Hi, I don't post much but I read a lot and check back here ever so often because it's the best Honda tech forum around for info

My problem is this, I installed a Haltech air/fuel meter a few months ago in my EG. I simply spliced the wires into my o2 sensor and it worked fine until I took it out. A day or two after I took it out my car started running like ****, unstable idle and misfiring a lot. I thought it was something to do with my Field vtec controller so I tried turning it off and what do you know the car ran smooth right away. So I figured the vtec controller was causing the problem and just left it off for a while, about two months went by and ever so often I would turn it back on to see if it would still run like **** and it did. So I ended up buying a new Apexi VAFC thinking it would solve the problem and I would be able to adjust my fuel settings again. I installed it with a friend that is an expert at performance Honda’s and other JDM cars he has done many VAFC installs without any problems. All the wires were checked twice, settings were correct and the TPS was calibrated. Started the car and she ran smooth, seemed good drove around the block a couple of times and it was perfect, but a couple minutes after I started adjusted the fuel settings she went back to unstable idle and misfiring. WTF?? I am still getting the same problem as with the old Field vtec controller, unstable idling and misfiring . At this point I was clueless why this is happening and I don’t get any check engine lights, not one. At this point I knew it wasn’t either vtec controllers but something else wrong with the car that only gets affected when I adjusted the fuel settings with the controllers. I was thinking because I spliced the O2 sensor for the Haltech meter that it may have damaged the O2 sensor somehow but for some reason not showing a CEL for it . So I replaced it with a working O2 sensor from a friend’s car and I still get the same problem.

Please help me, any thoughts or possible solutions would be appreciated.

Here is my car setup,
93 EG hatch
OBDI lsvtec motor.
RC saturated 310cc
chipped p28 ecu
94 octane, Sunoco 94


I think thats all the would be needed but let me know if I missed something.

Thanks in advance

 

if your using a fuel pressure regulator check to see what kinda of fuel pressure your getting when you start to adjust the vafc

 

doublejz what should I be looking for? loss of psi or gain of psi??

 

Why don't you just get Hondata? vafc's are good and all, but you can't correct timing with them only fuel. Therefore if you are dropping your vtec ingagment point and raising fuel with the vafc, your engine will go into vtec but your timing will still be on the low cam timing (along with the extra fuel your dumping in, doesn't help the engine run well) until the ecu reachs its stock vtec ingagment point, which then you will be on the high cam timing.

Which is why you should get hondata instead of wasting time and money on a vafc hack, and buying sensors that probably aren't broken, but your just guessing they are (do some troubleshooting, get a mutlimeter and check the sensors before replacing them, especially if you don't have a CEL). Hondata can adjust both low/high cam timing and fuel maps, sensor checks and much more with one easy installation.

Plus if your are going to use your vafc for tuning, why aren't you using a dyno? Its not very partical to try a tune it yourself by just guessing in the driveway or highway or using other people correction points b/c it works with their set up. Even if its the same engine the tuning is different for everyone and ever setup

 

Turboxsi, you made some good points about hondata and I agree but are you trying to help me or flame me and sell me hondata? I havent bought any sensors yet just borowed one and no where in my post do I say I am doing the VAFC hack. All the fuel tuning was tried on a dyno with a wideband but after a couple of minutes of adjusting the fuel the car started to misfire and idle rough so I had to stop the tunning session. As soon as I can get the car running smooth with fuel being adjustable I will be back at the dyno to finish.

Something I fergot to mention but might not matter is that I am only taking fuel away not adding any and the most I would be taking away is 15%.

 

well then you could be running lean, why not just hook up your air/fuel gauge and see where you are. or pull a plug or two and look.

 

Sorry if i made it sound like i was flaming you, i wasn't though. I was just in a hurry and was trying to cover everything my friends have gone through with this same problem

And I'm not trying to sell you hondata either . But i've seen many people go through what your going though with the vafc (and the vafc is a hack no matter how your look at it, think about it your hacking into select wires your wiring harness at the ecu) and they have usually found hondata as a great solution to their problem.

Good luck

 

doublejz, i dont have a air/fuel meter but wehn i was on the dyno a couple of months ago and the car was runing good without any fuel adjustments it was rich accros the whole rpm band. It was at like 11 to 12 on the wideband scale. My plugs are for sure black beacuse when it has rough idling and misfires you can smeel fuel in the air very strongly.