I replaced the map and it still hesitates and wants to cut off at idle especially when turning or when ac is on and the cel came back. What else could it be?

 

just for clarification the original cel was for map voltage too high AND fuel system lean (bank 1). i reset the cel after replacing the map and the symptoms were still present. Another CEL followed shortly after; however, this CEL is only for "fuel system too lean (bank 1)" nothing about the map sensor.... whats going on here?

 

I'd check fuel pressure, vac leaks, exhaust leaks, o2 sensor.

 

Okay.thanks zman. Fuel pressure should be good since I just replaced the pump a few weeks ago. But ill check the o2 and vac. I'll also reinstall the map I guess to be sure, since the map did initially.seem to be causing the issue

 

I'd still check fuel pressure.


Make sure the little hose on the map sensor is not damaged also.

 

okay, so there was a loud hissing coming from the IAC (AHA! the vacuum leak you told me to check for ), i replaced the IAC and things improved to 100%, i returned the $90 map sensor and things were great. then after a little driving things returned almost to where they were, the change, however, was not immediate, there was no hissing and the symptoms werent quite as bad. it will likely stall with a/c on and the steering wheel turned a good bit. but its not as bad. it just wants to cut off when you let off the gas, but it will usually stabilize if its not under an accesory load.

still getting a CEL for lean fuel, but no map code. ill check for 17" of vac tomorrow. if the vac is good. i will try the map again.

could a lean fuel condition caused by a bad IAC (stuck open) trick the computer into beleiving the map voltage is too high?

 

You are removing the neg battery cable while doing the swaps and letting the pcm reset right?

 

How old is your O2 sensor? and what brand is it?

 

OLD enough that it cant be removed having said that i'm really hoping that isn't the issue

just theorizing here, but since the map provides a variable voltage signal to the computer (the more voltage the lower the vacuum, and vice versa) if the vacuum was low enough to cause the map sensor to output a voltage greater than 4.5, could a CEL for "map voltage too high" and "lean fuel condition (bank 1)" be triggered because of a vacuum leak (in this case an IAC that was stuck open), rather than a bad map sensor?

mind you, the IAC that i used for a replacement was not new, just a spare i had lying around. also once the idle speed stabilizes, it will pretty much continue a normal speed until the throttle is pressed.

yes, i did remove the negative battery cable. i find it odd that after replacing the IAC that the condition went from good to poor instead of vice versa because I was under the impression that after disconnecting the IAC the computer would have to relearn acceptable idle speed under varying load (in which case it would get progressively better).

i have noticed that accesory load does cause the idle speed to vary (and in some cases the engine stalls completely) more so than with no acessory load.

 

I guess that would mean it's the original cat too huh ?