P0302 - Running Rough

jac100

jac100

New member
I've started having some issues with my '97 Limited. First thing in the morning it starts up fine and runs well. Once the car has warmed up a bit (20-30 minutes of driving) it starts to run rough and the Check Engine light comes on. I checked the code - it's P0302.

I did a search for information on the code and tried some basic troubleshooting:
1) Checked the spark plug wires were on tight.
2) Cleaned the MAF.
3) Switched the Coil to see if the code followed from cylinder 2 to the next (it didn't).

So I'm at a bit of a loss for what to check next. Anyone else have recommendations on what I can troubleshoot next?
 
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i would honestly think that the problem is the ignition coil. ignition coils on toyotas are known to give out a little early...take out the coils and look for some carbon marks. usually if it has any carbon marks,its about time to change them,sealing thing will only fix it for like 4 months then symtoms come back. good luck on fixing it tho
 
Injector bad

It's been a little while but here's what's happened so far.

I had changed the plugs and wires a few months ago. I bought the dual prong'd Denso's and when i did the install I did re-gap them. In my recent searches I found that was very BAD. So, yesterday I went and bought single pronged NGK's and installed them. They were pre-gapped so no worries there. Install went fine. I hoped this would fix it but no go.

I gave up at about this point and took it to an independent shop to have them troubleshoot it. They called me just a few minutes ago and said the fuel injector is bad. They want to replace the fuel injector, intake gasket and fuel filter, total price - $650. Sounds a bit crazy high to me.

I can turn a wrench once I know what to replace, I just suck at troubleshooting the issue. So I'm going to pick up the car this evening and order a new injector and gasket. I'm searching for any posts related to how to replace those parts now. Anyone know any good links to this?
 
jac100 said:
It's been a little while but here's what's happened so far.

I had changed the plugs and wires a few months ago. I bought the dual prong'd Denso's and when i did the install I did re-gap them. In my recent searches I found that was very BAD. So, yesterday I went and bought single pronged NGK's and installed them. They were pre-gapped so no worries there. Install went fine. I hoped this would fix it but no go.

=
Click to expand...

Did you not see the big sticker on the engine that says USE ONLY DUAL PRONGED SPARKPLUGS ?
What did you gap the Densos to? If you bought the OE ones they come pregapped. The NGKs you bought are the wrong ones, you should have bought part number #13235.

I believe that the problem lies with a fuel injector. ask them how much they want if you get the parts
 
That's high, the shop must be quoting a brand new OEM injector from Toyota which costs a fortune. But you can get a rebuilt injector for about $80-100. The labor should be ~2 hours for the #2 injector. The fuel filter (which isn't necessary but still a good idea if it hasn't been changed in 30K+) is <$20 at most auto parts stores and it's .5 hr labor to change out that. You should be looking at ~$270-320 total if you get a rebuilt injector. Don't pay $650, that's what most shops charge to do the timing belt and water pump which is a much more labor intensive job.
 
conclusion

It's been a while but I finished fixing the 4Runner. Thanks to everyone for input and helping aim me in the right direction.

After all the troubleshooting and advice I decided to try to replace the fuel injector on my own. I couldn't find any step-by-step directions but did have the shop manual to get some information on torque settings and how things fit together.

I ordered the parts from a local CarQuest shop (fuel injector - $100, intake gaskets (2) $60, injector o-rings (6) $1 ea.) and got into the job. It was a very easy job with the hardest part being the reach. I have a 3" lift and 32" tires so it sits a bit higher. I did a lot of standing on the tires to reach what I needed.

I'd say the whole job took about 4-5 hours because I took it very slow. I could definitely do the job in under 2-3 hours if I ever had to do it again.

I still have to replace the spark plugs with dual prong plugs, but that's it.

Thanks again to everyone.
 
jac100 said:
It's been a while but I finished fixing the 4Runner. Thanks to everyone for input and helping aim me in the right direction.

After all the troubleshooting and advice I decided to try to replace the fuel injector on my own. I couldn't find any step-by-step directions but did have the shop manual to get some information on torque settings and how things fit together.

I ordered the parts from a local CarQuest shop (fuel injector - $100, intake gaskets (2) $60, injector o-rings (6) $1 ea.) and got into the job. It was a very easy job with the hardest part being the reach. I have a 3" lift and 32" tires so it sits a bit higher. I did a lot of standing on the tires to reach what I needed.

I'd say the whole job took about 4-5 hours because I took it very slow. I could definitely do the job in under 2-3 hours if I ever had to do it again.

I still have to replace the spark plugs with dual prong plugs, but that's it.

Thanks again to everyone.
Click to expand...

Nice. Glad you were able to do it yourself.

You should just re-gap the denso's you already have. I gapped my denso's myself (they might have been pre-gapped, only a couple needed adjusting) and they work fine. No need to buy new ones. Be sure you are gapping to the correct spec.
 
wish I had seen this thread earlier.. exact same problem, tried plugs and wires first and moved the coil. Same code, replaced the injector (90$) problem solved.

I accidentally scratched one of the 0-rings on a good injector and had a strong gas smell after the fact (it was leaking). I replaced the 0-ring last weekend, now the engine runs great. Time for something else to break.. :D (usually because of me..)
 
I'm having the same issue.

I had this problem but installed new plugs and wires and it went away.

Now I have this on #2. Runs perfectly fine, park it and drive again after a short time and it runs rough. Leave it for a long time and it runs ok again.
 
I know this is an older thread, but I found it looking to fix my P0302 issue. My issue is now resolved, and would like to share what I did.

Issue: We have a '99 4Runner SR5 V6 with 275k miles. 1-2 weeks ago, 4Runner started to lunge/surge under load at highway speeds. Day-by-day it would get worse, to the point where my wife didn't want to drive it anymore. We then received a CEL, which was P0302.

Troubleshooting: I've experienced this before, which was resolved by carefully cleaning my MAF sensor, but this didn't resolve it this time. I had a spare MAF sensor, but that didn't fix it. Swapped coils, and the issue was immediately worse. I didn't consider replacing spark plugs because they were replaced less than 2 years ago.

Resolution: Simple. Replaced all 6 spark plugs with Denso Iridium plugs, and the problem went away.
 
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