All right guys, what's next in this trouble-shooting endeavor?

My wife drives an 03SS that she's had since brand new. It's been an awesome car and still is. We just got the fuel pump and fuel level sensor changed because of the infamous sensor going bad and the gauge not reading right. All other gauges are fine. Here's the story...

The car has been having this starting issue for about 2 years now. When the car is cold, it starts right up, just like it should. When it's warm, it will start up, then die. Then trying to start it again takes some effort with the gas pedal. Not sure if the gas pedal is making any difference, but you play with it anyway and it eventually starts.

After the car starts, it runs great! Still gets good gas mileage, no stutters running down the highway or in the city, still runs like brand new.

Car has almost 90k miles. We have replaced: Spark Plugs and Wires, Air Intake is a K&N that gets cleaned regularly, Fuel Filter, Fuel Pump/Level Sensor.

Some people asked about the fuel pressure regulator, but it starts up fine when it's cold, but we checked it anyway and it held pressure, no problem, so I don't think it's that, never did...

The only other things I can think of now are the Cats or the Coils. But if either of those were bad or going bad, wouldn't we notice it in the gas mileage/driveability of the car?

One other thing I want to mention is we just found out through a CEL that just came on within the last couple of days, that the thermostat has frozen open. We are getting that replaced along with a radiator flush this weekend, but I don't think that has anything to do with this starting issue.

Thanks guys for all the help! What else to check out?

 

Coils rarely go bad and if they do, you get a misfire, so I think it's safe to cross that off the list.
My first thoughts are:
- Clean the MAF sensor (use the MAF sensor cleaner sold at the parts store and use as directed). The MAF's on these cars are known to be tempormental to debris. The other reason I suspect that is people have had issues with oiled air filters like the K&N that if there it too much oil in the air going by the MAF, it gunks the MAF up. When you are having your issues starting the car, the quick MAF test is unplug it (the MAF is on top of the throttle body, uses two security torx, which I replaced mine with stainless hex bolts). With the MAF disconnected, the car will throw a code BUT substitues the values the MAF should provide with other ones to try and keep the car running.
- Normally this would be an issue on a cold start, but change the fuel filter. Odds are it hasn't been changed and would benefit from being replaced.

Start with the MAF. BTW - Many say "Oh, I'll just replace the MAF". A new MAF is rather pricey compared to the less then $10 can of cleaner and 10 minutes of work.

 

Thanks Maniac! We have replaced the fuel filter, it was listed in my original post, but it was kinda long winded, so I understand you missing it. lol

I will clean the MAF as you suggested. I hadn't thought about that. Thanks for pointing that out! I'll do some searching around this site and see if I can find the write up.

Thanks again and I'll report back if it fixes it or not!

 

Well, I bought some MAF cleaner, took the plastic engine cover, looked at the MAF, and put it all back together again... Are you kidding me? 10 minutes my *** from the write-ups I saw online. Of course those weren't for this particular car...

We are taking it out of town this weekend and letting my brother-in-law, who is a mechanic for a living, take it off and change out the thermostat while he's at it. I might attack it if I had a day to take it apart and put it back together, but not yesterday afternoon.

Check back after the weekend and let you know how it goes...

Also, I had my other brother-in-law, who works for a Chevy dealership in the parts dept, check on the price of a new one? $175 out the door was his cost! I hope cleaning it works!

 

The MAF is very much so a 10-minute job.

You disconnect the negative terminal of the battery. Take off the plastic engine cover and look at the throttle body. There is a flat sensor near on the intake side (to the right of the IAC Valve in the lower pic). Unplug that sensor. Remove the 2 bolts (with a Security T-20 Torx Bit) and the MAF pops right out. Clean with the spray, let it dry, put it back in, screw it in, plug it in, add engine cover, connect battery. DONE.

However, since you mention the gas pedal can be used to keep the car alive. I'm going to be it is your IAC (Idle Air Control) valve (on the TB to the left of the MAF, the upper valve)



The reason that it might be staying alive on a cold start, is because the engine requires MORE air to start it up, and the RPMs are probably staying higher (like 1300). However when you start the car when it is already warm, it wants to idle at 700-800 and the IAC is sticking and not allowing the car to keep such a low idle.

 

Also, check prices on Amazon for a MAF.
That's where Chibi recommended for me, and got one for less than 175.
Good luck.

 

Thanks ChibiBlackSheep! The MAF looks to me to be part of that whole cast part that connects to the TB. That's why I didn't bother.

Makes more sense to be the IAC though. I'll see if I can get one of those too!

Thanks man, I really appreciate it!

 

Both the IAC and the MAF are super easy to remove (pending you have a security torx bit set). I replaced my security torx with stainless hex heads. Time per MAF and IAC cleaning should be rather short and easy.

 

Nope, just easily screwed in!

 

My Monte does the same thing and I replaced the Maf after I broke it being rough lol. It still does it. Cold starts are perfect but after I run in the store and restart it, it starts then immediately dies then I crank it again after a few seconds it turns over. I would like to add that it starts harder than the cold start, feels like the engine is shaking. ALSO (lol) sometimes when I start it up (warm) sounds like the exhaust is pulsing. Like 5 low rumbles before the exhaust note smoothes out like its about to kill.