Fwiw- No fuel injector issues with either one of my 100s and i don’t use any fuel additives. Both over 250k miles now.
When to Clean or Replace fuel injectors
- Thread starter 2001LC
- Start date
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Interesting, no one mentioned Berryman B12 Chemtool. I use it on all of my vehicles, really good product. These guys have been around for over 100 years.
www.berrymanproducts.com
Fuel Additives / Treatments
Never tried b12 for injector cleaner but we use it at work on the Audi 3.0T for oil consumption issues, it helps to clean/free up the rings.
As far as injector cleaner I'm a big fan of Redline SI1 or Techron.
As far as injector cleaner I'm a big fan of Redline SI1 or Techron.
- Thread starter
- #44
I've used 44K, Chevron Techron, Seafoam, CatOclean, etc. They do a good job of cleaning fuel system, cylinders/pistons/valves, spark plugs, A/F & O2 sensors even CATs.
But none tells us anything about spray pattern, flow rate cold/hot or leak down of fuel injectors.
But none tells us anything about spray pattern, flow rate cold/hot or leak down of fuel injectors.
Reviving this thread as I need some MUD wisdom to help isolate a persistent P0306 on my 2006 LC (307k miles, unknown injector history).
Coming off the highway on Sunday, I hit the gas to accelerate hard and felt a clear loss of power. At the next light, the truck started shaking and the CEL began flashing under load. I pulled over, scanned it, and pulled P0306 (Cylinder 6 Misfire). Drove it home gently.
Current Symptoms:
Everything seems to point toward a partially clogged or poorly atomizing #6 injector (restricted spray under low pulse-width idle conditions), but I'd love to hear if anyone has run into this exact diagnostic pattern. If the soak doesn't clear it tomorrow, my next move is swapping injectors #6 and #4.
Any thoughts or something obvious I missed?
Coming off the highway on Sunday, I hit the gas to accelerate hard and felt a clear loss of power. At the next light, the truck started shaking and the CEL began flashing under load. I pulled over, scanned it, and pulled P0306 (Cylinder 6 Misfire). Drove it home gently.
Current Symptoms:
- Smooths out on cold startup for the first 10–15 seconds in Open Loop, then the stumble begins once it transitions to Closed Loop.
- Idles slightly shaky in Park/Neutral with a solid CEL.
- Revs semi-smooth all the way to redline in Neutral/Park (clears up ~1,500 RPM, 100% smooth at a steady RPM).
- Putting it in Drive or Reverse under load creates heavy driveline bucking and triggers a flashing CEL.
- Cylinder #6 has had rare, intermittent pending misfire codes over the last year, but never anything that impacted drivability until now.
- Compression: Cylinder #6 tested at 150 PSI (3 crank attemps).
- Ignition: Swapped coil packs AND spark plugs between #6 and #2. Code stayed on #6. (Plugs/coils have ~5k miles).
- Injector Circuits: Injector #6 resistance/ohms tested within spec, and I can physically feel/hear it clicking identically to the others.
- Live OBD2 Data: Short-Term Fuel Trims are near 0% (-0.8% to +3.1%), Long-Term Trims at 0%, but I have recently cleared CEL so that data does not exist yet, MAF reading 0.7–0.8 lb/min, Timing advance +10° to +13°, Lambda sitting at 1.0. No global air/vacuum leaks detected.
- Maintenance History: MAF and Throttle Body cleaned recently. Ran BG44K through the tank about a year ago.
Everything seems to point toward a partially clogged or poorly atomizing #6 injector (restricted spray under low pulse-width idle conditions), but I'd love to hear if anyone has run into this exact diagnostic pattern. If the soak doesn't clear it tomorrow, my next move is swapping injectors #6 and #4.
Any thoughts or something obvious I missed?
Update 2:
I have done some more "testing". The truck runs fine holding steady at 1,500RPM as stated before, and will rev nicely without any stumbling. The second it returns to idle the misfire returns with a CEL. The CEL will flash if at idle speed, and once RPM's are built to 1,500RPM it will go steady, then turn off.
I can only assume I have a partial blockage of the #6 injector, and the additional air going into the intake is atomizing it enough to create a good spark.
I did unplug the injector from the harness and did a warm start. The engine sounded normal, with no shaking but I did not let it run longer than 15 seconds and only did a small throttle blip to maybe 1,200RPM and felt a little shake.
@2001LC - Give me some wisdom here, and see the above if you have a moment, please!
I have done some more "testing". The truck runs fine holding steady at 1,500RPM as stated before, and will rev nicely without any stumbling. The second it returns to idle the misfire returns with a CEL. The CEL will flash if at idle speed, and once RPM's are built to 1,500RPM it will go steady, then turn off.
I can only assume I have a partial blockage of the #6 injector, and the additional air going into the intake is atomizing it enough to create a good spark.
I did unplug the injector from the harness and did a warm start. The engine sounded normal, with no shaking but I did not let it run longer than 15 seconds and only did a small throttle blip to maybe 1,200RPM and felt a little shake.
@2001LC - Give me some wisdom here, and see the above if you have a moment, please!
- Thread starter
- #47
Typically we pull wires off injector while engine running. RPM should drop. If not, can be fault in wires or bad injector.
If felt better with FI disconnected. Very likely bad injector. They do go bad. Try driving around, with FI disconnected. You'll have slight loss of power. But it should smooth out, if bad injector.
Note: If vehicle sat parked for prolonged periods. This can (not will) result in rust on FI needle.
If felt better with FI disconnected. Very likely bad injector. They do go bad. Try driving around, with FI disconnected. You'll have slight loss of power. But it should smooth out, if bad injector.
Note: If vehicle sat parked for prolonged periods. This can (not will) result in rust on FI needle.
Did you check the driver side of the connector for a good pulse? A test light or noid light works for this test.
I know you mentioned that compression at #6 is 150 psi, did you do all cylinders?
I know you mentioned that compression at #6 is 150 psi, did you do all cylinders?
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I did not check anything on the driver side. I can feel the injector on #6 pulsing, the same as the others but I do believe it's clogged.
I could not get a good seal on #2, but I am happy with the results of #6, holding at 150PSI. If it was 120 or below I would have pursued a better test against other cylinders. Cold start and hot starts are completely fine, until the engine completes the Closed Loop Cycle. I can also hold the engine at 1,500 RPM and everything clears up. I'm confident it's not a mechanical issue.
I ordered 8 rebuilt Denso's from GB Manufacturing. at $35 a piece, I'm going to throw one of them in and test. I don't want the 100 down for long, as I have a ton of travel for work coming up. I plan on swapping all 8 injectors out, holding onto the OEM ones and getting them fully cleaned, flow tested, etc and at some point, put them back in and sell the rebuilt GB's.
- Thread starter
- #52
No change, at this point. Indicates Fuel Injector issue.
Once your sure you've good current to FI. Either just replace that one FI or pull and test on the bench.
Good point/test, and should be done before R&R of FI.
A test of all 8 cylinders, is best. 150 PSI is weak, but enough for combustion and shows rings & valves sealing well enough.
But was it done by the book. Which is hot engine, fuel cut off, T-body open and at 250RPM. If liquid in cylinder we get high PSI reading.
Did spark plug look normal and same as other more or less.
But for now I'd move on to R&R that FI. Assuming you did check spark. i.e.
The test was performed when the engine was warm, not hot.
I will need to redo the test then. The engine was only warmed up for about five minutes. Since I had the air box off, I could not keep the engine running. I thought it was dangerous to remove a plug from a hot cylinder head. I plan on digging in today at some point, to start tearing down. If I can get the fuel rail popped up, I'll swap an injector around. I am a little tight on budget, so buying a bunch of stuff isn't an option right now. Dang kids!
The spark plug, and coil looked totally normal, and no different than the other cylinders. The truck ran fine prior to this event, despite having a P0306 every blue moon as a pending code. I have always wondered about the fuel injector condition on this engine, since it has 307K and no prior history of the FI being serviced/replaced.
How much of a difference would a cool engine make verse a hot engine?
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- Thread starter
- #54
Warm is good enough for now. If doing a compression test later. Then get up to norm op temp, and all 8 sparks plugs out. Check them all. And low check wet.
Since you did hear #6 FI. That's a good indicator wires good. Also FI not dead.
Do check spark, if good. Next check for misfires.
Then if all good. Pull and test or R&R that #6 FI.
Swap coils, may or may not show a coil misfiring. Check for misfire. They fool many.
Since you did hear #6 FI. That's a good indicator wires good. Also FI not dead.
Do check spark, if good. Next check for misfires.
Then if all good. Pull and test or R&R that #6 FI.
Don't worry about it. Cold engine we do see 150PSI. You have compression.
Good!
STOP. OH----Once in a blue moon P0306???
Swap coils, may or may not show a coil misfiring. Check for misfire. They fool many.
I've seen from no difference to as much as 40PSI. You have compression 150PSI, move on for now.
I'm not going to claim victory just yet, but I went back through everything and realized that I had cranked it a few times with the fuel pump relay in. I pulled the #6 plug and it was covered in gas and oil. I swapped it out for yet another plug, and installed the coil pack that was on that cylinder when the original misfire started. I tightened down everything, primed the rail and watched for any leaks, all good.
I cleared the CEL, and turned the key a few times and then gave it a start. She fired up, stumbled and recovered. I let it idle up to temp, put in and out of gear, and once warmed up I started some easy revs, building to to full throttle jabs while watching the misfire count on my laptop.
0 misfires
If it’s good for a while, I plan on pulling #6 plug again and check the condition. The plug referenced above, the "different plug" was the second thing I did. After I swapped the plug, I continued to troubleshoot and test things while starting it. I assume the first time I started it, I fouled it out.
I cleared the CEL, and turned the key a few times and then gave it a start. She fired up, stumbled and recovered. I let it idle up to temp, put in and out of gear, and once warmed up I started some easy revs, building to to full throttle jabs while watching the misfire count on my laptop.
0 misfires
If it’s good for a while, I plan on pulling #6 plug again and check the condition. The plug referenced above, the "different plug" was the second thing I did. After I swapped the plug, I continued to troubleshoot and test things while starting it. I assume the first time I started it, I fouled it out.
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Can you guys still get Toyota LC100 OEM injectors from Toyota? I cannot find it at all
- Thread starter
- #58
For the non VVTi 4.7L 2UZ (98-05):
I see some new in UAE today.
There may be some in Japan also.
en.impex-jp.com
You can have used tested, cleaned and rebuilt.
3rd choice after market.
I see some new in UAE today.
There may be some in Japan also.
New parts search — IMPEX JAPAN
en.impex-jp.com
You can have used tested, cleaned and rebuilt.
3rd choice after market.
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