wont go over 2000 rpm

I have a 454tbi mefi 1 motor that when I reach 2000 rpm it backfires out of the throttle body and bogs down to 1000 rpm. After I pull back the throttle I can run the engine at 1900 rpm all day with no problem, just not beyond that. I have changed the ecm, coil, checked base timing, plugs and wires but nothing has worked. Where should I look next? Thanks.

What about advance timing,sounds like it could be the issue but Im not sure about EFI engines.

To either eliminate or confirm an ignition advance problem, I'll suggest the following to you.

Mark off (in degrees) your harmonic balancer up to approx 35* from the TDC slot and in the direction shown below.

On a warm engine, strobe these timing marks with a standard timing light, or with a digitally advancing light in Sd Mode.
Increase engine speed in increments of 250 rpm, up to the OEM spec'd Full In advance RPM.
Job these numbers down in graph form.... I.E., spark lead vs RPM.

Find your OEM advance curve specs, and compare.

NOTE: most OEM Marine advance curves do not include BASE/Initial advance in the degree column. Yet when you strobe your marks, BASE/Initial will be included and will be seen. So...... when doing the math, BASE/Initial must be included in the specs.


This is an example of a marked-off balacer for a Std LH rotation BBC engine.




If this engine is not seeing the correct amount of progressive advance as per RPM, it will not produce the expected power.


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Ayuh,.... Check the contents of the fuel filter for water, 'n install a new filter,...

Fuel system and fuel are all new. Gonna check timing advance and fuel pressure first. Thanks boys.