Venturemmltd
Texas Chapter member
- 3
- 0
A year ago I was getting upwards of 8mpg pulling my boat, but one day everything went downhill. It ran just fine when cold, but then started surging at light throttle after it got warm and the MPG went to about 2. I replaced the ACT and HEGO with no change, then began looking at vacuum leaks, etc.
Found a slight open on the tps, so replaced that as well, but still no change in MPG or surge.
Replaced the timing chain and gears.
Replaced cap, rotor, wires, and plugs.
Checked compression and all good with less than 5% differential.
Figured the previous owner hadn't changed virtually any of the sensors in all of the 220k miles, so went ahead and replaced the EGR, EVP, CTS, pressure regulator, and even the injectors, thinking there may have been one leaking.
Vacuum is great in both open and closed loops, and I sprayed the entire engine with some good intake cleaner with no change in RPM or vacuum.
I then bought a Rotunda monitor and went through every test I could find, but the only problem was the HEGO running at .9 constantly after it warmed up. So I figure the surge is probably a lean miss since the HEGO is reading rich...?
I plugged the purge line, thinking it might be stuck open, but still no change!
I then connected a permanent fuel pressure gauge to the rail with the power going directly to the battery and found that the max pressure was 30psi (low) and after the truck warmed up it went to a max pressure of about 20. Also, when turning on the blower switch, it would drop as low as 10psi. Now I'm wondering if I've got a ground problem somewhere that's affecting the ECM. Ran new ground wires from the frame to engine, battery to frame, everywhere I could think of, and still no change. This is driving me nuts! Only good thing is that the truck is paid for, it's a 4x4, and only cost me $1,100.00 to begin with, so I don't mind putting the money into it. Can anyone think of something I might have missed??? I'm in Round Rock, Tx and thanks for the great forum!
Found a slight open on the tps, so replaced that as well, but still no change in MPG or surge.
Replaced the timing chain and gears.
Replaced cap, rotor, wires, and plugs.
Checked compression and all good with less than 5% differential.
Figured the previous owner hadn't changed virtually any of the sensors in all of the 220k miles, so went ahead and replaced the EGR, EVP, CTS, pressure regulator, and even the injectors, thinking there may have been one leaking.
Vacuum is great in both open and closed loops, and I sprayed the entire engine with some good intake cleaner with no change in RPM or vacuum.
I then bought a Rotunda monitor and went through every test I could find, but the only problem was the HEGO running at .9 constantly after it warmed up. So I figure the surge is probably a lean miss since the HEGO is reading rich...?
I plugged the purge line, thinking it might be stuck open, but still no change!
I then connected a permanent fuel pressure gauge to the rail with the power going directly to the battery and found that the max pressure was 30psi (low) and after the truck warmed up it went to a max pressure of about 20. Also, when turning on the blower switch, it would drop as low as 10psi. Now I'm wondering if I've got a ground problem somewhere that's affecting the ECM. Ran new ground wires from the frame to engine, battery to frame, everywhere I could think of, and still no change. This is driving me nuts! Only good thing is that the truck is paid for, it's a 4x4, and only cost me $1,100.00 to begin with, so I don't mind putting the money into it. Can anyone think of something I might have missed??? I'm in Round Rock, Tx and thanks for the great forum!
