*Like the topic says, It`s just doesn`t want to rev up all the way to redline. it bogs on 5K and it stays there. What`s wrong with my car?

* Helpful hints from my 91 CRX Si:
- it runs good
- No check engine light
- Just tuned up and Timing is dead on

* Things I have doubt on:
- PM6 ecu not sure about the chip tho
- 92 Civic Vx 1.5 head


****I know there`s a lot of peeps here that has some information about this problem. Please help. Thanx in advance.

 

How abused are your valve springs?
Could the valves be floating?
Have you checked the ignition output at 5k+ RPM?
Do you see sparking under the hood at night?
Does the problem change under load / under no load?
Do you have good fuel pressure on the injectors?
Find the answer to those and you may find a problem, and if not, get back to me with the results and maybe I can help.

 

If it has a VTEC (especially VTEC-E) head then likely it's not revving up because VTEC isn't engaging. It's only running on 3 valves per cylinder.

 

*No sparking under the hood can be seen @ nite.
*Good fuel delivery on the injectors.

*Like I said the car runs really good and pulls stong! I just couldn`t get it pass 5Krpm. Rev. Limiter maybe???? Computer chip gone bad???

*BTW I don`t have a VTEC head and If it`s NOT running on 3 clylinders It would be easy to identify if it`s running on 3 cyls.

 

VX = VTEC-E

3 valves per cylinder, not 3 cylinders.

 

I'm not extremely knowledgable on honda computers.... but I seem to recall some of the engines having a lowered rev limit when they are cold. Anyone know about this? Perhaps this and a bad temp sensor could be the problem?

 

The lowered rev "limit" is because the oil isn't warm enough to generate the pressure needed for the engine to switch to the VTEC cam lobes. There's a sensor on the head that looks for ~60 PSI if I remember right.

That could be one of many reasons for the problem. Other potentials could be a dirty filter screen on the VTEC solenoid, a bad solenoid...



To clarify on the 3 valves per cylinder issue: The VTEC-E heads were designed for fuel economy, not performance. Below 2000-2500 RPMs the engine only operates 1 intake valve. This promotes swirl in the combustion chamber and therefore fuel economy. From 2000 to redline it operates as a normal VTEC engine, running on 4 valves on primary and secondary lobes until VTEC engages, at which point it swaps to the high lift lobes.

 

*I`m sorry qtiger I guess I might have confused you and the other guys. What I meant is the car has a 1.5 DX head NOT VX so it`s not a VTEC-E head also the dizzy is from a 1.5 DX. again I`m sorry.

*So i know there`s a problem why it`s not revving over 5K I just can`t pin point what the problem is. Please guys help out a brotha.

*BTW what`s the normal setting on the rev limiter for a 91 CRX Si?

 

NonVTEC head eh... :thinking:


If this is a recent problem then I'll put my money on spark. Maybe bad plug wires, nasty plugs, or a dizzy problem.


If it's never run with the chip then I'd start looking around for an OEM chip or ECU you can use temporarily. If the chip you have in your ECU is like the vast majority of the cheap chips on the market ("mugen," "spoon," "skunk2") then all check engine lights except the absolute worst are disabled. Those "race" ECUs ignore the vast majority of your unneccessary sensors. If you can borrow an OEM ECU, I bet you'll pop up a CEL.

 

*I just put a brand new spark plug wires set, new plugs but didn`t have a chance to check on the dizzy. Like I said the dizzy is from a 1.5 DX

*Now would an aftermarket chip or OEM ecu will fix this rev. limiter and be able to pass that 5K rpm The ECU I`m running is a PM6 with some other #`s with it. I believe that`s the stock (OEM) ECU right?