What causes engine surge when rpm reaches 1950 to 2050.
Engine starts and idles good. When rpm reaches 1950 engine surges up to 2050 and back down to 1950. Above or below 1950-2050 engine runs good. Engine is a 2400 with a 5 speed trans with 306000 miles.
Could be as simple as a vacuum leak.
surging or bogging if you hold down cuts out backfires, black smoke,????
Engine does not cut out ,backfire or smoke while surging.
Tom may have the answer vacuum leak my answer was addressing a more drastic actual cutting out of engine power.
Tried testing for a vacuum leak with propane while holding throttle at 2000 rpm.This did not help the surge problem. it kinda acts like a rev limiter but at such a low rpm there is no way that it could be hitting the rev limiter because it will rev past that after it reaches 2050 rpm.
Thanks for the help. If you have any other suggestions I would appreciate it.
I did have surging with my 86 but found that to be due to loose EGR valve The bolts holding it were loose and it would move on the studs causing the engine to surge. Easy check to see if yours is loose.
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