Surging idle when warm
11-24-2013, 12:27 PM
#1
Banned
Thread Starter
Surging idle when warm
A couple of days after reinstalling my rebuilt 4.5L on my 82 5 speed the car developed a surging idle after coming up to temperature.
The engine starts fine with no hesitation or delay and idles at about 800 rpm with AC off. After driving and getting up to temperature, the engine will surge from 800 to about 1500 rpm while sitting at idle at a stop light.
Sometimes it does this, other times not. If you shut it down and restart the rough idle usually goes away. Could this be a throttle switch or a vacuum line that came off? I deleted the cat and air pump, but this idle problem did not manifest itself until the weather turned cold here in Houston, the car ran great for 150 miles before the idle problem showed up. Thanks!
The engine starts fine with no hesitation or delay and idles at about 800 rpm with AC off. After driving and getting up to temperature, the engine will surge from 800 to about 1500 rpm while sitting at idle at a stop light.
Sometimes it does this, other times not. If you shut it down and restart the rough idle usually goes away. Could this be a throttle switch or a vacuum line that came off? I deleted the cat and air pump, but this idle problem did not manifest itself until the weather turned cold here in Houston, the car ran great for 150 miles before the idle problem showed up. Thanks!
11-24-2013, 01:17 PM
#2
Burning Brakes
Join Date: Nov 2010
Location: Alpine - Southern CA.
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On my 81 I had this issue and replaced the AFM sealing ring and removed the vacuum limiter under the spider and capped with plugs. No more surging. Ref. page 42 of - 928_USA_78_82_KATALOG. Could be your problem?
