Another question, should I have a cam/crank relearn done now that the Vvt has been replaced? Fairly certain that's the issue since it fixes each time the solenoid is changed. Unrelated, just got the trans filter and atf for a change, fluid looks pretty brown, not sure the when last change was.
2007 Colorado I4 P0171 code??? Vvt? Cam/crank relearn?
So I'm making this post as a last resort for my 07, 4 cylinder. It's got 205000 on the dash. I've had it for about 13 months now and it's had multiple issues. Many I've fixed with a basic Launch scanner and old timer diagnosing. Here's a list of everything I've changed
Vent Valve Solenoid
MAF
Purge Solenoid
PCV hose
Gas Cap
Throttle Body gasket
Cleaned the throttle body
Spark Plugs
Thermostat
Multiple rounds of fuel injector cleaner. (Lucas or high mileage Seafoam)
Seafoam Spray one bottle through the tb
Changed the Vvt solenoid twice.
Here's the next part however, after all that I still have a P0171 code and check engine light. Has a rough idle with it and terrible gas mileage around 12 mpg (highway and city driving mixed). While driving it bogs down around 45-60 mph and has a roar on start up also. I understand O2 sensors can go bad or the map, but all the scanner readings seem ok with what I've heard. 5 psi on intake MAP, O2's are 0.09-0.9 on the first and 0.4-0.7 on the second. Another thing to note is that after replacing the Vvt solenoid each time the roar dissapeared and gas mileage went back to normally temporarily 2-3 days. Not sure what else could be wrong, intake vaccum leak? Coils? Timing chain or cam phaser advanced? Any help would be severely appreciated!!
Vent Valve Solenoid
MAF
Purge Solenoid
PCV hose
Gas Cap
Throttle Body gasket
Cleaned the throttle body
Spark Plugs
Thermostat
Multiple rounds of fuel injector cleaner. (Lucas or high mileage Seafoam)
Seafoam Spray one bottle through the tb
Changed the Vvt solenoid twice.
Here's the next part however, after all that I still have a P0171 code and check engine light. Has a rough idle with it and terrible gas mileage around 12 mpg (highway and city driving mixed). While driving it bogs down around 45-60 mph and has a roar on start up also. I understand O2 sensors can go bad or the map, but all the scanner readings seem ok with what I've heard. 5 psi on intake MAP, O2's are 0.09-0.9 on the first and 0.4-0.7 on the second. Another thing to note is that after replacing the Vvt solenoid each time the roar dissapeared and gas mileage went back to normally temporarily 2-3 days. Not sure what else could be wrong, intake vaccum leak? Coils? Timing chain or cam phaser advanced? Any help would be severely appreciated!!
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Update on the code
after a while of Youtube research and talking to mechanics and buddies at work (Trucking company repair shop), we suspect that the bolts on the manifold being a known issue have rocked loose. Found a video from Mike Smith about it and he had the same intermittent lean code and an audible roar in the background. Said the shop changed his gaskets and tightened the bolts snug and it worked perfectly. Gonna try to snug them down, I have the gaskets, but it's such a pain to take off I'd rather not unless the problem doesn't go away.
after a while of Youtube research and talking to mechanics and buddies at work (Trucking company repair shop), we suspect that the bolts on the manifold being a known issue have rocked loose. Found a video from Mike Smith about it and he had the same intermittent lean code and an audible roar in the background. Said the shop changed his gaskets and tightened the bolts snug and it worked perfectly. Gonna try to snug them down, I have the gaskets, but it's such a pain to take off I'd rather not unless the problem doesn't go away.
Another update on the situation. Manifold bolts snugged, had a smoke test and fuel pressure test done and both were good, new upstream 02 sensor as well. A mechanic told me the roar leads him to believe it could be the exhaust manifold gasket or a crack in it itself. Ordered a Fel-Pro gasket (wanted the Mahle full metal for OEM and not composite steel, but need to get the truck fixed asap, and I can get it later) and we'll see in two days when it arrives. Also learned my 07 doesn't have the smog/ secondary air pump. My guess is they started it later in the year since my block doesn't even have the hole for the pump nor one for the hose in my airbox. 🤷♂️
Last update on this thread, issue found and solved mostly. Turns out a badly cracked exhaust manifold, two snapped bolts, and a blown gasket really mess with fuel trims. Aftermarket manifold is in now, Fel-Pro gasket but a Mahle steel one on the way. One of the bolts we removed, and I'll remove the other a week or so when the better gasket comes in too. New Dorman bolts in all holes except that one that is still snapped. Still a pretty big leak after idling, but once you get on it and heat up the gasket it works great. Hopefully the bolt and new OEM gasket finally finishes the issue, no engine light as of right now even with the leak still. Hope someone finds this and gets something out of it sometime. Would have saved me a couple hundred bucks and alot of pain and stress.
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