When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
This issue is stumping me for sure. I had my truck running like a top for 3 months without a check engine light after I replaced the PCV and the line going to it. These last 2 weeks, I've had nothing but issues with check engine lights. The truck runs smooth, feels great, but it says it's running lean both banks. Mechanic and I smoked the whole system, no leaks what so ever, but when he plugged his code reader in he found a pending code for a knock sensor. Could that be the issue? Im lost at this point, I'll be changing the fuel filter tomorrow morning. Any input is greatly appreciated
Lean codes both banks? You have a vacuum leak.
You said you checked already but you definitely missed something.
Its ALWAYS a vacuum leak when you get lean codes on both banks.
Its ALWAYS a vacuum leak when you get lean codes on both banks.
Definitely not "always", but usually, probably 90% of the time. Low fuel supply or a MAF that is mis-reporting the intake air charge will also cause "lean" codes on both banks.
The live data displays indicates that the PCM is still in open loop mode and there are no DTCs present. Something does not compute, perhaps the PCM was reset before those displays were photographed.
You need to explicitly identify your truck in the post. Year, model, engine, and transmission as there are multiple combinations of calibrations and it's impossible to get the right information without the explicit identification. Also, if a Super Duty, look at the label on the underside of the hood to see if it's an OBDI or OBDII calibration.
Update: My mechanic and I just replaced the fuel filter and the codes came back, there went that hope. The truck in question is a 2003 f250 crew cab long bed with the 5.4 and an automatic transmission, 4 wheel drive. I am positive that we properly checked for vacuum weeks for smoke since he has been in business since the 70s and he is ASE certified. The only thing I've noticed is the dipstick has a hole in the side, would that cause a problem? I already ordered new motor craft oxygen sensors, figured it wouldn't hurt to replace them and they are part of a tune up. When I took the pictures of diagnostics, there was no check engine light, but the codes were pending. I'll get some pictures now that I replaced the fuel filter. And there are no oxygen sensors after the cat, so I believe it's OBD1 compliant not OBD2
Last edited by Collision; Jul 3, 2018 at 11:53 AM.
Reason: Additional information
Fix the hole in the dipstick before doing anything else, then retest.
I know they won't fix anything but I heard change them every 100k miles with motorcraft parts only, so I figured I'd give it a shot. Can I just wrap the dipstick tube with tape where the hole is or should I just replace the whole thing? It's cheap off of Amazon to buy a new one but Im just saying temporarily
Here's the video to the live data, first is idle, followed by 2500 followed by 3500 rpms. Nothing really looks off to me in the live data, and yes this was all done at Park.
Maybe it isn't a vacuum leak.... That's why we do troubleshooting, it eliminates guessing.
Another member on this thread alone said "Lean codes both banks? You have a vacuum leak.
You said you checked already but you definitely missed something.
Its ALWAYS a vacuum leak when you get lean codes on both banks." That's why I'm trying to figure out what else it could be. I'm thinking of trying a junk yard throttle body and seeing if that fixes the problem, maybe that gasket has a break or something... I'm reaching at straws here. It appears long term fuel trim is fine below 2500 but when I hit 3500 it goes up to 14
Update: I just listened to the injectors, all sounded normal and consistent (listened with a mechanics stethoscope) then I checked the resistance and got about 16.5 ohms for each one, so it's not fuel injectors. I'll be testing for fuel pressure on Monday when the tester comes in. I'll keep everyone posted on what's happening. If anyone has any input please feel free to add it.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
