I am asking this question for my friend. He has a ef with a b16a, and the car runs, and idles good up until about 5000 rpm. Anyway at about 5000 the engine starts to sputter, and is hard to rev past 5200, but you still can if you really try. Anyway if he holds the engine in the sputter, he gets a code 43, which is fuel supply system. He has replaced his fuel pump, injectors, fuel filter, fuel rail, and has a fields vtec controller. We have also tryed to switch his ecus, and distributor. By the way he is using a chipped pr4 ecu. Thanks

 

I am getting the same code. I have a PR4 in a 90 civic with B20Z. Before I had a B18B and never had the problem, after a swap to the B20Z the code appeared. All I did was change long blocks. It still uses all the sensoors from the previous motors.

b16a1sirhb- does your buddies tack act irratic when given more than half throttle in gear? How do his plugs look? Mine get fouled from too much fuel.

 

Yeah his plugs get pretty fouled, and yes his tach stumbles around, but his tach stumbles around all the time, and I don't think his tach has ever worked though. Anyway we are pretty sure that we figured out his problem, we think that his timing is off, and he might need a new belt, You might want to check that out as well. Its weird when ecus throw codes that have nothing to do with the problem, but it does happen. Thanks again.

 

Mine turned out to be the IAC connector and ACT connector were swapped. MY ECU threw a code 43(fuel supply), 16(?), and 14(IAC valve). ALl becaus ei had two connectors backwards.

I had a similar problem with stumble and it was one of the wires that conected to the distributor was loose. Inside the big ole connector to the distributor, one of my wires had managed to come loose, never made a full connection when the whole plug was connected together. I didn't notice it until I tugged on the back of each wire and tyhe white one came out. I just simply reconnected it outside the connector.

 

Check your o2 sensor. Alot of times it's the o2 sensor that gives that code.