Auto Mechanics, does this sound right?

[Band]

I took my wife's car (2004 Honda CRV) in for a valve adjustment because it was due and because the guys from Car Talk specifically called out the need for that service on this vehicle recently.

For highway driving this car for years consistently had 27 mpg but it has dropped to 24 consistently in the last year or so.  The first tank after the valve adjustment it dropped to 20, an unprescented low, and I can see that the second tank is producing similar results.

I asked the mechanic what he thought about that and he said lower mpg is to be expected right after a valve adjustment and "in about a month" it will improve and get better mpg than before the service.  I always have my BS meter on and this one made the meter glow a little.  What say you, is the mechanic right or is this a line of BS?

[timberghost72]

BS. If your valve adjustment was out of spec and then adjusting them to spec, it would improve milage by some. Either he did not adjust them correctly or there is another issue. Or you figured your fuel mileage wrong.

I would ask him to explain that reasoning and how that is physically possible in detail.

[jackelope]

Are you actually calculating your gas mileage or are you going off what the car is telling you(if it has that feature..?)

I call BS too, but the last valve adjustment I had anything to do with was on an older Cummins.

[Band]

I calculate gas mileage myself.  It is very simple to do, and trust me, my calculations are correct.  Unless someone has a better idea I'll wait until I figure the mpg on the 3rd tank and if it's still down I'll be looking at the service place to make it right.  Can't imagine an unrelated problem that makes such an obvious difference in mpg would hit exactly coinciding with the service.

I'll withhold the name of the place for now but so far they have a couple of strikes against them apart from this issue.

[coachcw]

id try a computer reset first and idle learn . remember winter fuels cause a 10-15 percent drop as well.

[Band]

remember winter fuels cause a 10-15 percent drop as well.

I measure mpg on every tank and I've never seen a drop in the winter.

[jackelope]

remember winter fuels cause a 10-15 percent drop as well.

I measure mpg on every tank and I've never seen a drop in the winter.

That is completely abnormal FWIW.

[HUNTINCOUPLE]

Maybe the squiral under the hood needs a friend?

[HUNTINCOUPLE]

No that would not be correct. Check your rice level and calculate how many grains per mile you get. Then tell the mechanic he owes you a couple bushels of rice.

[timberghost72]

Was that the only thing done at the shop? Any other recent repairs even if you think unrelated?

[Boss .300 winmag]

I have a 1998 civic that has never had the valves adjusted after 300,000 plus miles and still gets 32-34 miles a gallon. 

[Jonathan_S]

No that would not be correct. Check your rice level and calculate how many grains per mile you get. Then tell the mechanic he owes you a couple bushels of rice.

  yeah buddy

[LEN]

There COULD be a logical thing here. The compression may have gone up with the valve adjustment. And if the plugs and wires are on the down hill swing, then plug firing COULD drop mileage.

LEN

[timberghost72]

There COULD be a logical thing here. The compression may have gone up with the valve adjustment. And if the plugs and wires are on the down hill swing, then plug firing COULD drop mileage.

LEN

How would compression go up? IF that was possible, that would mean the valves were so far out of adjustment (WAY too tight) before hand and the car would have been running terrible along with very bad MPG before the valve adjustment. This is not even a possiblity IMO.

[Seahawk12]

Sounds like he (the mechanic) adjusted them wrong and they are now too tight. He probably thinks that in a few months they will have loosened up a bit.
Personally, I would ask a different shop what they think and then confront the original mechanic with some more information.

[dewandgin]

remember winter fuels cause a 10-15 percent drop as well.

I measure mpg on every tank and I've never seen a drop in the winter.

That is completely abnormal FWIW.

Yes it is and if you have a good relationship with this shop. Ask them to recheck the valves sounds like they got them to tight.

[Alchase]

Honda recommends 108k on valve adjustments, everyone in the Honda forums thinks that is suicide!
They recommend 70k, and every 30 k after that.
To many Honda heads done because the valves have not been adjusted.
I would take it back to the guy who did the work and have him make it right.

[timberghost72]

Keep in mind that even though the mechanic gave you a line of BS, the valve adjustment may not be the problem. Something as simple as a vaccum line not put back on or something else not hooked up correctly could also cause your issue. I'd go get a second opinion from a good shop and have them check the valve adjustment just for piece of mind and eliminating that possiblility. Also have them check over the previous workmanship.

[Band]

Was that the only thing done at the shop? Any other recent repairs even if you think unrelated?

They also changed the oil and the cabin filter.  No other services were performed recently and the vehicle is up to date on all maintenance service intervals.  I am in the dark about all but the most simple auto maintenance procedures but I can't imagine the problem could be caused by those.

However, there is another piece of information to consider here.  They checked my air filter during the service and while doing so they apparently manhandled the air filter housing and broke it where it connects to a 1" diameter rubber hose that attaches to the oil compartment.  I noticed this just today when I went to change the air filter.  I took it back to the shop and they recognized their need to replace the broken housing (they have the part being overnighted so they can replace it tomorrow).  When I asked them what consequences could come about by driving around with that connection broken the guy said all it would do is eventually cause traces of oil to splatter around on the engine.  I have no idea how accurate that response was.

[Band]

IF it helps, I'm pointing at the broken connection here...


And yes, they did fail to put the clamp back in place, but with the broken connection that doesn't really matter so much in this case.

[Fl0und3rz]

Sounds like PCV (positive crankcase ventilation) valve connection.  I suppose you might see some mileage change from that, but I'd be surprised if it would decrease that much.

[dewandgin]

and that right there could be the whole problem.. Unmetered air entering the engine downstream of the maf causing the motor to think it is running lean there by making the system add more fuel.

[Band]

and that right there could be the whole problem.. Unmetered air entering the engine downstream of the maf causing the motor to think it is running lean there by making the system add more fuel.

Yeah, I wondered that.  It would throw off the correct air/fuel mixture!

[Band]

I appreciate the help, guys.  After they make the fix tomorrow I'm going to have a discussion with the service manager about why the service guy failed to disclose this problem when he was finished with the job.  I think they have some explaining to do.

[timberghost72]

That is upstream from any air metering. That is right off the air box so there is no unmetered air entering the intake. But it still could cause your issue and needs to be fixed. Look for other vaccuum hoses that could also be disconnected causing vaccuum leaks (unmetered air)

[HUNTINCOUPLE]

IF it helps, I'm pointing at the broken connection here...


And yes, they did fail to put the clamp back in place, but with the broken connection that doesn't really matter so much in this case.

Yep that's the spot! The spot where the rice is injected for proper performance of your fine rice grinder! Thanks for the pic to clarify the rice issue....

[timberghost72]

Wait a minute.........Are you talking Long Grain Brown Rice or White Rice? If fueled with the wrong rice, well then we have a bigger issue 

[Band]

That's the problem, I've been using gas all these years instead of rice!

Say what you want but if you look at reliability of used automobiles in Consumer Reports the CRV tops all the rest.  And last I looked, our 2004 was the best year for CRV reliability.  Gotta like that.

[HUNTINCOUPLE]

See how this works. We talk in depth of true mechanical stuff and if we use the K.I.S.S. method we figure it all out. Short or long grain is better than gas any day.

[timberghost72]

That's the problem, I've been using gas all these years instead of rice!

Say what you want but if you look at reliability of used automobiles in Consumer Reports the CRV tops all the rest.  And last I looked, our 2004 was the best year for CRV reliability.  Gotta like that.

They are great vehicles. My wife has a 2007 and with Goodyear TripleTred tires, that thing is unstopable in the snow. I am impressed with it. Only thing I hate about it is road noise. But overall a great vehicle.

[Band]

Only thing I hate about it is road noise. But overall a great vehicle.

Yes, definitely a problem with the CRV.  We made road noise a big factor when choosing replacement tires and it diminished significantly.  The only other complaint is that the seats are not made with tall Americans in mind so it can be uncomfortable on long drives.

[Band]

The shop replaced the air filter cover this morning.  I thanked them and told them they need to research to find out who checked that filter and failed to report the broken hose connection.  Then I topped off the gas and reset the trip odometer so I can figure mpg on the next fill up.  Hoping for the best so I don't have to bring that valve adjustment back into question.

[xd2005]

I really want to ensure you get this figured out as soon as possible. Therefore, I think you need to drive it down here to use up that gas. I suppose if you're going to drive all the way down here we could go out and try to get me a buck on the last day of late buck...just a thought. 

[Band]

It's too cold outside.  I think I'll stay here with my footed Spider-Man pajamas and sip cocoa.

[xd2005]

Can't argue with that!

[Zardoz]

I don't know much about you're Honda, but did you get this changed?