420A Engine RPMs drop, then go back up.

[wootimbored]

I am driving a 1995 Eagle Talon Esi with 82,000 miles on it. The car is fully stock, and has an automatic transmission. Recently when I was driving it, the RPMs of the engine dropped by about 200 RPMs when I was accelerating, and a split second later, they jumped right back up to where they should be. The car does this quite often when I am driving it, but only does it when i am accelerating. The car has not done this when the RPMs are below 1500. At one point, we had to replace a valve gasket cover because one of the spark plug wells was filled with oil and the problem ceased for about a week or two, but then the car began doing it again. Also,I had a mechanic take a look at it, and he found a bunch of worn parts in the engine and a loose spark plug. He replaced the worn parts, but after I got the car back, it was still having issues. I believe it may be something wrong with the transmission, but am not sure. Does anyone have any ideas as to what it may be?

 

[Clinical]

Sounds like the trans is starting to slip possibly.

 

[wootimbored]

That is what I thought might be happening but i wasn't sure. When I was searching about it on the internet, every case I found didn't quite seem to fit what was happening with my car.

 

[patton98]

i agree that it sounds like transmission is slipping have u ever had it flushed?

 

[wootimbored]

This will sound dumb but I know nothing about cars. How does one flush a transmission? To my knowledge, that has not been done to my car.

 

[Matrout218]

Try replacing spark plug wires. I know my car is very picky with spark plugs and spark plug wires, and had a somewhat similar problem and it was fixed from new plug wires. Good luck.

 

[wootimbored]

We also replaced one or two of those. The previous owner did not screw a spark plug into the well the whole way and it shot out of the engine and stripped the head. So, we put a hellicoil in it. Thanks for the suggestions guys! I'll try some of them and get back to you!

 

[wootimbored]

I have a new symptom to add to the ongoing list of problems. We tried replacing the spark plugs, and we made sure that they were tight in the wells. However, when I was test driving the car, I pushed down the gas pedal about half way perhaps, and the RPMs jumped from 3000 down to 1000 then they stayed at about 1500 until i took my foot off the gas, and depressed the pedal again. Thanks again for all the suggestions! I can't wait to get it running well again.

 

[nc_dsm]

Has a compression test been run? I had a car with low compression on 2 cylinders and it cause very similar problems, especially putting helicoil in head ... may not be holding good compression and low compression can cause engine to overload.

 

[inix92]

Iv been having the same problem i switched my throttle body and that solved the issue if that doesn't work then your egr valve could be clogged those are you usually the issues. If not then the spark plug wires / spark plugs / ignition coil / fuel filter.

Im about 120% sure its your IAC.

 

[wootimbored]

Car is running. We had to take the bumper cover off, and when we did, we unplugged a cable. We plugged it in and the car now runs fine.