i have a 1998 avenger with a 2.5 v6. when i come to a stop the car kills or idles roughly or erratically. the ses light blinked a while and now stays lit. so i had the codes pulled and got the " mutiple cylinder misfire" code. so i changed the plugs,wires, cap and rotor. didn't help. still idles like it has a miss, dies when coming to a stop, and doesn't start like it use to. brought it to a shop and had a scan performed. the mech said the map sensor was out and #3 injector wasn't operating. so i changed them. no change. another shop visit (elsewhere) and the "tech" says the fuel pump seems to be the culprit. so i changed the fuel pump,fuel screen, and filter. no change. i should have known better because as long as i accelerate the car runs great. just kills when i come to a stop. suggestions?

 

Idel control motor is bad and/or the computer. The IAC is know to go bad and short out the computer, either way you replace thye IAC and hope for the best.

 

1st, thank you for your reply...the IAC? i get no code stating this. but for $50 if it works, what the heck. i'll let y'all know.

 

Sorry 'bout the abbreviation, IAC is Idle Air Control, the idle controller is called different names depending on the car maker...

 

I have a strong hunch that the EGR valve is stuck partially open. This causes a vacuum leak at idle, which creates a whole host of symptoms that get interpreted as other things. 1 The vacuum leak drops measured intake vacuum- so some guess that the MAP sensor is bad. 2 The vacuum leak creates a "lean" fuel mixture at idle. This will make the car misfire. The computer is trying to compensate by increasing the injector pulsewidth, which some people assume has to be poor fuel delivery (pump, inlet, filter).

Here's a trick. Loosen the bolts on the EGR valve. Cut a piece out of a soda can that is able to fit between the bolts. Slide the aluminum down between the gasket and valve (or manifold, whichever it comes off of). Basically, you just made a EGR block-off tool for testing. Snug the bolts and start it up. Let it run for a couple minutes to get the PCM to compensate the fuel trim. If it idles OK, you need an EGR valve.

By the way, dont just leave the shim there if it idles better. It will set codes for EGR performance, and will have driveability issues at cruise speeds.

 

buckw1, i knew you were talking about the idle air control. i was just questioning the suggestion, not the abbreviation. you see, i'm under the impression the IAC controls the idle in situations like load factor (ac on or off, engine warm or cold, etc.). someone else had suggested the IAC before but with no codes appearing i wasn't sure of the suggestion.

ken, thank you for replying. i too suspect the EGR but with no codes setting i wasn't sure. but your telling me the symptoms that can occur match much of the problems i'm having. so it's worth looking into. thanks for the test tip.

thanks again to both of you you for your help.