I have a intermittent flat spot at 3200RPM during acceleration. It most often occurs when the engine is under load ie going up a hill or when I move the accelerator forward to increase acceleration.
I've had the TPS changed and the exhaust manifold changed/fixed and I've had the O2 sensor changed and I've cleaned the injectors and given the engine a flush.
I would like to know - what causes a flat spot?
what is happening in the engine at 3200rpm?
and any other ideas as to how I can fix this problem.
Your 'flat spot' is due to the fact that your car's engine doesn't produce enough torque to pull you up a hill in the gear you're in. You need more rpm. Downshift to a lower gear.
I would love to see a dyno print of the so called "flat spot" so we can confirm with real data and not just "butt-dyno" readings.
I'm not spending money to find something that I know happens. There is a very obvious short loss of acceleration and power at 2300rpm(in all gears), almost as if the car has suddenly run out of fuel but after approx 2400rpm the acceleration picks up again.
Which engine are you running? Which ECU are you running?
There are some people that experience a hesitation around 3k rpm after doing JDM H22A swaps. Maybe some of them will chime in here. I recently did the swap and haven't experienced this hesitation (knocks on wood). I am running a '93 JDM H22A with the OBD1 USDM P13 ECU.
I'm not sure what JDM is, the car has an H22A and is stock standard, I've had the car sine new and the problem has gradually come on over the past couple of years but is getting much worse and more noticeable.
JDM is "Japanese Domestic Market". In other words... a "Japanese-Spec" engine. If yours is stock then that issue wouldn't pertain to you. I would check all your vacuum lines for leaks. How many miles are on the engine?
It sounds like it could be your timing belt tension.
If you have an auto tensioner (stock tensioner for h22) then it might be going out on you.
If you have a manual tensioner, try tightening it using the procedure in a Helm's manual.
That's the only thing I can think of outside of fuel/ignition issues.
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