stalling when slowing down for a stop

[wewfords]

i have 89 stang w/306 24lbs injectors explore intake e303, t-5 convertvison done it still has the auto ecu in it. the car stalls when i push the clutch in to slow down for a stop but if i rev it up when i it push the clutch in to stop it don't do it and it gives no signs when it happens beside it acts like i turn the key off than back on to the run positon. it will idle all day long with no surging and a new iac on it and no codes

 

[bcam347]

mine did this when I had no vacuum line on the fuel pressure reg.

 

[ID89GT]

I would try replacing the fuel filter, and check the gap on the plugs

 

[wythors]

I had this exact problem after my AOD/T5 conversion. I also have the same cam, injectors and a GT40 intake. After much diagnosis by my local Mustang shop, it was discovered that the A9P computer doesn't have an "idle hold" function to keep the idle up when you put in the clutch. They flashed me a chip using A9L values and it has been fine ever since. I would think that swapping in an A9L would also fix the problem.

Cue the "I've never had this problem and I've done a dozen tranny swaps" crowd. It apparently doesn't happen very often, but I've encountered two other folks on various forums with the same complaint and a MT 'puter fixed both of them.

 

[Kdubslugga]

Pull the codes in your car, I gurantee you have a VSS code. Vehicle Speed Sensor code. Very common problem after a t5 swap.

 

[Chuckman]

check your idle speed, timing, and tps voltage before going too far into replacing parts. my tfs-headed combo would do the stalling thing before i blew it up (long story), but the explorer motor i have now doesnt do it with the same sensors/electronics (same tfs cam too), just a higher idle (about 900rpm vs7-800iirc) and lower base timing (stock 10 vs 14). mine is also an AOD->T5 conversion using the stock auto cpu, didnt do this before i built the tfs-combo.

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems.

The quick and easy way to dump the codes is in there too, and all you need to do it is a paper clip! The first two posts contain all the fixes & updates. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[f8tlfiveo]

check your idle speed, timing, and tps voltage before going too far into replacing parts. my tfs-headed combo would do the stalling thing before i blew it up (long story), but the explorer motor i have now doesnt do it with the same sensors/electronics (same tfs cam too), just a higher idle (about 900rpm vs7-800iirc) and lower base timing (stock 10 vs 14). mine is also an AOD->T5 conversion using the stock auto cpu, didnt do this before i built the tfs-combo.

i agree the vss sensor somtimes causes this problem

 

[Mustang5L5]

Pull the codes in your car, I gurantee you have a VSS code. Vehicle Speed Sensor code. Very common problem after a t5 swap.

+1

This is a symptom of a VSS issue. It would come up as a code 29 which doesn't trip the CEL.

I don't know if "no codes" means you got three "11" pass codes, or you just assumed no CEL means no codes.

This is common in speed density cars where a vss is not present on cars without cruise control. Mass air uses the VSS to raise idle when you push the clutch in. When the vss is not wired in, some cars tend to stall out when clutch is pushed in. Sometimes, in t-5 swaps, the sensor is omitted as well...or it could be faulty.