Hondata

S300 v2, Smanager v2.3.2.0, 98 civic, B18b1 turbo stock block, Deatschwerks 750cc injectors, -6an fuel system, Walbro 255lph fuel pump, 55psi fuel pressure, AEM UEGO wideband

I cannot seem to get my idle AFRs better than 11:1. If I lean it out it starts hunting and my AFRs go back and fourth from 10 to 20. If I add fuel the idle settles but it runs very rich. Also part throttle around 10% the AFRs bounce all over the place. Once again adding fuel makes it smoother. These injectors were used previously in a B20 VTEC and idled perfectly around 15:1. They had about 10 hours on them when I bought them. I previously had precision 1000cc injectors in. It was the same situation except it would only idle at 10:1 with the same hesitation around 10% throttle. I have checked for vacuum leaks, cleaned and changed my iacv and wired my injectors direct to the battery (with a relay triggered by ignition) and to the ECU. The car is currently running in open loop. The wideband is hooked up to D10 and I have removed the required resistors. Before the turbo went on the car ran strong with no issues. I've been trying to figure this out for over a month. Any help is greatly appreciated!

Thanks

Hi,
I don't think it's a injector problem.
check this link : http://www.hondata.com/forum/viewtopic. ... 728#p66728

I had the same symptome at 10% throttle (2000RPM), the solution i took is to use another ECU without S300 in my car (EF9 civic with B18 turbo) and the problem disapeared.
Hmm... you would say : "well the ECu with the S300 was causing the pb"
I would answer : "not really because i put the ECU with S300 in a friend's Integra turbo(with the exact same setup : same injector, same cams, same map...) and all was fine

Thanks Bubleguy. I tried a different s300 (V1) and the problem persists. Never thought to try crome so I will give that a shot. I have been told by a very experienced tuner that it could be the ignition module inside the distributor. Im also running NGK 4554 non-resistor spark plugs so I think I will try new resistor type plugs as well.

Still fighting this. I tried a different distributor and ngk resistor plugs. Ran new wires direct from the ECU to the injectors and power direct to the battery. Still having this problem. I smoke tested the system looking for vacuum leaks but everything looked good. I'm back to playing with the injector dead times. Under light acceleration and WOT everything is great, its just cruising and idle that I am having issues with.

Your tune is way off. You need to start from scratch. You have way too much fuel in the lower cells and the numbers are all over the place in each column.

Adding fuel to the lower cells was the only thing I could do to make it idle smoothly. Taking it out made the AFRs bounce all over the place. That being said, turns out my new OBD2a to OBD1 harness was the problem. It has been replaced and my car was tuned by a professional yesterday. Anyways thanks for the input!

Good to hear that you got it figured out.