2004 honda crv 250000 gettin coed of random misfire(for a...

Hello and welcome! My name is \*\*\*\*\* \*\*\*\*\* I can assist you with your question. I am a former master tech and I have worked in this field for 20 years. I specialize this type of problem you are experiencing so I am confident I can assist with this issue. I am sorry you are having this issue and I understand this can be frustrating so I will try my best to help. While we are working on this issue together, please allow up to 30 minutes (or more) between replies as I might be online helping other customers or offline spending time with family. Please understand I can only see what is on this page and what you have already shared with me. Please keep in mind, I don’t know the history of the vehicle and I don’t know your mechanical ability, however, I will try my best to help. The phone call prompts are automatic and are coming from the web site, not from me. If you would like to speak on the phone, please request a phone call on your end and I will call you right away. I am going to start by asking some basic questions to get up to caught up to where you are at with this situation so I can assist you in a timely manner. I appreciate your time and patience while we are working together on this issue. My goal is to provide you with a pleasant experience and ensure all of your questions are answered. Please reply back at anytime so I can fully answer or address any questions or concerns you may have. _Please download or save any documents or images I may send you as they will automatically expire after 7 days._ Can I start by getting your first name? Thank you

doug

Thank you Dog. Can you start by getting the code or codes stored in the computer?

typing is fine

So you know the code or codes stored in the computer?

2004 honda crv - 250000 miles rough idle and rough running...I have had the car for 1 week. plugs appear to be new, however i changed them anyway...no carbon build up and any of them, no streaking showing on the boots, mpg is 23 highway, I drove this 600 miles to get home and ran 3 tanks of gas thru it, 2 with seafoam, and that seemed to help a little but not much... compression is at 165 or 164 on all cylinders.... intake pressure (via a fixd reader- so take that for what its worth) is 58 kpa... getting codes 300, 301,302,304 and evap systeem failure note- but no code. erased all codes , ran it for 20 miles and they came back battery is new and checked out fine,,, I would guess its NOT an injector, as this is coming up random...I was thinking fuel pump, but what about a dirty egr valve?

Thank you. The most common cause for a rough idle condition on this vehicle would be mis-adjusted valves or an air/vacuum leak. Your best bet would be to start by checking for vacuum leaks under the hood with the engine running (as long as it idles). A good visual inspection might reveal a simple/obvious vacuum leak causing these codes. Look near the throttle body and gasket, intake manifold and gasket, vacuum hoses and lines and even at, around and near the brake booster. Fix or replace anything that is leaking vacuum. Sometimes these are obvious once you pop the hood. If not, it may need to go to a shop to get the intake system smoked checked for vacuum leaks. This should be done by a professional technician at a reputable repair facility. A smoke machine makes it super easy to locate a small or hard to find vacuum leak. [Here is an example of a smoke machine that we use at the shop.](https://www.jbtools.com/redline-95-0003c-smoke-pro-total-tech-3c-with-easy-intake-leak-detector/?gclid=Cj0KCQiAqdP9BRDVARIsAGSZ8AkycuSs7fo7AHdouD3x__7_JTrxuZZRRyTh15KhzeAvTmLJhWtYvBEaArMMEALw_wcB) Once the vacuum leak is located and fixed, you can retest the system as needed. If the problem remains and there are no air/vacuum leaks, then we check engine vacuum using a hand held vacuum gauge. A careful study of the vacuum gauge reading while the engine is idling will help pinpoint trouble areas. You can measure engine vacuum at any vacuum hose or line coming from the intake manifold while the engine is at idle. Always conduct other appropriate tests before arriving at a final diagnostic decision. Vacuum gauge readings, although helpful, must be interpreted carefully. Most vacuum gauges have a normal band indicated on the gauge face. The following are potential gauge readings. Some are normal; others should be investigated further. NORMAL READING: Needle between 51-74 kPa (15-22 in-Hg) and holding steady. NORMAL READING DURING RAPID ACCELERATION AND DECELERATION: When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure. NORMAL FOR HIGH-LIFT CAMSHAFT WITH LARGE OVERLAP: Needle will register as low as 51 kPa (15 in-Hg) but: will be relatively steady. Some oscillation is normal. WORN RINGS OR DILUTED OIL: When engine is accelerated (dotted needle), needle drops to 0 kPa (0 in-Hg) . Upon deceleration, needle runs slightly above 74 kPa (22 in-Hg). STICKING VALVES: When the needle (dotted) remains steady at a normal vacuum but occasionally flicks (sharp, fast movement) down and back about 13 kPa (4 in-Hg), one or more valves may be sticking. BURNED OR WARPED VALVES: A regular, evenly-spaced, down-scale flicking of the needle indicates one or more burned or warped valves. Insufficient hydraulic valve tappet or hydraulic lash adjuster (HLA) clearance will also cause this re action. POOR VALVE SEATING: A small but regular down-scale flicking can mean one or more valves are not seating. WORN VALVE GUIDES: When the needle oscillates over about a 13 kPa (4 in-Hg) range at idle speed, the valve guides could be worn. As engine speed increases, needle will become steady if guides are responsible. WEAK VALVE SPRINGS: When the needle oscillation becomes more violent as engine rpm is increased, weak valve springs are indicated. The reading at idle could be relatively steady. LATE VALVE TIMING: A steady but low reading could be caused by late valve timing. IGNITION TIMING RETARDING: Retarded ignition timing will produce a steady but somewhat low reading. INSUFFICIENT SPARK PLUG GAP: When spark plugs are gapped too close. a regular, small pulsation of the needle can occur. INTAKE LEAK: A low, steady reading which can be caused by an intake manifold or throttle body gasket leak. BLOWN [HEAD GASKET](/topics-head-gasket-honda/): A regular drop of fair magnitude can be caused by a blown head gasket or warped cylinder head-to-cylinder block surface. RESTRICTED [EXHAUST](/topics-exhaust/) SYSTEM: When the engine is first started and is idled, the reading may be normal, but as the engine rpm is increased, the back pressure caused by a clogged muffler, kinked tail pipe or other concerns will cause the needle to slowly drop to 0 kPa (0 in-Hg). The needle then may slowly rise. Excessive exhaust clogging will cause the needle to drop to a low point even if the engine is only idling. When vacuum leaks are indicated, search out and correct the cause. Excess air leaking into the system will upset the fuel mixture and cause concerns such as rough idle, missing on acceleration or burned valves. If the leak exists in an accessory unit such as the power brake booster, the unit will not function correctly. Always fix vacuum leaks. Most gauges are graduated in inches of mercury (in.Hg), although a device called a manometer reads vacuum in inches of water (in. H 2O). The normal vacuum reading usually varies between 18 and 22 in.Hg at sea level. To test engine vacuum, the vacuum gauge must be connected to a source of manifold vacuum. Many engines have a plug in the intake manifold which can be removed and replaced with an adapter fitting. Connect the vacuum gauge to the fitting with a suitable rubber hose or, if no manifold plug is available, connect the vacuum gauge to any device using manifold vacuum, such as EGR valves, etc. The vacuum gauge can be used to determine if enough vacuum is reaching a component to allow its actuation.

It has been a pleasure working with you so far. Keep in mind this is a “starting point”. We can always continue as needed at a later date or at any time. Feel free to run some tests and reply back for further assistance as needed. My goal is to provide you with excellent service. If you have follow-up questions on this same topic, please use the reply box below. To start a new conversation with me on a new topic, you can [request me here](http://www.engine-misfire.com/justanswer-downloads/). Glad I can help. Please let me know if you have any further questions. Thanks and have a great day!

next step was a vacum leak test ( I have to use carb cleaner) so your guess is NOT a fuel pump, or injectors

No. As long as the fuel injectors are not leaking (which would not be very likely), a low fuel delivery concern would not show up at idle. It would only affect it under a load. Since the issue is happening at idle, this means it is likely a vacuum leak or tight valves. Most likely you simply need a valve adjustment.

ok - that gets me farther down the right direction other places have said the same --- what is the proper valve adjustment, and spark plug gap?

Click on the links below. [https://www.dropbox.com/s/cxegiwx5z8ucw4t/spark%20plug%20gap.pdf?dl=0](https://www.dropbox.com/s/cxegiwx5z8ucw4t/spark%20plug%20gap.pdf?dl=0) [https://www.dropbox.com/s/wwzs2rsug8croka/valve%20adjustment.pdf?dl=0](https://www.dropbox.com/s/wwzs2rsug8croka/valve%20adjustment.pdf?dl=0)

ok thanks- I'll check those out ( and vacuum) thanks for the help - I was leaning towards a fuel pump - a 200$ hypothesis....LOL thanks again

You are most welcome!

doesn't appear to be vacuum - when sprayed with carb cleaner there is no noticeable change in rpm's, so Im gonna assume valve adjustment..( hopefully not a burnt valve). one other thing - maybe a mass airflow sensor? or other sensor?

Nope, check engine vacuum next.

no change upon sspraying around cylinder head also

Ok got it!