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tx20m4u
tx20m4u, Auto Mechanic
Category: Ford
Satisfied Customers: 173
Experience:  12+ years as a mechanic and shop owner
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1994 Ford probe: 2.0L 4cyl, Manual Trans..Intake manifold..surges

Customer Question

1994 Ford Probe 2.0L 4cyl, Manual Trans. that has just had it's Intake manifold replaced has an high idle and surges sometimes up and down before settling down to normal idle.
It also takes a long time to get down to normal idle when the engine is warm eg when you are driving and come to a stop at a stoplight or a que the engine takes about 30 seconds to get down to the normal 750 idle revs from 1400 revs.

All new gaskets.
Checked for leaks with leak test gas = No leaks found.
All vacuum hoses are connected and are not leaking.
"Burped" the cooling system.
New plugs.
Any suggestions ?
Submitted: 4 years ago.
Category: Ford
Expert:  tx20m4u replied 4 years ago.

tx20m4u :

Hi how are you?


 

tx20m4u :

This sounds like a bad idle air control valve. It can be unpredictable on wether it will rev up or down or just stay normal react slow to maintaining idle. You can remove this part and try to clean real good with rubbing alcohol you can use a q-tip to clean out the hole. If you replace the part because cleaning it didnt work be sure the hole is clean before installing new part.


 

JACUSTOMER-v67h3vly- :

IAC is brand new along with the EGR (reason for replacing the intake manifold was broken bolt to the EGR)...

JACUSTOMER-v67h3vly- :

The resistance is within specs as well...

tx20m4u :

The intake manifold if bought used could be dirty in the hole that the IAC fits into make sure it is very clean with alcohol. Around the throttle plate may need cleaned also. It could have carbon build up not allow it to close all the way and sticking a lil when no throttle applied.

tx20m4u :

allowing*


 

JACUSTOMER-v67h3vly- :

No offense but there isn't a hole on the intake manifold that is connected to the IAC. The IAC on the Probe is in situ on top of the throttle body which was cleaned before mounting it to the Intake manifold. The Probe is also not an Ford, it's an Mazda 626 engine.

tx20m4u :

The iac valve is a large cylinder that bolts on with four bolts to the intake close to the throttle body. If you remove these four bolts there is a hole the iac sits into. All ports and sidewalls should be carbon free for proper operation.

tx20m4u :

They are phillips screws typically.


 

JACUSTOMER-v67h3vly- :

Actually... The IAC is fastened with four screws on the throttle body and not on the intake. The problem is however solved now. The fault was a faulty EGR Solenoid valve on the vacuum side.

tx20m4u :

I am happy to see you got it fixed.