Hey guys -

My SC4 has been having trouble starting. I have to put my foot in the gas for it to stay running right after start-up. It doesn't matter if it's warm or cold, all the same. My buddy and I ran codes on it with a snap-on code reader. It brought up the MAF sensor. I put a new one in, still does it. However, it does seem to idle a little higher than it did before, which is good because it seemed to idle too low prior. I've searched and the only other closest thing I've found that could potentially be a problem is the fuel pump ecu. But, supposedly it starts up fine after it's warm as a symptom for the fuel pump ecu. Does anybody have any thoughts? It's really annoying. I didn't take the sensor housing out to see if the honeycomb mesh is dirty, but I wouldn't think that would have much to do with it. Other than this it runs excellent. No hesitation or missing, it's as smooth as can be. I'm stumped! Just lookin for some ideas before she goes to the dealer. Thanks everybody.

Matt

 

how many miles?
when was your last tune up?
when was your last induction service?


need more info to better assist you...good luck

 

150,000 miles. Last tune-up was 20k ago. Not sure about the last induction service. What all does that consist of?

 

I tested the TP sensor. According to the test, it needs replacing. But, I'm not sure that it could cause the symptoms I'm having. . .anybody?

 

The Throttle Position sensor is bad? You mean the thing that senses the Throttle position and keeps the car running?

Yeah, i'd say that's it bro. Mine did the idle down - idle up thing back and forth up and down almost to die out when my MAF was unplugged, but the symptoms your describing seem to self diagnose themselves. the car cannot sense the throttle position and is dying out.

My two cents worth of a guess.

 

It's definitely worth a shot! Very easy to install. I just haven't priced it yet.

It doesn't ever actually die (it did until I cleaned the first MAF sensor). Here's what would happen if I started it without touching the gas pedal; it would jump up to about 2-300 rpms and then drop back to zero.

Crazy Lexus. . .

 

sweetsc my friend had this problem with his car... his fuel injectors were all clogged up. he would drive the car and everything would be fine but when he would come to a stop his car would sometimes just shut off on him.

 

Check your IAC (idle air control) valve and make sure all passages are clear.

DJL