I’m trying to get things ready to pass a smog test and I’m seeing a misfire code (P0305 - misfire cylinder 5) that keeps returning and another P1451 that might have just been the gas cap as it hasn’t returned. I’m wondering if I should clean the MAF sensor since I’ve read that some people have had a lot of trouble afterward. I could clean the sensor by removing it from the air intake then reinstalling it. Also, I’m not sure if people use the same cleaner (the CRC stuff?) to clean the electrical connector for the MAF sensor as well. I’d like to see what people think these days since a lot of the posts I read through were really old.

 

Run some seafoam thru it. It can clean up carbon deposits, and help a vehicle pass emissions. Did it several times on an old Ford Ranger I had as a company truck and it would always pass emissions after a seafoam treatment. I'd also pull the #5 plug and inspect it and the #5 spark plug wire. I personally don't spray an MAF down, but it all depends on the quality of the air going past it. A dirty air filter won't help, an intake tube with a leak can cause air to get sucked in behind the MAF and cause issues as well.

 

I've sprayed one down with contact cleaner and let it air out real good. I had an issue with my snorkel not sealing in the fender (i don't have liners either) so I soaked through the air filter on a snow day and the maf got wet. Sprayed it down and it worked just fine once and is still going strong.

 

I clean the throttle body and MAF once a year. When I got the truck the throttle body was kinda dirty. After cleaning it the throttle response was smoother.

 

I doubt a problem with the MAF would cause a misfire on cylinder 5 only. What have you done to diagnose the misfire itself?

 

Dang, I just changed oil about a month ago - I read just now that Seafoam (as a crankcase oil treatment) is best used 100-300 miles before an oil change).

Or did you mean to just use Seafoam (high mileage?) in the fuel? I'll get some of this at the shop. Fuel tank is nearly full now so I guess I'll add the whole bottle and maybe fill up again and add another entire bottle after.



Should I use this too? Even with the oil change I just did? I could change oil again, I suppose. I should have enough motor oil leftover, but I wouldn't want to be wasteful.

About the air filter, I bought a new Mahle filter in September 2019 and I don't think I've driven much since, so it's probably still clean enough.

I do know that the air intake has a broken latch on it... I've been wondering about that. I replaced the throttle body heater plate and removed the throttle body to clean it, installed new gaskets with tacking on everything - seems to be OK - really should have done the thermostat mod, but wasn't aware then and had a bad coolant leak to get through - this D2 is my only car. The RRC my family has is parked an hour and a half away and it's been sitting for 5 years - ABS problem. I've been dreaming of having time to get the RRC back together, but the D2 is more important and I just haven't had time to get out there. I'd need to replace the ball joints in the D2 before I want to get on the freeway for a longer drive... things have been getting a bit squirrely.

I haven't done anything to diagnose the misfire other than get the code - I'm wasn't sure what I'd do to look into this, but I'll see if I can get the spark plug out and inspect the wire itself too. I'm not exactly sure what I'd look for there, but I'll see if I can find a guide on spark plugs and wires. I've seen someone check compression by removing a plug and putting a sort of pressure gauge in the spark plug hole, but I'm not sure if that applies here. I have a compression testing kit and I could try that when I have someone else to help me start the car while I hold the tester in place (unless it will stay on its own - not sure about this).

Just yesterday after driving home, when I pulled into the driveway the red oil light came on and I shut the engine off as soon as I could. There was some steam coming out from the radiator... I checked before driving out that there was enough oil and it was a little below the notch in the dipstick, so I added maybe a quarter of a quart. I've seen the oil light in the past which happened when going up the driveway when I'm not putting much gas to it, but also shut off as soon as I could and that problem two years ago went away after an oil change (using the recommended Shell Rotella oil). When I changed the oil both times, it didn't look cloudy, just very black. This D2 is a 2003 and I know there were oil pump issues. I don't really know if I'd need to get into the oil pump this time as a way to prevent a serious problem or if there's something else this could be.

I appreciate everyone's input.

 

agree on the misfire on a cyl. is not likely a MAF issue - no harm in cleaning the MAF - there are MAF specific spray cleaners available

 

Thanks - I have the CRC MAF Sensor cleaner and I'll try that just in case since I understood I was supposed to try to simplest treatments first and I've never cleaned the MAF sensor in the 5 years I've owned the D2. From what I understand, I make sure the vehicle has been sitting for a while so it's cold, then spray it clean, make sure it's dry, reinstall, pray I didn't ruin my engine somehow.

 

yes cold and let dry - but that stuff evaps fast so no big wait

 

Please don't leave us hanging after you clean the MAF. Let us know whether or not it cured the cylinder 5 misfire.