Betcha Can't Answer This Problem!

mjgrosso93
Sat, 07 Aug 2010 20:04:11 +0000
Maintenance/Repairs

I have a 93 infiniti J30 and when I start it up in the morning it runs fine for about 10 to 20 minutes, when the engine gets heated up.

Once the car is warmed up however, it won’t rev past 3000 rpm in any gear, and has no power. It misses and surges, the rpms jumping from 2200 to 2600 to 2400 to 2800 and so on even when the gas pedal is pushed to the floor. It idles just fine though, and it runs ok when i press pedal lightly (around 1500 to 2000 rpm) but messes up as soon as it hits 2000 rpm.

I have checked to see if the catalytic converters were backed up, replaced the mass air flow sensor and ignition control module, and none of this was the problem.

There is no check engine light on, even when I unplug some of the sensors. I know that the ECU is only OBD1, but shouldn’t the check engine light still come on anyway?

Right now I have some theories as to what the problem could be. The fuel pump? but why would it start acting up after the cars been running for 10 to 20 minutes? Wouldn’t that cause the problem immediately?

Another theory is the engine is overcharging the battery, which in turn could be affecting the way the sesors read. I have no voltage meter so i can’t test it.

My last theory (and the one i’m leaning most towards) is that the Crank Angle Sensor is going bad, giving the ECU a bad read.

Well this is all I can think of, if you think of anything better, then reply to this post. But I betcha can’t answer this question.

31 posts - 12 participants