Rough idle

Tiny
STAR52
  • MEMBER
  • GEO STORM
My 93 geo 1.6l won't idle smoothly. Will even stall at complete stops. Replaced plugs, wires, cap, rotor. ECM tells me nothing wrong. I suspect MAPP sensor but it checks out okey. I've adjusted idle up and advanced timing by turning distributer to keep it running. This can't be good for to long. Is there something I've missed? Does anyone have any ideas what I should?
Tuesday, August 14th, 2007 AT 10:23 PM

2 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
14yo car and has a 1/2 tune-up-my friend there's more to it especially my way.

Do you know how to track a vacuum leak?

If it has an EGR and PCV valves find them and clean it make sure its getting vacuum to it, then comeback and we'll take to the next level of the engine conditions.

Good Luck
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Wednesday, August 15th, 2007 AT 3:44 AM
Tiny
JUSTALUCKYSHOT
  • MEMBER
  • 10 POSTS
Like the prior poster said, check for vacuum leaks. First off, back the off on the timing, take it back to 10 Degrees TDC cyl 1.

If all else fails, take the engine back to stock, you know?

Replace all vacuum lines, its like 7 dollars for a 3 ft tube, just remove one, cut a new one, replace. Dont mix up the tubes to wrong holes though =)

once you replace all the tube, take a can of starter fluid, with a straw attached. Spray in short bursts all around any intake. Vacuum lines, all around the throttle body, the EGR, the carbon canister, everywhere that goes into the motor.

If the motor goes WAAAAAY up in idle (its starter fluid remember =P) then you have yourself a leak.

If no leaks are found, pull up on the bottom of the EGR valve, does the motor try and die? If its already dying, maybe the EGR valve is stuck open? That would be my best bet honestly. Does it idle Strong, but low? Or low and weak, like sick sputtering sounds? Shaking real bad?

If the EGR valve checks out, check your cam timing. Pull off the Belt cover, lower the engine if you can, and check to see if those white marks line up. On the DOHC the white lines should FACE EACH OTHER, and be INLINE WITH THE HEAD. If not, adjust accordingly. The SOHC Geos cam timing lines up with a white mark, running with the head, and a black mark pointing to 12 oclock. Go check a manual, like Haynes, for more info.

If it aint your Ign timing, Cam timing, Vac leak, EGR, or IAC/TPS. Well my friend, im out of ideas.

=D hope I helped!
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Friday, September 19th, 2008 AT 9:39 AM

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