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Forum namePerformance/Engine
Topic subjectRough idle after complete 420a rebuild.
Topic URLhttp://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=127717
127717, Rough idle after complete 420a rebuild.
Posted by quikshot, Dec-31-69 06:00 PM
Hi guys,

I am new to the forums, but I thought someone here could help me to get my eclipse idling correctly. I recently rebuilt the engine with new pistons, rings, rods, water pump, oil pump, pretty much a complete rebuild. Other mods it has are unorthodox underdrive pulley, AEM intake, Greddy SP2 exhaust, megan headers, and magnaflow catalytic converter, all of which were added at the time of rebuild. Also, new spark plugs, wires, and coil were added. I tried re-using the old coil and plugs from before the rebuild but the problem still existed

The problem is that the engine lopes at idle and seems like it wants to stall, but runs fine at 1500 RPM and up. It did not do this before the rebuild so I think it was something I did but I have checked everything I can think of. Vacuum hoses appear to be in the correct locations. I checked the resistance of the Idle Air Control motor and the Throttle Position Sensor on the throttle body and they are within spec. If you guys have any idea on how to help, please post. I will try to post a sound clip so you have an idea of what I am talking about.

Thanks,
Mark
127718, RE: Rough idle after complete 420a rebuild.
Posted by RoninEclipse2G, Dec-31-69 06:00 PM
I'd bet that you forgot to bleed the coolant system for air bubbles. They get caught behind the T-stat and freak out the temp sensor. It causes the ECU to freak out and makes the engine run like crap at low RPMs.

Another thing to check is the timing of the engine. Sometimes higher rpms can mask misaligned timing.
127719, RE: Rough idle after complete 420a rebuild.
Posted by daes_venge, Dec-31-69 06:00 PM
Originally posted by RoninEclipse2G
Another thing to check is the timing of the engine. Sometimes higher rpms can mask misaligned timing.

+1

Timing is likely off.

127720, RE: Rough idle after complete 420a rebuild.
Posted by quikshot, Dec-31-69 06:00 PM
Thanks for the help guys. I did not bleed the cooling system, just filled it up and went. But I looked in my Hanes manual and it says to fire it up without the radiator cap on and let the thermostat open. Then let the engine cool and refill the coolant and squeeze the upper hose to remove bubbles. Is this the method you guys used?

Thanks again for the help.
127724, RE: Rough idle after complete 420a rebuild.
Posted by dalesmitsu, Dec-31-69 06:00 PM
yup, thats the method I use when I do a flush/fill.
127731, RE: Rough idle after complete 420a rebuild.
Posted by bullettdsm, Dec-31-69 06:00 PM
In probably 90% of these cases (yup, I just made that number up :)), its the timing.
127734, RE: Rough idle after complete 420a rebuild.
Posted by quikshot, Dec-31-69 06:00 PM
Thanks for the help guys. I bled the coolant system and took it out for a drive and it idles perfect, but now the CEL is on. I'll take it to autozone and see what the code says.

Thanks again,
Mark
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