jcrheingans

Hello everyone! I have been on here for awhile just under jrheingans and i closed my email account so i had to start another user name on here! Anyway to the issue....

Driving along one day the 4runner stumbles and has a pretty bad miss. Check engine light comes on and I don't have a code reader so I get it home and start pulling plug wires and no change when I pull the spark plug wire off of cylinder #2. So i have some leaking valve covers that need attention and I haven't done a tune up in about 100,000 miles so I decide its time to put some money into the old girl. I put in 6 new injectors, 6 new NGK 2 prong spark plugs, new vacuum lines, all plug wires and coil boots, new valve cover gaskets and spark plug well seals and she fires up an purrs like brand new!!

So We drive it out to the woods (driving for 1 hour) and we stop to get out and look at a trail and then she starts missing hard! Way worse than before. We limp it home, I get a code reader and it has 3 codes: Random misfire p0300 and Cylinder #1 and Cylinder #5 misfire. I have read so many posts on several different forums and I know others have had similar frustrating issues and I have tried several things to try and remedy them.

Swapped ignitors from another parts 4runner that was running before it was wrecked- No change
Swapped around coil packs- No change
Ohmed out coil packs- 1.5ohms on all three
Sent ECM out to get checked and all reports came back good- No change
Double checked the wiring for the spark plugs- All are correct
Sanded and re-installed all grounds- No change
I am so lost.... Its driving me nuts!! The only thing in the system I haven't replaced is the wiring harness for the injectors. The plastic was really brittle so I re-wrapped it with heat shielding and installed.
Please if someone has any ideas let me know. Its just really weird that it ran perfect for an hour

Egardner

Computer might be out. Does it start up just fine and then immediately start missing. Mine was doing that and the computer quit sending a spark to the plug after the ignition sequence. Took me taking it to a shop to figure that out but that’s besides the point. I could see that each plug was sparking and switching them around didn’t help (the wires and coils only have 5k on them so I didn’t think they were bad) so I even replaced an injector.

fierohink

I know you said you replaced all the injectors. Where did you get the injectors? We’re they new? Used? Remans?

Runnjng fine cold and up to operating temp, but running like crap when you come back and everything is hot is a classic heat soak symptom of bad injectors. I went thru 2 New old stock sets with bad injectors in each until I could piece together a complete good set. Pull the plenum and move those 2 injectors. You can reuse the gaskets while you’re troubleshooting and then put a new hood one in once it’s sorted.