Rough idle sometimes.. other times she seems fine... any suggestions?

[RL2000]

I have a '91 escort with 160,000 miles and she runs great... except for a little bit of rough idle. Normally speaking it runs pretty good with just a tiny bit of "roughness", sometimes no roughness at all, but it seems like every now and then I find myself sitting at a stop light and the thing gets rough for no apparent reason!

It's kind of a come-and-go problem. Here's what I've done about it so far:

- Replaced all wires
- Replaced all plugs (properly gapped and firmly seated)
- Replaced PVC valve
- Replaced oxygen sensor
- Ran Lucas through the gas to clean the fuel injectors
- Replaced fuel filter

Here's what else I'm thinking could be the problem:

- Worn out coil pack ($50 to replace... which is no biggie if it does the trick)
- 4 new fuel injectors ($200 to replace... ouch, but still worth it if they make the car run perfectly smooth)
- EGR valve ($50 to replace... again, no problem there if it's the answer)

For the most part, it seems to run fine when driving down the road, so the issue seems to be when she's idling. Of course, I have had it run rough while driving a time or two now that I think about it...

I wouldn't be concerned because it runs so good normally speaking, but once in a while I start getting worried when the thing just takes of running rough with no warning. If I'm up in Canada out in the bush... 100 miles away from the nearest mom 'n pop store... and some friendly black bear is looking me over... I don't really like the idea of having car issues.

Any advise or input would be greatly appreciated!!

Thanks!
Robert

[mightymoose_22]

Try to find a vacuum leak. Check the vac port on the top of the intake, check the head, all the vac hoses.

Make sure your air filter is not plugged up.

Perhaps a loos timing belt? Maybe the tensioner has worked its way loose a bit.

Start with the vacuum leak though.

[RL2000]

Originally Posted by mightymoose_22

Try to find a vacuum leak. Check the vac port on the top of the intake, check the head, all the vac hoses.

Make sure your air filter is not plugged up.

Perhaps a loos timing belt? Maybe the tensioner has worked its way loose a bit.

Start with the vacuum leak though.

I will do that! Thanks for the input!

[joeh100]

I have a 95 with 173K. I did all the repairs you mentioned above. However the timing belt was the biggest improvement, and now it runs like a new car. I had to damn near pull the motor to change it though. If you go through all of that trouble you might as well get the water pump while your in there. The tentioner is on the water pump also (on a 95 anyway), so you kinda kill 2 birds with one stone.

My egr valve is in question though. How do I check it?

[RL2000]

Thanks for the input!

I just replaced almost all the vac hoses (except for a 6 inch piece which I still need to buy) and the PVC hose. It seems that most of the problem has went away, now there's only a slight "roughness" to the idle.

The key difference these hoses made was that it went from a rougher/lower idle to a higher/smoother idle, and also instead of a inconsistent roughness, it seems to be more consistent now.

I'm not sure if that makes sense or not! LOL

Any more input would be greatly appreciated!

Thanks!