tjwashow

iTrader: (2)

Ok so i am trying to get a dyno tune but i cant. i know this has been covered i have already replaced the extensions and both o2 sensors. Accordgin to speed inc who is helping me tune it they can not find a signal to the o2 sesnors. i am trying to find a fix for this, a replacement harness, a fuse something that isnt going to take alot of time to sit and diagnose a wire if i can just buy a new harness for 30$. I have long tube headers that currently have an exhaust leak that may be causing them not to heat up? i dont have a problem just getting a mail tune for the time being if that will even work with this o2 sensor issue.

But the car does not have a check engine light for the o2 sensor and it does not run that poorly before or after my cam swap. i am getting a tune because i just did a cam swap. tr224 114. but anyway it does not run bad it never did run bad. this is why it is confusing.

edit; i should mention that the o2 sensors were not plugged in when i bought the car. i found this out when i tried to get a bolt on tune through speed inc and they said my o2 sensors are bad. but i looked under there and found they werent even plugged in, so i bought extensions and plugged them in thinking that this would solve the problem. but it didnt.

Exidous

iTrader: (11)

Your DTC's may be disabled from the previous owner.

James@ShorTuning

I don't personally require o2's be working to do a tune on a car. Even if they do work I turn them off when I calibrate tunes for cars. If they don't work I give the customer two options, I can leave them off and run open loop or I can replace or solve the wiring issue.

I personally like keeping o2's when I can because it allows evap purge to operate which in itself helps fuel mileage by burning fuel vapor.

tjwashow

iTrader: (2)

Wouldn't speed inc be able to tell if it was switched off?

tjwashow

iTrader: (2)

Why wouldn't they just tune it in open loop then? Would I be better off just getting a mail tune for the time being?

James@ShorTuning

That's what I was asking... The o2's aren't a huge issue to tune a car and can always easily be turned back on once the wiring/o2 issue is fixed. Are u sure that's all that was wrong? I couldn't see a reputable shop pushing away a tune due to an o2 sensor or wiring problem...

tjwashow

iTrader: (2)

Yea man that's what they told me. I was shocked and pissed I drive up there to not get a tune and spend 100 bucks on new 02 sensors to not have them worm or fix anything. I have a friend with hp tuners I may be calling to see if he can do anything, but I really wanted to get this on a dyno an tune it right. I can't believe they turn away a paying customer either to tune it but something is just not giving me a good feeling about them.

Edit: I should say that I am not trying to bash anyone here. There ha got to be a way to go around this.

jimmyblue

iTrader: (11)

You could go to full time open loop and tune on that
basis (legal matters aside).

Check the ENG SEN fuse before you start swapping
parts. You can use a DMM to determine whether the
sensors are alive. Stuck at 450mV steady is a fault
response, you'd see it jump around at idle if they
are working.

minytrker

iTrader: (13)

I check the fuel trims when Im done, main reason I prefer them to have working O2's.

tjwashow

iTrader: (2)

so is it necessary to have them working for a tune? i really just want to get everything sorted out.

James@ShorTuning

It is necessary to have them if you intend on running closed loop. However the tune itself can be done without them and run in open loop. Once that is done you only need to turn closed loop on with working o2's and verify the o2's switch at the right voltage and delay to achieve stoich on a wideband.

minytrker

iTrader: (13)

It can be tuned without any O2 sensors BUT IMO to tune it correctly you need everything working mechanically and electrically including O2 sensors. Your car has no reason to be left in OL (open loop) its basically just a carbureted engine with fuel injectors at that point. OL defiantly has its place but not on a daily driver street car.

tjwashow

iTrader: (2)

yea i am using brand new denso sensors so they should work but for some reason the PCM isnt reading them. I am not sure if they are switched off with a tune, or if they are just cut somewhere, I am going by straightline performnce to see if they can find out for me. Speed inc didnt really tell me a whole lot. maybe i can find out some more info wednesday with straightline as to why the sensors are not being read by my pcm.

tjwashow

iTrader: (2)

but wouldnt my car technically be in open loop with my o2 sensors not being read anyway?

Slowhawk

iTrader: (12)

Back in the day tuners use to cut the purple wire in the 02 harnesses to keep the cars in open loop.
Check the wiring.

MUSTANGBRKR02

iTrader: (91)

Some tuners will not tune a car unless everything is working.

tjwashow

iTrader: (2)

i will check this today? so check to wire off the pcm?

gagliano7

I would think the wire would be cut by the 02 sensor.You could do a continuity test oneach wire from 02 sensor to pcm.Disconnect battery.Disconnect wiring harness from pcm and test continuity.Here is a wiring diagram i found for your car. http://www.chevythunder.com/199798_ls1_pcm_pinouts.htm

qqwqeqwrqwqtq

If we're talking daily driver where gas mileage is a concern then generally I will tune them in closed loop so yes, I require the o2 sensors to be working in order to do that.

o2's are new, extensions were replaced, eng sensor fuse was checked of course (and maf works so it wouldn't be that).

It comes down to a problem with the wiring somewhere as the o2's are locked at 450mv.

Can it be tuned open loop? Yes, but there is really no reason that everything shouldn't be working correctly on a car like this.

We offered to work on the car but of course this would take diagnosis and repair time. How that's unreasonable I don't know????

tjwashow

iTrader: (2)

for sure it is i gotta figure out the wiring issue, you guys were more than helpful and i have nothing bad to say at all. i will be diagnosing this wiring issue at some point here.