Speed Kills

2000 CRV, B20/5 speed.


Came in with a random misfire code, sputtering, definitely not running properly. Fresh plugs and wires, no difference in how it runs. New Distributor, still throws code, sputtering gone, clear code, code still returns. Put the old distributor back on, now runs, throws code for different cylinder misfire.


We've cleared the code multiple times, and it stays off at idle no matter how long you let it idle, but comes back on after application of throttle.


This is boggling me. I've never seen one do this. Any insight?

eghatch4sale

Bad valve ..... How much do u wnt for it ?

Speed Kills

Funny....it's not mine anyways. Haha.

It runs 100% perfect now. For some reason just keeps throwing the Cyl. 4 misfire code upon driving it/revving the engine.

JDM_Ej

Common problem... the valves were not adjusted properly and they become too tight and recess into the head, which causes the misfire.

How many miles on it? You can try a valve adjustment, but you will likely have to replace the head.

Speed Kills

176K, as far as I know, it's never had a valve adjustment, unless it was done with the T-belt, which we did not do.

It doesn't miss anymore. It's still picking up a misfire code for some reason after it runs perfectly fine.

I highly doubt something is fouled up with the head. The compression/leakdown was perfect, and it's not missing right now, at all. It came in having a steady miss that progressively got worse over time that a distributor cleared up, but It still has a misfire code. The "bad valve" theory does not explain the miss being cleared up. It points to something in the ignition system, and I'd think the comp/leakdown would be enough to squash that theory as well.

If there was "something wrong with the valves" to cause it to have a misfire, it most certainly should show up in the compression/leakdown test. So now I'm extremely confused.

JDM_Ej

I agree with you there. It wouldn't get better if it was the valve/head issue, it would get progressively worse.

Hope you find the fix!

Duane_in_Japan

You need scan data to monitor what is going on OR hook up a portable oscilloscope and a technician who knows how to read spark lines can tell what is going on inside the engine based on the heartbeat of the spark plugs. If you know what to look for you can see mechanical problems, injector problems, spark delivery problems, compression and timing problems, or look at the sensors that would report the misfire (CKP, CMP) and see what kind of signal are they producing and what is the amplitude in case the sensor is misadjusted.

What is the MAP sensor voltage going back to the ECM at a fully warmed up idle with no accessories on, should be just a hair under 1V DC, use a digital multimeter to test. Above or below this means you need to clean the throttlebody, IACV, recheck and if still not in spec, do a valve adjustment.

raidacaipo

Sometimes the check engine light goes away but its temporary. Trust me he needs to replace the head or replace the valves. This also happened to my CRV b20z2. I also got random misfire codes. After changing the spark plug wires, spark plugs, distributor, cleaning the fuel injectors and tried doing valve adjustment the motor starting dying slowly. It was so bad to the point where the whole car started to shake everytime I turn it on. I couldn't even adjust 3 of the exhaust valves cuz my filler gauge wouldn't go in between. Then I decided to replace the head and I found out that the valves were so bad on 3 cylinders. Also the headgasket was bad. Just 3 days ago I replaced it with a new head gasket and a p8r head and it runs perfect! no check engine lights either.

ADVICE! REPLACE THE HEAD REGARDLESS OF WHAT YOU SAY!

Problems - Bad headgasket, burnt valves

*note - B20 heads are notorious for giving out when you don't adjust the valves. From research, the valves should be adjusted every 30,0000 miles and not just "adjust only if noisy" as stated by the manual. You said the valves has never been adjusted and after 176k miles? I'd say your valves are definitely gone.. regardless of the compression/leakdown test you did.

If you really want to find out, remove the head and inspect it.

Duane_in_Japan

A compression test or leak down test will not show sunk valves, they are still seating good but the overall lift and duration are affected lowering the HP of the engine overall. This should be noticable while the engine is running while monitoring a vacuum gauge. A good technician can also see low vacuum on the Spark Line while viewing spark on an oscilloscope. It takes some good training to see mechanical problems via the spark line on the Oscope. I also believe that the MAP sensor output voltage will be affected since it is directly proportional to vacuum, thus affecting fuel delivery thus affecting, well, you see what I mean.