1993 J30 power loss

[imbgrad]

Whenever I accelerate hard, the engine suddenly suffers a loss of power and jerks kind of violently as soon as it reaches about 4500 rpm. Last night I also tested this with the car in park by revving the engine, and again it starts to cut out around 4500... But it recovers as soon as the rpm drops below that.

It has been idling just a little rough lately, but that usually goes away after it warms up. Other than that, everything else seems totally fine.

I love my J30, it's been in the family since it was new and I've had it since '99. Never had any trouble with the engine... until now.

It seems like this started last week... without warning!

I don't have a good mechanic here, and don't live near an Infiniti dealer. I had the timing belt, etc. replaced last year at the Nissan dealership but I'd rather not take itback to those slimeballs unless I have a good guess as to what the problem is before I even walk in there.

Can you folks offer any suggestions?

[NismoChi]

Give is a good tune up (plugs, aiir, fuel filter), check the coils, and see what happen.

[driverdriver]

Checked your MAF? Is it working correctly?

[gr8scott72]

Give is a good tune up (plugs, aiir, fuel filter), check the coils, and see what happen.

Don't forget your fuel filter.

[imbgrad]

Thanks for the replies. I changed the fuel filter today, but that didn't solve the problem. I tested it a little more by gently accelerating on the freeway keeping it in 3rd. Around 55mph, or 3,500-4,000 rpm, it started bucking like crazy and the tach went nuts. I'm suddenly concerned it isnt just a loss of power, but something with the timing? Wish I knew more "car speak" .. at least keeping it at low RPM has been good for my gas mileage!

I've been googling around trying to find the location of the MAF. Can anyone tell me where this is, and how to determine if it is good or bad?

Also, someone suggested testing the coils. Is that something I can do myself?

I should mention that I've replaced the air filter and the plugs are only have 20k miles on them.

[elwesso]

have you tested fuel pressure?

[imbgrad]

Problem solved. It was the cam shaft position sensor. It was going berzerk at higher RPM and screwing up the timing. New sensor fixed everything, and now the car runs perfectly.

[J30tman]

Glad to see that you figured it out.