surging idle when cold out

[97vulcan]

Hello all,

I'm still having a surging idle when in gear issue when the weather is cold, like in the teen or 20's. It was in the 40's in WI the other day, and my car was fine in gear at idle.


not sure if this sheds any light on the problem, but I'm at a loss.

Changed the plugs, rotor, cap and wires, and fuel filter.

[97vulcan]

today when it was about 5 degrees out, my car after sitting for 9 hours wouldn't start. It would crank, and the engine was chugging as I held the key in run. I eventually got it to start by holding it in run and it finally started. It took about 5 minutes of cranking, stopping then cranking again.

What does the chugging mean? the tach was raising as I was cranking too btw.

thanks

[hill8570]

Once it caught, what was the idle speed (at first, and then as it warmed up)?

[WISHYWASHY]

probably you car trying to get the engine warm?

[97vulcan]

idle started out low, and choppy, then it increased to a high idle when warming up. It took a bit for the idle to "smooth" out. once it's running, aside from the surging idle in gear when cold outside.

I didn't see any smoke from the exhaust.

[KiDGiB]

Have you checked your air filter? Possible hose disconnected from the intake?

[97vulcan]

I have checked the air filter and it's clean. There are no disconnected hoses to my knowledge.

[KiDGiB]

Its possible that it could be the IAC

[97vulcan]

Originally Posted by KiDGiB

Its possible that it could be the IAC

I cleaned the IAC with Deep Creep about 2 weeks ago.

[KiDGiB]

Have you tried running some injector cleaner after you got your new fuel filter put in?

[hill8570]

I having trouble keeping track of what's been tried here (seems like there are multiple threads about the same issue?), but has anything been tried with the coolant sensor (the one on the engine)? The hard start / low idle when started cold almost sounds like a classic symptom of the coolant sensor reading too warm. Generally doesn't give a surging idle, 'tho.

If you have a multimeter, could you try checking the resistance of the coolant sensor (the one with the green connector, where the upper radiator hose enters the engine)? Failing that, you could score another one from a junkyard and try to shotgun the problem.

[97vulcan]

hmmmm I have not checked the resistance on the coolant sensor. Whats weird is the car will start sometimes when its super cold and has been sitting overnight, but other times it won't want to start when sitting for 9 hours in cold weather. If the car has only been sitting for a few hours, it starts up like a champ. I just can't put my finger on this problem. If it didn't start at all when it was cold, I would have a better idea, but since it sometimes does, and sometimes doesn't, I'm left scratching my head.

I've got nothing to lose replacing this part. Whats a good aftermarket brand to go with?

Thanks again!

[hill8570]

Originally Posted by 97vulcan

hmmmm I have not checked the resistance on the coolant sensor. Whats weird is the car will start sometimes when its super cold and has been sitting overnight, but other times it won't want to start when sitting for 9 hours in cold weather. If the car has only been sitting for a few hours, it starts up like a champ. I just can't put my finger on this problem. If it didn't start at all when it was cold, I would have a better idea, but since it sometimes does, and sometimes doesn't, I'm left scratching my head.

I've got nothing to lose replacing this part. Whats a good aftermarket brand to go with?

I the wrong person to ask about aftermarket -- I won't use it for anything critical to the engine's operation. Ever since they started making most aftermarket stuff in China, most aftermarket stuff a total crapshoot.

If you can find a Denso (Toyota's OEM for most electronics), you should be OK. Beck/Arnley tends to be good more often than bad. I guess pretty much anything else would work long enough to get a go / no-go, and you haven't spent a lot of money shotgunning the problem. Be sure to grab a replacement o-ring or at least some Permatex (or your favorite brand) Blue (medium strength) thread sealer to put on the threads so you don't have coolant dribbling out later.

Or, you would swap parts between the '92 and the '94 -- the coolant temp sensors should be identical.

[97vulcan]

I will replace the sensor with one from say Autozone, and see if this helps me out. It's an intermittent problem, because sometimes it will start when it's super cold out, then other times it will want to start, but just won't. It doesn't seem to help giving it a bit of throttle before starting, this seems to make it worse.

THanks,
Adam

[97vulcan]

so.....here's the test I performed as I couldn't test the resistance of the sensor. I performed another test. First as the car was was cold after sitting overnight, I unplugged the ETS and tried to start the car. It wouldn't start, I cranked it and cranked it and no go. I plugged in the sensor back in, and it started right up. As the car was idling, I unplugged the sensor and the idle dropped down, and was a bit rough, then I plugged it back in as the car was running, and the idle increased.

so my question is, could the sensor be failing intermittently? Does this sound like the source of my no start?

Thanks,
Adam