I was woundering if anyone has had a problem with thier "check engine" light after installing an aftermarket muffler. I recently installed a flowmaster 40 and had it exit the side in front of the rear passenger tire. my mech. tells me the engine is running lean and is probably due to the new muffler. anyone else had this problem, if so what did you do about it.
Thanks
-tim

 

Which engine?

I put the MAC cat back on my 98 5.4 and have not had any problems with check engine lights.

Did you pull the code? That is probably the best thing to do.

I also have buddy with straight pipes on his 99 4.6, and he never had the light come on either.

 

I have true duals on mine and the lights been on since the day i got them never had anyproblem with performance of anything else just have it scanned like mentioned above and maybe something can be done with the comp.
JJ

 

On my 2000 5.4, I chopped both headpipes behind the cats and ran entirely different from there back. No codes for 4 years.

 

I have a hi-flow y-pipe with a dumped magnaflow but i got a CEL for running to lean after i put an intake kit on my truck. But the exhaust never caused a problem.

 

the only way (as far as my experience on other brand cars) to get a check engine light with an exhaust system is if you mess with the actual catalitic converter or if you by accident mess with the O2 sensors. I am not familiar with the exhaust system on the F150 so I am not sure where this (or these) O2 sensors are .. (if ther is any ?)

check your sensor, you may have loose or damage or disconnected one of them ..

chinin

 

there are accually 4 sensors - 2 before the cats and 2 after the cats - the mech. said the sensors all looked fine and that they should not be the problem. so back to the drwing board i suppose

 

Funny you should mention, I had my Flowmaster system installed about 3 months ago and so far no problem...until today !! Check engine light came on as I was pulling into a gas station, came home pulled the codes and came up with P1000 and P0401, the first is "monitor testing not complete" the second is "exhaust gas recirculation flow insufficient detected", I am going to clear the DTC's and see if it pops up again before taking it in. Incidently I found the DTC codes available online for free at

http://autorepair.about.com/library/ts/bl-dtcs-main.htm

maybe ya'll knew this but I didn't so if it is of use to anyone else well their ya' go.

anyone else have these codes pop up before?

thanks.

 

my light stayed off for about 3 days after i had it reset the first time, i just had it reset monday and it has yet to come back on. so we will see how it goes - thanks for the info
-tim

 

I had a cat-back exhaust put on my 2000 about 1 1/2 years ago. About a week after it was done the CEL came on. Everyone I talked to said it was because of the new exhaust but I wanted to be sure so I took it to the shop. The code came back as a "random engine misfire" and the mechanic said the same thing; it's because of the exhaust and once the truck's computer figured out that it was not life threatening it would adjust and there would be no more problems. Well, it must have figured it out because the light went out the day I took it in and I've been CEL free ever since!!

 

interesting.... hopefully mine gets there. i hate that light. but i love your pics! Alaska rocks!

 

Thanks, I absolutely love it here!!