2004 with p0302 ( or not ? )

Alright guys been reading through this forum and many others for hours today, I've lost count at this point. Purchased a 2004 Toyota Tacoma 4wd - 2.7 4 cylinder - 170k miles. Came with check engine light, scanner said cylinder 2 misfire. Previous owner had spark plugs changed and apparently tried switching around coil packs* , I got it home, got lucas cleaner, threw it in with full gas tank, probably quarter through so far. Re-read codes, now got hit with p0135 ( o2 sensor upstream ), p0302, p0303, decided to hit the sensor code head on, bought a new denso sensor, replaced it, cleared codes, got rid of check engine light, drove probably 40-50 miles, and now its back with a single code, p0302. Any recommendations on where to start? Thinking about checking coil packs first thing tomorrow as its quite late now, coil packs as in wiring towards them? perhaps switching the cylinder 2 with another to see if code moves, if it does not, move onto fuel injectors, screwdiver diy method ( constant pulse / click = good fuel injector ? ) if not coil packs and or coil pack wiring, if not fuel injector related, whats next? Thank you all, sorry for the messy post.

Oh and compression test for leak etc, believe my friend can help with that, i keep adding things on sorry, but maybe a good idea to get wiring and spark plugs brand new again just to make sure, saw someone post that it costed them <$100 at advanced auto so might aswell if the coil packs dont work out.

 

Compression check as you mention. Next will be a leak down.

 

and as for compression numbers, the higher the better overall, but as long as they are quite close to each other correct?

 

Correct. I will say within 10% difference of each other is safe

 

Under stood, To do list for tomorrow
1. Check Coil Pack Wiring
2. Switch Coil Pack from cylinder 2 to whatever to see if code transfers
3. If 1&2 dont work, go grab a compression tool from autozone / oreilly, and check compression ( and hope its 10% or so within each other ), if not that indicates loss of compression, which i hope I dont have to go down that rabbit hole trying to figure out the cause.

 

Probably pretty safe to replace the coil packs. Chances are they've never been replaced and have 170k on them. A compression test would be good too.

 

appreciate the reply, im seeing its about $90 per for a Denso Original Equipment Quality Direct Ignition Coil

is that normal pricing i assume? I purchased a denso o2 sensor so thinking might aswell go along with the theme of denso parts as its same priced as any other brand of coil packs at advanced auto

 

You might as well rent their (oreilly) combustion leak down tester as well.

 

That's OEM quality, not necessarily OEM from my understanding. They can be pricey, but I believe you're supposed to replace them every 100k miles or so (don't quote me on that though). Definitely check them first, but if one is bad, I'd replace them all.

 

yup that was the plan, hopefully they got some there.

 

gotcha, so recommended to replace all 4 at once, even if i narrow it down to 1 bad one yes?

 

Yes, I would. Kind of like headlights or turn signals. If one goes, chances are the other(s) may not be far behind.

 

After you do your testing, if you decide to replace the coil packs, this may save you some money over AutoZone:
https://www.rockauto.com/en/catalog/toyota,2004,tacoma,2.7l+l4,1429073,ignition,ignition+coil,7060

Looks like the Densos on here are $67.

 

thank you for the reference, after testing if needed, might grab a set of coils and spark plugs. Although the convivence of having it same day from the store is great, not sure if its worth the $100 or so dollars in this situation.

 

actually with shipping it comes out to $320~ on rockauto, with my discount code for 25% off on advanced auto it comes out to $337, might just grab them online for instore pickup through advanced auto and utilize that discount code.

 

That's the main thing with Rock Auto. The parts were usually cheaper, but you have to weigh shipping time and cost to see if you think it is worth it. I find most of the time it is, but occasionally it isn't.

 

yup yup, i see they have other accessories such as side steps, front bumper attachments etc so ill probably end up grabbing something after i figure out this darn cel, one thing at a time haha

 

alrighty, changed coil pack #2 to #1, checked reader, 2 codes now, p0302 and p0352, I reset it, waiting for new check engine to pop up , drove like 20 miles probably nothing yet, but still running rough i think.
Also took out the spark plug, spark plug in cylinder #2 was slightly wet, not sure if its gas or what, maybe oil but comparing it to spark plug from cylinder 1, spark plug 1 was dry and more grey on top, looking normal, while spark plug from cylinder two had black build or something like that on the tip. Not sure if I should move to compression test, or fuel injectors?

 

I'd check both if possible. I believe o'reilly has stuff to do both. Not sure about AutoZone. Also, the code could take a bit to reappear. If it's not actively doing it, it may need so many miles before triggering it.

 

yea thats what I thought too, Drove it around for probably 10-15 miles probably, nothing yet. Gonna go check the fuel injector with a screwdriver listening method