HEre's my deal. I have recently sold my T/S and installed my VAFC II but I have not yet tuned it, it will be tuned tomorrow.
Before I switched out the ECU's, didnt have any probelms (codes)with the car... it was running good.
Now that its running off of the stock computer, its throwing out code 0701, which is multiple cylinder misfire... The car feels fine though.. on occasion, it gets a rough idle. But it does not hesitate on acceleration. I'm assuming its because of the stock map its trying to feed onto the 3.5. I have stopped driving it because i'm afraid of messing it up.

Have any of you 3.5swappers experianced this with the stock ECU untuned??

Another thing I was wondering... have any of you tried the HKS twin igniton system on your Maximas or know anything about it?? Is it really worth the $350+?

 

No no one has 0701 codes because of a swap and no one has tried the HKS ignition on a maxima to my knowledge

 

So how is that the car was fine with the T/S ECU but is now misfiring with the stock ECU. The only changes are the Fuel and ignition map. When I first switched it, it was reading cylinder 2 misfire and then I erased it; and now multiple misfire.
The stock ECU was working fine when I switched it out.. and its been sitting in a safe spot ever since.

 

First thing I would check is pull off the ECU harness and verify that all of the pins are undamaged/ loose.

I know a guy that had a 97 with the HKS Ignition. He was running it all motor. Pretty much from what he told me all it did was improved response and much smoother revs. But I think the ones that could really take advantage of this is boosted or sprayed folks, since they are the ones that have to worry about a weak spark or the spark blowing out, so gotta close up the gap, etc... For an NA application we really dont have problems with our ignition

 

Could the reason be that there is to much fuel being thrown that its not allowing the spark to ignite?

Its just strange cuz I plugged in the stock ECU back on Sunday, and it wasnt showing any codes until a couple days ago. I did notice that the car is smelling a lot like gas when its left idling. I gotta take care of this today or I might have to cancel the tuning session tomorrow

 

So with the stock ecu it is still throwing the same code? I don't see why you would be getting too much fuel

 

This is real wierd.. it sucks cuz i'm at work right now so I cant check the problem right now. I just went home for lunch and resetted the VAFC as well as the computer, started it up again, and the car started up and idled okay... still smells like fumes though.

 

untuned and stock ecu, no problems


make sure the ecu screw it in its right location.

fuel fumes?

 

I'll have to unplug it and plug it back in.... So I read the fsm on troubleshooting the problem and one of the things that came up was a bad front O2 sensor, which is what I have. The right bank has been reading bad since I did the swap, which I know I have been needing to replace it. Now, I'm thinking the reason why i'm actually getting the code for multiple misfires may be because a combination of the crappy timing that we get with the vq30 ECU and the VQ35 and the bad O2 sensor. I didnt get a chance to check the O2 sensor today, but it has been reading code 0503 since the swap.

 

This thing is mind boggling!
I got up early this morning to check the car beore taking it to get tuned. Without resetting the code 0701, I turned the car on and it hesitated a little because I dont have the IACV hooked up + it had a very small rough idle.. I let it warm up for about 5-10 minutes... I got my s***hascope and heard every injector and every coilpack and they seem to be working(pulses were sounding normal). The VAFC was reading correctly (rpms and throttle position).

I turned the car off, resetted the computer, turned the car back on and it started up no problem. The car's idle was very smooth and maintained constant at around 7-8rpms. I let it sit idling for about 3-5 minutes. With the car idling smooth and constant, I'm assuming the spark plugs and coilpacks are not the problem, because if they were, the rough idle would have occurred right at start up.

After that, I turned off the car, started it up again, and the car started up but within a matter of 3-5 seconds, the car died out and right before the car died out, the check engine light turned on. I checked the code and it read 0701 multiple cylinder misfire.

I then resetted the codes again, disconnected the ECU harness, checked all the pins to make sure non of them were disconnected and/or damaged, checked all the wires from the VAFC and everything looked good. I Plugged the ECU harness back in and did the same routine(started up the car and let it idle for about 5-7 minutes). No check engine lights(other than my back O2 sensor) The car was idling smooth, constant idling 7-8. I decided to take it out for a drive it was running smooth. The thing I did notice is that the VAFC is not reading the throttle anymore.
I got home, unplugged the ECU harness and plugged it back in but it still didnt read it.

The same thing happened earlier in the week. The VAFC was not reading the thottle and the multiple misfire code wasnt showing. All I did was disconnect the TPS, the ECU harness, plugged everything back in and it read. Could the TPS be the problem??