Infamous Idle surge

[akfodysvn]

So I have the surge. Reset my base idle and checked TPS and both are good to go. Initially I get a solid surge on start up... below 500 up to 1300ish...not my concern.


I get a HUGE surge when I turn on my A/C and it will even kill the car at a stop. Eventually if I drive long enough with the AC on and without stopping it no longer will die for the most part (like the computer is learning). If it goes to die I can give it gas and then it seems to level out okay.

Any leads?

Also curious what fuel pressure I should be running and how to properly set the pressure with the AFPR.

Mods as below

BBK 1706 Adjustable regulator.
BBK 8004 76mm 24lb mass air sensor.
Ford 24# injectors M-9593-A302

Explorer intake manifold upper and lower. (appears to be a VERY thick gasket between the upper and lower, like at least 1/4 inch)
Edelbrock EGR plate 65mm #3827.
Edelbrock 70mm throttle body #3824

GT 40 steel heads.
Ford valve springs M-6513-A50
Ford E303 cam.
Crane 1:6 Roller rockers

MAC equal length headers.
Off road BBK H-pipe.
Flow master's 2 ½ cat back system.

3:73 rear gears.

[Mysticcobrakilla]

Is this a new set up or one that has been running fine and just started having this issue?

[akfodysvn]

I just bought the car. It has 30k miles and the guy said it has been surging.

[Sleeper]

Needs tuned. Or could bandaid it with one of thos air idle bleed things that goes where the iac bolts.

[BigDumbRedneck]

Fuel pressure 39# with the hose off the regulator. Make sure the IAC is clean. Don't set the TPS voltage too close to 1 volt--none of the .98 type stuff. Set the base idle with the IAC unplugged.

[akfodysvn]

Needs tuned. Or could bandaid it with one of thos air idle bleed things that goes where the iac bolts.

I've considered that too. Do you think that all the guys who are untuned with good idles are fibbing about how nice their car idles without a tune? IAC does not have the adapter plate between the IAC and TB

Fuel pressure 39# with the hose off the regulator. Make sure the IAC is clean. Don't set the TPS voltage too close to 1 volt--none of the .98 type stuff. Set the base idle with the IAC unplugged.

I will clean the IAC and spray around the intake for leaks (carb cleaner correct?)

As far as fuel pressure I've never messed with the regulator. Just disconnect the vacuum and adjust the screw while the engine is running? Once I reconnect the vacuum will the pressure decrease? I know the 39# is the stock setting but didn't know if I should adjust it for my modifications.

I read quite a bit about TPS and read that really anywhere between .7-1 is just fine and within normal limits. That was from some of the well trusted veterans on corral.net

[BigDumbRedneck]

I will clean the IAC and spray around the intake for leaks (carb cleaner correct?)

As far as fuel pressure I've never messed with the regulator. Just disconnect the vacuum and adjust the screw while the engine is running? Once I reconnect the vacuum will the pressure decrease? I know the 39# is the stock setting but didn't know if I should adjust it for my modifications.

I read quite a bit about TPS and read that really anywhere between .7-1 is just fine and within normal limits. That was from some of the well trusted veterans on corral.net

Remove the IAC and clean with Q-tips and carb cleaner. Don't worry about intake leaks until you make sure the IAC is right, the TPS voltate is set, and the fuel pressure is adjusted. Need to be above .8 on TPS voltage. Just set it at .90 volts. Make sure you set the idle speed with the IAC unplugged.

Yes, set the fuel pressure with the car running and vacuum hose unhooked. Fuel pressure will drop when you reinstall it.

[akfodysvn]

Thanks.

I set the base Idle with the IAC disconnected.

TPS is at .88

I will adjust fuel pressure tomorrow when I clean the IAC

I was looking at intake leak because there is a hairline crack (possibly) around the front intake bolt.

It still doesn't really make sense to me though as the AC is the only variable.

Right now it had a pretty jumpy cold start idle

[akfodysvn]

Also the car smells rich... might be lack of cats... I have been out of a stang for awhile

[TX21]

Throttle stop screw may need to be adjusted if someone turned it down to get the idle lower.

[akfodysvn]

In process to find out if my maf is calibrated for cold air or stock air box. I can't tell and part # doesn't make sense. i emailed bbk

[JV106]

I've been dealing with the same on a very similar setup. I ended up completely rewiring the car. It used to do crazy things to the idle when I'd turn on the headlights, A/C, electric fan, etc. Those issues are gone now. Next I'm going to do the 3G alternator swap and then it is going to a shop for a tune.

I did not listen when people on here told me to go get it tuned. In hindsight I wish I would've just gone that route.

[0393gt]

I thought tps needed to be about .98 or as close to 1 as possible..

[akfodysvn]

I thought tps needed to be about .98 or as close to 1 as possible..

I did a ton of research and the old theory was yes... as close to .98 as possible but below one.

Newer theory from the most knowledgeable sources on corral indicate that you can have values much lower than the .98 with great drive-ability.

[akfodysvn]

I've been dealing with the same on a very similar setup. I ended up completely rewiring the car. It used to do crazy things to the idle when I'd turn on the headlights, A/C, electric fan, etc. Those issues are gone now. Next I'm going to do the 3G alternator swap and then it is going to a shop for a tune.

I did not listen when people on here told me to go get it tuned. In hindsight I wish I would've just gone that route.

Not a chance in hell I am going to re-wire a 30k mile car... at least I hope it never comes to that LOL. You are a good man to do that. All other accessories don't effect the idle/surge at all. Even once the car is going it won't really surge with AC... just initially.

First start up still has a crazy ass idle though...


Well the car has a "bama" SCT chip in it. Currently set at stock position because I've heard nothing but bad shit about BAMA. They have lifetime re-flashes though so I might give it one more chance to see if they can get it straight.

One question I have is can I take that chip I have and have it re-written with a custom tune from a local shop? Or will I need a new chip?