2G Idle surge at 3000rpm NEED HELP

[Devontw]

I have a 1997 Eclipse Spider GST and ever since I got it it has had a surge at idle. It idles at 3000 and drops to 2500 when surging. I have got a new map sensor and mass sensor and didn’t change a thing.

I really wanna have this car running right soon let me know what y’all think.

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[DSMPT]

Welcome.
And the engine can't rev that high without air. This means you probably have vacuum leak (leak in somewhere between the throttle body and cylinder head) or/and the throttle plate doesn't fully return for some reason (Most likely the thtottle cable is improperly adjusted or worn) or/and the throttle body is not adjusted properly. You should start from boost/vacuum leak test.

 

[Devontw]

Welcome.
And the engine can't rev that high without air. This means you probably have vacuum leak (leak in somewhere between the throttle body and cylinder head) or/and the throttle plate doesn't fully return for some reason (Most likely improper adjustment or worn) or/and the throttle body is not adjusted properly. You should start from boost/vacuum leak test.

I did a smoke air leak down test there was one on the mass sensor because of a bad o-ring and cracked and got new one of those and still doing it no changes. I also got a new MAP sensor and that didn’t do anything either.

I put a new rad and fans in and haven’t had time to put coolant in it could that do anything as well? I was going to get some after work and forgot

 

[pauleyman]

It's not physically possible to idle at 3k if all systems are working. ECU cuts fuel at 1500 if throttle is closed. Check your throttle cable. 2g uses TPS as a closed throttle switch.

At a minimum ECU does not know your throttle is closed and /or the throttle is not actually closed.

And I put a new rad and fans in and haven’t had time to put coolant in it could that do anything as well I was going to get some after work and forgot

Hold up....you're running the car with no coolant in it?

 

[Devontw]

Its not physically possible to idle at 3k if all systems are working. Ecu cuts fuel at 1500 if throttle is closed. Check your throttle cable. 2g uses tps as a closed throttle switch. At a minimum ecu does not know your throttle is closed and /or the throttle is not actually closed.

I’m very new to the DSM community and liked them for a very long time.

Here’s the thing your talking about me and my uncle have messed with the cable the position sensor and idle screw and nothing changes other then idle and surge higher.

 

[pauleyman]

I’m very new to the DSM community and liked them for a very long time.

Here’s the thing your talking about me and my uncle have messed with the cable the position sensor and idle screw and nothing changes other then idle and surge higher.

Refer to the factory manual regarding TPS setting. As pointed out you must have air bypassing somewhere. It's a leak, through the BISS, through the FIAV, malfunctioning ISC, intake leak or past the throttle plate. If the TPS isn't adjusted right the ECU won't know throttle is closed. If the TPS is right the behavior should be when idle hits 1500, ECU cuts fuel, RPMs drop and cycle keeps repeating. To fix it you find the leak. If TPS is right but it idles consistently above 1500 then the throttle isn't actually closed. Physically work the throttle with your hand and make sure the cable isn't too tight.

 

[Devontw]

Hold up....you're running the car with no coolant in it?

I’ve never ran it more then 1 min with the surge and low coolant but getting coolant asap but can that do anything with coolant pressure or anything I read there’s a thing in the throttle body controls by coolant temp

 

[pauleyman]

I’ve never ran it more then 1 min with the surge and low coolant but getting coolant asap but can that do anything with coolant pressure or anything I read there’s a thing in the throttle body controls by coolant temp

Yes. Fast idle air valve (FIAV) needs coolant to work properly but that shouldn't be a problem if you're just low on coolant. I would still fix it first before running. The idle control is still as I mentioned.

 

[Devontw]

Yes. Fast idle air valve (FIAV) needs coolant to work properly but that shouldn't be a problem if you're just low on coolant. I would still fix it first before running. The idle control is still as I mentioned.

How would I fix that tho?

 

[DSMPT]

I alr did a smoke air leak down test there was one on the mass sensor bc of a bad o ring and cracked and got new one of those and still doing it no changes I also got a new map sensor and that didn’t do anything either

Smoke test is good but sometimes it's hard to see since a common vacuum leak spot is under the intake manifold. You should do a boost leak test by applying pressure, too. And leak that is located pre throttle body won't cause the idle that high. In case if the leak is the direct cause of high idle, then the leak should be between the throttle body and cylinder head.
And if you don't have a factory service manual, should download one. It shows how you properly adjust the throttle body.

 

[Devontw]

Smoke test is good but sometimes it's hard to see since a common vacuum leak spot is under the intake manifold. You should do a boost leak test by applying pressure, too. And leak that is located pre throttle body won't cause the idle that high. In case if the leak is the direct cause of high idle, then the leak should be between the throttle body and cylinder head.
And if you don't have a factory service manual, should download one. It shows how you properly adjust the throttle body.

The one I did was boost, it was with a air hose and smoke so pushes through the whole motor.

 

[pauleyman]

How would I fix that tho?

I mean add coolant before you do anything else

 

[Devontw]

It was surging for a while I got that fixed now I don’t know why it still idles high it wild perfect but it won’t idle down from 1600 the throttle screw it all the way in and everything is down so I should idle normal but it won’t any ideas?

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[dwb]

Culprits could be but not limited to:
Boost leak, ISC, FIAV, TPS, improperly routed vacuum line(s)

 

[Devontw]

Culprits could be but not limited to:
Boost leak, ISC, FIAV, TPS, improperly routed vacuum line(s)

I did a boost leak and a normal leak down test and I already replaced what was leaking so I will have to look at the TPS and ISC ordering a new FIAV because that’s what I originally thought it was

 

[dwb]

I'm not saying to start throwing parts at it. You should do what you can to test and diagnose them first.

 

[Devontw]

I'm not saying to start throwing parts at it. You should do what you can to test and diagnose them first.

Yes, I know. How would I for the three that you listed?

 

[miliman13]

I adjusted my timing in link recently to resolve my high idle surge , if you have EcmLink you can check for this.
Otherwise ignore.

 

[dwb]

Yes, I know. How would I for the three that you listed?

How to fix your idle surge problem.

In hopes to eliminate many of the posts in regards to an idle issue or "idle surge" I have put together a list of things to check when dealing with an idle problem. I would say that 99% of you will find the answer to your problem here. I have done a lot of research on this issue and if any of...

www.dsmtuners.com

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)