Oil Pressure...

[ckinart]

Once my 94 MTX reaches temperature, i have this little symptom: when i push in the clutch with the engine revving higher than idle, the tach drops to around 500 rpm before bouncing back to idle at around 800 rpm. The problem is, as the tach bounces off the lower rpm, the oil pressure light flickers for a second. I'm wondering if this is a serious problem, or if i just need to reset my idle, or something else... any thoughts?

 

[sdpatt]

The oil pressure light is doing its job. The low rpm is resulting in a low oil pressure. You would be well served by resetting the idle program. The idle air conrtol (IAC) valve is responsible for working like a throttle damper to prevent the revs from dropping like you have described when the throttle is closed. Try the idle reset first and if that doesn't change the behavior, you may want to try cleaning the IAC valve.


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Scott

1991, 254K miles, glass hood, police grill, SVO shifter, Catz fogs,
K&N, 73mm MAF, Superchip, PP Y-pipe, Borla cat-back, 190 lph pump
Eibach/Tokico/polyurethane, SHO Shop front & rear strut braces,
16x7.5" Moda R1, 225/55ZR16 Bridgestone RE730, -1 deg camber x 4,
6 disc CD, Class II hitch, Silver award at SHOklahoma Car Show

 

[ckinart]

Thanx for the info Scott... I've finally gotten around to taking a look into cleaning the IAC valve, and have one quick question: I have a Chilton's manual (not sure if that's a good thing or not) that is sometimes helpful, and it indicates that before removing the IAC valve, the fuel system pressure is to be relieved... in doing a little research, i came across these instructions on cleaning the valve: http://www.shotimes.com/SHO3iabclean.html but my question is, these instructions make no reference to relieving the fuel system pressure, so i'm just wondering if this step is entirely necessary?

thanx again

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ck
94 MTX, 100k
Stock

 

[sdpatt]

There is no reason that I know of to require that the fuel system presure be relieved. The IAC valve only throttles air. The only connection to the valve is the electrical plug. There are two, 5mm Allen head bolts that hold the IAC valve to the intake. Be sure to catch the thin, metal gasket that will fall when the second bolt is removed.

Scott

 

[sho_dwn]

What should the oil pressure be at when the engine is at idle?
Alan



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1989 SHO
80mm MAF,UDP's,y-pipe,
NOS,Warlock muffs,slicers
[email protected]

 

[DeaconBlue]

Per the Helm's manual, hot at idle speed minimum oil pressure of 12.8 psi.

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95 MTX
with a few mods

 

[ckinart]

scott, just to let you know, i cleaned my IAC valve this weekend, and the car is running perfectly... no more dropping beneath idle, or anything... thanx alot for the advice!!

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ck
94 MTX, 100k
Stock

 

[sdpatt]

I am very glad to hear that the simple cleaning of the IAC worked for you. An old saying states that 85% of the effort to fix something is finding out what is wrong. This Forum can help with that 85%.

Scott