Engine/Transmission (1998.5 - 2002) New question on LP

[Mille4212]

Ok I took my truck to John Elway dodge today for LP. At idle I have 11 psi and WOT 3 without the EZ box. With the EZ box I can pull it down to zero. John Elway Dodge did a flow test on the pump and said "It has 48. 5 fluid OZ of fuel flow with no bubbles so your LP is good" Also John Elway said my boost gauge is 10lbs off. Their computer said that Absolute boost presure is 10lbs at idle verses my gauge at zero.



So my question is, does this sound right to do a flow test on LP, and does the boost sound right, so I add 10 lbs of boost to what the boost gauge shows? I felt like :-{} with the dealer but know it wouldn't do any good. Thanks guys for any info.



One more thing I asked what would happen to my warranty if I moved the LP Dealer said it would void the whole fuel system

go figure.



Matt

 

[BillGotthelf]

Your dealer is wrong. Your boost gauge measures increases in boost pressure over ambient pressure. At idle there is no boost pressure from the turbo and the ambient air pressure runs around 14. 7 at sea level and 68 degress. Also they will not replace the lift pump unless it is below 10 at idle. Try cleaning the plug in connections to the pump and use some dielectric grease to keep them from corroding-some people are reporting this has helped.

 

[Sticks]

Originally posted by renegade681



One more thing I asked what would happen to my warranty if I moved the LP Dealer said it would void the whole fuel system

go figure.



Matt

That would be a fun day in court. They can't void your warranty unless something in the fuel system failed, and the failure was caused by the modifications, then they have to prove it. Since there is soooooo much documentation on the VP44's taking a header due to dead LP's, they would be hard put saying your moving the LP caused a failure of the VP44, or the LP itself.



The New DC test for the LP has to meet certain flow requirements. PSI has little to do with it anymore. If you can get the FP to drop below 5 with out the EZ, take the service manager or the tech for a drive. If they say your gauge is off, have them bolt up theirs to the schrader on the VP and hit the road again.



When in doubt, take the truck to another dealer and have it checked again, although I would not mention the results that you get with the Edge EZ, and it's better if it's not there.



Jonson Auto has competent techs. They are a bit far north east, but worth the drive.

 

[WestTN]

AMBIENT AIR PRESSURE

Ambient air pressure is 14. 7 psi absolute. This is 0 psi gauge. So the dealer is saying the engine pulls a 1/3 atmosphere vacuum at idle. With no throttle plates or other seroius restrictions in the intake tract I seriously doubt that. It sounds like the dealers equipment is a. ) uncalibrated, or b. )improperly set up.

 

[BillGotthelf]

WestTn-you are correct I must have had a brain cramp.

 

[Sticks]

Re: AMBIENT AIR PRESSURE

Originally posted by WestTN

Ambient air pressure is 14. 7 psi absolute. This is 0 psi gauge. So the dealer is saying the engine pulls a 1/3 atmosphere vacuum at idle. With no throttle plates or other seroius restrictions in the intake tract I seriously doubt that. It sounds like the dealers equipment is a. ) uncalibrated, or b. )improperly set up.

c. ) Tech does not know what he is doing, time to run

 

[Mille4212]

I agree with you guys. After thinking about it last night, the tech said "we tied into the computer and took it for a test drive" and thats how they came up with the boost being 10lbs off. So could the computer be reading air flow instead of boost and they are confused? Thanks for the replys so far guys.



Matt

 

[A Johnson]

ECM is reading boost pressure.



Boost sensor should read @ 14. 7 PSI with key on engine off, sea level and 68*F.



If it does not read pretty close to this then the sensor may be out of calibration, or the signal voltage from the sensor has a problem.



Your dealers software displays a value of PSI. Cummins Insite will display Inches of Mercury (Hg).



Bottom line is the ECM sees a voltage and decides what to do based on the other given input voltages.



I went to our parts dept. the other day and got three sensors, and they all read slightly different, but within . 1 signal voltage. Depending on the given fueling table written to the ECM this . 1 may or may not have a noticeable affect on performance.



Your boost gauge is not off, based on the info you have given. Use it as a reference to help troubleshoot performance. Just because your engine has . 5 PSI less boost than your neighbors, does not neccessarily mean you have low horespower for your engine rating.



A Johnson

 

[PRout]

So if the 14. 7 lb atmosphere is the reference point. It is the null or the "0".



It sounds like they are saying the motor on idle is pulling 10lbs vacuum from the reference point, not boost. It is a -10 lbs from the 0 point (1 atmosphere).



A boost gauge cant really read a negative pressure since it is sitting on the "0" pin.



Maybe they are saying your turbo needs to push 10 lbs pressure to comphensate for the 10 lbs vacuum from the idling motor. Which would cause the gauge to balance out at 0. It would take 10 more lbs (20lbs total) to make your gauge read 10.



Or am I missing something here. .



"Shields Up Scotty"

 

[Gary - K7GLD]

Someone's HIGHLY confused...