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I was just trying to clean up the engine bay and I capped off the vacuum port that goes to the CCP solenoid. The car started running really lean at idle. I disabled the error code, what else would I need to do in the tune to prevent this?
It went from Idling at 14:1 to 17-18:1. I hook the line back up and the afr goes back to where it's supposed to. Very strange.
Any ideas?
disabling the error code is my currently preferred way of dealing with a CCP delete, and just let it generate a CCP duty cycle.
i've never seen such a jump in AFR from capping that off. technically it should give you a richer AFR? im almost certain you disturbed something else while deleting the CCP.
on my own car when i went vented i only had to trim out a few percent
it is really strange. I disabled the error code, then I took it all off. When i cranked it up after that it was way lean at idle. I searched all over for something that I may have disturbed, but found nothing, so I hooked it back up and the afr went back to normal. I then realized that I had previously had problems with a very rich idle and leaned it out, so I corrected that part of the tune back to stock. Idle went back to where it should have been, but way lean everywhere else cruising. I noticed that the solenoid may have been stuck, because there's always vacuum going through it. I hooked the vent line straight to manifold vacuum and it ran richer. It seems like it should have the opposite effect. Anyway, I just disabled it and adjusted the tune some to compensate and the afr looks good now. It just really caught me off guard, wasn't expecting it at all.
Constant purge will cause rich mixtures. It's important to investigate potential causes of problems before trying to tune around them. :innocent2:
What causes it to create a rich condition?Quote:
Originally Posted by 1project2many
It seems like it should cause a lean condition because it is unmetered air entering the intake. Just trying to understand. I would never have thought that a stuck open evap solenoid would create a rich condition.
Everything I've read says the opposite, that a stuck open evap solenoid causes a lean condition.
There are two valves: Vent and Purge. If the valves are stuck so vacuum is constantly applied to the tank then the engine will be picking up fuel vapor. If a vacuum is created in the tank then the combination of warm fuel returning from the engine and low pressure in the tank will cause the fuel to create excessive vapors. Even if both valves are not stuck, a stuck closed vent valve can cause the engine to draw excess vapors. In your case it sounds like both valves may be bad. Follow the link below for a basic explanation of how the purge system functions.
http://i42.tinypic.com/df83g9.gif
(Original image at http://chevroletforum.com/forum/taho...olenoid-46364/)
Very informative.
Thank you