[help] Cold Tip-in Issue

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
Ok, I have tried just about everything and I am getting no results. Its a 2004 Cobra with a 2.9 Whipple at high altitude. It runs absolutely perfect when warmed up. But when I first start it up, especially after sitting for a couple days, its got a major hesitation when its cold when I blip the throttle from idle. I've tried messing with manifold volume, transient fuel, and Cold Base Fuel table with no results. After its been running for about 2-3 minutes and/or ECT is around 105 or higher it goes away.

The worst part is that I have to wait 24 hours or so between testing different settings. I've been pulling my hair out for a month.

There has to be someone out there that has run into this issue also and fixed it. Please help! Its so annoying.
 
Last edited:

fbody83

Z06 to Raped Ape
Established Member
Joined
Feb 10, 2003
Messages
1,350
Location
CT
I have a similar problem, 2003 cobra with a 2.9 whipple but I'm not at high altitude. When cold, I can rev it without a problem but as soon as I start driving I have a lean tip in with every gear. As soon as the car warms up it runs perfectly. Let me know what you find out, thanks.
 

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
I have a similar problem, 2003 cobra with a 2.9 whipple but I'm not at high altitude. When cold, I can rev it without a problem but as soon as I start driving I have a lean tip in with every gear. As soon as the car warms up it runs perfectly. Let me know what you find out, thanks.

I got mine pretty close now messing with the transient fuel tables. The problem is I basically had to max them out below 100 degrees ECT in order to get any positive results. At start up for the first 0-5 seconds, I leave them stock across the board though. I also lowered my manifold volume to 7 also.

If you have the pro racer package and want to duplicate my settings for experiment, let me know. Its not 100% solved, but its 90% better. Unfortunately I have to pull my blower and send it back to whipple because the front end at the drive shaft is making some weird noise. So I won't be able to do anymore testing for a while.
 

fbody83

Z06 to Raped Ape
Established Member
Joined
Feb 10, 2003
Messages
1,350
Location
CT
I got mine pretty close now messing with the transient fuel tables. The problem is I basically had to max them out below 100 degrees ECT in order to get any positive results. At start up for the first 0-5 seconds, I leave them stock across the board though. I also lowered my manifold volume to 7 also.

If you have the pro racer package and want to duplicate my settings for experiment, let me know. Its not 100% solved, but its 90% better. Unfortunately I have to pull my blower and send it back to whipple because the front end at the drive shaft is making some weird noise. So I won't be able to do anymore testing for a while.

Ok thanks for the information. I do have PRP and have played around with the transient fuel tables before so I'll take a look and will try what you've suggested.
 

itzl0l

Angry Bald Man
Established Member
Joined
Dec 21, 2009
Messages
278
Location
GA
From what I can tell, if i force open loop the car is MUCH richer when cold than it is when HOT. These cars go to Closed Loop so quick even when cold, so if the car is in Closed Loop cold and trying to maintain stoich it applies a large correction factor. I've seen stft corrections of 1.15 and up (about 15% rich) when cold. When rolling into the gas just a bit it will go lean until the stft's can pull that correction out.

I have another odd issue with a lean spot @ 1500 rpm's. I've tried everything to fix it even messing about with injector slopes. I'm starting to think its some sort of mechanical issue...maybe flaky cop, cam sensor or something...very wierd.
 
Last edited:

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
From what I can tell, if i force open loop the car is MUCH richer when cold than it is when HOT. These cars go to Closed Loop so quick even when cold, so if the car is in Closed Loop cold and trying to maintain stoich it applies a large correction factor. I've seen stft corrections of 1.15 and up (about 15% rich) when cold. When rolling into the gas just a bit it will go lean until the stft's can pull that correction out.

I have another odd issue with a lean spot @ 1500 rpm's. I've tried everything to fix it even messing about with injector slopes. I'm starting to think its some sort of mechanical issue...maybe flaky cop, cam sensor or something...very wierd.


Hmm, might be on to something. What about just holding it open loop until it reaches 100 degrees? Your car is doing exactly what mine is though going super lean and then pulling it back in to stoich. I was able to get rid of most of that by maxing out the transient tables under 100 degrees.

Now your lean spot at 1500, that's kind of odd. Is it lean all the time at 1500? Even hot, cruising etc? How lean is it?

My blower is at whipple right now getting rebuilt - front bearing/seals went bad on me :-(, so I haven't played with it in a couple weeks. Its supposed be done tomorrow and ship out.

Someone asked about my injectors, if so, I'm running 100 pound Deatsch Werks Injectors
 

itzl0l

Angry Bald Man
Established Member
Joined
Dec 21, 2009
Messages
278
Location
GA
SD60's here. I've toyed around with running it in OL until warm, and maybe adjusting the cold fuel table and temps it switches between tables...all things I wanna try when I have time.

Funny thing is the lean tip in when cold issue is actually what lead me to discover my lean spot issue. I initially tuned the MTF while stationary and then tweaked it during slow driving... no acceleration or anything. Then I dialed in WOT. Well turns out that I had basically added enough to the MTF so it wasnt lean at 1500 @ 270ish counts...but at 2000+rpms its actually quite rich in the same maf count area. WHen its cold its WAY WAY rich....so with CL turned on and the car cold I then have the lean tip in when cold.

It definitally seems that with bigger injecters the car is more rich when cold.....probably due to wall wetting, evaporation and such.
 

01yellercobra

AKA slo984now
Established Member
Joined
Oct 5, 2005
Messages
21,125
Location
Cali
Have you adjusted the cold start fuel table? I had to lean mine out because of the bigger injectors. Don't forget to dial in your LWFM table as well.
 

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
Have you adjusted the cold start fuel table? I had to lean mine out because of the bigger injectors. Don't forget to dial in your LWFM table as well.

LWFM is good. I removed all the "enleanments" from the cold fuel area and richen'ed up a little bit.

Another thing I should mention here is that I run E85... that's why I have the 100 pound injectors.

Is there any consequence to holding it open loop until it warms up? The other problem with trying to do that I think is that as soon as you crack the throttle open the PCM goes closed loop I think... not sure if there is a way to disable that and only let it go OL when you reach a certain ECT.

**** this is turning into a great thread BTW!! Keep the ideas and experiments rolling in! I knew I couldn't be the only one having this issue. The problem is the shops tune for WOT and cruise, they can't afford to spend this kind of time on annoying drivability issues.
 

itzl0l

Angry Bald Man
Established Member
Joined
Dec 21, 2009
Messages
278
Location
GA
I've been wanting to play with the cold start enleanment table. I'm thinking since the car is so rich at startup when running OL i can use it to lean the car a bit....then perhaps stay OL until the car is warmed up. I think i remember seeing a time delay for CL, and you can set how long it takes the car to go CL based on ect.

Question for you. If you are cruising in OL and under 2k rpms at say 280 maf counts what is your afr? If you are about 2500 rpms and again at 280 maf counts is your afr still the same?
 

H8TOLUZ

Member
Established Member
Joined
Aug 21, 2013
Messages
186
Location
kansas
I have an Eaton swapped Mach and had same issue. Pulled hair out trying to fix it. Ended up raising load % @ idle and fixed!
 

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
I have an Eaton swapped Mach and had same issue. Pulled hair out trying to fix it. Ended up raising load % @ idle and fixed!

Oh no shit huh?

So leave everything else stock, but raise your load % at idle? ....interesting. How much did you raise it? I just got my whipple re-installed and its running good (same as before at least), so I have a baseline to continue testing.

Please send me some ball park number to raise load %.... very interesting! :beer:
 

H8TOLUZ

Member
Established Member
Joined
Aug 21, 2013
Messages
186
Location
kansas
It's gonna be different with every setup and I don't remember what stock is but mine ended up around 18% or in sct terms .18
 

SnakeBoostE85

whipped and korned
Established Member
Joined
Feb 16, 2014
Messages
500
Location
Colorado
It's gonna be different with every setup and I don't remember what stock is but mine ended up around 18% or in sct terms .18

Is this the table you are editing?

15276795538_823f9f7752.jpg
 

Users who are viewing this thread



Top