[DemonGT]

my 89GT has a bad surging idle and after a few minutes it dies if you dont keep reving it up...after awhile it will smooth out and idle..i was told the maf on the car was a 93 cobra meter...and the car has 24lb injectors...but i dont know if it has a cobra EEC or if its stock...but i pulled the meter and am not sure what it is..pictures can be found here
http://spaces.msn-ppe.com/demongt/

if it IS a cobra meter..and ill have to check the EEC

P.S. i swaped the IAC from my 91 that idles fine..over to the 89 and it still surged

[DemonGT]

well i just looked at ebay at 93 cobra meters and it sure looks just like it....how exactly do i get to the EEC? and how do i tell if its the stock EEC or a cobra??

[bsedwebt70-5.0]

looks like a cobra or a v-6 1994-5 unit - computer may have a problem with it. Pop open the passenger side kick panel and look at the 7 inch square aluminum box thing there - it will have a label on it - if it is the factory regular mustang box it will have A9L for a 5spd box or A9P for an automatic box - once you get the kick panel off it is easy to see how to pop it out.

[DemonGT]

im crossing my fingers its the factory computer...cause then i just need a new maf and its done...hopefully

anyone know what the symptoms might be of a cobra maf used with a stock 89 computer? i would think it would run alot worse then it dose...it just has the bad surging idle at start up but if you keep reving it eventually it will smooth out...most the time

[bsedwebt70-5.0]

You can unplug the MAF and see how it runs then - also you can spray it with electrical parts cleaner on the heated wire coils inside it to see if it helps - let it dry first.

[ONEBADPNY]

i might be wrong but the cobra meter is setup for 19lb. injectors, not 24lbs. i think the tune for the 24lb. injectors is in the cobra computer i pretty sure i have read that a time or two.

[jrichker]

Originally Posted by ONEBADPNY

i might be wrong but the cobra meter is setup for 19lb. injectors, not 24lbs. i think the tune for the 24lb. injectors is in the cobra computer i pretty sure i have read that a time or two.

You are 100% correct...

[DemonGT]

yes, i am aware of the tune being in the EEC for the 24lb injectors the cobra has..thats why i made the comment bout not knowing what EEC the car has is a cobra EEC or stock....

and i asked about how it would run if the computer WAS the stock computer with the cobra meter...to see if the symptoms were what the car has

if i check the EEC and it is indeed a cobra computer..then im at a lose as to what the problum might be..thats why i said i hope its the stock computer cause then chances are that might be the problum..and when the idle DOSE smooth out i was thinking mabe its just cause the computer is componsating for the maf/injector miss match

[Daggar]

The further up the flow scale the meter gets the more that the differences will show. There is as much as a 20% difference in signal output at the top of the RPM range on an N/A stock cammed application using the Cobra meter vs. a stock one. Look around for the flow sheets. I've seen them posted on this forum before.

[ONEBADPNY]

try clocking the meter. that's what i did to get mine to idle right on start up.

[DemonGT]

ok guys..i did a few things to the 89GT today...after installing a fuel pressure gauge i set the pressure vac off to around 36? any suggestions as to what a good fuel pressure would be? will list mods for the 89 at the end of the post...also noticed when i hooked the vac back up to the regulator the psi droped alot more then my 91GT's dose...anyway

started the car and it surged badly but after blipping the throttle a bit it idle nice...bout 10 min later i started it and it surged badly the whole time my scanner was doing the KOER test..it stalled just as it finished...here is what the scanner got
KOEO - 11 system pass
KOER - 94 Thermactor air system inoperative bank 2 or fuel control circuit failure

what dose this mean...and would it cause the surging....also, i checked the EEC to see what it was..it says A9L, so its not a cobra EEC...in your guys opinion...do you think the eec not being right for the cobra maf is what is causing the surging?

mods for 89- TFS heads,TFS #1 cam,TFS street intake,70mm BBK TB, BBK ceramic shortys,offroad H,Mac catback,cobra maf,1.6 TFS rockers,deleted A/C

[vristang]

Bump the fuel pressure to stock ~38psi. Make changes from there.

I agree with Daggar...
The use of a cobra air meter (70mm) and an A9L (set up for 55mm) is less than ideal. Any mix and match setup will not work well.

pick a combo and get the parts for that.

It would be good to run through the surging idle checklist though, to eliminate the possiblity of other problems.

jason

[DemonGT]

i have done some of whats on the list...but im hoping the maf is the problum