CEL coming on after new short intake put on

[Gorilla0178]

Ok so I had made a make shift intake out of PVC, actually I had made 2 the second on as nicer than the first. Never had a issue with the CEL coming on. So i made a fiberglass intake , it looks nicer, and its not PVC. Now the CEL is coming on. I've reset it a few times. Sometimes it comes on after a few miles, and other times it takes days. The code says. To lean at idle right bank. Says it could be MAF malfunction, large vacuum leak, fuel problem, ignition prob. I cleaned the MAF sensor and made sure everything was tight. Still came on. Its reset now, so just waiting till it comes back on. Any advice? Ill try to post pics later.

 

[rodslinger]

Ok so I had made a make shift intake out of PVC, actually I had made 2 the second on as nicer than the first. Never had a issue with the CEL coming on. So i made a fiberglass intake , it looks nicer, and its not PVC. Now the CEL is coming on. I've reset it a few times. Sometimes it comes on after a few miles, and other times it takes days. The code says. To lean at idle right bank. Says it could be MAF malfunction, large vacuum leak, fuel problem, ignition prob. I cleaned the MAF sensor and made sure everything was tight. Still came on. Its reset now, so just waiting till it comes back on. Any advice? Ill try to post pics later.

Whatever you put your MAF sensor in probably has a larger inner diameter than the stock MAF housing. This is skewing your fueling demand lower. The air fuel sensor is picking up this lean condition and having to correct for it. You need to decrease the diameter of the tubing section where the MAF is located closer to stock which is about 2.47". You could probably get away with something near 2.75 but a 3" or larger is likely causing the problem.

 

[Gorilla0178]

The intake is the same size as the throttle body, and only slightly bigger than the pvc intake I made. here are some pics. The light came back on so I reset it and put a thin foam gasket under the MAF to make sure there is nothing leaking around it.

 

[Secondtyme]

Rodslinger hit the nail on the head. The difference in size may seem small to the naked eye (or a micrometer), but the difference to the ECU as it computes fuel charge is HUGE. It only take a few thousandths of an inch to start screwing things up royally. Prove it to yourself by putting the PVC intake back on the car without changing anything else, watch your CEL woes disappear.

 

[rodslinger]

The intake is the same size as the throttle body, and only slightly bigger than the pvc intake I made.

The only part that really matters is the cross section area at the point the MAF is mounted. The rest of it can be 50" or 1". There is also some influence from turns or bends in the line near the MAF. Turbulent air can throw the readings also. If the airspeed at the measuring point of the MAF has stalled due to some eddy currents it will do the same thing. Try rotating the MAF sensor 180 degrees in the line and see if that changes things. .

 

[Gorilla0178]

Well I couldn't keep the CEL from coming on so I reinstalled the stock air box. The only differences I can see from the PVC intake to the fiberglass one is the diameter and that it's curved and not straight. The stock box and PVC one had the MAF in a straight tube. I can only think the difference in air speed through the curved tube is setting it off. If not the larger diameter is letting too much air in at idle. Oh well, back to the drawing board.