93 Eclipse 2.0 NA – rough idle then sudden jump to 1800 RPM – need help

[chevy305]

Hey guys, I’ve got a ’93 Eclipse 2.0 NA with an automatic trans and it’s giving me some trouble.

Right after startup the idle is all over the place — either it wants to stall or it bounces between 500–1000 RPM. Then, after about a minute, it suddenly shoots up to around 1700–1800 RPM on its own, and after that it finally settles down and runs steady.

Plugs are brand new, but all 4 of them turn black with soot pretty quick. Gap is set at 0.40".

Here’s what I’ve done so far, but nothing changed:

• New fuel pump
• New fuel pressure regulator
• All new vacuum hoses (shouldn’t be any leaks)
• Cleaned injectors (they do spray fuel)
• Swapped in a spare ECU

I recorded a vid of the tach from startup until it evens out — it suddenly smooths out at 1:16.

Any ideas what else I should be looking at to fix this?

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[pauleyman]

Start here.

Terry's Talon troubleshooting Tips

 

[chevy305]

Start here.

Terry's Talon troubleshooting Tips

Thanks! I’ll give it a try and report back.

 

[chevy305]

I followed the troubleshooting steps from the link above.
In step 5, it says that when you remove the ISC and turn the key from ACC to ON, the ISC plunger should move in and out smoothly. I tried that, but I’m not sure if mine is actually “smooth” or not.


I’ve attached a video—could you take a look and let me know if this is the correct behavior?

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