What happens if one were to just unplug there front (and rear) o2 sensor besides a check engine light and the car not adjusting itself?

Can't you then use your wideband to adjust your SFMU correctly, and not have the ECU changing anything?

Umm, the ecu needs the to see the 02 mixture. It will run like shit, and eventually die without the front o2 sensor.

Could you not trick the ECU into thinking the throttle position & engine temperature are always within the range the ECU expects for open loop operation (I think its 95% throttle and normal operating temp? not entirely sure)? The only problem with that is that your car will run madly rich until full throttle since our cars only have a few fuel trim values as opposed to the 100+ standalones have. I don't think this is a good idea...
Why not just ditch your SFMU and run a Megasquirt, wickedESI? the rest of your setup is kickass, almost wasted on a stock ECU powered car... with a MS you could take it to even greater heights.

edit: one quick question, what was your ET when you ran 101mph on your stock bottem end?

yeah, but it'll idle like shit.

Originally posted by jsupetran
Umm, the ecu needs the to see the 02 mixture. It will run like shit, and eventually die without the front o2 sensor.

Why?

On our (Auburn's) Formula car we tune a fuel map with the wb02 in then take it out. A built CBR600 race motor sounds sick as hell idling by itself at 450 rpm.

Originally posted by BumpinTalon
Why not just ditch your SFMU and run a Megasquirt, wickedESI? the rest of your setup is kickass, almost wasted on a stock ECU powered car... with a MS you could take it to even greater heights. edit: one quick question, what was your ET when you ran 101mph on your stock bottem end?

14.8 with a 2.5 60' lol! (outside temp was 103*) If I can't figure out why my car isn't starting and come down to the option of having to buy a ECU from the satan just to see if that's the problem I may try to megasquirt it in the parking lot of my college apt with minimal tools.

How did you run 101mph on stock bottom end? Have you done alot of weight reduction? How much boost was that? I can't seem to make it past 100mph with 14 psi on built bottom end at close to 12:1 AFR. My best time was 14.437 @ 99.46 with a 2.495 60', and my best trap speed to date is 99.77mph. I can't keep the wheels on the ground through first and 2nd, they break loose in high rpm. I can get 2.2 60' but it isn't easy.

Originally posted by sike
How did you run 101mph on stock bottom end? Have you done alot of weight reduction? How much boost was that? I can't seem to make it past 100mph with 14 psi on built bottom end at close to 12:1 AFR. My best time was 14.437 @ 99.46 with a 2.495 60', and my best trap speed to date is 99.77mph. I can't keep the wheels on the ground through first and 2nd, they break loose in high rpm. I can get 2.2 60' but it isn't easy.

You my friend need an LSD! Its a great add-on for high boosting :)

Originally posted by sike
How did you run 101mph on stock bottom end? Have you done alot of weight reduction? How much boost was that? I can't seem to make it past 100mph with 14 psi on built bottom end at close to 12:1 AFR.

Something's wrong then... You should be seeing traps somewhere between 105 and 110 MPH. Are you running a T25? How's your ignition timing? If it's pulled back really far like to 15 degrees then it will be slow as hell.

Sike and I talked on AIM.

Yeah something I forgot to mention was that my timing was being pulled to around 14* before I unplugged the knock sensor, due to either a bad sensor, or it picking up one of the many rattles on my car (solid mounts/busings...everywhere). So, before I went to the track, I tested no knock sensor, and my timing went back to normal, and never was there any detonation.

Sike, I'd check your compression, what ratio are your pistons? You might just need to run more boost if your low comp. I was running 10 lbs of boost at the dragstrip with 190 compression across the board. It was also 103*F out so I would have even a faster time in more normal conditions.

Yeah, from what I've always heard around 2GNT is that on a healthy 8.8:1 motor you should trap exactly what Nathan said at that boost.

Something to note though, is you still had a .4s faster ET than me, with just a *slightly* faster 60'. My traction problems are insane without being able to part throttle boost, and the boost threshold at 2200 rpm. I'm trying to figure this out... what would cause you to have a 14.4 @ 99 and me a 14.8 @ 101.5 with practically the same 60'. Maybe it is just those heavy ass wheels holding back your top end.

ot but i ran a 13.9 on my stock bottom and shitty wheels.at 8 psi intercooled.

I made this device a while back, search for the thread... It was sort of a crude AFC for the TPS sensor. This thing used a voltage comparator and a relay so when the MAP sensor voltage went over a certain limit that the user sets it would trip the relay, and send the TPS wires over to a pre-set resistor, fooling the thing that it had full throttle. It worked great, but there was something wrong with my resistors (R1 and R2 in the schematic below) so that the ECU was seeing 5.0 volts for the TPS line and not 3.8 which is WOT. I sort of gave up with it and never got around to completely fixing it.

An awesome product would be an all-in-one solution to fuel cut and the open loop issue for those using the stock ECU - a much larger market than those using MS's and other standalones... I've never really gotten around to making a prototype, though. Here's a schematic I've always wanted to build:



The circuit in the top left is the FCD. I lifted the schematic from the fwdmopar site. The bottom left has the power supply and to the right of it is the variable resistor which sets at what point the comparator's output gets enabled, or the point at which the relay gets tripped in relation to whatever the stock MAP is doing. The transistor is an amplifier to flow current for the relay. The 10k resistor is a pull-down for the output of the comparator and the 2.0k resistor is to limit the flow of current to the amplifying transistor.

The relay's normally open pins act as a pass through for the TPS sensor. When the relay is energized the TPS wires from the ECU now are only connected to 2 resistors, which simulates a TPS at WOT.

I just realized that I screwed up in the schematic. I could change it and upload the picture again but I am too lazy. Next to R1 and R2 are a +5 feed and a ground. These should not be there...

I just realized another thing... In order to minimize the amount of wires to splice, the schematic could be altered so that only the TPS output is passed through. However, the +5 and the GND next to R1 and R2 would now be needed, and this device would have to share a ground with the TPS ground wire.