Maybe someone here can help me out with this one.
I have had the B16a swapped in for about 8 months now and it has been acting up for the last month or so. When I am accelerating under light throttle, the car seems to have a lack of power but when I give it a little more throttle, it runs ok.
When the car is hesitating, my Autometer A/F guage goes into the stoich range but is still in the green (during acceleration). I have all of the orange and all of the green lit up at the same time.
At WOT, the meter reads full rich(just the last green LED is lit up) and life is great. So, at first, I thought I had a bad distributor cap..changed it. Did a MSD 6AL, cap, rotor, plugs, wires..still there.
Changed the fuel filter..still there.
Also, I have noticed that if I am keeping a constant speed, then give it a little bit of gas, my A/F guage quickly goes to lean before it jumps to rich...
The only things I haven't changed or checked yet are the injectors, pump, regulator...
I will be keeping a close eye on this post so please if you have any questions on what I have changed or checked feel free to ask...just please help me figure this one out!
Thanks
Jay

 

it could be so many things. hopefully other people will add there opinions, but from my experience on something similar the car could have one of these problems. A bad MAP sensor, The distributor itself is bad (happens on 1st gen b16's a lot. Your problem should not be fuel related, if under full throtle it is ok. it is very....and i say very rare that something goes wrong on a fuel system on a honda, whether it be the injector or regulator, etc... maybe a fuel pump can go bad, but not like the way you say things are happening. Most likely it is the MAP though.

 

Are you running a 1st gen b16a with the 2 o2 sensor setup? If so this is probably where you problem is. When I firs had my swap done 4 years ago my car used to do the same thing and no matter how many shops I took it to no one could fix the studdering. It only happens at partial throttle and never at wot. Well the whole time it turned out to be my o2 sensors on thir way out.

 

Yeah I knmow what you are sayin' about the fuel system, but I don't know where else to turn...
About the o2 sensor..yes I have the pr3 ECU which requires 2 seperate o2 sensors but when I was doing the swap I was told by someone who had the already done the same swap only to use 1 o2 sensor and splice it into both inputs on the ECU. Everything worked good.
I thought it was the original o2 sensor which was on it's way out, so i changed it for a NTK 4 wire sensor (i didn't hook up the heater, just the signal wire and the ground). However even after I changed the o2 sensor, the problem was still there.

 

This happens so often here is my standard reply text:

With the early VTEC engines there are two oxygen sensors. A common problem is to wire one oxygen sensor into both pins in the ECU, or reverse the wiring of the primary and secondary oxygen sensors. In both cases the car will run badly under light throttle until sufficient load is placed on the engine for it to run out of closed loop.

The ECU uses each oxygen sensor to tune the mixture in one pair of cylinders. Normally the ECU will slowly lean the mixture for one cylinder pair, and look for the oxygen sensor showing the mixture going lean. Once this happens the ECU will start to richen the mixture until the oxygen sensor shows a rich mixture. The effect of this is to swing the mixture over a narrow range close to stoichiometric, typically lambda 0.98 to 1.02, which keeps the mixture close to the ideal range for the catalytic converter. The ECU will tune each cylinder pair, possibly out of synch.

If the oxygen sensor wires are swapped around then the ECU will still try to see a response from each cylinder pair. The ECU will start to lean out one cylinder pair, but will look at the oxygen sensor for the other cylinder pair, so will keep leaning the mixture out. The ECU will see that the other cylinder pair is lean, so will richen the mixture for that cylinder pair. The effect usually is that the ECU will run one cylinder pair about 20% lean, and the other 20% rich. The result is that the engine will run flat, without much response and may miss badly. A lambda sensor placing in the exhaust after the secondary pipes join will show that the mixture is roughly correct. Once the load on the engine is increased to a point where the ECU will stop running in closed loop then the engine will run much better, but will still run one cylinder pair lean and the other rich thanks to the long term closed loop adjustment.

Wiring one oxygen sensor into the two ECU pins will produce a similar problem, except the ECU will alternate between running each cylinder pair rich and lean.

The problem can be diagnosed by unplugging the oxygen sensors completely, and resetting the ECU by removing the power in order to clear the long term closed loop mixture adjustments. The ECU will show an oxygen sensor error code but the engine should run much better.

The problem can be fixed by swapping the oxygen sensor wires around (in the case of two oxygen sensors), or by not running any oxygen sensors at all. It is possible to make a ROM for the ECU which allows it to run permanently in open loop without errors.

Derek.

 

this is the EXACT problem i have been having, i replaced my fuel filter and pump, and have run fuel injector cleaner also. Everything in this thread sounds exactly like what im going through, Doug, i emailed you my question to see what you thought about my problem. Thanks

 

Same problem here too.

 

i just called my local shop and the moron answered the phone and i couldnt get through to him that ONE of my o2 sensors isnt spliced in the ecu. So i dont know what to do, i guess ill just have to take the other route and unplug both sensors and run without any and reset the ecu ? i dunno, im getting pissed now

 

You're definitely going to throw a code with no O2 sensors plugged in. That means 6500 redline and no VTEC.

 

Well, here is part 2.
I removed the NTK sensor I bought and replaced it with the stock one wire sensor from Honda...huge difference. The car doesn't hesitate as much and accelerates much smoother.
Hondata is right about the 2 o2 sensor thing though. I will try to find a shop around here that can weld new o2 sensor bungs onto my DC header and I will try both o2 sensors in the header.
I will keep everybody posted and let you know whats up.
Jay



[Modified by CanuckCRX, 6:53 AM 7/11/2001]

 

Exact same problem here as well! Got worse when I piggy-backed both oxygen sensor wires into 1 for my JDM header. Although I respect the theories and inputs from Hondata, I'm not sure about removing both o2 sensors.... seems dodgy.

Canuck, how much did the Honda oxygen sensor set you back?


[Modified by Lyonel, 11:30 AM 7/11/2001]

 

Here in Canada they are around 200.00 CAN (130.00 US) from Honda. I know that is a lot more than a universal but TRUST ME there is a difference.
Save your 30.00 for the Bosch and spend the extra for the stock Honda o2 sensor.
Jay

 

Unplugging the o2 sensors will give a check engine light but will not affect the rev limit.

Which sounds better? Using fuel tables for the engine which have been made as a result of a lot of tuning by Honda engineers, or allowing a sensor which can only read a very limited lambda range, responds slowly, varies it's output with temperature, has so much hystersis that it can't settle on one value to fiddle with your mixture? I think open loop is less dodgy than closed loop. Closed loop only works well if the fuel tables are well tuned to the engine so that the mixture does not need to be varied too far from the standard fuel tables.

Derek.

 

what is closed and open loop?

 

i unplugged the only o2 sensor that was hooked up and ran it after resetting the ecu by pulling the negative on the battery and its faster now, i can tell. We will see how bad my mpg is now . Oh well im happy for now

 

It's faster you say? Hmmm... mine feels the same. Did you throw a CEL and code?

Odd thing is, I have no ECU codes given and the Autometer gauge still reads 1V. Still trying to figure that one out...

 

i've read the post like 3 times i sorta confused maybe its kuz its late but neways
so if you do switch the o2 sensor wires as in putting sensor a wires on sensor b and vice versa that should correct the problem? assuming both sensors are functioning correctly im just building up info for the day i swap if it comes

help the village idiot
thanks!

 

its running richer and up top it pulls easier and harder... i filled the tank too and it was still being out

 

Heya,

Heck, hook it up the way Honda originally intended the first way around. This gives you the greatest amount of tweakability in the event that it doesn't work out right. The 'fix' that Hondata suggested (and elusiveracing23 and I have now verified works wonderfully) is simply to unplug BOTH oxygen sensors from the harness. That means the computer is now receiving information from neither the primary, nor the secondary O2 sensors, but instead is using the premapped fuel and ignition tables instead of calculating its own on the fly.

HTH .