Too much MMO in gas? Help!

Status
Not open for further replies.
Joined
Sep 6, 2019
Messages
4
Location
Seattle, WA
I have a 2002 Honda CR-V with 260k miles on it, was running just fine, maybe burning a bit of oil. I decided to clean it out a bit and screwed something up.

I ran 6oz of MMO thru a rank of gas, no problems. The next time I filled up I did the same, but that afternoon the engine started sputtering and I'm getting CEL for misfires in 2 of the cylinders, as well as a Random Cylinder Misfire.

I know I messed up because the 2nd time I used the MMO I added it while I was waiting in line to the pump, and the car idled for a minute or two with only couple gallons of gas in it plus about 6oz MMO, so much higher concentration than recommended. I think that was a bad idea!

I'm guessing I dislodged something too aggressively?


What do you guys think is there issue, and how do I go about fixing it?
 
Last edited:
Originally Posted by Miller88
Something else is going on. I've dumped a whole can of the stuff before into a 20 gallon tank and never had an issue.

+1
 
260K miles is a lot. Are they the original plugs? If not, how many miles on them?

All the other ignition and fuel delivery components original? If not, any one or a combination of several could be at fault.

It is a heck of a coincidence in timing, I agree, but I can't see the MMO being the main cause here...
 
Start pulling off plug wires. Start the engine and see what happens. I bet you have a bad coil or wide gapped plug.
 
Last edited:
The spark plugs are OEM, replaced about 12k ago- these are NGK iridium, should last 100k+ miles. I pulled them last night and didn't see any heavy fouling, but will replace just in case.

I don't know what else it could be, I always fill up at the same gas station (Costco), I'm half way thru a 3,000mi OCI, nothing else I did was out of ordinary...
 
Try running acouple gallons of the highest octane they sell around your parts. From now on, use Chevron Techron Fuel System cleaner per instruction on bottle every 3000 miles. Hopefully the higher octane will clean up or help to get you back to idoling again normally.
 
Last edited:
Originally Posted by locomaster1969
Start pulling off plug wires. Start the engine and see what happens. I bet you have a bad coil or wide gapped plug.


NEVER EVER pull off high tension plug wires and start the engine with them disconnected. Al that stored energy has to go somewhere, it can go somewhere unintended and cause further issues. Either ground the wires or put them on a spark plug grounded. If you have coil on plug, then you can disconnect the harness from the coil, there is no stored energy and no problem.

Rod
 
Originally Posted by dbaryl
The spark plugs are OEM, replaced about 12k ago- these are NGK iridium, should last 100k+ miles. I pulled them last night and didn't see any heavy fouling, but will re in case.

I don't know what else it could be, I always fill up at the same gas station (Costco), I'm half way thru a 3,000mi OCI, nothing else I did was out of ordinary...


Take a plug from a misfiring cylinder and swap it with one from a cylinder that doesn't have a misfire code set. Clear all codes and go for a drive. Does the misfire code follow the swapped plug?

If not, the plugs are fine, which is expected given their relative newness.

Do the same now for coil pack/plug wire(s). If no change in misfire codes, move on to next component. Fuel delivery would be a good possibility. It may be an injector or weak fuel pump. Test them accordingly.

Personally, my list of suspects would be sorted by age/miles on component. Any component that's still OE, i.e. Has 260K miles on it gets put at the top of my list of suspects to test.

Start at the top and work your way down the list, testing each component to verify it is working as expected. Sooner or later you'll find the problem...
 
Does your CRV have a changeable fuel filter?

I ran fuel cleaner through our older SUV and because I hadn't run any for quite a while, I think it flushed some junk into the fuel filter. The SUV's engine stumbled and missed while we were driving, changed the fuel filter and it was all good. Didn't happen again.
 
Basic reasons for misfires are plugs, wires and coils. After that it can start getting exotic. As for the MMO, if it ain't broke, don't fix it. Lots of people never use the stuff and get by fine.
 
Thought it would only be right to post an update:

The problem I had ended up being a bad spark plug coil and a daily knock sensor. I guess it just happened to all go bad when I messed with MMO.

Thank you guys for the help.
 
Originally Posted by dbaryl
Thought it would only be right to post an update:

The problem I had ended up being a bad spark plug coil and a daily knock sensor. I guess it just happened to all go bad when I messed with MMO.

Thank you guys for the help.

Glad to hear you got it straightened out. Happy Holidays ahead!!!
wink.gif
 
Originally Posted by gfh77665
Basic reasons for misfires are plugs, wires and coils, and Marvel Misery Oil.



I just caught the Marvel Misery Oil. I always thought it did something but that before I discovered Techron, Redline Si-1, and Gumout.
 
Status
Not open for further replies.
Back
Top