Long-Tube headers. Can the 02's read properly WITHOUT aftermarket computer?

Pokageek · Oct 6, 2009

Hi All,

My issue: I have a hesitation at 2400 rpm that simply wont go away completely. It happened ever since I added 42# injectors and LT's (at same time). Originally I had an sct chip that programmed the car from 0-6000 RPM. It still didnt get the hesitation out. I dont know why.

With my current set up, my PMS kicks in at 4KRPM and up with manual tuning below that(0-4000RPM. I leave the shop and the car runs INCREDIBLE! Then 3 days later it seems like the computer adjusts and hesitation again.

From all my research this screams "02 issue" as they are now distanced much further from their original factory location. My options as I see them:

1. Go mid-length header. Sell LT's and dont buy computer upgrade. I pay$ for new headers, midpipe and removal and install, tune...
2. Keep LT's and get PMS upgrade that kicks in a 2kRPM and not just 4kRPM. I pay for upgrading the computer, have it tuned.

My main concern is that - whatever tuner I take it to - I am giving him the right tools so that he can do the job AND that I can stop hemorrhaging $$ and trying to do the impossible!

If I pick number 2, WILL it get the car to run right considering the sct chip never got me there? Are the 02's simply too far away from the original location, no matter what I do? OTHER people have LT's on these cars! WHY CANT I!!!??

HISSIN50 · Oct 7, 2009

Why do you think it's the O2s, considering it's in the relatively high RPM's that you see the issue (it's not like you need for force an OL idle because of the O2's)?

I guess I would just suggest that if you cannot datalog or see PIDs, just don't get tunnel vision with the O2's.

The tuners have not had any ideas as to what's going on?

GTA_V6_Mustang · Oct 7, 2009

HISSIN50 said:
Why do you think it's the O2s, considering it's in the relatively high RPM's that you see the issue (it's not like you need for force an OL idle because of the O2's)?

I guess I would just suggest that if you cannot datalog or see PIDs, just don't get tunnel vision with the O2's.

The tuners have not had any ideas as to what's going on?

I agree with hissin. Usually long tubes cause issues at idle because the o2's are moved further down stream but after that its fine. HAve you tried doing a hard reset of your PCM and seeing if its really after the PCM starts adjusting adaptives that the problem starts? I have long tubes and see no issues

nmcgrawj · Oct 7, 2009

Yea the long tube issue, like the guys above have said, is at idle because the o2 sensors cool off. But if you are giving it gas then they should be heating up. Hesitation at what rpm's? Do you have a wideband?

Have you spent time at stangtuning? There are some guys over there that really know the PMS....when i had mine they helped me out a ton. On a 302 and a 351, i never had a problem tuning with long tubes. And that was with the old generation PMS with the black keypad.

But i do have to ask, if you are taking the car to someone else to tune, why did you buy a PMS? Are you using any of its built in features? I just dont see why you would spend the money on a "self tuner" to have someone else tune it. Unless you are taking it to them for the wideband access....which again, would be cheaper to just buy a wideband yourself. The PMS's biggest advantage to me is how easy it is to use, and its built in features. But if you arent taking advantage of either of those 2 things.....why get it?

revhead347 · Oct 7, 2009

I've never seen any issues with a car after putting longtubes on it. I seriously doubt putting mid length's on the car is going to make any difference at all.

Kurt

Pokageek · Oct 7, 2009

Ok. Thanks guys.

1. Reset ->Yes I have unplugged the puter and it seems to be fine and then learn or something and go downhill after 2 or 3 days or runs.. But I cant confirm that for sure isn't the 42# inj with stock tune until 4kRPM, killing my spark plugs. Even tho I reset the puter..the car still gets a little funny and never quite gets right again.
2. Hissin, are u saying 02's do not effect the car at 2400RPM? The is an honest question because I simply am not sure.

nmcgrawj · Oct 7, 2009

Pokageek said:
Ok. Thanks guys.

1. Reset ->Yes I have unplugged the puter and it seems to be fine and then learn or something and go downhill after 2 or 3 days or runs.. But I cant confirm that for sure isn't the 42# inj with stock tune until 4kRPM, killing my spark plugs. Even tho I reset the puter..the car still gets a little funny and never quite gets right again.
2. Hissin, are u saying 02's do not effect the car at 2400RPM? The is an honest question because I simply am not sure.

It depends what "mode" the computer is in on whether or not the o2's readings affects how the car runs.

The bottom line is the problem with long tubes and o2's never was anything while u are driving or giving it any gas.....it was while you are idling sitting at a light and the car will "load up" and maybe stall. This is because the o2's would cool off since they are further from the engine than the computer expects (which this value can be changed with a tweecer/moates/chip).

So at 2400rpms im gonna say that long tubes and o2's are not your problem.

Do you know how to tune using the PMS? Do you have a wideband? Its so easy to adjust things while you drive that you could probably easily solve your hesitation issue or whatever is happening. Have you played with the timing in those cells?

I even tuned a 302 to run smoothly with 42s using my PMS....so i KNOW you can get your big stroker tuned just fine with 42s. You(or your tuner) just have to know how to do it.

Go over to stangtuning and check out the PMS section....its so easy man. You can fix it!

Edit: If you describe your problem in detail then you can get some easy ideas on how to adjust the PMS. For instance, when one of my combinations was hesitating at part throttle cruise, gary over on stangtuning said hesitation is either from (trying to remember now, i've been out of the game for 2-3 years) too much fuel or not enough timing (im pretty sure double check though). So while i was driving i would make tiny changes in the timing to see if it worked. If not, i'd try adding/taking out fuel. I fixed the problem in less than 5 minutes. And even if you dont have a wideband, as long as you make small changes, you arent going to hurt anything since you are n/a. The PMS tells you all you need to know....you know what rpm it happens at, you know what load the PMS is using for its tables...so just try small changes....

Grn92LX · Oct 7, 2009

Since you have a PMS, just look at the screen when the issue occurs and see what the o2's are actually doing. Are they switching like normal or sitting at 0? If they're sitting at 0, its the typical longtube header issue and the result is a lean condition. Try adding fuel in that range in low/med load.

Pokageek · Oct 7, 2009

Grn92LX said:
Since you have a PMS, just look at the screen when the issue occurs and see what the o2's are actually doing. Are they switching like normal or sitting at 0? If they're sitting at 0, its the typical longtube header issue and the result is a lean condition. Try adding fuel in that range in low/med load.

Thanks man. I am not sure I have that option as it only works at 4k RPM and up. I will check. Hey you sold the 347!? I thought you'd keep it forever.

nmcgrawj · Oct 7, 2009

Pokageek said:
Thanks man. I am not sure I have that option as it only works at 4k RPM and up. I will check. Hey you sold the 347!? I thought you'd keep it forever.

No you are referring to the standalone part of things....Mike is referring to the screen that gives the readings out constantly...like timing, o2's, etc etc etc. Do you have the manual for the PMS? If not go to their site and open it up...then you'll understand more.

And that goes with what it old you before...its in the tune. Not the function of o2's with long tubes. A wideband would make it pretty simple also....if it is a fuel issue. It could be timing!

nmcgrawj · Oct 7, 2009

page 10 from the manual....

You're welcome

final5-0 · Oct 7, 2009

I know nuthin about PMS
Well
PMS with a tuning device ... that is

I almost got sidetracked before I even got started

Just thinkin out loud with ya here Keith

Just like the other members have said
Don't see how the O2's would be cooling off at that high of a rpm

Sure ... O2's can cool off at idle with LT's

Many have seen it happen and that includes me
but
Many who have run LT's have not had issues

So ... I know it ain't all that precise
but
Real world results say ... Some do AND Some don't

Just a Wild Azz Guess or two here

Maybe the hesitation is the CL/OL transition

Also ... You'd think it would be fuel related since it happened after
the big inj's were added

If ya can't tune at that low of an rpm ..........

Maybe ... You might wanna make sure you don't have the fuel pressure
jacked up too high

Grady

Pokageek · Oct 7, 2009

Ok. With this added knowledge, I'll let my "peeps" know and see if we can get somewhere. Thanks everybody.

1slow95 · Oct 7, 2009

You can try disconnecting the O2's. My car seemed to run better when I did that. Just a warning, if you unplug the O2's and leave them installed in the exhaust they'll be about worthless when you plug them back in.

revhead347 · Oct 7, 2009

Low-5.0 said:
You can try disconnecting the O2's. My car seemed to run better when I did that. Just a warning, if you unplug the O2's and leave them installed in the exhaust they'll be about worthless when you plug them back in.

Hit them with a torch, and they seem to come back alive. Unplugging the O2s is an old trick, I haven't heard of anyone doing that in years.

Kurt

nmcgrawj · Oct 8, 2009

final5-0 said:
Just a Wild Azz Guess or two here

Maybe the hesitation is the CL/OL transition

Also ... You'd think it would be fuel related since it happened after
the big inj's were added

If ya can't tune at that low of an rpm ..........

Maybe ... You might wanna make sure you don't have the fuel pressure
jacked up too high

Grady

Just to be clear, the PMS CAN tune the entire RPM band from Idle to Redline. The standalone feature is something that does not use the stock computer at all....but the PMS still has tables that adjust the stock computers settings. Yes, the PMS, depending on your version, only adjusts at certain RPM intervals.....but it still "connects the dots" inbetween. Depending on your software and hardware, those intervals vary. Still, at the end of the day you can tune it just as well as any other tuning device. Find the problem in the RPM band. Find the load it happens under. Analyze, or just experiment, with timing and fuel, the problem will go away.

Also, are you paying to have this looked at again? I dont know what kind of deal you have with you tuner, if its free then thats all good. If not (or even if it is free) i would say to pick up a wideband o2.....that way if the problem "comes back" its easier to tell if its fuel. But like i told u before, since you are n/a, u can make small percentage adjustments to see if the problem gets better or worse. Keyword being SMALL. A couple percent at a time...

revhead347 said:
Hit them with a torch, and they seem to come back alive. Unplugging the O2s is an old trick, I haven't heard of anyone doing that in years.

Kurt

PMS guys do that but only when u have the software to tune with just standalone. When using the stock computer and standalone...you need the feedback from the o2's.....

I think lol I havent looked into it, does disconnecting the o2's force open loop or closed loop? Then u tune based off that prior to standalone kickin in? I dunno, but i dont think u have to go to this extreme yet....

revhead347 · Oct 8, 2009

No, way back in the day, Mustang Folk used to unplug the O2s and drive around with a check engine light on. Suposedly it made the car faster.

Kurt

nmcgrawj · Oct 8, 2009

revhead347 said:
No, way back in the day, Mustang Folk used to unplug the O2s and drive around with a check engine light on. Suposedly it made the car faster.

Kurt

I wasnt trying to correct u

revhead347 · Oct 8, 2009

nmcgrawj said:
I wasnt trying to correct u

I know, I was just talking about a different circumstance. I don't know anything about computer tuning anyway.

Kurt

Stanger007 · Oct 10, 2009

If you have a tuner around you that can datalog and has a loaded dyno I would duplicate the issue on the dyno and see what is going on.

Reading your symptoms it sounds like a problem in how the vehicle is tuned for the injectors. I would not think it is O2s. Likely just poor a calibration.

Wes

Long-Tube headers. Can the 02's read properly WITHOUT aftermarket computer?

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