97 LX450 with 312K and misfire in cylinder #6

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

B

bj70alex

10 Year 15 Year 20 Year
Joined
Feb 28, 2003
Threads
133
Messages
482
Location
Clearwater, FL
About 6 months ago I had the same thing (misfire in #6 cylinder). I ordered fuel injector and didn't have to replace it, the problem got solved by itself. (maybe was a bad gas???)
I always use 89 octane. Yesterday, it happened again. Checked the spark, new spark plug, and #6 spark pug wire, but was still misfiring in #6.
Is there anything else I should check or just go ahead and replace just #6 or all of them. Thank you
 
Check your wiring, issues don’t solve themselves they are a intermittent issue which is a common problem with our cruiser wiring harness getting compromised from the egr valve pipe at the back of the engine by the firewall and heater control
Valve. We really never see bad injectors come up as a issue it’s almost always the injector clip on the harness side is broken or the wiring harness is burnt and causing the injector to ground out dumping fuel into the cylinder. Try searching 80 series injector issues or burnt wiring harness Fzj80. Should come up with a lot of post with your same issue.
 
bj70alex said:
About 6 months ago I had the same thing (misfire in #6 cylinder). I ordered fuel injector and didn't have to replace it, the problem got solved by itself. (maybe was a bad gas???)
I always use 89 octane. Yesterday, it happened again. Checked the spark, new spark plug, and #6 spark pug wire, but was still misfiring in #6.
Is there anything else I should check or just go ahead and replace just #6 or all of them. Thank you
Click to expand...
As a side note...
A stock engine NOT pulling a heavy trailer will actually perform better using the the lowest (decent quality) octane available for your area, typically 87 or 85.
Why pay more for less performance? Especially on a thirsty beast like our beloved 1FZFE.
 
Fj80oregon said:
Check your wiring, issues don’t solve themselves they are a intermittent issue which is a common problem with our cruiser wiring harness getting compromised from the egr valve pipe at the back of the engine by the firewall and heater control
Valve. We really never see bad injectors come up as a issue it’s almost always the injector clip on the harness side is broken or the wiring harness is burnt and causing the injector to ground out dumping fuel into the cylinder. Try searching 80 series injector issues or burnt wiring harness Fzj80. Should come up with a lot of post with your same issue.
Click to expand...
Exactly this...my #6 injector harness plug had crumbled (heat from EGR) over the years...it was literally just sitting on the injector and would have an intermittent misfire. I actually found mine when trying to add the EGR bypass test plug...the harness wire for the EGR temp sensor is taped to the #6 injector wire on the loom and when I was wiggling the EGR wire, it would cause the plug on the injector to loose contact and miss.

You can see the corrosion that formed from the bad seal to the injector and the missing tab on the injector plug...

tempImagebhVLSi.webp


tempImageRSdd0t.webp
 
You'll need to pull the upper manifold off...and the tricky part is getting the studs out for the EGR. I was able to get mine out without removing them, but I was pulling the EGR anyway for some keychains.

A quick diagnostic for you may be to wiggle the wire to the EGR temp sensor while the truck is running to see if you can get it to stumble...that's how I found mine.

Injector plugs have pink tape in the pic...I replace all of mine since I had it apart.

IMG_3804.webp
 
"How you were able to remove the studs out of EGR????"

IME when you try to remove the nut on the EGR studs the stud and nut come out together as they're frozen together by corrosion. If the stud doesn't come out with the nut you can use a stud removal socket. Plan ahead to replace the studs and nuts anytime you work with parts that have gone through extreme heat cycles (ie: exhaust/manifold, EGR,---)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------

"Can I just replace the #6 injector harness plug without removing intake manifold and EGR Valve?"

Haven't tried it myself with the harness in the vehicle but likely possible (if you have a strong back) by first removing the throttle body and valve cover (wait for more tips from others who may have tried replacing just the harness connector) but expect it to break when it's handled. You can order new replacement harness connectors from Toyota.

Number 6 iinjector with valve cover removed.webp


Number 6 injector harness connector valve cover removed close up.webp
 
bj70alex said:
How you were able to remove the studs out of EGR????
Click to expand...
Heat, PB BLaster, for days on end, and more heat. They will come off.

Oh, and you'll need beer...for afterwards. Trust me.
 
I guess you can get to it with some stuff off including the valve cover as shown above...I was taking mine apart to replace all of the vacuum lines and some other disintegrating connectors underneath. I used a bosch 4 hole injector, but the stock ones are just fine. That said, you probably just need the harness connector, not the injector itself. Keep in mind that the wires are pretty short up there, so you really would need to lay across half of the motor from one sider or the other to reach. Since I had my manifold completely out, it was easier from the driver's side to reach them.

Again, if you haven't tried first, I'd see if you can wiggle the EGR temp sensor plug to also wiggle the injector clip below it to see if it re-creates your misfire. I'd hate for you to go that deep and not have a problem there.
 
EGR temperature sensor.

done1.webp


I had #6 injector fail on my 80 about 12 years ago. Resistance should be around 13ohms and my #6 was >20k ohms. It failed hard and not intermittent.

I would be checking wiring harness around the EGR valve (that has the injector wires) and also where the harness goes past some potential sharp edges below/behind the glove box. What folk have written above are some good things to also check.

My writeup from way back then -> Injector Service - https://george4wd.taskled.com/injectors.html

cheers,
george.
 
bj70alex said:
My friend was able to check resistance on #6 injector and it was about 212 kohm, but on the first two cylinders resistance was between 13 and 14 oms
#6 injector is bad or it the harness issue???
Click to expand...
Were the injectors checked with injector plugs plugged in?
 
If measured at injector #6 pins, then injector is bad.

Cheers,
George.
 
As I wrote above, dead injector. It's essentially gone open circuit. All that's in an injector is a solenoid that opens the path to let the pressuring fuel rail fuel to go through the injector. The ECU deals with the timing and pulse width etc.

I would buzz the negative side of the injector (that is the signal driven by the ECU) to ensure you don't have a short to ground, All the injectors get +12V when the engine is running, the ECU pulses the ground side to energize it. If you have a short to ground (harness etc) then the injector will be continuously energized -> not good, the coil inside will overheat and can fail and of course up till that point, fuel will continue to pour through the injector.

When mine died, I had no wiring/ecu issues, the injector just died. I replaced it with a new OEM and also sent the other 5 in to an injector service company to have them cleaned etc. The dead one I used as a 'core' at Rockauto to purchase a remanufactured injector (was pretty cheap) and I keep the reman as a spare. Since I have a spare, I will never have a future failure :rofl:

To replace the injector the fuel rail will need to come off. So, get new grommets/o-rings for all of them, send the working ones in for service, replace all vacuum lines that live under the intake (remove the upper part of the intake). Things to do while you 'are in there' :)

cheers,
george.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom