'87 GT idle surge problem

[quickfox87]

I have a '87 GT i just recently put a ford racing F303 cam in it and it idle surges. I have checked for vacuum leaks and found none. It sucks because i have to idle it at 1000 RPM at least where it won't go dead due to the surge, SO I CAN'T HEAR THE CAM!AHHHH! It is drivin' me nuts! I am stumped any advice would be deeply appreciated!

[QWKSNKE]

What is the timing, fuel pressure, and tps voltage set at?
What is the rest of your combination?

I have never ran the F cam (several on here have) but it maybe that it is to big for the EEC to compensate for when trying to idle without having a custom EEC tune

[04 Mach1]

The vert has the f cam. Go ahead and check everything Lee has said but most likely you'll have to have it idle around 1000 rpms. That where ours idles.

[quickfox87]

it has 70 mm throttle body, underdrive pulleys, 3:73's, PP intake, CAI, 2400 stall, BBK shorty headers, borla exhaust. timing is around 12 degrees over top dead center, and how do i check tps voltage
could it being a speed density car have anything to do with it?
would it maybe help to carbeurate it?

[QWKSNKE]

would it maybe help to carbeurate it?


No!!!!!!!!!!!!!

[quickfox87]

how do i check tps voltage and if i dont need to carbeurate it what about converting to a mass air flow?

[QWKSNKE]

MAF conversion would help but when you get into decent size cams whether you are carbed or fuel injected you will have to bump the idle up unless you get a custom tuned chip or EEC tuner

[04 Mach1]

Do a MAF conversion should straighten everything up. I heard on a speed density car you really can't do much other than a set of 1.7 rockers with out killing the ilde quality. Or you could have a chip burnt for it.

Tps voltage is check on the green wire at the tps. Should set around .98 volts.

[coupe]

Yes, a MAF conversion is your solution.

The Speed Density computer gets its airflow numbers based on a MAP sensor (Manifold Pressure) and ACT (Air Charge Temperature). So the computer uses temperature and pressure in the manifold to calculate a volume of air present...no airflow measurement.

The cam is drawing more airflow into the motor and causing the O2 sensors to see what it thinks are problems with too much air, so it tries to regulate the Idle-control causing surging. The MAP and ACT don't change with the cam...the pressure and temperature of the air stays the same...this is the defficiency of Speed Density in our application.

Do the MAF conversion (MAF meter, MAF computer, and the wiring swap in the harness). The car will quit making you mad. :nice:

No Carb.

[Italian LX]

. . .The car will quit making you mad. :nice:
I wouldn't go that far - I've had many MAF cars make me go mad. :D

. . . hell, ask Marc about his glow-tech issue. :rofl:

No Carb.
:werd:

[coupe]

...I've had many MAF cars make me go mad.


Oh, I know. :yup:

But his list of mods is quite short...it should be pretty smooth still.

Only MAF cars I've had issues with are...well...
my damn blue one. :shake:
It's got EVERY bolt on you can do...without a tune. :nono:

I'll tune it when I get the 160# injectors installed. :D

[TheJeanyus]

I bet Luke would put a LS1 in it. :jester:

I agree with doing a MAF conversion. Speed density just isn't all that mod friendly.

[quickfox87]

I bet Luke would put a LS1 in it. :jester:

I agree with doing a MAF conversion. Speed density just isn't all that mod friendly.
you got that right obviously ... i guess i just didn't know that much about them i have always had LT1 Z 28's until now ... i finally realized that ..... uhhhhh how do i put this... they SUCK!
:chug: thanks guys!

[quickfox87]

i will let yall know how it goes!

[04 Mach1]

. . . hell, ask Marc about his glow-tech issue. :rofl:


:werd:

NOT FUNNY.

I'm about to start back on the blue POS this weekend. Have a couple of leads I'm looking into.