Strange MAP/IAC readings

TYTILIDIE

METH HEAD
I had a problem the otehr day with a bin. I made some minor changes on it and when I went to drive the truck again it didn't run well. After extensive trouble shooting, I found that I had to replace the bin. Now I am not so sure. I noticed something on my data log today.

Before: truck idled at 800 rpm in park. MAP was in the 38 range, IAC counts were around 06-20.

Now: truck idles at 650rpm in park. MAP reads 45-48, IAC counts at 195-220.

I checked all of my wiring and everything seems fine. I am not sure what to look for but will likely swap 3bar maps tomorrow to see if anything changes. Also plan to pull IAC to check it out and maybe reset it. Other than that, anyone have any ideas?
 

WyoSyclone

Active member
Re: Strange MAP/IAC readings

I had a problem the otehr day with a bin. I made some minor changes on it and when I went to drive the truck again it didn't run well. After extensive trouble shooting, I found that I had to replace the bin. Now I am not so sure. I noticed something on my data log today.

Before: truck idled at 800 rpm in park. MAP was in the 38 range, IAC counts were around 06-20.

Now: truck idles at 650rpm in park. MAP reads 45-48, IAC counts at 195-220.

I checked all of my wiring and everything seems fine. I am not sure what to look for but will likely swap 3bar maps tomorrow to see if anything changes. Also plan to pull IAC to check it out and maybe reset it. Other than that, anyone have any ideas?

First guess would be an IAC going bad... probably the coil breaking down. Higher counts means it's trying to open, low rpm indicates it's not able to pull open... just my guess tonight :D
 
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