Engine/Transmission (1998.5 - 2002) MAP Sensor

[HBarlow]

A friend with an '01 24 valve just called with a problem and a question.

He needs to hook up and pull his fifth wheel in a couple days to the Dallas area to be near a hospital while his wife has major back surgery. He just discovered his truck won't develop more than 10 psi boost. He's asked around and talked to several and been advised it is likely caused by a sooted MAP sensor.

He wants to pull and clean the sensor before buying one but doesn't have a set of deep sockets and doesn't know what to buy. Does anyone know off the top of his head what size socket is required to remove the MAP sensor from the block? And does it require a 6 pt. or 12 pt. socket?

 

[Wiredawg]

Harvey,



I called our friend yesterday w/ the info from Dave Fritz' website: 13/16" deep well socket. Either 6 or 12 point will work as the sensor shouldn't be too tight.



I'm going to call him to see if everything worked out.



Ron

 

[HBarlow]

Thanks, Ron. I and Rowdy both appreciate your help.

 

[SHobbs]

Best of luck to his wife. Plenty of members near Dallas if they need anything.

 

[Wiredawg]

All,



Just got off the phone w/ Rowdy... 13/16" isn't the right size, so I went out and physically pulled the wire off mine (the 2002) and it is 27 mm. I've never removed mine before so never had an idea. Further, I'm always left it alone because I have my boost tube p/u right in front of the MAP sensor, making it difficult to see. I amy send Dave Fritz an e-mail to let him know about the size.



talk to y'all later,



Ron

 

[Wiredawg]

Well, just pulled mine off and was it cruddy. Took parts/brake cleaner and got it soaking. Never been cleaned in 7 years and it had the exhaust brake on it from day one. I'm a constant user of the BD exhaust brake too. I'll see if it makes a difference next week driving to work.



Rowdy, I'll call later to see if cleaining it fixes your problem.



Ron

 

[HBarlow]

Rowdy told me that someone explained to him that trucks with an exhaust brake soot the MAP Sensor and reduce the voltage output which reduces maximum boost. I had to replace a MAP sensor on my '01 at around 100k miles but assumed it had been accidentally tweaked when a mechanic pulled the starter to put a Larry B's kit in. It may have simply been sooted and I didn't know. My truck also had a Jacob's exhaust brake from day one.

My symptom was a lack of full power towing, low boost, and unable to make it smoke at full throttle applied at low speed (MH 275 injectors).

 

[WardJ]

All,



Just got off the phone w/ Rowdy... 13/16" isn't the right size, so I went out and physically pulled the wire off mine (the 2002) and it is 27 mm. I've never removed mine before so never had an idea. Further, I'm always left it alone because I have my boost tube p/u right in front of the MAP sensor, making it difficult to see. I amy send Dave Fritz an e-mail to let him know about the size.



talk to y'all later,



Ron

1-1/16" is correct for S. A. E. to remove the MAP sensor. The IAT is right behind it and it uses 13/16".

 

[hsmith]

But if you replace it, the new one will be smaller. Can't remember yesterday so can't say what size it is.

 

[Wiredawg]

I really noticed more power on my '02 today. Maybe that also translates to better fuel mileage too. I guess 1 1/16 = 27MM.

 

[HBarlow]

Ron,

Do you have a boost gauge installed on that truck? An engine that is unable to produce maximum boost is a good indication of a possible bad MAP sensor.

When the MAP on my '01 failed several years ago I was returning home from a trip to Boulder, NV pulling my old Airstream. As soon as I got on the highway and into the hills I realized I didn't have full power. Low max boost was pretty strong evidence something was wrong.

 

[Wiredawg]

Harvey,



Yes I do, on a fitting on a port right in front of the MAP sensor. It's interesting the effect the MAP has on the performance of the engine. I'm thinking about adding checking/cleaning it to my preventative maintenance schedule. Have you heard from Rowdy if cleaning his fixed the problem?



Ron

 

[HBarlow]

No, Rowdy ALWAYS tells me he'll call back and let me know how his latest challenge works out but always forgets.

He was probably getting pretty stressed about getting his truck runnng right again and getting his wife and fiver over to the DFW area for her surgery and never thought about it again.