really stumped.
- Thread starter rckymtngx
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- #22
Sounds good, again thanks a lot for your advice.
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- #23
It wasn’t at full operating temp, however it had dropped to 1k rpm before I drove away, and that most recent screenshot is from this morning I was driving to work.
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- #24
@aztoytec hey, I’m sorry for the bother, however I just wanted to confirm whether or not I should be focusing on the VSV’s on the engine, or the purge valve down on the canister. The vsv’s it looks like there may be 3 different ones on my gx, so just wanted to check! Thanks so much!
Edit : NVM it looks like the ones I’m thinking of are for SAIS.
Edit : NVM it looks like the ones I’m thinking of are for SAIS.
The evap purge valve is on the driver side top of the intake. It’s has two vacuum hose and electrical plug. One vacuum hose goes from the throttle body to the purge valve. The other from purge valve to hard line (then to canister).
The easiest way to check your issue would be to pinch off the vacuum hose from the throttle body to the purge valve while watching your fuel trim and see it it goes down.
There is other ways to properly checking the purge valve with a scan tool commanding it off and on while checking for operation and vacuum.
The easiest way to check your issue would be to pinch off the vacuum hose from the throttle body to the purge valve while watching your fuel trim and see it it goes down.
There is other ways to properly checking the purge valve with a scan tool commanding it off and on while checking for operation and vacuum.
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- #26
Certainly, I have techstream on an old laptop so I’ll bother with it this weekend. Thanks again!
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- #27
Quick inspection of the hose, show they’re probably the problem. The small hose to the little vacuum cell is cracked, and the hose going to the TB if I squeeze it, it’s gonna crumble. It sounds like I may have been over thinking this way too much.
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A few dollars in vacuum hose from the local auto parts store may be all you need!
Just FYI but prolonged running with a problem like that will throw off many, many learned parameters in your ECU. Once you fix it, I'd disconnect the battery for about 10 minutes. That will re-sent the learned ECU parameters to factory and allow it to re-learn under the hopefully corrected vacuum/air/fuel conditions.
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- #29
Let’s hope it helps it at least, I’m gonna get that replaced and then smoke test since I know those are leaking.
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- #30
I got the hoses replaced, got confirmation the valve is still functioning and it is, so back to the drawing board I reckon. I notice if I’m at 50%+ throttle or 2500+ rpm, the LTFT drop to around 4.5% and the truck runs much better then in the lower rpm range…
Plug off that vacuum port at the throttle body and see if your full trim goes down….
There is a possibility that your purge valve is leaking and/or sticking open creating a vacuum leak, which would increase your fuel trim and give you p0441 and p0455.
You can also disconnect the connector and vacuum hose from the backside of the purge valve(going to the tank) and see if vacuum is present all the time.
There is a possibility that your purge valve is leaking and/or sticking open creating a vacuum leak, which would increase your fuel trim and give you p0441 and p0455.
You can also disconnect the connector and vacuum hose from the backside of the purge valve(going to the tank) and see if vacuum is present all the time.
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- #32
Disconnected connector and fuel side hose disconnected there is no* vacuum.
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- #33
so after some testing, it doesn’t appear there’s a vacuum leak, the purge valve is opening and closing when commanded to… After disconnecting the battery earlier, and reading fuel trims there was a point where they were 25.8-28%…. Am I crazy to consider the catalytic converters being clogged and clearing out enough to run decently after hard driving? I’m gonna next check fuel pressure, waiting on the hardware to show up. I really appreciate you guys.
This is after running the smoke machine for 5-10 minutes, the flow meter dropped to no flow.
This is after running the smoke machine for 5-10 minutes, the flow meter dropped to no flow.
The O2 sensors that monitor air/fuel ratio for setting fuel trims are upstream of the cats, so cat function should not affect them. 25%+ fuel trims indicate the engine is either getting air somewhere past the MAF (vacuum leak), has an incorrect MAF reading, or the fuel supply is low.
Did you try unhooking/rehooking the MAF connectors yet? What are your MAF readings at idle (in park, HVAC off, with the engine warm)? That's free/easy to check.
Did you try unhooking/rehooking the MAF connectors yet? What are your MAF readings at idle (in park, HVAC off, with the engine warm)? That's free/easy to check.
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- #35
I did try that, but it didn’t do anything. I am sometimes seeing readings up to .5g/sec over 4g/sec. However it’s pretty close to 4 at idle warm no ac.
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- #37
Sure, I have quite a while considered it to be fuel related but haven’t thought much about it bc it has been cold the last few months. Every now and then, after the trucks been driven somewhere and sits for an hour to 2 it’ll be slightly hard to start/ almost stall out as if the fuel pump isn’t staying primed, however the vehicle hasn’t sat long enough for cold start fuel prime.