Engine miss

[General337]

I have a '94 3000GT 5-speed that has developed a miss. The miss is only around the 1500-2500 RPM range when I am accelerating. At idle and cruise it runs fine, and revs fine in neutral. A better way of describing the way it feels is if you are going up hill in too high of a gear. I do not have a check engine light to run for codes. Has anyone ever had this problem before?

Thanks

[Raven Blayde]

Sounds like you're having basically the same issue that I am. Mine is a 91 Stealth ES with a 3.0 DOHC and 5 speed. It idles good, no check engine light on, no codes and I can't find anything wrong with it. I accelerate slowly at 1500-2500rpm and it misses and jerks horribly. If I stomp the throttle down, it comes to life and problem goes away. I've tried bypassing the egr valve, recaliberating the throttle position sensor and taking the excessive slack out of the throttle cable. So far, nothings helping. I'm thinking of moving on to the oxygen sensor next. Mine also misses at slow cruising speed (again, that 1500-2500rpm range). On the highways, it's not an issue, but in town I'm having to cruise at around 3,000rpm to keep it from missing. Let's hope someone here can help us.

[Jimvr4]

When you stomp on it you are going open loop which ignores the O2 sensors. Cruising is closed loop where the fuel is controlled by the O2 sensors. So definitely get a logger and verify the O2 sensors are cycling

[Raven Blayde]

I tried something yesterday- I unplugged the O2 sensor and drove the car. It ran SO, much better without it! I've already checked and my local Advanced Auto has the sensor in stock for $67, so I'm gonna go pick one up today. If nothing else, it probably needs replaced anyway since the car has over 120,000 miles on it. From what I've been reading, most recommend replacing them after around 70,000 miles. I'll keep you guys posted on the results.

[Jimvr4]

Sounds like it will be the fix. Make sure you rent the O2 sensor removal tool. Those things are VERY tight after all the heat cycles. You might need a breaker bar too to get enough leverage.

[Raven Blayde]

lol... I should have read before starting that project today. I spent 3 hours just trying to get that old sensor off with a wrench, but I got it after much prying and yanking. Good news- Got it changed and the car runs better. Bad news- All the yanking and prying on that sensor has now given me an exhaust leak!

[chrisorbics]

quiet here

[chrisorbics]

Any help would be great.