Po171 Chevy Express
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New Delphi MAF has been installed and it’* still lean, but maybe slightly less so.
the new sensor does seem to have helped, it’* not quite as lean as it used to be. LTFT are usually between 10-15%, lowest when accelerating from a stop, sometimes 7-8%, and highest when maintaining about 35-45 mph, at about 15%. At idle about 11-12%or so. The biggest difference is when I start coasting it no longer jumps 5-15%, now only maybe 2%. Everything else on the live data looks fine except the downstream o2 sensors are both still reading 99.2%.
not sure where I’ll do from here, I guess recheck for vacuum leaks maybe?
Edward
the new sensor does seem to have helped, it’* not quite as lean as it used to be. LTFT are usually between 10-15%, lowest when accelerating from a stop, sometimes 7-8%, and highest when maintaining about 35-45 mph, at about 15%. At idle about 11-12%or so. The biggest difference is when I start coasting it no longer jumps 5-15%, now only maybe 2%. Everything else on the live data looks fine except the downstream o2 sensors are both still reading 99.2%.
not sure where I’ll do from here, I guess recheck for vacuum leaks maybe?
Edward
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What are the before/after readings, complete with negative signs where applicable?
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I think the intake manifold pressure is actually ok. I’ve been trying to find normal readings for all these data points and I found the wrong thing. The IMP has stayed the same throughout.
I’ll resmoke for vacuum leaks, in a day or two when I get a chance.
is there anything I can do to check the pvc system? The intake manifold was kinda oily when I removed it for the gaskets. But as far as I can tell it’* a non serviceable kind.
thank you,
Edward
I’ll resmoke for vacuum leaks, in a day or two when I get a chance.
is there anything I can do to check the pvc system? The intake manifold was kinda oily when I removed it for the gaskets. But as far as I can tell it’* a non serviceable kind.
thank you,
Edward
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It loses a little oil, doesn’t smoke but I may add a quart or so between oil changes.
the pcv valve unfortunately isn’t the serviceable variety, but perhaps one advantage of a van is that I can actually get my face in there and blow and suck it without taking it out. Air passed easily both ways. Which I’m pretty sure means that valve isn’t doing its job, right?
thanks
the pcv valve unfortunately isn’t the serviceable variety, but perhaps one advantage of a van is that I can actually get my face in there and blow and suck it without taking it out. Air passed easily both ways. Which I’m pretty sure means that valve isn’t doing its job, right?
thanks
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It loses a little oil, doesn’t smoke but I may add a quart or so between oil changes.
the pcv valve unfortunately isn’t the serviceable variety, but perhaps one advantage of a van is that I can actually get my face in there and blow and suck it without taking it out. Air passed easily both ways. Which I’m pretty sure means that valve isn’t doing its job, right?
thanks
the pcv valve unfortunately isn’t the serviceable variety, but perhaps one advantage of a van is that I can actually get my face in there and blow and suck it without taking it out. Air passed easily both ways. Which I’m pretty sure means that valve isn’t doing its job, right?
thanks
Should only go one way.
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Well, I replaced the valve cover with one from an 2000 Tahoe that had the serviceable PCV valve. At first, and I didn’t clear the fuel trims this time, all seemed better, long term fuel trims were like -3 to 5%.
after maybe 10 miles it was at up to 15%. What’* left to check?
thanks
after maybe 10 miles it was at up to 15%. What’* left to check?
thanks
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I did the blow test on the junkyard one and it was fine. I also tried a new acdelco valve, which didn’t seal as well as the junkyard one, and that didn’t do better either.
Im confused why as to why it worked for a few miles then revert.
Edward
Im confused why as to why it worked for a few miles then revert.
Edward