Unexplained Honda troble

My car has been misfiring, the throttle has been replaced, and spark plugs and coils are new. Month later engine light on and the engine light starts blinking. Checks out it’s misfiring again. The Honda dealership now has changed out the spark plugs and coils again. Fuel injection cleaner fluid called sea foam has been used and gas cleaner. The light has come on again jerking but this time it comes on and blinks or it just stays on and don’t blink. The Honda place said they couldn’t find anything else and to drive it and then bring back after I try using a higher grade in gas.

What is the model year and mileage on your hybrid Accord?

The next time the check engine light comes on, take it to an auto parts store that will read the alphanumeric trouble codes for free and post those codes here. Post the actual codes, not the clerk’s/mechanic’s interpretation of those codes.

Ok I will it’s a 2006 Honda Accord hybrid and the last codes read was codes for misfiring I left the dealership with the light on because they said the diagnostic didn’t pick up anything as a problem. That’s crazy!!!

Like he said.

Another poster here @Nevada_545 claims that’s common for misfire problems. Apparently a diagnostic code isn’t posted just b/c there’s misfiring happening during a particular drive cycle, even though the CEL light is flashing. For a diagnostic code to be stored there has to be subsequent misfiring events on other drive cycles. I was sort of surprised to hear that too.

I have no experience with hybrids, but assuming misfires are caused by the same thing as on non-hybrids, you are looking at a problem with one or more of these

  • coils
  • ignition module
  • spark plugs
  • wiring
  • bad gas
  • fuel pressure
  • clogged injectors
  • clogged exhaust system
  • clogged engine air filter
  • engine compression or other major mechanical problems with the engine

It sounds like your shop is doing all the right stuff. Is there a reason they suggest to use a higher grade of gasoline? Did you put a brand or type of gasoline into the gas tank just before this started happening that you normally don’t use?

We are having the same problem with our Honda. We also have replaced coils and plugs. We have heard from a similar Honda owner and from two reliable mechanics, the problem is most likely a needed valve adjustment. So that’s the direction we are headed. Hope it helps. Here is Yumacat’s prior reply to my very similar post:
We own two 2008 Honda Fits. The valves do need to be adjusted around 80 to 120,000 miles. Long story short, a mechanic told me my problems were a timing chain after I replaced my coils and plugs and it didn’t help much. (You can get some decent coils without it costing a fortune - about $250 for all four.) The Honda dealer said it was a timing chain, but that didn’t sound right to me, so I did a DIY search with my symptoms and found several resources on how to adjust the values yourself. It is not fun and you have to be careful, but it can be done. The exhaust valves tend to work their way closed (which can damage your engine and make it run terrible.) The intake valves tend to work their way open. After the valves we’re adjusted, it ran like new. I have 185,000 on the one I drive and still going strong. My wife’s has about 140,000 on hers, and I just adjusted her valves because it was running rough, as well as replacing the coils and plugs. Same dramatic results as when I did mine.

Does “higher grade” mean that they recommended the use of premium/high-octane gas?
If so, that recommendation is bogus.

On the other hand, if “higher grade” means that they recommended the use of gas from a brand that complies with Top Tier guidelines for detergents, then they were on solid ground.
Using Top Tier gas is unlikely to prevent misfiring, but using it is a good thing for the fuel system and the intake valves, as it keeps things much cleaner.

Can you clarify what “higher grade” means?

Do you think this might be an issue with variable valve timing? It’s such a sophisticated and complex system that I’m hoping my next car doesn’t have it. I’d rather have an under-powered four-cylinder economy car than something that unreliable.

Interesting point. I don’t think it does have to do with variable valve timing in particular. Honda has had variable valve timing since the early 1990s and pretty much every vehicle made today has the technology. One of the mechanics here at the group may have a better take on that.

I have adjusted the valves in my 1999 Civic about every 3 years - along with spark plug replacement. Each time several have needed adjustment. The car is running well at almost 180,000 miles. The owners manual calls for valve adjustment if some are making noise, but that is not a wise recommendation. Too-tight valves are more likely to be damaged, and don’t make noise along the way.

If the valve adjustment is out of spec, good chance putting it back in spec will improve engine performance. For 30+ years I’ve checked the valve clearances every 30K on my VW Rabbit and Corolla, but never once found any of the valves to be out of spec. Currently one of the Corolla’s intake valves is right on the edge of the spec range though.