This is topic Check engine light post o/r h-pipe in forum Tech Talk at Northern California Ford Owners  .


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Posted by jsmaze (Member # 617) on :
 
I have recently installed a BBK o/r h-pipe on my 88 5.0. Just this morning my check engine light came on and Im curious if anyone has had any similar experiences?
The O2 sensors are installed, but since there are no longer any catalytic converters before the O2 sensors, could they be malfunctioning/damaged?

I didnt see any other design changes to the exhaust setup that would cause a check engine light...hopefully its not something else with the motor.

Also, is there a way I can diagnose the problem using the check engine codes? Im a bit unfamiliar with the procedure.

Thanks a ton!
Jeff
 

Posted by TORQUEPIMP (Member # 386) on :
 
did you put o2 sensors in all the way or touch the heads.. i am pretty sure that does make a difference. the change in the exhaust content might cause a check engine light..

[ February 07, 2002: Message edited by: TORQUEPIMP ]


 
Posted by jsmaze (Member # 617) on :
 
I didn't touch heads of the O2 sensors but I didnt have a torque wrench that would fit under there. I think they are the torque spec is 18 or so, so I took my best guess. I doubt that fitting is the problem, but you never know.

I have been told that mileliminators will solve the problem, as they are designed to fool the computer into thinking you still have forward cat's. I think whats happening is that since the removal of the forward cat's, the O2 sensors are giving the computer a reading far enough out of range that the check engine light comes on.

Im gonna check out http://www.mileliminators.com and see what info they have.

Thanks!
Jeff
 

Posted by TORQUEPIMP (Member # 386) on :
 
quote:
Originally posted by jsmaze:
I didn't touch heads of the O2 sensors but I didnt have a torque wrench that would fit under there. I think they are the torque spec is 18 or so, so I took my best guess. I doubt that fitting is the problem, but you never know.

I have been told that mileliminators will solve the problem, as they are designed to fool the computer into thinking you still have forward cat's. I think whats happening is that since the removal of the forward cat's, the O2 sensors are giving the computer a reading far enough out of range that the check engine light comes on.

Im gonna check out http://www.mileliminators.com and see what info they have.

Thanks!
Jeff

wholy cow i swear i though i put mil eliminators in my post.. but that i am sure that is your problem.
 

Posted by RiddlerGT (Member # 113) on :
 
u shoudnt need mill eliminators for a 88 mustang
 
Posted by jsmaze (Member # 617) on :
 
Aye, after looking at the mileliminator site and emailing them, it seems that only the 96+ stangs with 4 O2 sensors need the eliminators.

The check engine light comes on after about 10 miles of driving. Is that about the time that it takes for the sensors to heat up properly?

I know there are guys out there with fox's and o/r h-pipes
 

Posted by st5150 (Member # 51) on :
 
Here is how you can scan for codes:
http://www.corral.net/tech/maintenance/eecivtest.html


Sounds like you do have some O2 sensor codes going by how the check engine light is turning on. It only takes them a minute to warm up. They're self heated. If worse comes to worse, AutoZone has the best price on new ones.
 

Posted by jsmaze (Member # 617) on :
 
Thanks a ton everyone! Ya I searched corral for "check engine light" and found some tips, mainly that tech article. Its a lot simpler than I thought.

I imagine that doing a KOER test would result in one of the EGO codes coming up. It will probably tell me its running rich because since I just tightened up the header flange I might have a bit of an exhaust leak.
 

Posted by Lady Cobra (Member # 857) on :
 
Have you tried to reset the computer? disconnect the battery for a few min. and warm back up and see if the light comes back on.
 
Posted by 91sleeper (Member # 779) on :
 
Yo what up man. I have an 91 gt with a o/r x-pipe on myne. You dont need mil elimnators at all! My check engine light doesnt come on in my car. I only have two questions for u though, are you running mufflers? I ask because when i ran my headers and o/r x with no mufflers the check engine light did come on because i wasnt recieving enough back pressure in my exhaust system and the ligh only came on periodcally and flashed on and then went off sometimes. Also were your O2 sensors after your cats with your old stock pipe? If so thats defnatley why its coming on because your computer is sensing that your cats are all f*ed up. Your problem might be in your mufflers though so check it out.
 
Posted by jsmaze (Member # 617) on :
 
After driving it for about a week, heres how its goin.

The check engine light comes on after about 10 mins or 10 miles of driving, like clockwork.

The 91's and 88's probably had the same stock exhaust, but if not, my stock h-pipe has 4 cats. The O2 sensors are located after the first set of cats.

I have flowmasters on right now, they were welded in when I bought the car.

I am fairly certain there are multiple exhaust leaks and am positive theres at least one large one (I need to get the smog pump tube welded up). It may be the lack of backpressure...however I dont know how the computer would read that information. Ive tried to fix the leaks but argh...I hate exhaust fittings...

I'll drop it by a local shop (that will hopefully work on an illegal exhaust and see if they can take care of the leaks.
 

Posted by 91sleeper (Member # 779) on :
 
Hey i doubt they will work on your exhaust but you can try.
Yeah your exhaust does sound the same as mine. The only other thing i can think of is make sure the smog return tube is connected correctly and its all hooked up right.
You might also want to invest in some Mr.Gasket Copper Gasket set though. Just my 2 cents man.
Later!
 
Posted by st5150 (Member # 51) on :
 
Its leaks between the exhaust ports of the heads to the O2 sensors that can cause problems. Make sure you haven't burnt up your O2 sensor wiring harness/wires on your headers or anything else.

Have you pulled the codes from the computer yet?
 

Posted by jsmaze (Member # 617) on :
 
I havent had a chance to sit down and pull the codes. I'll have to use the check engine light method but it doesnt look very complicated.

I didnt use gaskets because I had changed my headers a few times on my old mustang (86 GT) and hadnt had any problems with leaks. If a shop wont touch it then its time to get a set of gaskets I spose.
 

Posted by STALLION98GT (Member # 867) on :
 
If you are still having problems with ur check engine light.. I work @ SNAP-ON TOOLS and I can scann ur car with my scanner. I did the same thing to my car but I have a 98 GT and the check engine light came on, I scanned it and it gave me a P1127 code wich means that the 02 sensor is not getting hot enough. I put a bassani x pipe with cats and my light still came on.

but like i said if you want me to scann it i can.
im located in san jose ca
 

Posted by 91sleeper (Member # 779) on :
 
quote:
Originally posted by jsmaze:
I havent had a chance to sit down and pull the codes. I'll have to use the check engine light method but it doesnt look very complicated.

I didnt use gaskets because I had changed my headers a few times on my old mustang (86 GT) and hadnt had any problems with leaks. If a shop wont touch it then its time to get a set of gaskets I spose.

You should get some copper gaskets so that you can take the headers on and off and use the same gaskets without having to keep replacing them.
 





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