 80lb injectors (i forget exactly). I forget the constant though; but it isnt "by the book".









"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Re: Strange Advance Issue
Monday, September 08, 2014 12:33 PM
Matt Linke wrote:

Mine does it with fresh tunes; or if i leave the battery disconencted for a period of time.

Drive it around a day or so and it stops. Of course mine lags a little more because of the size of the turbo; but thats nothing about 10-20% tps during shifts hasnt fixed .

Its never really concerned me too much; but also the tune isnt finished; so there may be something there that IS causing it.

my timing table is similar to that, but there is more advance in almost every cell.

iirc PJ used the injector constant to get the pulsewidth where he wanted it and drove the offset back down. Mine is only at 40 or 50 with 80lb injectors (i forget exactly). I forget the constant though; but it isnt "by the book".

I believe my trigger wheel is a little behind, causing my advance numbers to be slightly inflated. Thing is it does this all the time not just on fresh tunes. I'll log it again after driving around for awhile just to be sure.



"In Oldskool we trust"
Re: Strange Advance Issue
Monday, September 08, 2014 5:59 PM
I'm not sure on the drop in timing, it seems to be ramping up for some reason.

Duty cycle is only high if reved to 7k. I would keep it below that. Are you on stock fuel pump?

I have found when fuel systems are up to the task no need to touch VE offset.




FU Tuning



Re: Strange Advance Issue
Monday, September 08, 2014 6:01 PM
Running the racetronix pump. Though recent affairs are making me think maybe it's going bad.



"In Oldskool we trust"
Re: Strange Advance Issue
Tuesday, September 09, 2014 7:11 AM
Quote:

I believe my trigger wheel is a little behind, causing my advance numbers to be slightly inflated. Thing is it does this all the time not just on fresh tunes. I'll log it again after driving around for awhile just to be sure.


Since you think your pump is dying; get a larger one and switch to e85. You'll be able to run that much timing for real probably of not more. I dunno what the m62 heat would allow but id bet quite a bit on alcohol.




"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Re: Strange Advance Issue
Tuesday, September 09, 2014 10:28 AM
I'm not sure of anything at this point. Unfortunately no e85 around here. At least, not nearly enough to make running it possible.



"In Oldskool we trust"
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