O2 rich and MAP high, now what?

[mr_blasto]

After letting the truck sit for a while, now my check engine light comes on. I am pretty new to WinALDL, but the codes are 33 and 45 which it says are MAP high and O2 rich, respectively. I am hoping to drive to UT from CA tonight or tomorrow, so I am really eager to get this sorted out ASAP. What do I need to buy/replace/check to be running correctly.

I thought the computer controlled the A/F ratio, so I am a little confused as to why it is running rich. Let me know. Thanks.

 

[dave w]

After letting the truck sit for a while, now my check engine light comes on. I am pretty new to WinALDL, but the codes are 33 and 45 which it says are MAP high and O2 rich, respectively. I am hoping to drive to UT from CA tonight or tomorrow, so I am really eager to get this sorted out ASAP. What do I need to buy/replace/check to be running correctly.

I thought the computer controlled the A/F ratio, so I am a little confused as to why it is running rich. Let me know. Thanks.

I would put my hand held vacuum pump on the MAP sensor to see if was working correctly. I'd also use my AutoXray tool to see if the MAP voltages are changing with the hand held vacuum pump. Maybe there is a vacuum leak on the MAP sensor hose. I might even get one of my known good MAP sensors and give that a try? That's what I'd do to try and fix the high map error code. I'd only try to fix one code at a time. I don't know how to fix the high map error code without the tools / parts I have.

I don't know if this really helps?

dave w

 

[mr_blasto]

Sound advice. It sounds like the sensor is in question. I wasn't sure if it was a sensor issue or something causing the sensor to go wacky. After your post I was reading into MAP sensor issues and one of the symptoms is running rich. Seems like a good place to start. Thanks.

 

[eagle mark]

I would put my hand held vacuum pump on the MAP sensor to see if was working correctly. I'd also use my AutoXray tool to see if the MAP voltages are changing with the hand held vacuum pump. Maybe there is a vacuum leak on the MAP sensor hose. I might even get one of my known good MAP sensors and give that a try? That's what I'd do to try and fix the high map error code. I'd only try to fix one code at a time. I don't know how to fix the high map error code without the tools / parts I have.

I don't know if this really helps?

dave w

You can even use a volt meter and a vacuum pump. But I usually collect a set of sensors, modules and such and run them all till I have a known good working set as a spare. This way you are totally prepared and nothing, nothing at all ever happens...

In his case I'm sure the High Map is causing the other code. So either a MAP sensor went bad (not likely) or there is an issue with the vacuum line between MAP and center port rear of TBI unit.

 

[mr_blasto]

I got a new map sensor to see if that was the problem. I think the light went off, but I was still getting the error flag when I was running winaldl. It was kind of a rushed deal and I had to get on the road, so I figured I would check it out when I got to my destination. As I was driving, though, the light never came on. I think the vaccum line may have been loose where it connects to the back of the throttle body. I'll get to the bottom of this, but after the truck started spewing flaming ATF last night, my priorities have shifted a bit.

 

[eagle mark]

Spewing flaming ATF ay?

The ECM will save the eroor code for awhile even if the light went out. But seems like you fixed the issue.

If you want to remove the error code disconect the batterey or power to ECM for a minute and it'll be gone and you can see if it will reset.

FYI error codes and flags are two differant things in WinALDL...