Ok, I'm at wits end with this. I have a 2011 Honda fit. This has been an ongoing issue. A few weeks ago my car just lost all of its ability to exceed 3000-4000 RPMs. I got the vehicle home and tried to read the codes by shorting out the pins 4-9 on the diagnostic connector as per a thread on this site. the results pointed to the second cylinder as firing incorrectly but I thought I was reading the flashes wrong.


I read that this problem could be cause by bad gas from the summer to winter change over. this too was a thread on this site. I tried to burn off the gas, but damn the thing gets great gas mileage so this did not workwell. I had the car towed to a mechanic who I know is good. The shop takes care of most of the police fleets and they take care of a number of fleets from companys who I know well. they are a busy group of mechanics.


Anyway, they confirm that its a random problem with cylinder 2 but they cannot isolate it. They want to try replacing the computer. They get a used one and program it. They tell me they can do this as they have all the needed equipment to configure the system as per the Honda dealer. They replaced the computer,, so they say, and all is well for 15 minutes and thenn the computer dies, or so they say. I'm not sure what to do. If the codes zeros in on cylander 2 misfire and they change out all the parts related to this, ie. the spark plugs but the problem remains what would it be?

 

Honda may give you the option to flash the CEL, but is isn't supported anymore. What code/codes did a generic OBD2 scanner give you? I assume you are US based since you called it "fit" and not "jazz."

Winter/summer fuel change over? How many gas tanks do you have on your car? Mine has 1 tank I bet yours does too. Why do you think bad gas will affect 1 cylinder and only 1 cylinder? Fuel seasonal blends don't cause flashing check engine lights, they cause doggy performance when the season doesn't match the fuel.

You took the car to a grease monkey. How do I know that they were a grease monkey? Because the failure rate of Honda PCMs is less than 1 unit per 100k cars. Much like Honda fuel pumps PCMs do NOT go bad.

An automobile engine needs very few things to work. It needs fuel, spark (at the proper time), and compression. If it has all of those things in the proper quantity at the proper time it will run. Your fuel is delivered by the fuel injectors. Your spark is controlled by the PCM and delivered by the coil packs. Compression is internal engine components. A GOOD mechanic would be swapping injectors and coil packs between cylinders and checking to see if the problem moved. If the problem stayed in the cylinder if started with then they would be performing a compression test and checking valve clearances. Your "good" mechanic appears to have went straight for the parts cannon guess on a zero failure rate item.

You should have just taken the car to your local dealer when the problem started. $100 or so diagnostic fee is cheap compared to idiots throwing out random guesses and replacing components like PCMs.

This is just my advice you can take it or leave it.

 

That was helpful

 

And since I'm not a mechanic I lack the expertise to even explain all that they did and now I understand what they have done. As they did explain that to me. Despite your blanket statement I'm pretty sure they have a massive garage and are extremely successful. I was looking for help not insults but every time I'm come here for help I get insults. Such a great place to come to. God how I hate the arrogant

 

A quick addition to my previous post. I have been at a honda dealer for more than 10 years in the last 14. The time spent away from Honda was spent at a toyota dealership. In that whole time I have seen exactly 1 OE platinum/iridium plug that was actually bad. NGK and Denso plugs also have an insanely low failure rate.

The only times in recent years a misfire could be tracked to a bad plug, that plug was also oil fouled which is not a problem with the plug it is a problem with that car.

The "good" mechanic wanted to change out the spark plugs is another indication that they are not "good" at what they do. A good mechanic would realize that you drove in with 3 "known good" spark plugs residing in cylinders 1,3, and 4. They would realize that they could move plug 2 into any other cylinder and see if the problem moved with the plug. This method also works with coil packs and injectors (on non direct injection engines)

 

That's what the dealer did, when I had a misfire on cylinder 3, they moved the plug to another cylinder and the code still showed on cylinder 3, so coil pack was replaced under warranty

 

Coils and plugs have been replaced too

 

At ~26K, my 2011 Sport AT had a CEL and the codes read by a local parts store showed misfire in #2.

I took it to the dealer and they ran diagnostics for $50 and changed a coil pack on #2 for $160. I asked for the old coil pack and it smelled like gasoline. Odd

Within a 3 days, the CEL was back on and codes read misfire in #2 & #3. Then it hit me, why would a coil pack smell like gasoline when it is "outside" of the engine?

The spark plugs were lose on #2 & #3. Not sure why the plugs would come lose when no one ever touched the engine. I had to take off the windshield wipers, air system, etc to get to the back of engine to properly torque the plugs.

I reused the "bad" coil pack, as a test, and no misfired. So, it was never a coil pack but a lose plug. Plugs were still good too.