Coincidence? Catch can and cel/knock

[Jaymar]

My car is weird. The check engine light that comes on and off with the purge valve code differs each time. The first time it came on and my mechanic reset the code it went away after a few days. Other times it will stay on for a few days or a week, if I do a long pull it goes off, if I fuel up it goes off and other times when I fill up it will come back on the next day. My mechanic said don't worry about it and that it's not a big deal. I know it's a cheap fix but it would be annoying if it came back on after replacing it.

If it's the same code that's pretty much how it behaves when it fails. It only trips under certain conditions so it can take a few days to show up. It is cheap and fairly easy to do.

Sponsored

 

[FreePenguin]

My car is weird. The check engine light that comes on and off with the purge valve code differs each time. The first time it came on and my mechanic reset the code it went away after a few days. Other times it will stay on for a few days or a week, if I do a long pull it goes off, if I fuel up it goes off and other times when I fill up it will come back on the next day. My mechanic said don't worry about it and that it's not a big deal. I know it's a cheap fix but it would be annoying if it came back on after replacing it.

yeah, ive replaced it, but it wouldn't be as annoying, but I have like, engine strut tower, covers, caps, etc. its a pain to remove everything just to replace that little purge valve. Lol if I just had an engine cover, not a big deal

 

[Jaymar]

yeah, ive replaced it, but it wouldn't be as annoying, but I have like, engine strut tower, covers, caps, etc. its a pain to remove everything just to replace that little purge valve. Lol if I just had an engine cover, not a big deal

If you've just replaced it it's highly unlikely it's failed again so you're better off looking fo something that behaves like an open purge valve, like a vacuum leak behind the throttle body.

 

[FreePenguin]

If you've just replaced it it's highly unlikely it's failed again so you're better off looking fo something that behaves like an open purge valve, like a vacuum leak behind the throttle body.

my BoV.

its tapped off the purge valve. let me find pics

 

[EmCel]

If it's the same code that's pretty much how it behaves when it fails. It only trips under certain conditions so it can take a few days to show up. It is cheap and fairly easy to do.

Yeah it's the same code. If I don't sell my car I'll get it fixed soon. If the check engine light comes on due to other reasons and I ignore it thinking it's the purge code then it would be bad

 

[TeeLew]

is 10:1 the same thing as 10.5 afr? just curious, im assuming 10:1 is 10.1 to -10.9 in general.

Sensors read with higher resolution than an entire whole number. Tenths are a completely reasonable unit to measure. So there is a legitimate difference between readings of 10:1 & 10.5:1 AFR. Having said this, you will see differences from sensor to sensor, but these will tend to be relatively small, on the order of a tenth or 2.

 

[TeeLew]

I'm just looking at a couple data logs. It looks like Ford resolution in the ECU IS in increments of about 0.15 AFR.

 

[FreePenguin]

I'm just looking at a couple data logs. It looks like Ford resolution in the ECU IS in increments of about 0.15 AFR.

does that sound about right for 10.5 afr at wot? atleast apparently feasible for ford perf.

 

[Jaymar]

does that sound about right for 10.5 afr at wot? atleast apparently feasible for ford perf.

Our perpetually sooty tailpipes would tend to lean that way yes. Rudimentary understanding would suggest that the ECU target 14.7 and leave it at that but modern engine controls don't do that for a variety of reasons beyond an enthusiast's understanding of the subject, especially DI motors. It would only be alarming if this was a new behavior and if it was out of line I'm sure it would throw a CEL. These things will hand those out like candy on Halloween.

Edit: I myself am an enthusiast as well, I'm not claiming to understand the variations in AFR used, only that I know enough to say I don't know.

 

[FreePenguin]

it runs fine, I will quit worrying. honestly I wish I didn't have numbers on dash, I wouldn't look at them or even know about them otherwise.

 

[TeeLew]

does that sound about right for 10.5 afr at wot? atleast apparently feasible for ford perf.

It sounds completely reasonable, especially considering my HPP, which is mapped similarly, went as rich as 8.9:1. At that point, you're just pumping raw fuel through the engine. The FPP tuning must be a little better than stock HPP.

14.7:1 was mentioned as being theoretically perfect AFR, which it is, but you can't actually run it that lean at WOT in practice. On a N/A engine, you'd expect to see a little over 13:1 (maybe 13.2-4). Turbo engines generally run a bit richer, but I'm surprised a little by anything richer than about 12.5:1. If done for performance, that suggests the combustion chamber geometry needs some work.

 

[FreePenguin]

I reverted back to stock intake, stock intake tube. I took off my charge pipes and bov, I went back to oem charge pipes and stock bov, I also added a new evap purge valve/hose.

no cel's no knocking, nothing. im boosting and holding 23/24 psi on ford perf tune in 80-90* heat.

its an absolute hoot. I am assuming people get CEL's when they use a different intake tube.

 

[FreePenguin]

I lied, I just scanned and got this code on obd fusion.

when a code shows up on a obd reader, but not on dash, does that mean there's a chance its just a false alert and will go away? or does it have to appear so many times or something before it throws a wrench on the dash?

 

[Andrew@Lethal]

When I installed my passenger clean side ford perf catch can, I drove around last few days. I notice I hit 10afr on wot, but yesterday I pulled up my OBD fusion and showed I had a 1 knock on cylinder 4.

i went ahead turned car off and on, 1 knock was still on cyl 4. No cel present. So I scanned for cel’s and found “unable to bleed fuel tank” or something I didn’t save it. But I cleared it.

it removed the knock 1 on cylinder 4.

do you think it’s due to new catch can? And that on wot it gets to 10afr? Causing knock? I may have to removeit if it comes back. 2 warm up cycles since clear and no knock and no pending code

A catch can should'nt have anything to do with a knock. It could be your evap purge valve being faulty again. I replaced it twice on the Mrs's Ecoboost RS1. What brand catch can are you using and unrelated did you gut your PCV on the drivers side?

 

[FreePenguin]

A catch can should'nt have anything to do with a knock. It could be your evap purge valve being faulty again. I replaced it twice on the Mrs's Ecoboost RS1. What brand catch can are you using and unrelated did you gut your PCV on the drivers side?

I replaced the evaporator purge valve, but I think knock could of happened from the catch can hose, its touching the engine, I put a piece of like felt/cushion under it, so if it vibrates it will be dampened, havnt had any knock since.

I have 2 ford perf catch cans. I had right side (dirty side on EB) for last 20k miles, never a hiccup, I added the left clean side ford perf, and many have had the same CEL from it, (mine hasn't popped up on dash) but it did pop this up when I scanned.

as long as it doesnt illuminate dash light im happy, should I worry at all though? reason I ask, as long as its flowing just fine, the light can be considered a dummy light right? I am thinking there's too much volume in the catch can, and its throwing off the sensor/pressurization expectation by having to fill the volume of the catch can and not being what it expects, because the catch can has a electronic clip that plugs into fords harness.

I took a pic before I put everything back on, you can see the 2 catch cans.

the other people who used ford perf catch cans, any catch can really on clean side, all seem to get this code for most part. just wondering if its fine to ignore, and its actually fine, and disregard the code. as long as doesnt hit my dash I dont care really. but if its an actual issue, like pressure is being too much build up or not letting enough build up, then that could be an issue.

Sponsored