Motor runs extremely rich at high rpm
 

Hi guys,

I'm running a B20vtec on EG6, OBD1, S300 P30 ECU.

Motors runs ok at low revs, up to 3000rpm, above that and into vtec, the motor runs extremely rich. My LM2 reader jumps from 13:1 to 8:1 at high revs.

In order to tune the fuel down to 13:1 the map has to be reduced to almost 50% of the normal fuel map, which is too little fueling.

I thought the distributor wasnt firing properly at high revs and not burning the fueling and dumping it out. Swapped a new distributor and the problem persisted.

I can only imagine that the problem is with the wiring harness. Its an original OBDI harness but there are some wires might have been tapped by previous owner for gauges etc.

Could there be noise interference or grounding issues causing the distributor to run bad at high rpm or other issues that cause the injectors to run too rich?

Re: Motor runs extremely rich at high rpm
 

sounds like you need to use that fancy s300 and makes some changes in it (tune it)
fyi there was a ground wire test. dont put a ground on the dizzy youl lose power and function.
the best place for ground is the head, tranny, ecu, and block

Re: Motor runs extremely rich at high rpm
 

There is nothing wrong with the S300 map. I'm using a tuned map for the same engine. Something's wrong with the ignition at high rpms. Seems like its dumping the fuel unburnt causing the extremely rich AFR.

Just to give you an example, if your fuel numbers at 5000rpm is at 650 with afr of 13:1, and vtec engages at 5500rpm and the fuel number is 660 it jumps into 8:1. In order to bring the AFR back to 13:1, i need to reduce the fuel number to 300 and there is no power!

Can you explain the ground wire test? I think the harness is badly grounded causing some noise to the distributor.

Re: Motor runs extremely rich at high rpm
 

are you using all "stock" parts on the B20V? do you have cams or any other upgraded internals?