Straight piped, lost power.
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Elder User
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From: Ocala
Straight piped, lost power.
I put a 4" straight pipe and lost the cat onto my 3" downpipe on tues jan 7th. I lost a pretty good amount of power after this. Gave it awhile thinking maybe the PCM had to catch up but no such luck. I cant figure this out, do the stock turbos need more backpressure to work properly??
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Elder User
Joined: Dec 2008
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From: Ocala
I checked the map sensor, it's fine. I had the downpipe on for about a month before I added the straight pipe. It seemed to run the best with the downpipe, cat, and muffler. I do think I gained a little low end power, but lost it on the high end for sure. 
I notice it at cruising speeds, really have to stay in the throttle to keep at one speed or accelerate.
I notice it at cruising speeds, really have to stay in the throttle to keep at one speed or accelerate.
Postmaster
Joined: Sep 2007
Posts: 4,195
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From: Medford Oregon
Take the hose off and blow in one end and make sure it is not plugged up .. mine was.
Does the turbo spool up ?
You can unplug the MAP three wire plug and take it for a spin. If it runs better then could be the sensor. Unplugging the sensor you will get a CEL but it will not hurt anything.
Does the turbo spool up ?
You can unplug the MAP three wire plug and take it for a spin. If it runs better then could be the sensor. Unplugging the sensor you will get a CEL but it will not hurt anything.
Thread Starter
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Elder User
Joined: Dec 2008
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From: Ocala
Take the hose off and blow in one end and make sure it is not plugged up .. mine was.
Does the turbo spool up ?
You can unplug the MAP three wire plug and take it for a spin. If it runs better then could be the sensor. Unplugging the sensor you will get a CEL but it will not hurt anything.
Does the turbo spool up ?
You can unplug the MAP three wire plug and take it for a spin. If it runs better then could be the sensor. Unplugging the sensor you will get a CEL but it will not hurt anything.
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Elder User
Joined: Dec 2008
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From: Ocala
Ok, I pulled the hose, no clogs, so I unplugged the MAP sensor. Wow, it ran like it never has before. So I am assuming my sensor is bad, but if it was wouldnt it throw a CEL? It did like you said after I un-plugged it.
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Postmaster
Joined: Sep 2007
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From: Medford Oregon
As long as the sensor is putting out a valid frequency then the PCM won't CEL. If you are sure the hose is in good condition then it probably is the sensor itself, especially if it made a big difference unplugged. Either that or you have lots of boost leaks.
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Elder User
Joined: Dec 2008
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From: Ocala
Quick question, since it runs that much better with it unplugged can I just run unplugged all the time and save 100.00? I know the check engine light will be on but thats no big deal, or can/will it harm the engine?
Postmaster
Joined: Sep 2007
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From: Medford Oregon
With the sensor unplugged the PCM uses other sensors to make a guess what the boost should be and adjusts fuel flow accordingly. If you are not towing or doing anything stupid then IMO you can run without it.
I think you had another post on bad turbo blades so that might be the problem there, little or no boost. I agree they cost a lot so maybe if you had a friend you could take their MAP and try it before purchasing a new one.
And to answer you question .. I would not run it forever without the MAP sensor.
I think you had another post on bad turbo blades so that might be the problem there, little or no boost. I agree they cost a lot so maybe if you had a friend you could take their MAP and try it before purchasing a new one.
And to answer you question .. I would not run it forever without the MAP sensor.
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Elder User
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From: Ocala
Ok, I know someone who has one, I'll try that. I would hate to throw a 100.00 bucks away on a new one, but I guess I could always return it to the parts store if it didnt help. But I'm gettin the turbo issue fixed luckily.
Postmaster
Joined: Sep 2007
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From: Medford Oregon
Very wise decision .. do the turbo first if possible. Usually the MAP and any (electrical) device(s) are not refundable so if you have a buddy that will eliminate the buy the part now and kick yourself later syndrome.