sleeperGXE

I have a strange problem that is difficult to put into words, but i'll try; Sometimes under steady pedal pressure, I can hear my Max's engine revving up slightly, then down slightly without any input from me. It's kind of like reaching redline and having the limiter kick you back a couple hundred rpms, then reaching redline again and having it kick you hack again. I can also feel the car lurching very slightly as it does this....do I need a new fuel filter?

Thx,
-Ben

fusedtizzy

sleeper, i am having the same exact thing happen with my car, and i can't stand it!! i have a 98 SE 5 spd, and it seems to hesitate and lurch once and a while under acceleration. i replaced the fuel filter - didn't change a thing. i dumped 2 bottles of injector cleaner in the tank - that didn't work either. out of frustration i brought it to my dealer, and they said nothing was worng with it. whatever. i've driven many maximas, and none of them do this. i also checked to see if the computer was throwing any codes, and it wasn't. i have no idea what could be causing this. has anybody else experienced something similar?? i need to fix this, quick!! what about the throttle position sensor? maybe thats it?

damers7

im no mechanic but it sounds like your clutch is slipping.

SB97MAX

You must not be a Mechanic because Sleeper has an Auto, lol just playin with ya. Sleeper, if your fuel filter hasnt been replaced in a while just replace it. Even if it doesnt fix the problem it is money well spent. Take Care

sleeperGXE

Thx I will, was planning to anyways.

Daniel B. Martin

You may want to make a fuel pressure test. This is a standard diagnostic test. You will find instructions and a diagram or picture in the Chilton repair manual (page 5-3) and the Haynes repair manual (page 4-3,4).

Bleed the fuel rail pressure by pulling the fuel pump fuse (#32, 15 amps) and making several attempts to start the engine (it won't start). Install a T-fitting with a pressure gauge in the flexible rubber fuel line just downstream of the fuel filter. Install the fuel pump fuse. Start the engine. With the engine idling you should see the pressure maintain a stable 34 psi. Temporarily remove the vacuum signal hose from the fuel pressure regulator. The fuel pressure should increase to 43 psi. Reconnect the vacuum signal hose and operate the throttle to vary the engine speed between idle and 3000 rpm. The fuel pressure should vary between 34 and 43 psi.

Readings less than 34 psi could be caused by an obstructed fuel filter, a weak fuel pump, or a bad fuel pressure regulator. Readings greater than 43 psi could be caused by a bad fuel pressure regulator or an obstructed fuel return line.

After turning the engine off the fuel system should hold pressure for many hours. If the residual pressure bleeds off in only one hour that is a sign of a problem... bad fuel pump check valve, injectors with an internal leak, bad fuel pressure regulator, or an external fuel leak.

Daniel B. Martin

There are two tests the home mechanic can make, the sound test and the resistance test.

Sound test...
This test is performed with the engine idling. Use a mechanic's
stethoscope or a length of rubber vacuum hose, and listen to each injector.
All injectors should sound alike. If you find one which makes a different
sound (or no sound at all) you have found a problem.

Resistance test...
This test is performed with the engine off. Use an ohmmeter to measure the
resistance of each injector. This does not require removing the injectors.
I don't know the correct resistance value for the injectors on your model,
but they are typically a low number such as 16 ohms. The important thing
is they should all be equal. If you find one injector with substantially
higher resistance than the others, it is bad. If you find one with zero
ohms (short circuit) that is truly unfortunate, because the injector is bad
and it may also have damaged the Engine Control Module (the computer)
because of excessive current drain.

Measuring the resistance of the front bank of cylinders is easy because the
injectors are in plain view. Disconnect the injector electrical connector
for cylinder #2, measure the resistance, reconnect the connector. Repeat
for the cylinders #4 and #6.

Measuring the resistance of the rear bank of cylinders is almost as easy,
but it is difficult to reach the injectors. The resistance may be measured
at a conveniently located electrical connector. Notice the largest,
thickest electrical harness at the top of the engine. This is the Engine
Control Harness and it is shaped like a U, with the open top of the U at the
driver's side of the car. The U has two corners. Look at the corner
nearest the passenger seat. Just inside that corner you will find an 8-pin
electrical connector. This is connector F131. Disconnect this
connector. Now look at the male part, the connector half with the pins
exposed. They are arranged in two rows of four pins.
The pins are numbered 1 - 4 (top row) and 5 - 8 (bottom row).
Measure the resistance of:
- injector #1 between pins 1 and 2.
- injector #3 between pins 1 and 6.
- injector #5 between pins 1 and 5.
Be sure to measure the PINS, not the female receptacles.

The dealer's shop is equipped with high-tech diagnostic instruments. These are wonderful devices but they are expensive and the dealer has to recover his cost by charging you for diagnostic time. Sometimes the home mechanic can do legitimate diagnostic work with nothing more than a ohmmeter and a rubber tube.

fusedtizzy

Dean,
thanks for all the great suggestions. i'll give all of them a try until i find the right answer.

fusedtizzy

sorry, i meant Dan!!

deezo

iTrader: (3)

Good one!!!