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Greetings,

I have a 1989 Mustang with some odd engine performance.

1. I just replaced the Idle Air Sensor (IAS) and now it idles somewhat more normally.

2. However, after approximately 30 seconds, the engine chokes, loses RPMs and usually dies (unless fuel is increase with the pedal or by hand in the engine compartment).

3. It also makes some "vacuum" noises. Whenever the throttle is increased from idle, you can hear a Gasp :confused: of air (going from idle to about 1/2 throttle). Every time. Very unusual sound.

4. Along with the gasping vacuum sound, the engine now nearly backfires during this process.

Recent DIY repairs:

Idle Air Sensor (OReilly's)
Removed Air Plenum (air intake system) and cleaned (with spray [air mass] cleaner) the interior of the plenum.
Replaced Starter Solenoid (as recommended by the Alternator manufacturer)
Replaced the Alternator
Replaced the exhaust manifold (China model)
Placed a metal plate in-between the EGR and the Plenum (bypassing the ERG)
[I suspect this was a bad idea]
Flushed the cooling system (now all good & clean)
Flushed the oil & serviced it with Royal Purple
Replaced plug wires (OReilly's)
Replaced spark plugs (Motorcraft)
Removed & cleaned the valve cover (lost a bold in the process; but checked interior engine areas; not found)
Replaced head lights (after market; American Muscle version)
Replaced all Ground and Positive leads to battery and starter
Replaced Starter
Bypassed Ford thermal switch for Electric Radiator fan
Installed thermally adjustable electric switch (through radiator coils) to make radiator fan "on" temperature adjustable (worked nicely); (OReillys)

If you have any ideas, please let me know. I really appreciate your recommendations.

Tim Grimes
865-455-0398 cell/text
[email protected]
TimKGrimes (Skype)
 

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Sounds like a VACUUM leak according to your post. So look around for it and use come brake clean to spray around the manifold and vacuum lines. The rpm will increase when you shoot it on the leak. Also check the brake booster and check valve. Also do not forget the PCV valve i have seen the plastic ones break and cause all kind of problems. Well do some checking and post back. Good luck Peace Tom
 

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When you removed the EGR stuff and put the plate in it's place, did you use a gasket between the plate and the intake? Some people seem to miss this part and it creates a vacuum leak like Tom mentioned.
 

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Discussion Starter #4
Rough Running 2.3

When you removed the EGR stuff and put the plate in it's place, did you use a gasket between the plate and the intake? Some people seem to miss this part and it creates a vacuum leak like Tom mentioned.
Yes, I did install a "plate" in-between the EGR faceplate and the intake. I also put some red RTV in-between each side of the plate to make sure it was airtight. But, I haven't checked the two bolts to make sure they're really tight (since I re-installed it). I'll re-check that and report back. Good idea!

Tim
 

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rough running 2.3

When you removed the EGR stuff and put the plate in it's place, did you use a gasket between the plate and the intake? Some people seem to miss this part and it creates a vacuum leak like Tom mentioned.
Thanks Tom,

I'll find me some brake cleaner and see what happens. I'll also wear safety glasses and have a fire-extinguisher handy. haha
 

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That kind of sounds the same as when my TFI module was going bad. It would run fine at idle but give it gas and it would spit and sputter. Something to look at if the vacuum leak doesn't pan out. Can you check codes?
 

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My 1990 2.3 has this kind of problem on cold start up. The engine will start, but just sputters out until it warms up and I have to constantly gas it to keep it from cutting off.

I also have a problem of it lagging when I give it gas only until it warms up.
 
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