I took my '02 Protege 5 to my regular oil place yesterday and they did their job. When I went to leave, the car wouldn't turn over. It had been having some hard starts for a while, but this time it would turn over at all. The guy that works there (a friend of ours) recommended a new battery. We had one sent over and he replaced the battery, the car started up fine.

So we left the oil change shop and got down the stop sign. When I pushed in the clutch to downshift it started dropping RPMs down to 100-200, just nearly stalling. Gave it a little gas and it went back up to 800 or so, normal area. It's been doing that since yesterday. Whenever it's idling it really rough, almost stalling, but it hasn't stalled yet. A little gas will get it back to normal and it'll stay there.

All I've tried is driving around on the highway for 20 minutes or so, seeing if the computer will recalibrate itseft (something my father in-law suggested). Any suggestions from you guys? Could something from the battery change or oil change cause something like that?

 

Rough idle could be due to EGR. Do this and see if it helps. The battery should've solved your starting problems tho ...

 

Oh yea, it starts great now. I'll try that EGR cleaning. Just strange that it the rough idle just started when the battery was replaced.

 

It should help, but getting the EGR out of there is quite the task. I guess I would first check and see if a simple reset of the ECU does anything ... disconnect battery, pump the brake pedal a couple times, wait like 10 seconds, and reconnect. Start her up and take her for a spin, hopefully it's better so you don't have to crush your hand trying to get the EGR valve out.

 

Ok, I did the disconnect battery, pump brake, wait. Didn't help. Tried the EGR valve cleaning and that didn't do the trick either. The valve wasn't too built up, but I gave it a good cleaning. I think I'll replace the spark plugs tomorrow, but do you think it could be those? Maybe a fuel flow problem?

 

Give it a little while, i know that each and every time i leave the battery disconnected for a bit my ecu has to "relearn" the motor and my idle goes all over the place, from just above stall speeds to 1500 rpm, give it a few days to get it figured out and chances are the rough idle will go away. Mine takes a couple of days usually befor it gets back to normal

 

Well I went to check to make sure I tightened up the bolts on the egr valve. Discovered that the gasket wasn't in place, so took the valve off, fixed the gasket and put the valve back on. Still didn't fix it though.

I noticed tonight though that the RPMs only go down too low during decelleration while the clutch is in. It goes down to the bottom bar, like it doesn't register it's running. It doesn't stall, but power steering nearly goes out. It's running a little rough during normal driving also, not really noticeable if you hadn't been driving it for a while, but I noticed it tonight.

 

After you reconnect the battery following ECU reset, turn off all accessories (AC mainly) and let it idle WITHOUT touching the gas for 10 minutes or so. You will actually see that the revs are really high initially, then gradually fall. I think this is why you are seeing the erratic revs - didn't let it idle. If yours is a stick, idle should be around 700-800 rpm