Have a 2001 CRV that is running really bad. It almost stalls when I put it in gear or even when the RPM’s fall to idle. It is now throwing a p0172 code. I have a simple scan tool and verified the MAP reading and primary O2 voltages as suggested by the manual, both appeared to be normal. It seems all the symptoms point to valve clearance, however the valve were adjusted not 2000 miles ago by the dealer during the 150K service, and this issue has existed before and after that adjustment. I also cleaned the IAC screen with no changes. Any other ideas?
The valve lash should be inspected and adjusted as necessary every 30k miles.
If there was a problem with an exhaust valve being too tight 2000 miles ago then adjusting it properly is closing the barn door after the horses ran off. The valve face and seat would likely be burned and adjustment will not cure this; only a valve job.
What I would suggest is to connect a vacuum gauge to an intake manifold vacuum source and check the vacuum. This will vary based on a number of factors but what you’re generally looking for is 17"-20" of vacuum at idle and with a rock steady needle on the gauge.
After that, a compression test should be performed. If the dealer found a tight valve or two back then they should have gone a bit further and verified any problem at that time.
I should have been more clear, the valves are adjusted at every 30K service, give or take a couple 1K. Although the 120K may have been missed. The dealer did not say anything this time about anything unusual in the valves. I will have to go get a vacuum gauge. Where abouts would I hook it into the intake? Right now the vehicle has to go in for an alignment later this week and the behavior was going to be brought up since the code is still stored, but the MIL is off. I am just trying to find something simple before I pay the dealer cost to have it fixed.
My hat is off to you for having those 30k miles valve lash checks. Very few people have this done at all and a small number of them find out the hard way what the end result of not doing it is.
The code you have is for a rich running condition on Bank 1. This may or may not have anything at all to do with valve lash and compression.
How long have the spark plugs been in there? I’m wondering if this could be caused by plug with a subtle misfire and these misfires may not set a specific code for that.
Personally, I’m of the opinion that any time an engine has a performance fault the compression should be checked. Generally the plugs are out for inspection and it’s as good a time as any to weed out any mechanical faults that may exist.
Performing a vacuum check can give you a heads up on a compression problem because if one cylinder is abnormal it will show up on the vacuum gauge. The followup on that would be a compression test.
If you run a vacuum check locate a vacuum hose from the intake manifold and tee the gauge in with a T-fitting and an extra piece of hose. If you feel suction while the engine is idling then that will be the spot you will tie in to.
A vacuum gauge is one the cheapest, easiest to use, and most valuable tools in the toolbox. I couldn’t live without one.
Thanks for your support. I hooked up a vacuum gauge to the line from the PCV valve and got right around 17 inches. Needle was solid on 17. Spark plugs were replaced a couple months ago, although copper were used rather than the more expensive platinum version. They are OEM brand, nothing fancy. Again, no change was observed after they were changed. I am out of time since it is now at the dealer for a alignment and rotate and I told the owner to bring up the MIL light, so maybe they will find the issue. Again, thanks for your assistance.
Well bad news, dealer thinks it is a receded exhaust valve and wants to pull the head to check clearances. They have no record of the owner asking to have the valves adjusted even though I have been telling her all along to have them adjusted. No clue what we are going to do with it at this point.