Possible MAP sensor problem
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Senior User
Joined: May 2005
Posts: 104
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From: Miamitown, Ohio
Possible MAP sensor problem
Sorry for the long read guys didnt know how else to explain.
Okay when I purchased my truck used there was a wire spliced into one of the wires on the MAP sensor. It is about 7 inches long running to one of the bolts on the MAP sensor bracket for an unknown reason. After the purchase of a Bully Dog chip I started having overboost issues, and talked to a few people locally and did some research on it. I found that I could ground this wire and the problems would go away. So I moved the wire an actual ground and I had no more overboost issues.
After doing some research the other day I found info on th ITP overboost reg and how people had luck with it. Thought I would try disconnecting my little wire trick with my diesel site chip and see what happens. The truck seems to run better though I get no overboost shut down. Could my MAP be bad or am I just over reacting.
Any comments would be great thanks
Okay when I purchased my truck used there was a wire spliced into one of the wires on the MAP sensor. It is about 7 inches long running to one of the bolts on the MAP sensor bracket for an unknown reason. After the purchase of a Bully Dog chip I started having overboost issues, and talked to a few people locally and did some research on it. I found that I could ground this wire and the problems would go away. So I moved the wire an actual ground and I had no more overboost issues.
After doing some research the other day I found info on th ITP overboost reg and how people had luck with it. Thought I would try disconnecting my little wire trick with my diesel site chip and see what happens. The truck seems to run better though I get no overboost shut down. Could my MAP be bad or am I just over reacting.
Any comments would be great thanks
Butt-Head
Joined: Apr 2004
Posts: 9,453
Likes: 2,936
From: Reed Point, MT
I've run into this situation too. My truck as well as my brother's have the MAP signal wire spliced and grounded. There is no diode. My thoughts on this are that since chips are hard wired directly to the PCM and use the chip as a lookup table, the MAP sensor is a useless input. Grounding the signal wire simply keeps the PCM from "seeing" an overboost condition.
Tuners on the other hand flash the EEPROM and the programmers can make whatever boost threshold they want.
You've got no problems....just an easy way to keep the overboost code from setting.
Cody
Tuners on the other hand flash the EEPROM and the programmers can make whatever boost threshold they want.
You've got no problems....just an easy way to keep the overboost code from setting.
Cody
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Senior User
Joined: May 2005
Posts: 104
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From: Miamitown, Ohio
Right I am not running a diode just the ground wire
But I just unhooked it to see what would happen and it runs stronger and with lower EGTs. Boost pressure are at 27-30psi and it just runs. It also seems for some reason to hold boost better it will stay pinned at 25 psi on the highway unloaded no problem.
My thought is why not program our trucks to run larger MAP sensors like a 4 BAR sensor so it can see this air coming in for more control and effiency.
But I just unhooked it to see what would happen and it runs stronger and with lower EGTs. Boost pressure are at 27-30psi and it just runs. It also seems for some reason to hold boost better it will stay pinned at 25 psi on the highway unloaded no problem.
My thought is why not program our trucks to run larger MAP sensors like a 4 BAR sensor so it can see this air coming in for more control and effiency.
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
I'm with you on this one troubledsol. I like a lot of power just as much as everyone else, but when you leave a big cloud of smoke, that's just half burned fuel which is a waste of money at todays fuel prices and it makes your neighbors frown.
Anyone stopped to listen to some of the newest heavy trucks accellorate from a light. They hardly rev up anymore, make no smoke whatsoever and accellorate very quickly for moving 20 tons of whatever. I saw a box truck leave the stoplight yesterday and I was very impressed with the progress that is being made in engine management. The engine in that truck stayed well below 2000 rpm and it really moved off.
Anyone stopped to listen to some of the newest heavy trucks accellorate from a light. They hardly rev up anymore, make no smoke whatsoever and accellorate very quickly for moving 20 tons of whatever. I saw a box truck leave the stoplight yesterday and I was very impressed with the progress that is being made in engine management. The engine in that truck stayed well below 2000 rpm and it really moved off.
