View Full Version : need help with prelude... again...

06-16-2005, 05:34 PM
I bought a 27C256 chip that was preprogrammed for the PK2 ECU.

I removed my ECU and soldered in an IC socket. Then, I inserted the chip. Unfortunately, I had earlier removed the sticker on the back of the chip, and erased it via exposing it to UV light (the sun).

The car didn't rev past about 3300 rpm.

I thought it was the soldering job, so I had it professionally redone. Didn't fix it.

I thought it was the chip, so I returned it and got another. Didn't solve the problem, still.

Now I don't know what the problem is.
I have a new "good" chip, and there's no opens or shorts in the soldering, but I still can't rev past 3300rpm.......

What else could have blown in the process? Is it the ECU itself? Is it a relay, or a fuse?

Thanks for all the help.
And thanks for understanding why I posted it here...

06-16-2005, 05:39 PM
well, have you determined what's keeping you from revving? is fuel cutting? is spark cutting out? is the engine flooding? is timing not being advanced/adjusted with engine speed?

06-16-2005, 05:43 PM
it runs as smooth as glass. the rev limiter (which is normally set at 6750) is now set at 3300. make sense?

06-16-2005, 06:59 PM
Is it throwing a check engine code? That sounds like some sort of limp mode thing that happens. So it's clearly the same kind of rev limit as if you're bouncing around 7k? Or is it more instantaneous- in other words does it just hum at exactly 3300 instead of actually 'bouncing'?

Perhaps there's something relating to the crank angle sensor that would have detected a RPM every mark (on a b20a5), and maybe the crank angle sensor from your a20 sends a signal twice per RPM... because it would seem that your RPMS are very nearly half of what they should be when you rev out. Is it exactly 3300 or is it really something more like 3375? That's all that I can think of.

06-16-2005, 07:00 PM
And isn't the pj0's rev limit 7000? My pj0's is... And the pk2's rev limit is seriously lower?

That's odd.

And why not remove the rev limiter? Or is it not like others - and simple?

06-16-2005, 10:12 PM
err... this is on a prelude, with a B20A engine.

the rev limiter is exactly the same as the normal one. yeah, i was thinking it might be a sensor or something (or at least hoping)...

the rev limiter seems to be set right about half of the normal one, so it could be about 3375. I'm not 100% sure, since it bounces around up there. the regular limit is 6750, so half would be 3375...

the check engine light comes on as soon as the key is set to the "run" position and stays on until the car turns off.

the red LED is constant. no blinking.