I don't know what's wrong..but at high rpm, my 89 nissan pu, 2wd, 4cyclinder will jerk and can't acclerate pass it. I can't tell at what rpm because the car does not come with a tach. It happens on every gear even on neutral. Once it hit the rpm.. it begin to jerk and i can't speed passed it. i know on the 5th gear, at 75mph, it hits that rpm and i can't go pass 75mph. I have done everything. i change fuel filter, plug, caps, check timing, i tried a different ecu and still the same. Is it fuel pressure? someone help..please
If it's doing that at 2800 RPM, it's either the TPS of the MAF sensor. The ECU goes into "safe mode" if either one of those things causes a serious enough error or is unplugged. Try cleaning your MAF sensor first. Here's a link on how to do that:
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Admin of NPORA, mod for Nissan-Infiniti Forums, NissanForums.com, NissanHelp.com, AllNissans.com and VGPowered Forums
'88 Pathfinder: 6" of lift, 33x13.50 Swamper LTB's, Rancho 9000's, L&P Stage 3 steering system, K&N, Pacesetter headers and 2.5" exhaust, Lock-Right locker, 110A alty and electric fan swap, dual batteries, 700W+ worth of PIAAs, etc.
It could be any of a hundred things. It's up to you to start troubleshooting things. If you suspect vaccuum problems, go buy some generic vaccuum hose and start replacing one piece at a time(so you don't lose track of where they all go).
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Admin of NPORA, mod for Nissan-Infiniti Forums, NissanForums.com, NissanHelp.com, AllNissans.com and VGPowered Forums
'88 Pathfinder: 6" of lift, 33x13.50 Swamper LTB's, Rancho 9000's, L&P Stage 3 steering system, K&N, Pacesetter headers and 2.5" exhaust, Lock-Right locker, 110A alty and electric fan swap, dual batteries, 700W+ worth of PIAAs, etc.
I don't know what's wrong..but at high rpm, my 89 nissan pu, 2wd, 4cyclinder will jerk and can't acclerate pass it. I can't tell at what rpm because the car does not come with a tach. It happens on every gear even on neutral. Once it hit the rpm.. it begin to jerk and i can't speed passed it. i know on the 5th gear, at 75mph, it hits that rpm and i can't go pass 75mph. I have done everything. i change fuel filter, plug, caps, check timing, i tried a different ecu and still the same. Is it fuel pressure? someone help..please
Fuel pressure is a definite possibility. Can you get a gauge on the fuel line?
How's the exhaust flow at that RPM? Maybe the catalytic converter is clogging.
How's input to and output from the main coil and the dist. pick-up coil (if that model has one)?
It seems like the RPM at 75MPH would be too low for this problem, but how about valve float? You could remove the valve cover and look for a broken spring(s). There could be a weak spring or two, but you wouldn't know that unless you started pulling things apart.
You may want to try some SeaFoam in case there's enough carbon built up on the head to mess up valve operation.
Just some thoughts.
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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd My Frontier Page
Fuel pressure is a definite possibility. Can you get a gauge on the fuel line?
How's the exhaust flow at that RPM? Maybe the catalytic converter is clogging.
How's input to and output from the main coil and the dist. pick-up coil (if that model has one)?
It seems like the RPM at 75MPH would be too low for this problem, but how about valve float? You could remove the valve cover and look for a broken spring(s). There could be a weak spring or two, but you wouldn't know that unless you started pulling things apart.
You may want to try some SeaFoam in case there's enough carbon built up on the head to mess up valve operation.
Just some thoughts.
I have always wanted to test the fuel but i don't have the tools to test the fuel pressure and i don't want to purchase the gauge. I was going to change the fuel pump but i have to remove the bed to gain access and that's too much hard work. Right now i'm going to wait til i can find the pressuage guage to test it.
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