jonathncano

about a year ago i started a seemingly endless battle with the service engine light in my 02 4.6L supercrew. first it was the egr valve. i fixed that and shortly after it came back on. had it checked out again and replaced the dpfe sensor. again shortly after it returned and i was told that i had a misfire due to the intake manifold gasket. well i stoped driving the truck for a couple months and decided today to replace the gasket and get it back to normal. i went to autozone and had them check the codes again and i only pulled 3 codes: PO401, PO402, and PO405. i'm pretty sure this is the egr valve. i still feel the misfire and wonder why it is not pulling the codes for that. I'm close to just pulling the light out of my gauges lol

Mr B

I've seen this before on my buddies truck. We tried throwing parts at it to satisfy the code reader to no avail. He had EGR, DPFE sensor, IAC sensor, cam position sensor, and all O2 heater circuits. We changed all these parts and reset the OBD2 and nothing. He took it ti a shop and they found a wire bundle between the tranny and engine that had been cut. They repaired the wires and it solved the problem. His was a 99 though and I am not sure if they are similar, but I hope this helps. Good luck.

jonathncano

hmm . . . good to know i'm not alone but does anyone have any suggestions?

aerosurfer

Misfires are also caused by the coil packs going bad. Just changed my #7 coil a few weeks ago. It threw a code once, I cleared it, and could not make it code again, but I could feel the hesitation at lower RPMs. Changed the coil and the truck is running smooth as silk now! Give it a go, it cant hurt. I have found coil pack sets on ebay for around 80 if you shop around

jonathncano

how would i go about determining which one is misfiring?

jonathncano

how would i go about determining which one is misfiring?

aerosurfer

sorry had my codes twisted. 030_ means that number cylinder is misfiring, not 040_. but short of changing all the coil packs, I'm not sure of a way to bench test an individual coil. It sounds like you have checked or changed everything else. So by process of elimination, If its missfiring... then its not burning everyhting properly.. therefore EGR stuff could get dorked up and throw codes.

jonathncano

arghhh this is frustrating! i know if i take it to the dealer i'm going to pay a TON of money for labor that i'm more than capable than doing myself.

jonathncano

ive decided to change the spark plugs and see what happens. . .does anyone have a link for a how to. . .i have heard that the plugs in the back are really hard to get to. thanks