98 Chevy Tahoe MAP Sensor

[berth]

Car sometimes has no power until it gradually reaches 40 MPH then it runs OK. This problem usually happens on cold days. I suspect the MAP sensor is not working correctly but I can't find it even though I have found a photo of it. Where is it located. Any other ideas on what may be the cause of the problem?

[GMMerlin]

Originally Posted by berth

Car sometimes has no power until it gradually reaches 40 MPH then it runs OK. This problem usually happens on cold days. I suspect the MAP sensor is not working correctly but I can't find it even though I have found a photo of it. Where is it located. Any other ideas on what may be the cause of the problem?

The Map sensor is located on top of the intake plenum.
There are many things that can cause a hesitation or lack of power.
First I would check to see if the trans shifts through all the gears..if the trans defaults it will start off in 3rd gear.
Do you have a SES light?

[berth]

Originally Posted by GMMerlin

The Map sensor is located on top of the intake plenum.
There are many things that can cause a hesitation or lack of power.
First I would check to see if the trans shifts through all the gears..if the trans defaults it will start off in 3rd gear.
Do you have a SES light?

Thanks very much for your help. I drove the car again today and I noticed that the revs were very low when the problem happened and the SES light came on so I think you're right about it not shifting properly. Also, I didn't know the default was 3rd gear. Do I need to take it to a transmission shop or is there a sensor I can replace?

[rumblefish73]

I have a 98 Tahoe also, the default gear is 2nd unless you punch the gas from a dead stop.

You might try putting the transmission in 1st gear and manually shift to the next gear once your engine reaches a good RPM (3000-4000).

Be VERY careful not to shift back beyond D into Neutral or REVERSE!