Cylinder misfire CEL and spark plug ?'s

[WI Girl]

New poster, longtime lurker

1997 4runner ltd currently 145k. I've had it since 2002 and 40k.

CEL cylinder 3 misfire code about a month ago, drop from 18 to 14 mpg, no noticeable running issues. Went to O'Reillys got NGK plugs and new wires (was due). Trusted mechanic (TM) replaced. Reset PC and code comes back. Advised to run some injector cleaner through. Same issue. TM advised that he had switched coil out and same code remained so not coil issue. Advised likely fuel injector or vacuum seal and take to dealership to confirm.

Dropped at dealer. Gave them code sheets (fail from emissions) and all previous measures done. Stated to them that I don't need another code read but someone to actually get in and determine cause. I was called stating that the CEL not on, they attempted to drive it around to get it on, then said they didn't think the coils were ever moved or plugs done as no marks on bolts. And that it drives fine can't find any issues. If it was the code that probably need new coils since they are old and probably fuel injector.

I'm normally really calm, but now was really ticked. As they didn't find any issue and told me what I already knew, plus charged me $130. And accused my TM of not doing work. I insisted they pull a plug and confirmed they were new. After arguing they agreed I could have it looked at if light came back on. Which it did the next morning!!! (Though I was able to get through emissions same day I picked up on a fluke).

Dropped off again last night. Called today, code is what I told them. Their advise is replace coils and have injectors cleaned ($1200). And if that didn't work replace injector. And stated that the plugs are incorrect, the ones put in are single electrode and should be double.

I know it's not the coils based on work by TM. Called TM, he said cleaning injectors basically scam. And the spark plugs O'Reilly gave are fine.

What to do? Are the plugs wrong. Will it affect anything? Is it leaning towards being the injector? What about cleaning MF? Can't afford new car but don't want to make costly repairs unnecessarily. Any help? Sorry about this being a book but wanted to give all the info upfront. Thanks!!!!

 

[BrianSD_42]

What are the codes?

The truck runs correct? Meaning it's not constantly misfiring?

I'd pick it back up from the dealer and try to troubleshoot with help of the forum.

 

[WI Girl]

Code from initial reading at auto parts store and mechanic: P0303

From emissions failure: P0300, 0302, 0303, 0304 and "visual MH light check failure: the MH light on your vehicle remains lit with the engine running" (I don't see any light except CEL unless that's what they're talking about)

From today's Toyota dealer report: P0300, 0302, 0303. " spark plugs are newer Iridium , vehicle was not designed to run with Iridium plugs. With codes that were read tech recommends fuel injection cleaning service $249, replacing ignition coils $467, and replacing spark plugs $166. If fuel injectors need to be replaced price of injectors, upper intake gasket and lower intake gaskets plus labor $1948"

Like I said before it runs same as always, just has light on and loss of mpg.

Are the single electrode plugs an issue? Those were selected for me by the auto parts store.

I drive 70 miles round trip for work.

 

[BrianSD_42]

Replace those plugs with the correct ones first.

If your plug wires are not factory spec then you need to get the Toyota / OEM ones as well.

Do you have a code scanner? They sell them on eBay for $30. If you have a smartphone you can use the torque app. Look up "obd2 Bluetooth scanner" on Amazon and buy it for $25-$30. This will allow you to clear the codes and read new ones.

I don't have links for the plugs and wires parts but you can find them at "camelback toyota online parts" google it and call them. Way better prices trust us.

Also don't put any autozone parts related to fuel, ignican or timing in your vehicle. This especially means plugs, injectors, plug wires.

Say you order the scanner and the correct plugs and wires. That won't be that much $$$. Replace with the correct parts and reset the codes. See what codes come back, if any.

......

Don't touch your injectors until you have the right plugs and wires installed and fixed. You only want to chase one rabbit at a time.

 

[Ol'Blue]

I just went through the same issue and codes. I had two bad plugs. One of them was cracked. Also I replaced the injectors in my truck. I did new wires also. Issue fixed. One thing that I really Fed up on. When doing injectors make sure to be very careful with the O rings on the injectors. They will rip easy if not put in correctly. If you need injectors I have a few extras to same you some cash also. Just PM me if you need them.

Blue

 

[Singtoe]

Too many codes to to be ignition related. Sounds like you picked up some bad gas some place.


Doc2012 had similar issue. He had to replace his injectors (not all of them, just the ones with the codes) and it fixed his problems.

If the TM is a TM (Pro) then the ignition system is fine, you don't change anything.

Fuel system is the culprit.

 

[jonwilly2]

Take 2 coils and swap them. These coils fire 2 plugs at the same time. So there would be 2 cylinders not getting spark. Engines are picky about the plugs. One time I swapped to bosch platinum 2 plugs ran like crap.

Clean the maf

Spray srarter fluid around the vacuum lines. If it revs there is a leak

Fuel filter is a cheep and easy swap good to do about now.

 

[WI Girl]

I can change out the plugs/wires again but the important thing I'm trying to get across is that I had the issue PRIOR to putting these incorrect plugs in. And like I stated, it's not running like crap. If the light wasn't on I wouldn't know anything is wrong except that my mpg went down.

The parts are NGK which were expensive compared to what was in there. They aren't "autozone" parts unless that's who makes them. That mistake is 100% on the parts store as I didn't go in and ask for them. They tested my car and the first thing he asked was when I last changed the plugs. After confirming with my mechanic I bought the plugs/wires and they knew the make and model which I told them but the guy just was out in my vehicle minutes before.

 

[WI Girl]

The "bad gas" comment got me thinking. I log my gas and service back for years. Including where I buy it for the most part. Looking back when the initial drop in mpg slowly started I didn't find anything other than my regular one or two stations HOWEVER I noticed when pulling the repair logs in time with gas purchases that one thing was done at that time: oil change.

I use the same oil place all the time but two things different on this change : I put in the high mileage oil (synthetic blend) which now researching some say there is a loss in mpg! Additionally at that visit I got the higher priced filter figuring that because I would be going more miles. And I also noted that I bought some type of cleaner too...would need to find receipt for exactly what that was but not injector cleaner.

So maybe the fuel loss is not part of the code issue.

(Edit) see next post for second thing different at this oil change.

 

[WI Girl]

Take 2 coils and swap them. These coils fire 2 plugs at the same time. So there would be 2 cylinders not getting spark. Engines are picky about the plugs. One time I swapped to bosch platinum 2 plugs ran like crap.

Clean the maf

Spray srarter fluid around the vacuum lines. If it revs there is a leak

Fuel filter is a cheep and easy swap good to do about now.

We did the coil swap and the codes didn't change. I'm thinking now that the additional codes after changing plugs/wires (started with just the one 0303) are from the incorrect plugs. So changing to correct ones still leaves me with the initial cylinder 3 misfire issue.

Clean the MAF was also on my radar when researching, though it was noted that the way mine is tucked in it doesn't tend to get dirty and I'm not out off-roading. I'd like to do it myself but it just can't get to a decent temp here!

Coincidentally my app just alerted that I'm due for a fuel filter.

One additional thing that happened during that last oil change was that they had an issue getting at the oil filter. Now in the past they've said it was a pain to get off, but his time they wanted my front tires cranked to get to it? Never had them ask me to do that before and I've been going there for ten years.

 

[BrianSD_42]

Do you have the receipt for your plugs?

Maybe they are good? If you post the part number some guys here might know.
[MENTION=10169]TheDurk[/MENTION]

 

[tank_7]

I had a misfire in cyl 6 when I bought my runner. We trouble shot a few different things. Replaced plugs and wires, and had no luck. The stealership insisted it was the valve seals. Obviously I wasn't going to give them the money to replace those. Took the injectors out and had them cleaned and replaced the fuel filter. Re installed and a day later once again the same code appeared. Checked the current and it was just a flat out bad injector. Ordered a new one from Toyota and ran some BG MOA and 109 through it and bam. I've been running 4 months no issues. I would say that most likely since the problem doesn't follow the coil packs that it's an injector.

 

[Chi-Runner]

I had a misfire in cyl 6 when I bought my runner. We trouble shot a few different things. Replaced plugs and wires, and had no luck. The stealership insisted it was the valve seals. Obviously I wasn't going to give them the money to replace those. Took the injectors out and had them cleaned and replaced the fuel filter. Re installed and a day later once again the same code appeared. Checked the current and it was just a flat out bad injector. Ordered a new one from Toyota and ran some BG MOA and 109 through it and bam. I've been running 4 months no issues. I would say that most likely since the problem doesn't follow the coil packs that it's an injector.

Tank 7-
I just pulled two codes from my rough idling 02':
P0306- Cylinder 6 misfire
and
P1135- 02 sensor bank one

Planning on checking the voltage to injector #6 this evening. My question to you is, did you see any other codes along with the cylinder 6 misfire, or did that trigger by itself due to faulty injector?

Crossing my fingers that I can replace the O2 sensor and that the injector is bad.