tip in throttle lean/hesitation - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 13 Old 03-12-2009, 10:53 PM Thread Starter
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tip in throttle lean/hesitation

So ive been driving my car all this week since i got it running and am having a problem with bad lean condition and hesitation/misfire when i just barely give it throttle. Mainly occurs at crusing speeds and leaving from a stop. Wideband with go 17-18:1 sometimes leaner and will clear up with more throttle. Car hesitates and sounds like a misfire but it could be popping from being so lean. Im ordering a Tweecer and hoping ill be able to clear it up. Ive tried to up the FP, its at 48 w/ vac line off, but cant go too far w/o sacrificing idle (72lb injectors & no chip). Seems like it gets worse the longer i drive it, coolant temp around 190* or so. TPS is at .98. TPS, coolant temp sensor, MAF are all new. 02's are not. What do you all think??

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Brian


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post #2 of 13 Old 03-13-2009, 02:37 PM
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I had the same problem w/ my car. I wound up just forcing open loop and now the car runs smooth.


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post #3 of 13 Old 03-13-2009, 03:26 PM
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since you are buying a tweecer i assume that you are tuned on matched injectors alone. Even the slightest discrepancy in the low voltage of the MAF can make a big change in your Air/fuel. you should be able to clean it up with some slight changes to your transfer function in tweecer. Once you get the tweecer just tune your injector slopes for your 72's, enter the transfer function of the MAF, and set your FP to 40 with vac off, this should give you a good jumping off point.

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post #4 of 13 Old 03-13-2009, 03:32 PM
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It can be fixed in the tune..

My N/A car was doing the same thing..

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post #5 of 13 Old 03-13-2009, 09:41 PM Thread Starter
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thanks for the input everyone. stroker, your right, im running the 72's w/ a matching PMAS blowthrough meter right now. It actually drives and acts surprisingly well aside from this little problem. i see you are running a Tweecer too, i may hit you up if i got some questions. How bad is it to operate?

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post #6 of 13 Old 03-14-2009, 12:24 PM
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How does your a/f ratio look during part throttle cruising w/ no acceleration(tip-in)? If your a/f ratio's are right on target throughout the rpm's then I doubt that your maf transfer is the culprit of this problem. Typically when having part throttle(closed loop) operation and the car sees a lean tip-in/acceleration the functions/tables that might help are going to be your accel enrichment/transient fuel.

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post #7 of 13 Old 03-14-2009, 12:40 PM
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Also, on a second read-thru "stroker" is also giving good advice. I somewhat short-read the post and thought that you were using a tweecer, although my previous advice can still apply in that same situation.

When you are getting ready to start tuning w/ your tweecer you are going to have several things that need to be done to help baseline the tuning.

Set fp to 38-40psi w/ vac off
Set timing to 10* base w/ spout out
Enter your MAF transfer
Injector slopes
Injector offset
etc.

What is the code of the eec that your are tuning?

Get back on here when you are ready and I am sure we can give you some more help.

Also, check out eectuning.org it is a great site w/ loads of info.

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post #8 of 13 Old 03-16-2009, 10:45 AM
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There's other things that can affect the AFR besides the maf....but when I first read it I vote for o2 sensors or EGR....with the Tweecer you will be able to turn off each individually and you can figure out what's going on...Does it go away when you go WOT? Did you get the tweecer or figured out yet?
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post #9 of 13 Old 03-16-2009, 03:45 PM Thread Starter
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Tweecer is on the way. Its an A9L ecu. I tried clocking the MAF to where the electronics were towards the fender instead of straight up and that seemed to help cruising but still has tip in lean. When i let off of the gas and coast is goes to 12:1, steady pressure on the pedal cruising is 14:1 or so. Heavier pedal will go off the chart sometimes but usually 16-17:1.

I really havent had the pedal to the floor but it is lean when boost comes on 14-15:1. Havent pushed it, dont want to replace HG's lol. O2's are not new, no EGR.

thanks for everyones input, hopefully Tweecer will fix it, or at least let me see whats going on

1967 Mustang Coupe
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1987 Mustang GT Turbod-9.75 @ 140mph gone but not forgotten
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post #10 of 13 Old 03-16-2009, 05:00 PM
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Whats happening is when you let off the processor is seeing WAY rich in coast and pulls fuel to get the o2's to go back switching, when you tip in on the throttle then PCM is WAY over compensated and it goes lean for 2-4 seconds until it commands more fuel. My N/A car is doing the same thing and I have a TwEECer but I don't have a battery for my laptop so riding around with a 10 mile drop cord is kinda out of the question. If I were you log on to EECtuning.org and get some tuning advise over there when you get up and going with the TwEECer, they are very helpful.


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post #11 of 13 Old 03-16-2009, 05:32 PM Thread Starter
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Thanks Silver! Ill register over there and check it out. I appreciate every ones input

Brian

1967 Mustang Coupe
1990 Mustang GT Turbod DD
1987 Mustang GT Turbod-9.75 @ 140mph gone but not forgotten
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post #12 of 13 Old 03-16-2009, 09:27 PM
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I fought this issue at the beginning of last year - car was tuned but ended up being a bad 02, new out of the box.

Get those videos up on the turbo forum!



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post #13 of 13 Old 03-16-2009, 11:22 PM
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mine has a hellion kit i had run racing gas before the turbo. the gas tears up the o2's i replaced them and it was fine in a couple.
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