check engine light on after mods

[jtjwrangler]

I took my 2005 matrix to the dealer for the check engine light. They told me that the code is for the engine running lean. I have a magnaflow cat back and a mugan racing cai on it right now. Will these modifications cause the check engine light to come on. They told me that these may cause the problem but I have to put the stock exhaust and air intake back on so they can get a base line of where the engine is suppose to be. I already got rid of the stock parts. I checked for leaks on the exhaust and found none. Can anyone tell me what the problem may be? The dealer has no idea if these parts are causing the problem but told me that it is not covered under the warranty so I had to pay the $40 for the check.

[mistamatrix]

I doubt an intake will lean you out. Our cars run real rich, especially the XRS, out of the factory.
Most likely caused by your install. Double check the hoses for leaks. Also, the mass air flow (MAF) sensor on the intake is very sensitive. Did you mishandle it in any way during installation?
Try resetting the ECU.

[jtjwrangler]

How do you reset the ECU?

[xrs22]

I just recently started having that problem too. I cleaned the intake filter w/ the K&N cleaning kit and the check engine light was still on a couple of days after. It finally went off for a couple of days and then it came back on. So I checked the MAF sensor and it was clean, I made sure not to touch it when I was installing my SRI. Also i just got my oil changed yesterday, I was about 1k over the last due change. I was thinking of calling the dealer but they'll probably tell me the same thing they told dude at the top of the post.

[mistamatrix]

Originally posted by jtjwrangler
How do you reset the ECU?

Unplug the negative terminal battery for a few minutes.

[jtjwrangler]

I may have found the leak. The coupler for the intake tube is a little too big for the throttle body. I cut a piece off of a old intake off my jeep which is the proper size and installed it into the coupler. I hope that is the problem. It was about 1/8" to big so it may have not been sealing. I will reset the ecu and hope for the best. Thanks for all the info

[slipknot490]

A CIA NOT causing lean condition? Thats what the thing does...ALLOWS MORE AIR IN. More air means lean. Same with the exhaust. MORE AIR OUT. But, these manufacturers take that into consideration and it shouldn't affect it enough to cause a problem. Go with what mista said....probably a leak.

[mikes_matrix]

You might like to know that corolla and 4runners have had an on going problem with the Mass air flow (MAF) sensors in the past ... if the air leak is fixed you shouldn't have a problem any more.... Oh ya the air leak would have to be between the MAF and the Throttle Body ( is sucking in air thats not being measured ) or before the Oxegen ( 02 ) sensor for it to be a false reading ... In some cases the 02 sensor is not reading corectly because it doesnt potrude it the exh pipe far enough.....

I have only seen this problem once on a matrix and it was caused by to much oil on the K&n type filter the day before .. ... the MAF is a element that is heated to determine the amount of air that passes it .... a litte oil baked on and it's toast even if you cant see it... .

Do yu have a freind with a Corolls or matrix????? Swap your MAF sensor for a week ( is only 2 screws and one Connector ) if your problem is gone and he has the eng light on now you Know thats it . To reset the engine light when yo udo the swap with the KEY OFF remove the 15 amp fuse under the the Hood for 1 min then reinstall , start it , light should be gone ......

Make sure the Oil is under control ( air cleaner ) Dont mess up your Buds MAF sensor

I work in Canada at a Toyota Dealer I Have 15 years Toyota EXP....I Hope this Helps!!!!!!!!!!!

MIKE

[xrs22]

i just disconnected my batt. and the eng. light was off. I'm not sure if it will come on again, i guess i'll have to wait and see.

[Snouter]

Consider getting a carchip OBDII code reader to get any codes and clear codes easily. Also, high flow exhausts are known to give CEL in a number of different car manufacturers because the O2 sensors indicate more airflow than the range set at the factory.