Hello. Great forum; have used it many times to solve other issues.
I looked through this site and have seen some similar threads but nothing that really matches my current issue.
1993 Sidekick, 16v EFI, Manual, Mileage: 201,000
When accelerating, especially when accelerating hard, the engine bogs/hesitates/lurches/jumps and the result is very low power and RPMs unless you feather the throttle lightly to slowly build RPMs without putting lots of load on it. This only happens until about 2500RPM (in any gear). Once above 2500, you can accelerate as hard as you want and the problem doesn't occur.
It seems to only happen noticeably when under load, and it is only faintly detectable when parked and revving it in neutral.
No check engine light. Shop said timing was fine and they didn't report any codes.
I do have a cracked exhaust manifold,upstream of O2 sensor but just had welded a few months ago and it seems to holding, as O2 sensor not complaining.
Also, it does burn a bit of oil and has a decent cloud on startup which I believe to be worn valves, but this has slowly been building for years and has not changed with this new problem.
Finally, I did have the dreaded issue with the crankshaft keyway getting wallowed out due to sheered/loose crankshaft sprocket bolt, and I rebuilt the keyway and rebolted it 5 years ago and it has been running very well since, until current problem. Perhaps that is coming loose again?
Interested in ideas before I blow a weekend or two chasing an unknown problem.
Thanks for any input!
I looked through this site and have seen some similar threads but nothing that really matches my current issue.
1993 Sidekick, 16v EFI, Manual, Mileage: 201,000
When accelerating, especially when accelerating hard, the engine bogs/hesitates/lurches/jumps and the result is very low power and RPMs unless you feather the throttle lightly to slowly build RPMs without putting lots of load on it. This only happens until about 2500RPM (in any gear). Once above 2500, you can accelerate as hard as you want and the problem doesn't occur.
It seems to only happen noticeably when under load, and it is only faintly detectable when parked and revving it in neutral.
No check engine light. Shop said timing was fine and they didn't report any codes.
I do have a cracked exhaust manifold,upstream of O2 sensor but just had welded a few months ago and it seems to holding, as O2 sensor not complaining.
Also, it does burn a bit of oil and has a decent cloud on startup which I believe to be worn valves, but this has slowly been building for years and has not changed with this new problem.
Finally, I did have the dreaded issue with the crankshaft keyway getting wallowed out due to sheered/loose crankshaft sprocket bolt, and I rebuilt the keyway and rebolted it 5 years ago and it has been running very well since, until current problem. Perhaps that is coming loose again?
Interested in ideas before I blow a weekend or two chasing an unknown problem.
Thanks for any input!