rough idle in gear?

[lucksucks]

my 94 idles roughly when its in gear,and when i come to a stoplight. It acts like it is about to die but never has,thought it might be a bad map or maf sensor

 

[Sams01XplrSprt]

welcome

 

[DOHC4]

How many miles on the tranny?

 

[lucksucks]

100thou plus

 

[williams.cory]

maybe a fouled spark plug? When was the last time plug wires were changed? Is the idle smooth?

 

[robertoa1a]

It' always good to check the plugs, wires, and air filter. You know, regular maintanence. If the problem still presist then check out all them little vacume hoses for dry rot and leaks. When you get the plugs out any discoloration or deposits tell a story about the condition of your engine.

 

[lucksucks]

nah man,got new plugs ,wires, coilk pack ,air filter and oil change less than two months ago, no discoloration on plugs ,and they werent burned or covered in oil,i unpluged the sensor on the throttle body and it idled out running good now but check engine lites on,pluged it back in rough idle lite goes off,unplug again idles out lite on,so imma guess its that sensor think its the map sensor

 

[jtd1]

I had a similar experience. Turned out a bad O2 sensor was messing up the injection. Might have thrown a code, why not have auto store give it a check

 

[robertoa1a]

I think It's an Idle air control. I dont have a good picture of a 94 engine in my books. It could be a throtle position sensor. What does it look like and does the problem change with temprature? Im not sure if a 94 has a MAF or not. I dont think so.

 

[lucksucks]

it doesnt change with temp does it hot or cold and its righton top of the throtle bodie,held on with two screws no numbers on it so i dont know

 

[robertoa1a]

It's starting to sound like that part just needs replacing but look at auto zones on line store and see exactly what part you need and maybe I can look up how to trouble-shoot it with a meter.

 

[MazdaGreg]

Yeah, my first guess would be that you have a failing IAC valve, but if the computer is giving it false information from a failing sensor elsewhere, then you dont know. I've seen problems on my old 93 where it would hardly idle at all - rough idle simply because it was idling too low. Is that the problem here? What's it idleing at when it's rough?

 

[lucksucks]

its notso much a rough idle,more of a lope....like its v8 with a cam? make since??replaced plugs and wires again,new tps, think its an o2 or egr..and the BOY at az couldnt do a diagnostic cause he didnt know how?? goin back to aap.

 

[gtyates]

You are probably going to have to take to to a shop to get the codes read. The '94 model has an OBDI system but the auto parts stores only have OBDII readers which is why they can't read your system. My first guess would also be the Idle Air Control Valve, and it still might be part of your problem, but the IAC ususally does not throw a code, just causes very poor idle. My Uncle had a '94 Eddie Bauer model with a similar problem as yours. Took 2 shops to finally resolve the issue. Turned out his was the alternator. The altenator would send out occasional spikes in energy which was causing idling issues, ocasionally it would die for no reason, and was frying some sensors. It was found by the L/M dealer in our area quite by accident, but the tech working on his truck was determined to get to the bottom of the issue. So after replacing several sensors and the fuel pump to no avail, replacing the alternator solved the problem. That truck is still on the road daily with over 200k on it.