Got A Good One For You...lol

MY 85 GT

10 Year Member

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Mar 3, 2014

#1

• Mar 3, 2014

• #1

well I got a good one for you I went to check my FPR for fuel in the line well it doesn't have any but I started the car air fuels are pig rich...so with the vac line disconnected from the FPR its rich but goes leaner quicker with a controlled vac leak if that makes any sense...so I tried my theory just to see I plugged the FPR back in and took a vac line off car starts and runs barely surges and it starts out rich but goes back to normal AFs quicker if I plug the vac leak up the car will surge bad on re-start again and run rich ....take plug off make a vac leak it starts right back up barely surges and AFs go to normal quick again its weird really weird now what???

 

84Ttop

They make new pistons every day, so why worry?

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#2

• Mar 3, 2014

• #2

Problem with the iac being able to modulate the air at idle? Maybe the car needs some more air to idle correctly and the vacuum leak is providing it. Have you had the iac apart in all of your troubles?

 

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84Ttop

They make new pistons every day, so why worry?

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Mar 3, 2014

#3

• Mar 3, 2014

• #3

You could also try opening up the throttle blade a little to let more air in the motor. I run my tps at 3% for idle and not 0% and allow for the computer to compensate and manage the idle to where it should be.

 

MY 85 GT

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#4

• Mar 3, 2014

• #4

The Iac and Tps are brand new just put them on last week...lol....and it I adjust the Throttle blade more the car idles high like 1000 rpms or so....

 

84Ttop

They make new pistons every day, so why worry?

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#5

• Mar 3, 2014

• #5

Can you open the throttle a bit, reset the TPS voltage and reset the idle? Worth a shot...

 

MY 85 GT

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#6

• Mar 3, 2014

• #6

yes I can try that...but why does the car seem to run better with a vac leak because maybe its not getting enough air your saying?

 

84Ttop

They make new pistons every day, so why worry?

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#7

• Mar 3, 2014

• #7

A shot in the dark, but yes

 

MY 85 GT

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#8

• Mar 3, 2014

• #8

Ok I understand what your saying open the TB with the adjuster screw to let more air in and then compensate the higher idle with the TPS lowering the voltage? I might have to srill the holes a little more to get a bteer swing out of it...but adjusting the TPS will lower the idle but leave the TB blade open???...letting more air in...am I following you right?...

 

84Ttop

They make new pistons every day, so why worry?

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#9

• Mar 3, 2014

• #9

I think it's worth a shot. I know I have my t/b cranked to 3% at idle just to move enough air as the iac won't keep up.

 

MY 85 GT

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#10

• Mar 3, 2014

• #10

How do you do that with the Tb

 

84Ttop

They make new pistons every day, so why worry?

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Mar 4, 2014

#11

• Mar 4, 2014

• #11

MY 85 GT said:

How do you do that with the Tb

Click to expand...

I have a stand alone engine management system that tells me all of that kind of stuff. I would simply put a turn on your idle screw and reset the rest and give it a shot. You don't have much to lose at this point. I just cant see it being in your tune, I'm equally as confused as you are on this one.

 

MY 85 GT

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Mar 4, 2014

#12

• Mar 4, 2014

• #12

Yeah Nick...i know car ran great for yrs...all i did was change my AOD trans to a C4 didnt like that trans went back to a Lentech AOD...i installed a electric fan..and an 3G alt upgrade...thats all i did to this car in over 2 yrs...lol...then all of a sudden it will surge on HOT re-start and run rich on start up for awhile...weird is right i will give your idea a shot and let you know.....

 

Noobz347

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Mar 4, 2014

#13

• Mar 4, 2014

• #13

Is this the car we're talking about?

Turbo installed 87 GT Vert.On3 turbo.14 psi...Trickflow TW 170cc heads,TF street heat intake,70mm TB,stock cam,1.6 roller rockers,Snow performance stage 2 meth kit,42# injectors,340 lph fuel pump,tunning with Moates QH,AOD lentech full manual VB, electric OD, 3000 stall.3.55's

Click to expand...

It occurs to be that injectors greater in size than 30 lb can more easily be tuned wrong than right.

Have you gone through this?
http://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

 

Bullitt347

I have been doing it wrong this whole time

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Mar 4, 2014

#14

• Mar 4, 2014

• #14

There are a couple of other options to help with the idle issue. I have seen and used an adapter plate that bolts in-between the IAC and throttle body that has a couple of adjustable bleed screws in it to allow for more air to by-pass the throttle body, thus allowing for the throttle blade and T/P sensor to remain close to stock settings. I have also used a PCV valve from a 460 pick-up truck to allow the PVC system (if still used in your application) to operate better in a modified small block.

 

MY 85 GT

10 Year Member

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Mar 4, 2014

#15

• Mar 4, 2014

• #15

Noobz347 said:

Is this the car we're talking about?



It occurs to be that injectors greater in size than 30 lb can more easily be tuned wrong than right.

Have you gone through this?
http://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

Click to expand...

Ive been thru that list 100 time already...lol...it works im sure but maybe mine needs to be set up at a higher rpm. or something....

 

MY 85 GT

10 Year Member

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Mar 4, 2014

#16

• Mar 4, 2014

• #16

Bullitt347 said:

There are a couple of other options to help with the idle issue. I have seen and used an adapter plate that bolts in-between the IAC and throttle body that has a couple of adjustable bleed screws in it to allow for more air to by-pass the throttle body, thus allowing for the throttle blade and T/P sensor to remain close to stock settings. I have also used a PCV valve from a 460 pick-up truck to allow the PVC system (if still used in your application) to operate better in a modified small block.

Click to expand...

I dont have a Pcv valve...i have it vented to the atmosphere...its been that way for over 2yrs with no issues...just the last few months the car has been doing this...runs fine cold...go get gas shut it off go to re-start it HOT meaning up to temp it starts but surges badly...i have to keep my foot on the gas until it recovers..then runs fine again...did notice tho it goes really rich on a hot re-start...thats why i checked my FPR with the line off yesterday and with a controlled VAC leak ...meaning i made the vac leak it didnt do the hot rte start surge...its very weird...something isnt seeing something right or a sensor is no good...im almost thinking maybe a bad injector?.....if i let the car sit for 20 mintues it re-starts like a new car....its very weird....has me lost....

 

MY 85 GT

10 Year Member

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Mar 4, 2014

#17

• Mar 4, 2014

• #17

Ok came home today and I did what 84Ttop suggested so I took the TPS and open the holes a little more for more adjustment opened the TB up and got the car to idle with the tps set to .95 volts...the car is idling a little higher then I like but guess what the car starts HOT surges a little then levels right out I did this check a few times ran the car drove it and shut it off started it right back up it started surged for a few seconds then leveled out seems to be better then what it was is it right probably not..Question could it be the TB is bad????