Here is a challenge for all you jeepers!!!!

[qbert213]

1073332

I drive a 97 tj, added aftermarket headers, cold air intake a nice six inch lift with some super swampers and started up a pretty nice rig. Jeep ran fine with a nice rough sound from the borla installed exhaust. Now just a week ago I am driving home from work... day after hard crawlin, and the obd 2 computer stopped the engine(as well as putting the idiot light on) but it allowed me to "limp"home at about twenty miles an hour. Got home changed the plugs, rotor, tps sensor, cps sensor, o2 sensors(both), and she seemed to run great. Pull into the office the next day and there she goes again right back into "limp mode". When I open the hood I find a crack in the header larger the Rosie O'donald. Would this large exhast leak be the cause of the obd 2 running the motor in "limp mode". I went out and bought a reader ($150) but it keeps giving me bogus readings. I am replacing the header but would like to replace all broken parts at one time... what you think?????

null[addsig]

 

[Craig]

1073339

Mabye the mods to your exhaust and engine are causing your computer to get messed up from the air/fuel mixtures and backpressure and temp and whatever else it reads. I know nothing about the computer but it's just a suggestion.[addsig]

 

[qbert213]

1073343

I guess I could go back in time and assasinate the obd 2 creator, actually he should still be alive(him and his evil team of engineers). It is a great system but it is putting me in limp home mode which doesn't cut it out in the mud. Does anyone know how to sync the computer to modifications??[addsig]

 

[thehemi]

1073365

Get an OBD-2 scanner to see what codes you are a throwing.
I picked up the Harrison R&D software package for just $150.
I believe they have basic hand-held readers for $150, too.
[addsig]

 

[qbert213]

1073366

Well... I picked one up, the problem is it only reads the o2 sensors are bad. I just replaced them. I think it is something connected to the o2 sensors like the cat or maybe the header. I guess we will see when I fix that header crack.[addsig]

 

[K_K_PSI_GUY]

1073408

You would be surprised how sensitive the OBD II computers are. In GM cars, if the gas cap is not on properly, the computer will spit out codes. In my opinion, The crack in yor headers is causeing your O2 sensor to get an abnormal reading. When you get a code on your computer, the code does not mean that the component is bad, it only shows the technitian that the particular component is giving out abnormal readings. Replaced damaged components (headers), reset the computer and the codes should go away, and one more thing STOP playing the guessing game! you waste 4 times as much money on parts you do not need. Whenever you get a code, check to see what it is and then check all related components eg. vaccum hoses, timing , and other such things. In this case, it is exhaust related, so check everything and make sure that there is nothing abnormal. Now you have found tha abnormality (brocken header), so start there. Even if it is not the only cause of the codes, it will be necessary to replace it anyways. Hope this helps.-Al[addsig]

 

[Snitty]

1073428

the o2 sensors readings must match all expected mixture readings that the previous sensors will put out to calculate... if you are losing exhaust from anywhere BEFORE either or both sensors, then you will, without a doubt, be allowing the sensors to get an inaccurate reading... the obd2 computer will not know what is going on, and will start to make changes in the performance of the engine to make up for the information it takes in... and that virtual information will often be completely different than the actual physical behavior of the engine[addsig]

 

[qbert213]

1073437

So far so good... header got in yesterday. Changed it and so far no problems, I'll keep you updated. Thanks, [addsig]

 

[RAVEN13xxx]

1073673

If the leak is big enough, it will not allow enough back pressure to be built up. That will really play havok with OBDII systems.

edited by: RAVEN13xxx, Jun 28, 2003 - 05:54 PM[addsig]

 

[Snitty]

1073733

I just noticed my cracked manifold on mine... it might be what is causing my poor performance[addsig]