numotive

I recently did a valve lash adjustment for the first time and after driving for a good 20 miles or so, I threw a check engine codes 71 and 74 (misfiring on cylinders 1 and 4). Would I be right in assuming that a bad valve adjustment can cause misfiring? Or could it be something else that is causing those cylinders to misfire? Has anyone had this happen before? Thanks!

Dogginator

Yes, tight valves can cause misfires. It is effectively the same as a bent valve because the valve is not sealing properly.

goota

yeap, like dogginator said. Just go back and re-adjust them, it gets easier every time, before you know it, youll be able to do valve adjustments with your eyes closed.

numotive

ah ok... thanks guys! I guess i probably made them a little too tight.

how much drag should there be when i drag the feeler gauge between the gap? a lot or just a little?

.xcalibur.

it should be tight enough where a feeler gauge that is 1 size bigger will not slip through. So if you're aiming for .007", then adjust it so that .008-.009" will not fit.

crvglenn

I am currently troubleshooting my own problem on my 2000 honda crv with a misfire on cylinder 2. Performed a valve adjustment and noticed I was not able to loosen one of the valves on cylinder 2 beyond .003 in, very tight. I believe I am in the correct position, cam lobes pointing out. I assume this misalignment is causing cylinder 2 from firing because the check engine light is constantly flashing during idle. What could cause this valve to be so tight and unadjustable? Does the head need to be repaired/replaced? Does this mean the valve is burnt? I removed the spark plug from cylinder 2 which produced no effect on the idle. Unfortunately this does not confirm whether the misadjustment or a burnt valve is causing the misfire.

Anyway, from my research and understanding, a tight valve means it stays open to long which prevents the cylinder from firing. Yes misaligned valves especially tight valves are likely to cause misfires. Not likely with loose valves because it stays closed longer.

Feel free to correct me if this is not accurate.

CRVGlenn

Solster

if it's too tight the valve will not close and there by seal the cylender and biuld copression. when this happens there is no power generated by that cylender also when the plug sparks the fuel mix in the cylender can fire and if the valve is an intake it will disturb the airflow of the intake and make the car run like crap also as the burning fuel jets past the small opening of the valve head is heats up even more and startsto super heat the valve and over time starts to melt the valve. this is called a Burnt valve and when this happens you will need to pull the head and have it rebiult. the pix below ar the burnt valves i pulled out of my GSR head.

TheRealTegger

This is the problem. The factory method is WAY too finicky and difficult for most people.

The easier and more reliable way is to have the lobes pointing UP. Post back here if you want to know how to do it this way. You could do a search of this site instead, to find my previous posts on this matter, but the search isn't too reliable.

kchungb17a

B20 CRV's had problems with sinking valve seats. A sunk valve seat would cause the valve stem to extend further than intended, reducing the gap between the valve tip and rocker arm.

When adjusting valves, I recommend always having the piston for the cylinder you are adjusting at TDC for compression stroke. It isn't difficult to do at all and it guarantees you are set up correctly. Just check the timing marks, either on the crank pulley or cam sprockets and make sure valves are in closed position.

t_hickey

Ok I also have a problem I am not able to post a thread yet do I hope you don't mind if I try to get an answer for my problem. I have a 94 integra it's turbo charged. I'm boosting 10psi on stock internals. I just (3days ago) rebuilt the bottom end and also had the top end cleaned and the valves re ground to the seats. I haven't checked my valve lash yet but I will after reading this. My problem is no power band at all... From 4500 to 8000 there's no go, back firing, rpm jumps around. Now I know quite a bit about hondas in general so I have looked at the dumb crap that it could be. I haven't checked vtec but it shouldn't fall as hard as it dose even if it wouldn't engage. The car has been tuned at ma performance and I've done nothing to mess with it. This little guy used to put down 398 whp a now it's just sitting someone please help me think of something I missed or need to check!!!! Thanks

TheRealTegger

That was '99, '00, and '01 only. Honda's TSB 03-038 outlines the details. Apparently the problem is indicated by valve clearances that are down to .09mm, or .003", just what the OP reports.

Unfortunately, OP's CR-V is a 2000, which means the TSB covers him. I should have looked this up before posting my own message.

Whoever wants a copy of that TSB, PM me.

kchungb17a

I thought it might have been specific years only, but I couldn't remember exactly which. Just thought his had to be affected due to the description. Thanks for clarifying.

This is not a good way to get your problem resolved because people that can help won't know that your posting a problem that is buried in someone else's thread. I know you can't start threads yet, but you're almost there.

I'm inclined to think you have a VTEC problem. I assume you have a GSR engine. 4500 rpm is the engagement point for VTEC on this engine. Did your tune shop use an ECU that is IAB capable? Check for VTEC engagement.

t_hickey

I checked it I have the 12v key on and the selinoid opens when I jump 12v direct. Cleaned it inside and out screens are clean new oil. Not using gsr intake I have a ported type r intake so that has been flashed out. I did go and wash out the engine bay since my dirty hands were all over it today I might have gotten te distributor a little wet I did my best not to.... I had problem starting it after ward and when I finally did and I tryed getting on it I had same problem at low rpm... Im using an mad cap with an external coil. So no Im thinking ignition I do have new plugs and they are gapped correctly so any new ideas?

kchungb17a

Make sure there's no water in the distributor cap and coil connections. But I'd recommend going back to your OEM distributor. It can easily handle your setup and is the most reliable. Check your spark plug tubes to make sure there's no water in them. Blow them out if there is.

t_hickey

I had my oem distributor on at first problem was there then I switch back to see if it would change nothing... No boost leaks but watching my gauge it will make 4 psi then **** out ... Air fuel is running 10 so I got fuel

kchungb17a

What kind or plugs are you running?

Maybe you have a turbo problem in which case the forced induction forum may be your best bet.

t_hickey

I got it fixed I took my gap down to .25 (ngk coppers) and replaced my injector resistor box now she's running like a champ

el crapitan

interesting. i thought it was due to the longer service interval that honda had designated for the crv specifically. 99-01, i assume, would have tighter clearance due to the higher compression phk pistons utilized in the b20z. i guess the tighter clearances coupled with the higher compression are what make the 99-01's so susceptible

kchungb17a

A longer service interval could possibly result in a looser valve clearance actually, due to more time for the metal to wear away and opening the gap. I assume Honda upped the interval because they realized it could go longer without adjustment, possibly through improved materials or simply r&d. I don't see how higher compression pistons would effect valve lash.

In this case there must have been some problem with the manufacturing of the head or the valve seats to cause them to sink causing the valve stem to protrude so far into the rocker arm that the OP could not adjust the gap to spec despite backing the adjusting screw all the way out.

el crapitan

lash is decreased on the exhaust side over time. the valve face pounds into the seat, lowering clearance to the point that the face no longer makes good contact with the seat and therefore loses the ability to dissipate most of it's heat. it increases on the intake side, as carbon build up holds the face away from the seat and furthers the distance between the tip and follower.

certainly a longer interval will increase the chances of burnt exhaust valves. and that's why, from my understanding, the b20's earned the reputation for burnt exhaust valves. i mean, the casting is identical to a b18b. no difference. only difference is service interval for valve setting. i reckon the us did this to attract sales. they stated 100k intervals. euro and japan markets stated 50k. same as integra.

and the reason i figured the higher compression for the z was a factor is simply higher chamber temps. that, coupled with tighter clearance tolerance, and the same service interval.

but it's funny, cuz people with integras don't adjust their valve clearance every 50k either. and they aren't burning. same cast. maybe an issue with the fuel parameters on the crv? i dunno

gezatozser

I seems to me, very hard to get an answer for my question.
What is the VALVE LASH FOR A HONDA CRV?
THere is just writting, this or that for every one, this lash is small, that is to big.
Please send an answer to geza57@aol.com because it is better to me to get it.

f22b2

Hey guy
I own 90 acura integra with jdm b16a I found out my knock sensor was broke so I replace
But I still getting the same code and I just found out
I need valve adjustments its that can be a reason to get the code or can be other thing
and my vtec don't kick
and I didn't know b16a are high compressor so I put regura gas and not premium fuel can that affect too
​​​​​​​My 2 cylinder spark plug died