Help me get my car running right! Exhaust/O2 questions

1slow95

Founding Member
May 16, 2002
1,797
3
48
ohio
Basically I'm sick of the rough idle, bucking, missing, and generally running rough. I'm at the point where I'm thinking of selling my engine and going to to a mild 302 combo. I love racing and having fun with 450rwhp, but that's only about 15% of my driving time in the car...The rest of the time it just pisses me off and I can't wait to get out of it. :mad:

First of all, I need a new battery and I'm going to swap the u/d alternator pulley for stock. I don't think the alt. is putting out enough voltage at idle to charge the battery.

Next, I need to figure out what to do with my exhaust and O2 sensors. My plan was to get the computer retuned to run without O2's, but then I was thinking will the weather affect the tune? A friend of mine did this and he said the car behaved way different in the evenings when it was cool so he needs multiple tunes.

My reason for removing the O2's is we pretty much determined they're mounted too far back to stay heated up. So my question now is, if I get the headers Jett-Hot coated, will that keep enough heat inside the header so the O2's will work properly? My other option would be to go with a shorty or mid length header, which would also solve my ground clearance issue (mostly) and quiet the car down a bit, which I also need to do. Or I could continue with my plan to delete the O2's entirely... :scratch:

Once I get these two problems taken care of, I can post up my results and go from there.

Basically what happened is I tuned the car up with new sensors and stuff then had it dyno tuned. It ran great for a couple weeks then it just went downhill. It developed a surging idle, so I checked the tb stop screw(fox tb) and was all the way out. I adjusted it to where it should be and it idled at about 1400 and would hang at 2k+ when coasting. I got that mostly fixed with an IAC restrictor plate. Then it started missing and bucking, which comes and goes at random.

I think it really just needs a GOOD tune, but I want to make sure I don't have any other problems before I spend a couple hundred $$ on another tune.
 
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like you, i don't want a car that is a pain to be in.

i went with mid length headers for a few reasons:
- the kooks leaked
- they were to low and scraped
- the problem you raised with the O2s

the mid-lengths address all of them. i can also put cats back in which will quiet it done some and make the exhaust not smell so bad.

the accufab part number for the mid length headers is: bt-210

if you do that and get a good tune, i am confident you will be happy with the car again.
 
Mike, good to see you in here. :nice:

Is having Don or Rob tune your car an option? They're out in your neck of the woods (crudely speaking). And I betcha they'd know about the O2 stuff (since you dont have a real conventional set-up).

You're making so much power, personally I'd not give a second thought to de-modding back to where you enjoy the car (the U/D's, headers, etc). I like your plan in that regard..........

Welp, that wasn't any help but atleast it's a bump. Good luck brah.
 
I made this thread about eliminating the O2's several months ago, http://forums.stangnet.com/showthread.php?t=702642. Don chimed in there and the plan was to get the car to him so he could tune it to run in open loop all the time. That's still an option, but I got to thinking there might be better ways to fix my problems.

I'm thinking those Accufab headers sound like my best bet. I hate exhaust leaks, and my car has several. :notnice: Did you get yours installed yet Chris? I'm curious to see how well they fit...
 
Mike

I see you are running Kooks LT's. Where are the O2's installed?

I can share some things I've seen with my Mac LT's :)

First I wanna say I saw several other self tuning peeps say they had issues
with their O2's cooling too much during idle. Some even moved their O2's
to one of the primary tubes and reported that fixed the problem.

I did see a small amount of that but it took a good while for the adaptive
to make enough small changes that things would eventually deteriorate.

I finally went to forced Open Loop at idle only.
After that change ... all was good to go!

I've seen several talk about the slip joints used on Kooks headers leaking.
Seems like that could suck in air and cause the O2's to output a false
reading to the pcm.

Grady
 
Mike

I see you are running Kooks LT's. Where are the O2's installed?

I can share some things I've seen with my Mac LT's :)

First I wanna say I saw several other self tuning peeps say they had issues
with their O2's cooling too much during idle. Some even moved their O2's
to one of the primary tubes and reported that fixed the problem.

I did see a small amount of that but it took a good while for the adaptive
to make enough small changes that things would eventually deteriorate.

I finally went to forced Open Loop at idle only.
After that change ... all was good to go!

I've seen several talk about the slip joints used on Kooks headers leaking.
Seems like that could suck in air and cause the O2's to output a false
reading to the pcm.

Grady


Hey Grady,

What do you have to do in the Tweecer to make it run in Open loop at idle only?
Also want to clarify up one thing about spark tables while I got ya, I know how to cancel the 3 out with all 55's and just use the base spark table but is this the same for foxbodies? (A9L)
I'll be expecting a smilie-filled paragraph :jester:
About the thread I've had alot of bad driveability problems all related to the maf. Try cleaning it, worth a shot....sorry to hijack the thread
Thanks, Sean
 
I'm thinking those Accufab headers sound like my best bet. I hate exhaust leaks, and my car has several. :notnice: Did you get yours installed yet Chris? I'm curious to see how well they fit...
to me, they seem like the perfect compromise. i hope my bubble isn't burst after they are installed

i'm actually dropping the car off today on the way home from work for the headers and the new tranny to be installed tomorrow. i'll take pics of them at lunch today and post them when i am able

i hope to have an answer for you about the fitment by the weekend
 
Hey Grady,

What do you have to do in the Tweecer to make it run in Open loop at idle only?
Also want to clarify up one thing about spark tables while I got ya, I know how to cancel the 3 out with all 55's and just use the base spark table but is this the same for foxbodies? (A9L)

Thanks, Sean

Hey Sean

There are some significant differences between the Fox and 94-95 pcm :Word:

You got an extra spark table or function looking kinda thing that I'm not even
sure what to do about :rlaugh:

I love to help peeps here but my biggest concern in doing so is I might
unintentionally mis-lead someone :(

Having said that I would NOT even send you to my humble little site for a
tuning tip or two as the focus there is on 94-95 stuff :shrug:

however

Jason over on the Fox Tuning Forum is VERY knowledgeable :hail2:
on that flavor of self tuning ;)

He has all the ingredients one would need :banana:
to cook up a delicious go fast Fox feast :nice:

Grady
 
Mike you don't have a tweecer yet right? If not have you ever thought about getting one and trying to self tune? Or you could sell your motor to me cheap and then go back to a 302 hell I'll trade ya lol

Seems to me you need to sweeten the pot a bit to make that trade :D

Hey ... You could offer to put out the fire if his house ever caught on fire ;)

Maybe offer some self tuning tips ... or something :)

I mean ... Mike don't seem to be anybody's huckleberry :nono:

Grady
 
here you go Grady :nice:

http://forums.stangnet.com/showpost.php?p=6908446&postcount=8


My O2's are in my hpipe after my LT's myne don't run cold at idle, And I have stock 302 and heads. Ive always heard the bigger the cubes the hotter it runs.

I think you have a exhuast leak or vaccum leak.

Well I'm thinking I have two problems. I definitely have exhaust leaks at the collector right in front of the O2's. I've tried to fix it several times with slightly better results each time, but I think welding is the only way to fix it for good and I don't want to do that. Second, and this is just a crazy theory I thought of, I'm thinking since my headers aren't coated or wrapped most of the heat is lost before it gets to the O2's.

I know of four possible fixes, but I'm trying to decide which way is the best choice. Right now the mid-length headers look like my best option, they should fix my exhaust leaks, ground clearance, and O2 problems. My other options are to move the O2 to one of the primaries, get the headers coated and hope that fixes it, or tune around the problem.


I'm pretty sure I've cleaned the MAF, but I do know it's picking up some turbulence from the fan. That's on my list of things to fix after I get my exhaust setup straightened out.


Jinx, if I could do it over again I would have went with the tweecer. I've looked into the "pro racers package" for my SCT chip, but I can't find a price on it, and I'm almost afraid to ask. :stick:
And I might consider a trade if you throw in about $6.5k. :D
 
Well I'm thinking I have two problems. I definitely have exhaust leaks at the collector right in front of the O2's. I've tried to fix it several times with slightly better results each time, but I think welding is the only way to fix it for good and I don't want to do that. Second, and this is just a crazy theory I thought of, I'm thinking since my headers aren't coated or wrapped most of the heat is lost before it gets to the O2's.

Mike ... allow me to appeal to more help here :)

Hello ........ OTHER SELF TUNERS

Your opinion please :D

You guys think the exhaust leaks could be hosing things up here for Mike???

Grady
 
You guys think the exhaust leaks could be hosing things up here for Mike???

Grady

Most likely, yes...

Fresh air can get pulled in from an exhaust leak.
Now you have the O2 sensor reading lean from fresh air, regardless of what the real AFR is in the combustion chamber.


I've only glanced over most of this thread, but I'll try to get back in later tonight.
I need longer lunch breaks :(

Mike,
This is the 418w, correct?
Sounds kinda close to what I am trying to finish up right now... :nice:

jason
 
Most likely, yes...

Fresh air can get pulled in from an exhaust leak.
Now you have the O2 sensor reading lean from fresh air, regardless of what the real AFR is in the combustion chamber.


I've only glanced over most of this thread, but I'll try to get back in later tonight.
I need longer lunch breaks :(

jason

Those were my thoughts as well Jason :)

The O2's see more air ... thus ... more air parts to the one part of fuel for a
false lean reading being outputted to the pcm :(

btw ... Good to see you on our side of the tracks my friend :D

For those of you who don't know Jason :scratch:

He is one of those Fox kinda guys who is really sharp with making a Stang
with an A9L fly with a Tweecer :nice:

He helps tons of those Fox boys over on their site :Word:

Grady
 
Grady,
I think you have me confused with another 'Jason'...
:rolleyes:

Hey Grady,

What do you have to do in the Tweecer to make it run in Open loop at idle only?
Do you guys have an RPM Minimum for Adaptive Control???
I never looked into this...


Mike,
I would focus on the exhaust leak for now... especially since your complaints focus on low speed conditions...

Are you getting any diagnostic codes?

Just in case you want to reset the idle speed...
http://www.muscularmustangs.com/idlereset.php


Hope you get it sorted out, your setup sounds like a lot of fun :nice:

Please keep us posted,
jason
 
Thanks for the advice guys! I'm gonna start working on it once the weather warms up a little. :)


Mike stupid questions?

do you have Ford replacement O2 ins? or aftermarket ones?

and how many miles are on them?

They're Bosch replacements from Advance Auto. They had around 500 miles on them when the car started acting up more often.