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The weather has been below the 30's lately and my idle is also acting up! It is surging up and down at stop lights! It does it even after driving to work 35 miles away. How do I fix this? Is there an idle switch some where? I did a search but they are about the 4g61T/4g63T engine.

Thank you!

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How high is the idle surging to?

I had a small idle surge problem, it was my Throttle cable on to tight and it caused binding. When it was doing this you could watch the cable and ISC moving against each other.

My car also surged when my coolant temp sensor was on its way out. That threw a code. A vac or boost leak can also cause surge.

Have you tried to set you idle?

The TBI/TB system on these cars sucks

It surges above 1500 rpm and down to around 800. I will check the sensor like you mentioned. It idles perfect when the weather was warmer.

Thank you!

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un hook your coolant temp sensor and see if it still does it

could be a vaccum leak, or even be as basic as low coolent.

I got it fixed! It turned out to be a vacuum leak. I went ahead a replaced all the vac lines. Thanks to all who have responded to my issue.

There a too many vacuum lines in the engine. I will go through and delete most of them when the weather gets a little warmer. Thanks again for all your help!!!

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Dang, the idle surge is back!!! It was 37 degrees this morning, I went and unhook the temp sensor wire but that didn't make any difference. I sat there for about 15 minutes before the surges went away. Seems like when the engine is warmed up, the surges went away. Does that mean the coolant temp sensor is bad? Thank you.

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Just to double check, that coolant sensor has two prongs on it, for a two wire connector? If this coolant temp sensor is bad, your ECU will through a code.

Do you know how to check for a ECU code?

Check the resistance on that coolant sensor. I'm at work right now and can't tell you the values it should be. However if you check the online manuals for a 4g15/4g63 they should be similar.

How do I check for codes on this g32b? I'll check the sensor asap. Thank you!

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A search turned up this .....
http://www.4g61t.org/forum/viewtopic.ph ... de#p180409

I have a similar problem with my 2nd gen G15B. When the engine warmed up, the idle goes up to ~1300 and then back to ~1050 constantly, but only when the lights are on. Guess it would be a generator issue (idk).
My normal idle is ~750 without lights, but when lights are on it goes up to ~1050.

What engine is in your car, EFI or carb? What car? What year?

Maybe try making a thread on the general or the 4g15 section.