Rough idle! Need help

[RcamaroS]

Does anyone know why my car is idling hard? I left from a light and got on it and it suddenly fell on its ass and started idling rough. I turned into a gas station and bought some starter fluid and let it run and the engine looking for vacuum leak but couldn't find anything, then I took the air cleaner off and disconnected the O2 sensor and it started idling fine but obviously through a check engine light from the sensor. Once I plug the sensor back in it isles hard again and won't let rev up. I'm thinking the O2 sensor went out on it because it idles fine with it unplugged but plugged it idles rough. There isn't any weird ticks or noises and the fuel pump primes when the key it turned on and starts fine and it's not over heating or anything so that tells me it's not a head gasket. Many one have any ideas?


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[DanDalessandro]

Replace the O2 sensor. Replace air filter too of you can.

[DynoDave]

Does anyone know why my car is idling hard?

By hard, you mean rough? Like the engine has a slight miss?

I left from a light and got on it and it suddenly fell on its ass and started idling rough.

At this point...before you even got out of the car, was the check engine light on?

I'm going to GUESS that when you disconnect the O2, the computer is going into a fixed program. You have essentially "blinded" the ecm, so it goes to a fixed set of values for timing and fuel. Not optimal setting, but safe for limping home. When you reconnect the O2, and it starts running worse, that may be a sign the O2 IS working, and NOT broken. The computer is trying to adjust based on something it can now "see" with the O2. You need to determine what that something is.

[RcamaroS]

I'm sorry I meant the mass air flow, not the o2


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[RcamaroS]

But no check engine light when it first started to have trouble


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[DanDalessandro]

Your mass air flow thing is malfunctioning then. Is it in correctly? Arrow going towards engine?

[RcamaroS]

I never messed with it and it never had a problem until I got on her a little bit. Thats when it started to piss and moan and studder, almost all of a sudden

[QuickTop]

Running better with MAF unplugged usually points toward a vacuum leak or a MAF that took a crap.

[zeeman]

You need to do some diagnostics. Check your fuel pressure. Hows the filter? Check your wires, spray them with water from a spray bottle then run it in a dark garage, look for arching. Pull the plugs and see what they look like. Etc.

[RcamaroS]

Update: I had a buddy run a diagnostic on it with his code reader while it was running with the mass air flow plugged in and the car put back together and the check engine light on and the diagnostic didn't come up with any codes. We used the OBD1 (which is what I hear I had and I didn't get any kind of codes or anything. I sprayed the engine down (hoses, heads, intake, throttle body, everything with starter fluid) and I didn't get anything, fuel pump primes and everything seems good until it idles or I start driving( it acts like it wants to bog down) unplugging the MAF sensor it idles fine, and runs fine without any lag or problems.


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[zeeman]

Unplugging the maf forces the car into speed density mode. Computer cant see air flow, so it runs off of programed tables. Start with the basics. Check for vacuum l eak. Look at o2 sensor wires, make sure they're not burned, and are working. When was fuel filter changed...etc. Something is not right. You have to do work to figure out what it is. Exhaust leaks can also cause running problems.Check the basics and go from there.