MFI engine does not rev past 6.5K

[greyes59]

My mfi engine does not reve past 6500 rpm.

is this because the mfi pump is not pumping enough fuel to achieve higher high rpm(calibratrion problem) or there is not enough spark advance? I use a clewett engineering twin plug ignition module

[BK911]

Most fuel injection problems are ignition, so I would start there. Good luck!

[E Sully]

What do the spark plugs look like? Any carbon from running rich, or too white from lean? What is your maximun ignition advance? Less is better with twin plug than single plug.
ignition advanced with twin plug

[bavaria911]

Maybe it is as easy as the rev limiter rotor?

[gptom]

T engines had a rev limit of 6500. Rotor would cut out. Which engine do you have?

[pors1968]

Like Bavaria 911and GPTOM i would try a new rev limiter rotor or check on rotor it written rpm limit.

[greyes59]

I built this 2,9 short stroke MFI .
Yes. Probably the rev limiter is the problem.
I can reprogram the Clewett twin plug ignition moduleto limit at 8000 rpm instead of 7000 rpm. Max advance is 20 degrees

[stownsen914]

I think the other posters were speculating that if you still had the distributor, that the rev limiting mechanism in the rotor might be failing you. If you have a Clewett ignition, this shouldn't be an issue though. Can't hurt to check the rev limit on your ignition module though ...

Did you make any changes right before this started happening? If you can think of anything, I'd look there first.

As for diagnosing, do you have an A/F monitor or EGT on your car? If so, it would indicate if you're going rich or lean when the engine starts misfiring.

Scott

[greyes59]

I can place the rev limit at 9000 rpm on the Clewett ignition module. It is programmed for 25 degrees advance.

[greyes59]

good idea. I have an AFR meter which I have not hooked up yet and I will see where the mixture is