dr.stevil

So I just picked up a used 01 GT a few months ago. Lately, espescially on 'wet' mornings, I'll go to get in my car to get to work only to have the car stall on me right away (RPMs just drop to 0) unless I constantly give it throttle. Sometimes it goes away after a few miles of driving, other times it will persist all day long.

Someone told me that it's likely the IAC valve which is fine. I found a guide to clean it online, but I have a few other issues/symptoms that I'm not quite sure about.

First, whats considered a normal idle for an 01 GT (stock)? When the problem seems to go away, I noticed that the car idles around 600-800RPM which sounds okay, but when it's idling that low the oil pressure drops to 0... giving it a little bit of throttle (1100 RPM, approx) builds pressure back up and the guage goes back to normal.

This seems strange to me. I imagine that either the low RPMS are causing the pump to turn slower and in turn, dropping pressure. Either that or the RPMs aren't being reported correctly and it's actually idling lower (seems unlikely) or the gauge/switch for the oil pressure isn't working correctly.

I checked the oil and it's clean and the level is fine.

I don't recall ever seeing the pressure drop before having this issue either, but I also never really paid too much attention to it before now.

Can someone help me out? I'm sort of scared to drive the car as I'm affraid something could be wrong.

Car only has 50K miles on it (2001 GT)

mattdel

Possible tiny vacuum leak is the cause of the idle problem. IAC is a possibility, but your 'wet' morning description makes a vacuum leak more probable. Hot idle specs for that car are 660-700 RPM.

The oil pressure, however, is a larger problem. You might have a gauge or sending unit issue, yes, but the description you give points to worn crank bearings. They are really what is in control of your oil pressure, and having it drop to 0 @ idle means they've worn enough to allow that to happen. Continued driving at this point will gradually decrease pressure over a larger span of RPMs until it seizes from heat.

dr.stevil

Thanks for the reply. Is there an easy way to check the crank bearings without completely disassembling the engine? Like I said, this car only has 50K original miles on it so it seems unlikely that they'd be going already, but who knows.

Any way to rule out the sensor besides replacing it?

Shampue

Sounds like the IAC is the smoking gun. I had the exact same symptoms before I replaced mine.

Cleaning the IAC isn't a "for sure" fix. Its an electrical component.
Depending on your manufacturer date on the sticker inside your drivers door, you either have the early 01 or the mid 01 IAC valve. The early IAC has a breather cap on the top. The early model is almost 1/2 the price of the mid model IAC.

Just a heads up, may be worth spending the $50-$80 (depending on which IAC you have)

** FYI, the jack-wagons at Autozone only list one IAC in their computer system. Go to O'Reilly's.

dr.stevil

thanks for the reply. Did the oil pressure drop on you too? I'm really hoping that something isnt seriously messed up with the engine internals

I looked at the valve and it does indeed have the breather cap. So that's good news I suppose lol

Shampue

I actually had a faulty oil pressure sending unit ($10.00 part) that I replaced at the same time as the IAC. So I cannot say for certain. My oil pressure would read 0 when cold and after a few minutes of driving would jump to normal.

My car also had just over 50k miles on it at the time as well.

0 issues since.

Shampue

I also just remembered, make sure you disconnect the battery for approx 5-10 min then reconnect