Classic Replica Build (+ TVR resto)

**KugaWestie** · 07-05-21, 08:06 PM

Thanks everyone.

I have been chasing a few gremlins the last couple of weeks. Now the engine has a couple of hundred miles on it I have started to stretch it a bit. When doing so I discovered a misfire/hesitation starting at 4000rpm.

First port of call was fuel. The fuel pump was pretty noisy. So I decided to fit a surge pot and a low pressure pump to feed the pot. I did this all at the back of the car. After this was complete test drives showed that the hesitation had moved from 4K rpm up to nearly 5k rpm.

After some head scratching I turned my attention to the 123 ignition. I spent some time googling and managed to find the Rover factory advance curve and MAP curve, so I loaded these onto the system and tested again, no improvement.

I then turned my attention to the FiTech injection system. I plugged on the handheld controller and found a fault code of “RPM noise”. Googling showed me that this is fairly common. I checked my spark plugs and they were a non resistor style of plug. I changed these to a similar spark plug with resistor properties. I also checked my IAC settings on the FiTech and these were way off, so I adjusted this as well. I also changed the HT leads to some 8mm high performance silicone leads. I also added a direct earth cable from the FiTech onto the battery earth strap on the engine. The final adjustment was to alter the fuel pump settings under hard acceleration.

After getting though that lot a test drive tonight for half an hour or so had me hit the Rev limiter a couple of times with a good clean pull through the revs and no hesitation.

When I got back home I plugged my handheld controller back on the FiTech and checked for error messages and there were none, so the rpm noise issue has been solved.

Hopefully that’s sorted it for good and I can get on with ragging it to death now