J30 hesitation

[dbrunone]

I have a 95 J30t with 94k miles. When the engine is cold, the car runs great. But when it warms up after about 15 minutes of driving, I get fairly uneven acceleration, especially in 1st gear, and the power drops by about 25%. When it is cold, it is very quick off the line, but when warm, I can floor it from a stop and it still feels sluggish. I have tested the EGR and coolant temp sensors, I had the injectors cleaned, had throttle bodies cleaned, replaced the throttle position sensor, and replaced the air filter. I got a little more overall power from the injector cleaning, but other than that my efforts have been futile. Also, my gas mileage is not great; this car is supposed to get 18mpg city and i am only getting 15-16. What in the world can be causing this problem??

-David

[j30t]

I got around 17mpg when i first had the car until i began to use premium gas and added a can of BG44k. Now i get about 19.5. Not sure about your other promlem...im sure someone will help you shortly.

[Pearlm30]

Sounds like the knock sensor??!! Have you check the resistant according to the service manual?

[elwesso]

I bet it is running hot...... My car does the same thing, so I am going to do a coolant flush/Tstat also....... It wasnt a problem in the colder months, but now it is!

Question: Is using an aftermarket TSTAT (like beck and arley) OK??

[dbrunone]

A friend just suggested that the mass air flow sensor isn't working right. Is there a way to clean it? Or is replacing it the only option?

[elwesso]

It doesnt sound like a MAF problem to me........ if it was MAF related, it would happen regardless of cold/hot........ Spraying some brake parts cleaner on it should clean it off good...... make sure its dry completely before you start it up (its a hot wire element, and could catch fire)....

When the engine runs hot, the ECU retards the timing to help keep the engine cooler....... WHen it is running only slightly hot, this helps, but when it is running really hot it doesnt do much, and sometimes it can almost make it worse........ Chances are its time for a tstat and radiator flush anyway!

Until you can get around to doing it, avoid driving it too much in the city...... take the highway if you can........