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Bucking Bronco Honda

I own a 2004 Honda CRV-Ex. I bought it new and it now has 308,000 miles. I have a 60 mile commute each direction.
Background:
Earlier this year I had the timing chain replaced at the Honda dealer.
The check engine light goes on and off but it recently passed inspection in April.
I had a cracked crank shaft seal and this produced a big oil leak, which caused me to have to check the oil and add oil quite frequently. But, I got it fixed in April, so there is no leak now.
Problem:
3 weeks ago I was driving on the Taconic SP and when I tried to accelerate up a hill it started to buck. The same thing happened to me a long time ago when I let the oil get too low, so I thought that was the problem. (Honda explained that it is a built-in feature to prevent one from burning up the engine.) I pulled over, checked the oil and sure enough, it was too low. I went overboard and added 2 quarts of oil. I thought that would solve the problem. Nope. It continued to buck and chug, especially on uphill and acceleration. After that weekend I took it to a local mechanic. He thought an oil flush and change would fix it, but he said I had a “sh…load of codes” with the check engine light. After the oil change I drove about 40 miles and it did it again. I pulled over, waited a bit and continued my commute. It was fine until I had to slow down and try to accelerate again.
So, I brought it to my regular mechanic. He added thicker oil. He changed the cooling fan and a selonoid, checked the codes and $700 later, it still had the same problem.
I brought it back and he changed the catalytic converter and it still did the same thing after about 20 miles.
I brought it back and he put back my old catalytic converter so I wouldn’t have to pay for a new one.
Now he thinks it may be some oxygen sensor. I am supposed to bring it back to him and leave it for 2 days next week.
I can only retain a sense of humor through all of this so I thought of your show! Any suggestions? HELP!!!

What are the codes it throws?

If the engine bucks under a load, the fuel pressure/volume should be tested.

Tester

Being a non-mechanic, I am not sure what the codes are.

If the check engine light is on or has been on at one time, it means that something went wrong. The car flags what was wrong with codes that can be read by a special reader. Places like Autozone and Pepboys will read those codes out for you for free. Just report back with those here.

You don’t need to be a mechanic to get the codes. Many auto parts stores will read the codes and give them to you for free. They are alphanumeric, like P0123 or something similar. If you can get those codes and post them here, some of the more knowledgeable folks can help you.

Thank you. I will get the codes and get back to you!

It is so very hard to guess with the info supplied, but it sounds like your mechanic is just guessing what the issue maybe… He is thowing parts at it, hopeing to fix it… That is not good…

Since it maybe oil related (or may not be), I am going to guess and it is strictly an educated guess… I think the oil pressure switch on the VTEC cams on your CRV is no longer working… You CRV has two intake cam shafts, one for low RPM, and one for high RPM… A oil pressure switch engages the high RPM cams when the oil pressure gets to a certain point… It sounds like the high RPM cam is sticking OR not engageing correctly… This would explain why it is so intermitant, and why playing with the oil can make a differance…

Like I said just a guess, but I think its worth checking out.

I don’t want to sound critical from here . . . but it looks like your regular mechanic is just throwing parts at it and hoping for the best. Before engine sensors became the cool thing to look at, we actually had to diagnose problems like this without computers. I think that I might look for an independent mechanic who does a lot of honda work Look for an older guy . . . like some of us here . . . over 50 who know how to use diagnostic tools besides just reading codes and replacing parts. One more thing . . . I cannot imagine how an oil flush and change would be suggested by any mechanic for the symptoms you report . . . like bucking and chugging, no way at all. Or the other things you paid for . . . a new fan sensor . . . thicker oil . . . for engine bucking? No way. JMO. Good luck! Rocketman

Thank you for your comments. I was avoiding a Honda dealer service because they always seem so expensive, but do you think he (Honda-man) would have any better luck. I will definitely take these suggestions to whoever I go to.

You need a new mechanic. This one sounds honest and well meaning, but lacking in diagnostic skills.

First, follow Remco’s and Whitey’s advice. Get the codes read and post them here.

Second, learn to monitor your fluid levels more regularly. If Gsrag is correct, and he may well be, it is possible that running on low oil has caused the variable cam system to gum up. Your engine uses the oil almost like a hydraulic fluid to engage the high speed cam.

We’ll come back with some ideas when you post the codes. My first guess would have been the same as Testers, but if I start guessing wildly I’m no better than your current guy. But keep Tester’s suggestion in mind. Testing the fuel pressure may be as good a place to start as any other.