XJ Mods and ECU ?

Hello all,
I have a question about my 99 XJ, so I thought I should ask the experts. I found a crack in the exhaust manifold, so that must be a sign to get a header and upgraded exhaust right Now the question, which mods can I do on my 99 (intake,exhaust,etc) without throwing the stock computer outta wack? This is my DD that see's mostly muddy off roading, so I need it to stay somewhat dependable.

Thx

John

you woun't have any problems with the computer.

I have a custom intake, bored t-body, bored t-body spacer, relocated IAT sensor, portmatched intake to head, ported and polished head, bored over .030, cam, header, and highflowcat and flowmaster. I have not had to do a single thing to my computer. Mod away and you will be fine.

The only problem that I have is I run a little lean, but that had nothing to do with the computer, the injectors need to be bigger.

AARON

OBDII cars may throw a check engine light more often than older ones.
Especially if its more free flowing.

With the LATE 97-up XJ's being OBD 2.... I would stay away from ANYTHING that induces more fuel into the motor. There are pre-cat AND post cat O2 Sensors that will keep you from modifying (gutting) the converter, but as far as the other things, I have a 98 with OBD 2, and have a throttle body spacer and MP computer with NO problems.....Just passed AZ testing great....(it only has 27,000 miles on it though..)..


Joe

FreemansXJ said:

Hello all,
I have a question about my 99 XJ, so I thought I should ask the experts. I found a crack in the exhaust manifold, so that must be a sign to get a header and upgraded exhaust right Now the question, which mods can I do on my 99 (intake,exhaust,etc) without throwing the stock computer outta wack? This is my DD that see's mostly muddy off roading, so I need it to stay somewhat dependable.

Thx

John

Click to expand...

I just replaced my exhaust with a Borla exhaust. Header all the way to tail. I bought a high flow cat from Summit. I replaced the no. 2 O2 sensor due to it being bad. I have had an increase in low end torque and about 3 mpg better in city and hwy. I am very happy with the set up though expensive. You should have no problem with and sensors if you do this with proper repacements. Borla makes it for the XJ, so no worries.

Curt