P0302 check engine code confusion.

hey again

so the dreaded light is back. drove about 150 miles over 2 days before it came back. I was also able to check the gas milage….. poor. about 15.5 mpg all ~65mph freeway driving.

prob just coincidence but the light came back on right as I made a hard U turn. I've put a bottle of techron injector cleaner in and a full tank of gas just now.

other than a compression check any other advice for me?

cheers!

lucas

 

another question ...... how big a deal is a valve adjustment on this motor? I'm reading more an more on this fantastic site and there are many posts about valve leash adjustments every 60k miles or so and I'm not sure this motor has every had one (125k now). I've only had the truck a year or so and it came from a friend who had it about 2 years prior. I have his stack of maintenence records and there is nothing there other than regular servicing.

 

valve adjustment is a part of the longer term maintenance. if you can do it yourself, go for it. it should be fairly easy to do for the 2.7. but valve clearance really only affects a minor amount of performance, not enough to cause a CEL, (unless you have a bad lasher, which is possible). I say go for it, you can do the compression test while you're at it.

 

I personally have few skill and no tools at the moment , though I did help rebuild the motor on my first toyota (1979 pickup/20R) when I was 15. it was more about whether or not it was something I could trust to the shade tree characters I have around here or if I should wait until I have the truck back in the US.

 

wait til you get back to the us. or leave a couple days early and stop by the coachella valley if your heading north and get a mechanic to check it out there.

 

yeah that's what I thought. I should hopefully be able to get the compression checked tomorrow so we'll see if we can figure out whats up with the CEL. the issue now is time, we can put of the drive north a few days at most, then she'll just have to fly home and leave the truck here to deal with later (which will be a big drag). if there is low compression on that cyl would that mean it would not be wise to drive it north ?

 

yay new stuff to report. driving home from my moms house tonight and the CEL started to flash. first 5 times. then a pause of a bout 10-15 seconds then 10 times. I was driving about 65 so I slowed down to 45 and it didnt' flash again. fwiw I put the bottle of Cheveron injector cleaner with techron in today and fille the tank. when I started it up this eve the exhause smelled pretty rich as I backed out of the driveway.

I did not experience any loss of power or other changes in the way the truck was driving. it doesn't seem to be misfiring. we had an injector issue on our 99 runner (3.4L) and it was misfiring and it was obvious something was wrong. stuttering and loss of power etc.

I searched this forum and it someone mentioned that it's likely a constant misfir or something making it run rich and damage the cat. the CEL code we've been trying to figure out says misfire cyl2. new plugs a few days ago. I'm thinking our plan to have this taco drive back up to the US on sat is going to have to get pushed back a minute.

 

ok. compression test done:

#1- 180

#2- 170

#3-175

#4- 180

according to this info, the mechanic seems to think it's unlikely to be rings, piston, or valve problem. plus it's running ok.

gas mileage is low (~15mpg freeway).

checked MAF looked clean, cleaned it anyway. mechanic says if it were another sensor gone bad we'd see another code. same for bad cat.

scantool again same code P0302 but it's still not actually missing or running rough.

the mechanic has officially shrugged his shoulders and given up.

the only thing he can suggest is to have an electrician check every wire to the injectors and coils. that'll happen tomorrow am.

the one thing he noticed is that the socket/plug that plugs the cables into the #2 injector is a different color than the other 3? #1,3,4 are a reddish/brown colored plastic shroud around the plug and #2 is light grey.

any advice before I see the electrician? I am way out of my depth here so any info I can arm myself with would be much appreciated.
cheers!
lucas

 

have you looked into an electrical problem? I would check the injector harness and coil harness for any broken wires.

blinking CEL means severe misfire that will cause catalytic converter damage.

 

hey. not yet. tomorrow I get into it with the electrician. I get that the P0302 code means misfire cyl2 and the flashing cel means pull over and turn off the truck, but the damn thing isn't actually misfiring. seems to have full power and running fine, the only thing off is the gas mileage but to be fair the last time I checked the MPG was in the states. it's been down here near a year sucking on pemex gas. I have a full tank of "premium" (~91) and a bottle of techron in it now.

the flashing cel isn't constant either fwiw. did it twice briefly last night on the way home, then again once this morning. it stopped when I slowed down and/or stopped. didnt' start up again after. ?????

I wouldn't normally be so rushed to figure it out, but again my wife is supposed to drive this taco about 2000 miles on her own leaving in 2-3 days!. yikes.

 

If the CEL light is flashing, it means a severe misfire -- this should be quite noticeable.

 

right? but it's not misfiring at all?? idles fine, normal power, no shaking or hesitation and no noticeable misfiring. just drove it home from the mechanic, about 25 miles or so freeway speeds no problem at all except that after 10 miles or so the check engine light came back on (was reset using the scanner when we did the comp test). did not flash this time.

now this is the first truck I've had with this motor (my other taco and the runner both have the 3.4l) so I thought maybe when the 2.7l misses it's less noticeable but that doesn't really make sense. also the mechanic drove it around for a whole day, put 40 miles on it and didn't notice any misfiring at all.

we'll see what the electrician says.

does this kind of mystery ever end up being the computer itself? is there any way to check that other than install a new one?

thanks again for the all the help!!

 

that was going to be my next comment, ECM. The ECM will never tell on itself so it can be hard to diagnose without another ECM to swap in.

 

thanks! I'm off to see the electrician now, I will see what he says about swapping the ECM. Is that a major operation? we have two identical year/motor tacomas here ( my wife's and my mother's) so maybe if swapping isn't a huge deal we could try that??

cheers!!
lucas

 

at the electricians now. he seems to think the motor IS misfiring, but he says that when it's just one cyl is's mild and not so noticeable??

he also seems to think that the difference in compression numbers indicates a problem. the cyl we're getting a code on (#2) is the lowest of the 4 at 170psi. the others are either 180 or 175

he's about to start checking all the harness wires.

thoughts?

 

10 psi difference between highest and lowest is perfectly fine.

 

I'm going to start pulling out my hair in a minute.

got with the electrician he says no electrical problems . he says it IS misfiring but it's hard to notice since it's only one cyl. that has not been my exprience with misfires but again, I've not had this motor before. in the past when my 3.4 had injector issue and was missing it was not something one could ignore. stuttering, loss of power, etc.

now I'm onto yet another mechanic to see what he says.

is it possible that I have those comp numbers (170-180) and at the same time have a bad or stuck valve or bad rings etc?

 

ok yet another mechanic and yet another opinion. I should mention that none of these guys are shifty at all, just a bit incompetent. nobody has even charged me for anything.

so this new guy says it's def missing but only slightly. he points to the sound of the exhaust (more a a chug chug chug than a purr) and the slight vibration observable in the motor at idle.

he squirted some gas into the intake and the motor leveled out and the exhaust got smoother in sound.

he says this means the injectors need to be cleaned and calibrated at the lab.

he did his best not to slag the previous mechanic as they are friends and it's a very small town but the code reader showed two codes/ 0300 and 0302. the previous mechanic said the first code (random miss non specific cyl) didn't mean anything since there was a following cyl specific code. the new guy shook his head at this and said it does matter. the confusion is that we switched the injector between cyl 1 and 2 and the code reader still said 0302 making it seem unlikey to be the injector with just the 0302 code.

so tomorrow am we're supposed to pull the injectors and take them to the lab for service.

any thoughts or advice that I can arm myself with?? thanks again so much, I am SO happy to have found this forum. everyone has been so helpful despite my obvious lack of knowledge about engines. I'm on a few professional forums for my work and the general tone is so much less helpful. nobody new can ask anything without a few "read the damn archives" flames. anyway thanks again everyone.

 

my last thoughts are either the ignition control module, or the cam sensor/crank sensors. all of which are expensive to test with try getting a bottle of electronics cleaner and cleaning the connections for each. see what happens. also remove them if you can and clean them entirely, electronics cleaner is safe for these parts.

 

thanks! I'll mention both of those to the guy tomorrow. do they require special equipment to test or is it just that they're a pain to pull or access?