M20 revving past the 7k rpm redline

[phil540uk]

My M20 doesn't seem to have a rev limiter, (or the rev counter is reading too high) as it will sail past the 7k redline.

I've read that having 4pot clocks on a 6pot car makes the rev counter read higher, but to my knowledge, they are the original clocks and it shows idle speed at about 1,000 rpm which I presume is normal?

If they are 4 pot clocks, then I have read that changing the coding plug on the back of the clocks will sort the issue, but does anyone else know why the engine will rev past the redline?

Thanks in advance,

Phil

[m_jermyn]

Chip

[spp320i]

Chip

+1

[phil540uk]

I've tried 2 different ECU's on it with the same thing happening.

Phil

[georob]

2 chipped ecu's

[Ant]

4 cyl code plug will indicate around 1K idle ( actual is 680 rpms on stock M20B25 ) stock limit is 6.4K on facelift cars too.

codeplug goes in the front lower RHS of the clocks, only the outer surround needs to be removed to swap it out for the correct item.

[mattrs]

What rpm is safe for a chipped standard m20 b25?

[phil540uk]

Tried an aftermarket rev counter on before that confirmed the standard rev counter must have a 4 pot coding plug!
I'll try another coding plug which should hopefully cure it!

Thanks for the replies!

Phil

[Ant]

no more than 7K max, can show just over on the tacho though before the party pooper chimes in .

M20 will not make power past 6.5K so the rest is useful over rev should you need to hold a gear longer than anticipated, rtaher than upset the car with a mid corner upchange.

[phil540uk]

It's an 89 model. Is that early or late?