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Discussion Starter · #1 ·
I finally got 0754 tuned with the 2.1L Intercooled Kenne Bell kit. One thing I've noticed that has me worried is the fuel pressure at idle and cruise gradually rising as time progresses and it heats up.

Here's how it happens. I start the car and plug my DiabloSport Predator hand held into the OBDII port and set it to real time data monitoring to view IAT's, Fuel Pressure, RPM, Load, Timing advance and MAF voltage.
The fuel pressure starts off as it should at 38-41psi at idle. It ramps up as it should when the throttle is applied and goes back down when the throttle is closed. After I come to a stop at each stop light I check the stats to see where everything stands. The IAT's have risen due to engine temps and low speed driving and the fuel pressure at idle has risen to 43-46psi. It will rise incrementally every time I check it at a light. About 20mins into my drive It is idling at 61-62psi.

Is this normal? I never really monitored it before I installed the Kenne Bell. This condition happens everytime I drive it weather I beat on it or just cruise it. The fuel pressure will slowly drop back down if the car has cooled down for awhile(turned off). If I let it sit for 4+ hours or over night the pressure will be right back where it should be and then we start the whole process over again.

I replaced the Fuel rail pressure transducer(electric regulator?) that I got used with the kit due to it kepping the rial pressure pegged at 65+psi all the time at idle cold or not. I put my stock 88,350mile unit back on before tuning it and this is what it does(topic).

Ideas? Do I need a brand new rail transducer?

Also My Kenne Bell Boost-a-Pump works perfectly and only comes on above 4.5psi manifold pressure when activated by the hobbs switch. It has nothing to do with this problem.

Jerimie

PS. the car put down 383whp and 387wtq with a moderate tune and 150+ IAT's
 

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Not sure off the top of my head. If it can wait until Friday afternoon, I will ask my gas driveability guy at work and see what he says.

I will be in class in the morning, so I won't get a chance to talk with him until friday after I get back. If I get more of a chance, I will look throught the workshop manual for the fuel pressure tables to see if this is normal.


One question comes to mind, though, as I type this and the :wife: nags me about being tired- When was the last time the fuel filter was changed?
 

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After reading the manual, the base reading of 40 psi should hold steady, not increase at idle. As for why yours is increasing, ????? Since most of my diagnosis time is spent on the 6.0 Liter Diesel, I am really at a loss as to where to go next.
 

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Discussion Starter · #5 ·
It seems to be heat related. As the engine temps rise due to low speed driving and the IAT's increase the fuel pressure rises incrimentally. After 20mins or so of stop and go driving in the texas heat it is idling at 61-62psi. It only drops if you give it light throttle blips but then goes right back up.
Mike @ Kenne Bell is sending me the missing sandwich adaptor to put a pressure gauge on the rail under the rail transducer. We'll see what it registers compared to the electronic reading from the transducer.
 
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