2001 CR-V P0301 Code

[cassius987]

Context: hadn't changed oil for about 4000 miles (50-50 highway-city) and had just bought supplies, father-in-law just changed spark plugs for me ten days and 800 miles prior to malfunction indicator (MIL) coming on. Also had just added Heet fuel injector cleaner/antifreeze for the first time in ownership history (some 50,000 miles).

Incident: Driving home from work, MIL comes on. Checked it at O'Reilly's today, get code P0301 or Cylinder 1 Misfire Detected. Several possible causes (base engine mechanical fault, air leaks, fuel delivery component fault, or ignition problem) but what really stuck out to me was the possibility that a spark plug was involved (i.e. ignition problem). However I had already driven it 800 miles on I-70 from MO to CO and performance seemed fine most of the way, with some sluggishness getting into CO I assumed may have been the elevation/slope acting on the not-so-powerful engine. After all the 2001 CR-V has never been that powerful and always gives me a little grief on the highway over speeds of 70-75 mph on a hill.

What do you all think? Could a spark plug cause this issue even after so many miles on the highway? Or am I better off looking elsewhere? How much can I safely drive in the city with this misfire detected?

[Blue12EXL]

If the valves have not been adjusted in the last 30-50 thousand miles I would start there.

[cassius987]

Talked to father-in-law, he wants me to tighten the spark plug a bit with a socket wrench. I've never messed with spark plugs before, is it going to be hard?

I don't know what you mean by adjusting the valves. What valves exactly and how is this related to a misfire?

[Blue12EXL]

The intake and exhaust valves need to be adjusted on the older generation CR-V much more often than the newer models. The exhaust valves tend to get tighter over time and if they are not adjusted on a regular basis you can end up with a burnt valve which will require the cylinder head to be removed and an expensive valve job. If you have not had the valves adjusted do that now before you cause any damage. If you are not familiar with this very necessary maintenance take it to a reputable shop.You asked how this is related to a misfire, when the clearance of the exhaust valve is too tight the exhaust gas will escape past the valve because it is not closing all the way . The valve must close all the way to transfer the heat from the valve to the cylinder head, then the head is cooled by the coolant circulating through the engine.

[cassius987]

Thanks for the explanation. I do want to get the valves checked but I don't know a good shop to take it in Denver (any hints appreciated). It seems like it's sort of a Honda-specific issue? My father-in-law is a good shade-tree mechanic who keeps lots of cars running for the family and doesn't seem to know about routine valve maintenance.

As a test I checked the spark plug fit for that cylinder and it was fine, then unclipped the battery for a minute and reinstalled and the MIL did not come back on. Need to take it for a drive to really be sure. Either way, want to get it looked at somewhere so I don't have bigger problems down the road.

[Blue12EXL]

Most cars now have hydraulic lifters but the Honda 4 cylinder engines use roller tip rocker arms that need periodic adjustment. When you disconnect the battery the code will clear for a while. Don't be fooled thinking it is fixed. You should have a Honda dealer in your area. You need someone that is familiar with this adjustment perform the service. Sounds like you have someone that can help with other basic maintenance. How many miles does the vehicle have on it. If it has over 100,000 miles has the timing belt and water pump been replaced?

[cassius987]

Mileage is 113K. Not sure about either of those--I've owned this thing for 50K miles and I doubt these things have been replaced if they are "late stage"/high mileage maintenance issues.

[cassius987]

I've driven it for a couple days for just a few miles each, easy in-town trips. No MIL yet. What I'm planning to do is get the valves adjusted somewhere in/near Denver (hopefully a place that knows what it's doing). I don't know if the timing belt or water pump also need replacing, are there diagnostics to check?

[Blue12EXL]

Based on your mileage and the age of the car the timing belt and the water pump are due to be changed. The water pump is usually changed at the same time as the timing belt because they are in the same area and the amount of work to get at each part is the same. It is important to change the timing belt on schedule because if it breaks while the engine is running the valves will be bent by the pistons smashing into them. These engines are what is known as interference engines meaning if the cam and pistons get out of time with each other when the timing belt driving the camshaft breaks it will cause major damage inside the engine.Starting in 2002 the timing belt was replaced by a chain that will last the life of the engine. I would have the valves adjusted at the same time as the timing belt and water pump. If I am not mistaken the interval for your car is every 105,000 miles. My 1994 Accord calls for a change every 90,000 miles. It has 194,000 and has been changed twice. Another maintenance item you have not mentioned is the transmission fluid change. It is best to change the transmission fluid every 30,000 miles with genuine Honda fluid only. This is something you can do yourself easily enough for the cost of 4 quarts of fluid.

[cassius987]

Thanks for your advice. As previously stated I cleared the code and have driven for about 160 miles since because this is my only real means of transportation in winter (other times of year I'm a cyclist). Today I drove up to Broomfield, CO and got another MIL code while idling at a stop light, although just prior I felt the engine was struggling a bit as the car went uphill. Got back home to Denver just fine... 21 MPG at the halfway mark, which is low for me. (Normally between 25-30 MPG.)

I checked the transmission fluid and it was gray in color. My father-in-law said this was suspect. As you indicated 30,000 miles is the interval to change it and I've driven the car longer than that so this is probably another thing to address.

I think I'm going to start e-mailing local Honda-specialized/affiliated mechanics and get quotes for this handful of maintenance. I think if I read you rightly we're looking at a valve adjustment, changing the transmission fluid (not hard right?), and probably the timing belt and water pump. What is a realistic estimate?