88 stang stalling

[99turbostang]

ok so just bought a 88 gt, It has alum. heads, Cobra intake, long tubes,3:73's and a cam, I have no idea what cam. also It only has 19lb injectors??? seem kinda small to me. any way my problem is when driving everything is fine, Come to a light or stop sign take it out of gear and step on the brake and idle surges then dies. any help would be great also i usally take it out of gear step on the brakes then give it gas to keep it from stalling
has mass air conversion

 

[HISSIN50]

Since you don't know what parts are in there, that makes it kinda tough.

For simple things, I would pull codes and check to see if the VSS wiring is correct. If not, that can allow stalling during a rolling idle.

 

[DrunkPony]

Does it have any idle issuies at start up ever? like surging up and down trying to find its idle, or hanging idle? Coule be a number of things... to me it sound more electrical than any thing. your Salt and Pepper shakers (big white and black connectors between the firewall and the intake mani) some times get dirty inside. pry them open carefully and take a pick and carefully spread the connecters a little bit so they get better contact. fill the suckers with dialectric grease and snap them back. these are a leading cause in idle problems.

andother check you can make is with the Throttle Control Sensor. its on top of the mani around the EGR. its held on by 2 bolts. its very important to have it set right. Try doing some searches on how to hook the ohm meter to it and what readings you should be getting. all i can remember is if you hook your ohm meter to the wires, move it back and forth with the motor off, move it nice and slow back and forth the numbers should go up and down smoothly, if it jumps around your Sensor is bad.

 

[Mustang5L5]

Run the codes. '88's don't have a CEL. Could help narrow down what is wrong

 

[99turbostang]

VSS is correct i thought that might have been the problem but no, is it possible the cam is to large and not enough vacuum

 

[Mustang5L5]

Do a vacuum test. Since you don't know what cam is it in, hard for us to say that's the cause.


Does it only stall when you step on the brakes? At what RPM? near idle? Could have a vacuum leak or faulty booster.

 

[99turbostang]

i cleaned and greased the salt and pepper plugs, checked tps its set to .88 pulled the codes and looks like i have a bad coolant sensor, I got a code 21,24,82, 82 thermactor Smog pump is deleted so not worried about that, then pulled codes with engine running and got 12,21,94,44 44,94 thermactor but didnt get code 24 with engine running any ideas im thinking sensor but would that cause stalling when decelerating

 

[Mustang5L5]

You'll get a code 21 (coolant sensor) if you try to pull the codes with the car cold. You need to warm it up fully before running the test and the 21 should go away

Code 24 is the same thing. If the air temp is under 40 degrees, you may see this code. Let engine warm up and try it again.

82 is smog pump...won't affect how car runs

Code 12 means your idle may not be set correctly. Might want to perform the idle reset procedure. Basically unplug the IAC and start car, set the minimum idle using the throttle body screw to just about where the car barely runs. Then unplug the batt for 30 mins to reset the computer. This will also clear the codes, so you will want to run them again to see if you took care of the code 21, 24 and 12 anyway.

Code 44 and 94 are also smog related..no effect on how car will run.

So, set your idle, reset computer, let car warm up fully and run your codes again. See what goes away.

You could get the 21 and 24 again when the car is fully warmed up...in which case i'd put a multimeter across them and see if the resistance spec is in range. If not, replace.

Also, get some carb cleaner and spray around the engine bay for vac leaks. Your idle will climb if there is one present.

Also, hook a vacuum gauge up and see what you have for vac readings at idle and 2000 RPM

 

[99turbostang]

ok so reset base idle, checked vac. and codes. only codes that I get now are for smog stuff that i dont have. Vac at idle is 10 and at 2000rpm is 16. idles way smoother and so far doesnt stall when i go to stop. now the only thing i have to fix is the slight bucking at 2000rpm cruising.

 

[HISSIN50]

Vac at idle is 10 and at 2000rpm is 16.

Is this a typo?

 

[99turbostang]

no thats what it was getting 10 maybe 11 at idle and at 2000 rpm was 16. It does have a cam.