# 86.5 HB D21 VG30 Surging/Slowing Idle



## jcdenco (Jun 10, 2007)

Hello all,

First, I admit, I know just enough about working on cars to be dangerous. Nevertheless, I am careful and I follow the shop manual to the best of my ability.

I changed my spark plugs yesterday (NGK BCPR5ES-11 as per the shop manual), and upon reinstalling the air cleaner and starting the engine, there is a problem with the idle. 

The idle drops to almost stalling out, but just at that point the engine surges up to 1200-1500 rpm. Then it drops back down, only to surge again just before stalling. This was not happening before the plugs were changed. Despite the idle problem, the vehicle runs very smoothly when taken out on the street.

There are none of the misses, sputtering or other symptoms typically associated with improperly installed plugs. My plug wires are less than 1,500 miles old and have been working fine. The engine sounds good, except for the idle problem. I have no reason to believe that any part has failed, nor was there any noticeable prior symptom of the idle problem.

I have a suspicion that this is something relatively minor, possibly elated to a vacuum line, the fuel/air mix or something like that. But this kind of issue is a bit over my head and I would appreciate any suggestions you might care to offer.


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## 88pathoffroad (Jun 6, 2004)

Check your vacuum lines. A good leak will make it idle poorly.


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