95 Mustang idle issue?

[95GT_VERT]

1995 Mustang 5.0L car has worked fine for 2 season suddenly it started to surge only on cold start after sitting over night. it only surged a few hundred rpm for a minute or 2 ...its progressively gotten worst to the point where it will stall if i dont give it gas for a minute or 2.

once the car warms up it idles fine. any suggestions?

Car has Underdrive pullies and CAI but hasnt had issue with them before.

[Ponyryd]

Possible vacuum leak, tired Iac valve or tps.

[hsousa88]

My car does the same 25% of the time... couple of revs and it passes.

I need to build a motor :(

[95GT_VERT]

What kind of vacuum should it pull if there isn't a leak

[Ponyryd]

A small leak won't change the vacuum reading.

[ZR]

-plugs / wires / cap n rotor in good shape?
-fuel filter recent / confirmed cold start fuel pressure?
-cleaned all connections at battery / starter along with body and engine grounds?
-cleaned MAF?
-confirmed TPS voltage / done idle relearn procedure?
-at least visual check of all vac hoses?
-intake hoses / pipes, all clamps tight?
-no exhaust leaks cold?
-check values of coolant temp sensor?
-clean throttle body?

[RedSN]

I'll add my 2 cents:
Clean out the idle air valve.
Clean the throttle body.

Already mentioned, but those are the two likely culprits I've run into with my 5.0

[95GT_VERT]

Plugs, wires, cap and rotor are all under 10,000km....all vacuum lines were replaced during the build 2 season ago...MAF has been cleaned....IAC has been cleaned but didnt change anything

I did the KOER test and one code was for the ECT sensor....replaced it and it didnt fix the car..... i switched back to the original sensor....the new one was all plastic which was strange to me

[ZR]

For sensor, suggest OEM Ford only, having too much trouble with aftermarket.

[ZR]

Updated sensor comes with a new connector. Always suggest solder / shrink wrap vs using supplied crimp connectors.

http://www.americanmuscle.com/coolant-temp-sensor-8395-install.html

[True Blue]

IAC has been cleaned but didnt change anything


On a cold start, unplug the IAC's electrical connector and see if the idle improves or if the car stalls.

[95GT_VERT]

On a cold start, unplug the IAC's electrical connector and see if the idle improves or if the car stalls.

car stalls

[True Blue]

Did you try resetting the base idle? http://www.muscularmustangs.com/idlereset.php

The problem you are experiencing I'm facing the same exact issue with my coupe, started happening just before I put it away for the winter. I haven't had a chance to work on it yet, I'm hoping it's just a dirty IAC.

[Ponyryd]

Plugs, wires, cap and rotor are all under 10,000km....all vacuum lines were replaced during the build 2 season ago...MAF has been cleaned....IAC has been cleaned but didnt change anything

I did the KOER test and one code was for the ECT sensor....replaced it and it didnt fix the car..... i switched back to the original sensor....the new one was all plastic which was strange to me

I believe there are two sensors, one for the guage and one for the ECM, are you sure you changed the right one?

[ZR]

I just installed the updated coolant temp sensor + pigtail in a build today.

[95GT_VERT]

Yes , replaced the multi wire sensor in the coolant tube , not the single wire gauge sensor

[ZR]

http://www.torontomustangclub.ca/forums/attachment.php?attachmentid=8533&stc=1&d=1492290685

[ZR]

OEM vs updated version + pigtail.

[Darkhorse]

After you sort this stuff out, the 94/95 all do very well with an SCT tune, they will run cooler and smarter. You'll notice a big difference.

[ZR]

Too bad the A9L swap harness n related bits fell off the map, works wonders on even a bone stock one. In the same breath, as Corey said, decent tune is money well spent as well.