Re: Boost and fuel pressure
Quote:
Originally Posted by
GLHS444
I’m looking for a bit of knowledge on how the 2.4T’s manage the relationship of boost and fuel pressure to assist in diagnosing some cut out issues I’m getting on my 07 GT 5 speed.
I know on the 2.2 / 2.5 turbos, the fuel pressure would increase during boost, but I’m uncertain as to the 2.4’s in the SRT4’s and Cruisers.
Do they increase fuel pressure via a diaphragm regulator, electronic regulator, fuel pump voltage increase, or injector pulse time to offset the increased fuel demands during boost?
I know these 2.4’s can be hard on plugs, wires, and coils and it’s possible it’s the source of my issues, but I hear a bit more pinging than I care for over 5psi.
Low RPM and boost brings the cutout on quicker than high RPM / boost conditions (still shows up though, not as harsh) so I’m leaning towards fuel, but I’ve been wrong before...
I’ll be replacing plugs and wires (rpld at 57K) as I’m at 150K now so I’m sure they’re needed. So either way those will be swapped, but my gut tells me it’s fuel.
Thanks in advance...
Dan
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Hi Dan. The 2.4T's use a regulator in the tank with no boost reference. Fuel pressure should be a steady 58psi.
I know replacing plugs on a PT is not as easy as on an SRT-4, but replace my SRT-4's plugs every other oil change.
Re: Boost and fuel pressure
Thank you for the info.
I knew the plugs and Crane wires were getting a bit long on the tooth for these motors. The PT’s arent as easy as the SRT4’s plug replacement but it’s not too bad. Just need to include new upper intake seal orings on the parts buying list.
Too bad Daimler decided the a simple Schrader valve was too costly to install on the fuel rail to check fuel pressure. Guess I need to purchase that special inline tool to fit in to check pressure.
Thanks again
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Re: Boost and fuel pressure
Just an update on my pinging issue on the 07 GT.
During spark plug replacement, I had to dissect the upper intake assy and all related tubing.
Turns out the intake tube feeding the turbo was the source of the lean fuel mixture.
A section on the unseen side of the flex tube had deteriorated (about 1.5” long and 1/16” wide) and was bypassing the air box.
Once all the normal wear items were replaced along with the tube, the pinging cleared. I guess it was breathing too well and the system couldn’t feed the needed fuel to stop the pinging.
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Re: Boost and fuel pressure
Quote:
Originally Posted by
GLHS444
Turns out the intake tube feeding the turbo was the source of the lean fuel mixture.
A section on the unseen side of the flex tube had deteriorated (about 1.5” long and 1/16” wide) and was bypassing the air box.
Once all the normal wear items were replaced along with the tube, the pinging cleared. I guess it was breathing too well and the system couldn’t feed the needed fuel to stop the pinging.
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Strange. That really shouldn't effect it that much.
Re: Boost and fuel pressure
Wouldn't think so unless they are MAF??
Interesting none the less.
Thanks
Randy
Re: Boost and fuel pressure
Maybe it wasn’t so much as starved for fuel, more like overboost condition? She’d cutout just after pinging would start if I couldn’t get my foot off the pedal quick enough.
The boost gauge never reflected it, but its possible it was a bit slower on reaction than the actual pressure to the sensor. The line to the gauge is pretty long compared to the MAP being right in the intake.
Of course new plugs were done as were wires, since it had been a bit since they were changed.
Those plug wire barrels can hold a lot of oil when the tube seals leak. Valve cover gasket and tube orings done as well coupled with some other small wear items.
May have been a combo of the plugs, wires, and air leak in the intake track. It’s all good now though, except maybe the entire suspension is worn out...always something.
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