Could not having the first O2 sensor hooked up cause a car not to start?

[streetsoldier60]

okay I need some help quick and tried to search but didn't really turn up what I wanted. I'm trying to help out a buddy really quick and was wanting to know. Could not having the first O2 sensor hooked up cause a car not to start? I know total NEWB question and I'm pretty sure I already know the answer but want to get some second opinions thanks and please don't hate...just have a headache from working on this car and want some input thanks everyone.

well i would try and hook it up but the car is about 30 mins away across state line haha. I'm just trying to pick some brains real quick to maybe help him tomorrow. see the car wont start but if he puts either in then she starts and can only run on either...so i was just curious if without that first O2 plugged in at all shouldn't it not start because the ECU doesn't know the a/f ratio so it just doesn't pulse the injectors???!? come on pick the brains haha also there are 4 wires cut under the hood like right where the o2 sensor should plug in that's why i thought that. plus there are like 4 wires cut under dash but that is just different story i will have to just go look at it i guess. thanks for some help tho

yea probably the soonest i could get over to the guys house to get pics would be like Tuesday or Wednesday unfortunately but I will try and post back as soon as I can with what we find/ try and fix on this. its a 2g 96 eclipse with a jdm motor and the dumbF***S hacked the wires all up instead of just reading how to put a 6bolt in a 2g. anyways like i said i will try and post back soon. thanks.

 

[steve]

The ECU doesn't use the front O2 sensor until after it warms up so it's unlikely that's the reason for not starting.

Is it safe to assume the car hasn't run since the engine swap?

 

[jrohner]

Yeah, just having the front o2 unplugged, the car would start and run just fine, you'd just possibly lose some gas mileage.

Have you checked to see whether your missing spark or fuel or both? Does it kind of fire or does it not even try at all to start? If there are cut wires around, make sure they are not shorting out.

 

[Defiant]

It'll start, but it won't run well and you will throw a CEL very quickly.

 

[knochgoon24]

I drove my car more than 20 miles with a broken o2 sensor. Eventually my fuel trims were maxed out (rich) and it would barely move, but it would still start and idle.

Why doesn't he just put the o2 sensor in, reset the ECU, and see if it starts?

Is he getting fuel and spark?

 

[streetsoldier60]

okay i just wasnt quite sure on how that all worked. thanks for the input and no I don't think the motor has run since the Swap. the people we got this car from hacked up every wire i think they could find haha. so its just been a brain teaser trying to put everything back together right and get my buddies first dsm on the road. well i'll be going over to IN probably on Wednesday to look the car over at my buddies house and will hopefully have more updates on it after being over there. (also picking up my 1g talon project car) while over there. Again thanks for some insight. its just been a wiring mess. they literally hacked off like every sensor plug i think they could get their hands on. it was sad when i seen this and then like 10 wires on the ecu were cut as well and they put different color wires in there so its just been a mess. at least we got it cranking again now it just needs to fire up and stay running...

 

[streetsoldier60]

I drove my car more than 20 miles with a broken o2 sensor. Eventually my fuel trims were maxed out (rich) and it would barely move, but it would still start and idle.

Why doesn't he just put the o2 sensor in, reset the ECU, and see if it starts?

Is he getting fuel and spark?

He is getting fuel to the fuel rail and has spark its just the injectors are not pulsing. and i think its because like I said they hacked all these wires up and we are down to 4 wires under the hood we have to find. (which they are over by where the o2 sensor would plug in thats why i asked bout that.) but o2 sensor is pluged in so...i didn't know that before i posted he just told me today. also we are down to now only 4 wires under the dash so i think if we can find where these 8 wires go think we should be in business.

 

[jrohner]

The wires for the temp sensor are right by the o2 sensor plugin, I'd check those wires. If the temp sensor going to the ECU is unplugged or bad you won't get fuel. I don't see what any of this would have to do with a 6-bolt swap though, hooking up the 1G CAS to a 2G car doesn't involve wires over where you are talking about.

 

[rush2252]

go read a thread over the 6 bolt swap it should tell you pinouts on the ECU and wiring colors. If the injectors arent pulsing then one half the CAS isnt working. It has a TDS sensor and teh CAM sensor inside. Either bad sensor or my guess bad signal wire check under the hood this is to my knowledge the biggest reason people have issues with the 6bolts not starting.

 

[streetsoldier60]

Okay so kind of bringin this old thread back to life but my buddy and I finally figured out what was killin his JDM 6 bolt swap in his 2g. the guys that had the car before us never had this thing running since the swap. and thats probably a good thing because they had so many hacked wires it wasn't even funny. so we went to the junk yard where we got more cars and we got a new wiring harness and hooked everything up. all leads to ECU were good everything pluged in and still no injection pulse.

we checked the CAS we tried 4 of those and tried 4 different ECU's still with no luck getting injection pulse. then we noticed the ECT, or coolant temp sensor plug was cut also. one wire had been cut se we replaced that on the harness and put a new sensor in and presto! we had injection pulse and the car fired right up. guess what I'm trying to say is if anyone has a crank with not start and they have everything but injection pulse check for CAS, ECU, and the that damn coolant temp sensor. haha we didn't think that would effect injection pulse that bad but i guess we learned something new last night.

hey at least now my buddies first DSM is ALIVE! and sounds great.

 

[lou schmouder]

O2 shouldnt have any reason to cause it not to run