slow start + 20sec high idle; stumped!
 

Hey guys | I've had this problem ever since purchasing the car in Sept.

When the car has been recently turned off btwn 10min-45min, the engine will start very slow (read: rpms start slow) with a "drowning/stumbling" feel, and will then idle @ 1950-2000rpm for 15-20seconds. :confused:

The car does not do this if started sooner or later than the approximate 10-45min window. huh??

> could it be fuel-filter being clogged/unclogged depending on how recently engine is restarted?

> could it be my small rip on the bottom of the intake elbow @ the tb clamp; it's on good but i will be replacing with 1LE soon.

> the car generally takes longer to start 5-7sec than others; could this be due to an underpowered (not old, but too weak for 5.7L engine) battery?

help & expertise appreciated!!!

thanks, Brian

Sounds like you IAC is sticking... I think they're pretty cheap to replace. Wait for another reply before you rush out and get one, I'm asuming that's the effect you would get if it's bad.

I removed the IAC & TB to clean 2mo's ago, I was careful not to change the pintel position. Removed build-up, reinstalled with new gaskets. No difference.

> can it still be IAC sticking?

> the car has idled 5-10min several times, so I assume a misadjusted pintel should already be re-learned by the computer

> i suspect my fuel filter (stock, 58k mi.)

MORE help plz :confused: :bow:
thanks, Brian

:alert: more help plz?

have you plugged a scanner in? IAC might be bad.. change it out and see what happens.. Cleaning it out won't fix a bad one..
Steve

You might want to check to see if your fuel pressure is bleeding down when the engine is off. I had a problem just like that. After having the car to the dealer several times and they replaced all kinds of stuff that didnt need to be replaced I took some advise from this board to check to see if the fuel pressure was bleeding down and sure enough it was. I bought some new injectors and fixed it like new. If you dont know how to do this just hook a pressure guage to the shrader valve on the fuel rail. Turn the ignition to on but dont start. This will prime the system to give you a reading. Turn the key to off and leave the guage on the car. Check back in about a half hour or so and see if the pressure dropped. It should only drop no more then about 5 psi from @ 40psi if I remember correctly. If it does drop significantly then it is either your injectors or pressure regulator. Hope this helps and sorry it was so long. I know how it is when your car isnt running like it should. Later.

Matt

Any codes?

I had an 88 Iroc do *exactly* the same thing, but it would pop a MAF code. The MAF was replaced 3 times over a few years by my cousin but never helped. After I bought the car, I took it to the dealer with an exect description of what was happenning and told them not to call me until it was fixed. (I was fed up with it)

It ended up being the burn-off relay for the MAF. When you first start the car, the filiment in the MAF is heated up to burn off any contamination. Mine never burned off, so it always gave screwy readings and started hard, idled rough, then idled high.

Problem was solved, and it fired right up and ran perfectly after the new relay.

more:

When the car is about to do a hi-revs start, I turn it off & it will start up the 2nd time normally. When I start it twice like this, I smell some fuel vapor inside the cabin! :eek:. Maybe there's too much fuel going in to cause a slow start (too much fuel) and high rev (burning off excess fuel)?

This weekend I will be putting on a new 1LE elbow, replace fuel filter, run fuel system cleaner (Chevron? STP?), test fuel system pressure, & check IAC counts.

Till then, any additional advice appreciated! :bow: thanks, Brian

problem persists :mad: