Torque converter specs

LIGHTNING700 · 03-30-2009, 06:57 PM

Hey guys, having some issues with my fuel psi switching between high and low and not sure if my torque converter might be slipping some and causing this issue. When I accelerate moderately the fuel psi is around 42psi then it will jump up to 60psi and then back down to 42psi when it shifts again without me moving my foot further down or back off of the throttle. It doesnt seem to do it if I leave it out of OD. If anyone has any ideas or suggestions I would greatly appreciate it.

Wilderyzed · 03-30-2009, 10:19 PM

The computer bases the fuel off of the load not just pedal position. In other words if you are at 3 grand and go 1/4 throttle its much easier for the truck to get moving than if you were at 1300 and roll on 1/4 throttle. The computer calculates the load based on throttle position,speed, and rpm. Not saying your converter is not slipping but this is more likely. It sounds like your FP is doing what it should normally IMO.

quicksilver02 · 03-31-2009, 12:18 AM

The fuel pressure is generally controlled by the amount of vacuum or boost seen by the FPR. It should not be at 60psi unless the FPR is seeing about 20psi of boost. The load controls the injector open time, not the fuel pressure.

There is a resistor for the fuel pumps under the front bumper that drops the voltage to the pumps under most conditions. The ECU takes this resistor out of the circuit to run the pumps at full voltage, but I'm not sure if it's throttle position or load that triggers this to happen. You are likely seeing the voltage to the pumps kicking up at the shift, causing the pressure spike. I don't recall seeing this happen during normal shifts (not on the throttle). Some people remove this resistor completely and run the pumps at full voltage all the time.

LIGHTNING700 · 03-31-2009, 07:31 PM

It seems to be running okay, but I will be on the throttle maybe a 1/4 with the fuel psi around 40, then it'll jump up to 60psi, then a few seconds later drop back down to 40psi, which seems very odd to me.* It also doesnt matter if its out of OD or not, does it either way.* The L also hesistates when it does this, any ideas on what it could be or am I just being paranoid about it??

03-30-2009, 06:57 PM	#1 (permalink)
LIGHTNING700 Registered User Join Date: Sep 2008 Location: Richmond, VA Posts: 16 View this user's gallery iTrader: 0 / 0%	Torque converter specs Hey guys, having some issues with my fuel psi switching between high and low and not sure if my torque converter might be slipping some and causing this issue. When I accelerate moderately the fuel psi is around 42psi then it will jump up to 60psi and then back down to 42psi when it shifts again without me moving my foot further down or back off of the throttle. It doesnt seem to do it if I leave it out of OD. If anyone has any ideas or suggestions I would greatly appreciate it.

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03-30-2009, 10:19 PM	#2 (permalink)
Wilderyzed wildman Join Date: Jul 2008 Location: Davie, Fl Posts: 349 View this user's gallery iTrader: 0 / 0%	The computer bases the fuel off of the load not just pedal position. In other words if you are at 3 grand and go 1/4 throttle its much easier for the truck to get moving than if you were at 1300 and roll on 1/4 throttle. The computer calculates the load based on throttle position,speed, and rpm. Not saying your converter is not slipping but this is more likely. It sounds like your FP is doing what it should normally IMO.

03-31-2009, 12:18 AM	#3 (permalink)
quicksilver02 Registered User Join Date: Jan 2006 Location: Castro Valley, CA Posts: 253 View this user's gallery iTrader: 0 / 0%	The fuel pressure is generally controlled by the amount of vacuum or boost seen by the FPR. It should not be at 60psi unless the FPR is seeing about 20psi of boost. The load controls the injector open time, not the fuel pressure. There is a resistor for the fuel pumps under the front bumper that drops the voltage to the pumps under most conditions. The ECU takes this resistor out of the circuit to run the pumps at full voltage, but I'm not sure if it's throttle position or load that triggers this to happen. You are likely seeing the voltage to the pumps kicking up at the shift, causing the pressure spike. I don't recall seeing this happen during normal shifts (not on the throttle). Some people remove this resistor completely and run the pumps at full voltage all the time.

03-31-2009, 07:31 PM	#4 (permalink)
LIGHTNING700 Registered User Join Date: Sep 2008 Location: Richmond, VA Posts: 16 View this user's gallery iTrader: 0 / 0%	It seems to be running okay, but I will be on the throttle maybe a 1/4 with the fuel psi around 40, then it'll jump up to 60psi, then a few seconds later drop back down to 40psi, which seems very odd to me.* It also doesnt matter if its out of OD or not, does it either way.* The L also hesistates when it does this, any ideas on what it could be or am I just being paranoid about it??