Fuel issue: 92 LX Vortech V1 w/wideband gauge

[MikeR351w]

Hello,

I have a 92 LX 5.0 with an auto trans. About 130k. Mods for engine only are as follows.

Edelbrock Perf RPM II intake
38lb injectors w/80mm mass air meter and 65mm t/b
Anderson FMS intake w/k&n filter
8lb blower pulley
H-Pipe w/no cats
Shorty headers
Engine timing is at 14deg

I just hooked up my wideband Cobalt Autometer gauge and heres the issue. Sometimes when I start up the car the gauge never moves and stays at 14.7. Then when you restart the car, it works fine. So I am wondering if the o2 sensor is stuck or broke. Anyways, on normal driving, it seems to get up to 15.0 and goes down as far as 13.0 on decel. At IDLE, it STAYS at 15.1 and the gauge is maxed out and blinking red at the end of the dial. Again, when driving, and WOT it stays around the 13.0 to 14.8 range. Does this sound normal? The gauge is mounted in the stock location on the drivers side and I currently have both stock o2 sensors disconnected.

Any help would be much appreciated.

Mike

 

[lancec2c30]

So, are you running a fmu or is it tuned?

The cobalt is an actual wideband, with a designated o2 sensor?

So it will get up to 14.8 at wot? Thats pretty lean with forced induction.

 

[90 lx convert]

Ok, why did you disconnect the factory sensors? Mike

 

[MikeR351w]

I got the bar graph to read further by using the menu on the gauge. Now it is capable of going up to 20.0. So now it reads 16.5 at idle and it goes down to 13-14 at WOT. I disconnected them because I never had them with the car. The harness is missing too... When I get the other o2 sensor hooked up, will the car run better? Also, I do have an FMU but I took it off because I got a 255lph fuel pump installed...So I figured that would give me more than enough pressure and fuel...Should I hook it up again?

 

[90 lx convert]

Get a weld in bung and use that for the wide band. Don't attempt to tune the car untill you install the factory 02s. Whatever you do DON'T BEAT ON IT with that A/F ratio. Without the stock 02s the computer has no idea what the A/F is. A bigger pump is not a fix for A/F issues. It provides fuel, that's it, other than that it's dumb. OK, let's start at the beginning. Install the factory 02s, install the wideband 02 in it's own weld in bung, make sure the FMU is calibrated to the injectors you're using and install it according to the instructions. The FMU with the correct disc for the injector you're using will help you get the A/F where it needs to be. They are usually slightly rich so that the A/F is at a safe level. Later you can get it tuned and do away with the FMU if you want. Did you regap the plugs at 35? 14 degrees initial seems a little high. Mike

 

[lancec2c30]

If the o2's are disconnected it will just force the car into open loop. Which forces the computer to rely on the maf transfer.
I wouldn't sweat that too much.
But you still need that fmu connected. Installing a 255 in tank pump won't change your a/f. Because you still have the fuel pressure regulator controlling flow to the injectors.

Set that fmu for your injectors, maybe consider buying a fuel pressure gauge and adjustable regulator to tweak your a/f a little more.

Also, pull the spout on the distributor so its locked out, and set your timing at 20*.

 

[Noobz347]

If the o2's are disconnected it will just force the car into open loop. Which forces the computer to rely on the maf transfer.
I wouldn't sweat that too much.
But you still need that fmu connected. Installing a 255 in tank pump won't change your a/f. Because you still have the fuel pressure regulator controlling flow to the injectors.

Set that fmu for your injectors, maybe consider buying a fuel pressure gauge and adjustable regulator to tweak your a/f a little more.

Also, pull the spout on the distributor so its locked out, and set your timing at 20*.

That's not exactly true. Having the o2s disconnected will force an open loop but it also causes the EEC to revert to fuel table other than what would be the 'normal' fuel tables for open, closed, and WOT. It runs what it thinks would be a reasonably safe fuel table for STOCK SIZED injectors.

To the OP:

I have to assume that the method of tuning you have currently is a meter calibrated for your EEC and 38 lb injectors? That, ontop of an FMU... you're just asking for it.

Your wideband problem description sounds exactly how a 'wideband' meter would respond to a narrow band sensor. That said, what o2 sensor did you hook this meter to? One of the existing OEM sensors? If so... that doesn't make it a wideband. It makes it a light show.

 

[90 lx convert]

That's not exactly true. Having the o2s disconnected will force an open loop but it also causes the EEC to revert to fuel table other than what would be the 'normal' fuel tables for open, closed, and WOT. It runs what it thinks would be a reasonably safe fuel table for STOCK SIZED injectors.

To the OP:

I have to assume that the method of tuning you have currently is a meter calibrated for your EEC and 38 lb injectors? That, ontop of an FMU... you're just asking for it.

Your wideband problem description sounds exactly how a 'wideband' meter would respond to a narrow band sensor. That said, what o2 sensor did you hook this meter to? One of the existing OEM sensors? If so... that doesn't make it a wideband. It makes it a light show.

My point exactly, Ok so it goes open loop, with all stock parts the open loop tables are safe. With this setup maybe not. You know, I missed that reading on the wideband. So, MikeR351w which 02 did you use? Mike

 

[MikeR351w]

Ill try to answer all of the questions. Yes, I did gap my plugs to 35 and got new ones. Also, the Mass Air meter IS calibrated to the injectors. Since I currently dont have any stock o2 sensors, the wideband is hooked up to the autometer gauge. Its a Cobalt wideband. Ill hook up the FMU tomorrow and see if my a/f ratio gets a little richer. I definetely need to get the harness and o2 sensors asap.

My boost gauge is currently reading around 10lbs at WOT. I want to hook up the brown wire to my WOT switch but I dont know which wire to splice into.... Thanks so far!

 

[Noobz347]

Mike...

Do yourself a favor and take that car to a dyno-tuner and get it tuned before parts come flying out the bottom.

Whatever the current setup is on your wideband, IT IS NOT ACCURATE AND YOU CANNOT RELY ON IT. At all, my friend.

I'll bet everyone who's ever turned wrenches for more than a year, on a Mustang, has seen or heard stories about folks that have shredded their long blocks in boosted applications, while trying to, "self tune" with unreliable gear.

Under boost, is not the time to try and figure out whether your air/fuel ratio meter is working or not. Take a step back and get things working the RIGHT WAY before you spend even another second in boost.

 

[90 lx convert]

Mike...

Do yourself a favor and take that car to a dyno-tuner and get it tuned before parts come flying out the bottom.

Whatever the current setup is on your wideband, IT IS NOT ACCURATE AND YOU CANNOT RELY ON IT. At all, my friend.

I'll bet everyone who's ever turned wrenches for more than a year, on a Mustang, has seen or heard stories about folks that have shredded their long blocks in boosted applications, while trying to, "self tune" with unreliable gear.

Under boost, is not the time to try and figure out whether your air/fuel ratio meter is working or not. Take a step back and get things working the RIGHT WAY before you spend even another second in boost.

Yeah what he said. Why are you asking for advice and then not listening? Mike

 

[MikeR351w]

I am listening to the advice. I re-hooked up my FMU and it gave me some better reading with my a/f ratio and I am looking for stock o2 sensors with a harness. Thanks for everyones help