mjgrosso93 wrote: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? I don't know what the fuel psi is supposed to be on this car, and if someone could tell me that would be much appreciated.
Another theory is the alternator 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. I took it off and the shaft binds and is hard to turn, so I'm going to replace it.
Also, I have a timing light, and I know I'm supposed to reset the CAS at 15 degrees before TDC, but I don't know how to use it. Please tell me how to do so.
Well this is all I can think of, if you think of anything better, then reply to this post. Thanks for your time.
Ouch, a lot of guess work, and time, money and effort spent. Might be a good idea to pull codes, even though the CEL isn't ON, especially if you haven't been able to make it turn ON by disconnecting some items.
There's plenty of camshaft torque to turn the CAS, so the worst that a dry/binding sealed bearing might do is make some noise and come apart someday. I actually tore my CAS apart to replace the bearings, and in the process bent the rotating laser cut wheel inside. Fortunately I was able to flatten it enough to the gap of the pick-up. eBayed a $20 CAS from a Z32, but guess what, the connectors are different. And now I have the tools and know how to pull them apart and press things together again without bending things inside.
Think simple, focusing on ECM inputs that change as the engine warms up, such as coolant temperature and air sources. Verify the engine timing. Locate/clean the timing marks, connect power to the timing light from the battery, test the light, connect the pick-up to the #1 spark wire, start the engine (all wires clear!) and point the light at the timing marks (with the engine running and watching out for all moving parts!).
Print these instructions out and read through them too. How many miles on the engine?
What is the engine (fully warmed up) idle speed, with the car in drive and stopped with your foot on the brake? MAF is clean/good, air filter is new, no vacuum leaks?