warm up issues!!

ninety15.0

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Mar 10, 2004

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Sep 13, 2006

#1

• Sep 13, 2006

• #1

Hey guys...i finished a head swap a week ago and it runs great when its warmed up or has been driven a short while ago. The car starts great when its cold....but has a very difficult time finding idle after it tachs down. It drops to - 400 and bounces back up to 1500. This goes on for a while, it smells rich and i sometimes need to give it gas to stay running. Throttle response is horrible and if you try and use low revs...it bucks and surges and $h/t. its horrible until the car gets above 150* then its ok. Drives and idles perfectly fine when hot. I think my 24 lb inj. are a tad big so i havve the FP set at 37 psi vac off. TIming is at 16 (motor loves timing ) and no detonation. I still think im way rich when its cold...but how much further can i drop FP without causing fuel atomization problems? Any help's appreciated! thanks -Nick

 

vristang

15 Year Member

Mar 31, 2005

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Sep 13, 2006

#2

• Sep 13, 2006

• #2

That is as far as I would go with the fuel pressure, but that is just me.
It sounds like the problem is just with Open Loop.
How does the car run at WOT? Is it what you expected from the swap?

Have you pulled the codes?
I suspect something was damaged during the head swap, and its causing issues now.

jason

EDIT:
How sure are you that you have the corrct MAF calibration?

 

ninety15.0

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Sep 13, 2006

#3

• Sep 13, 2006

• #3

yea i agree FP sounds like the place to start. Im going to start by resetting base idle w/o IAC, and checking/setting TPS, cleaning MAF, checking timing, then set FP just a few psi lower maybe 35 vac off??

In terms of the swap...the car is very fast! (at least for me) tonight it was pulling very hard past 100mph. it comes alive after 3000 r's...but feels very rich below that....and no detonation what so ever. Once warm it runs amazing...but it smells rich. Any other suggestions? thanks guys

 

S

speedytang

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Jul 28, 1999

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Sep 14, 2006

#4

• Sep 14, 2006

• #4

Did you change other thing when you did the Heads or Just Heads.

 

vristang

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#5

• Sep 14, 2006

• #5

I am not trying to be rude, but anything that any of us comes up with is going to be a guess.

Pulling the codes may tell you exactly what is wrong.

That is always the best first step to take with these kinds of issues.

jason

 

ninety15.0

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Sep 14, 2006

#6

• Sep 14, 2006

• #6

When i did the heads i did 24# inj and a 75mm pro m as well. When i comes to this car...there arent too many things that confuse me except this one. No codes...except for inoperative air system codes. (no smog pump) everything else is perfect. I let u know what i find this weekend when i get some time to tear into it! thanks for the advise...anyone else?

 

8

86bluecobra

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Dec 20, 2004

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Sep 14, 2006

#7

• Sep 14, 2006

• #7

Looks like the mass air needs to be tuned.

 

vristang

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Sep 14, 2006

#8

• Sep 14, 2006

• #8

ninety15.0 said:

When i did the heads i did 24# inj and a 75mm pro m as well. When i comes to this car...there arent too many things that confuse me except this one. No codes...except for inoperative air system codes. (no smog pump) everything else is perfect. I let u know what i find this weekend when i get some time to tear into it! thanks for the advise...anyone else?

Click to expand...

I'm with bluecobra on this.
It would be worth the time to double check all the part numbers of the Pro-m meter.

Did you buy it new or used?

With no other meaningful codes, a maf/injector mismatch is most likely the cause of the fuel problem.

Let us know what you find.

jason

 

ninety15.0

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Sep 15, 2006

#9

• Sep 15, 2006

• #9

Theres no mismatch on the inj./MAF. For some reason im still leaning towards it running real rich on startup/warmup. I think clockin the MAF is a good idea as well...thanks bluecobra. Like i said it runs perfect once its warm...but still smells rich. Im going to take a look at it this afternoon after this rain lets up. thanks fellas