Bad Spark Plugs? Engine stalls and won't start. CEL, VSC TRAC and VSC OFF lights. P0430 DTC <help>

[2001LC]

I'd really like to hear what gap on the spark plus are. Hard to see in picture above. But some look eaten away, which increases gap. That could over heat multiple coils.

I see multiple misfires and some air intake issue. A good tune up from air box, MAF, battery clamps & post, sparks plugs, coils, vacuum lines leaks, coolant, etc is in order here.

 

[OEMGUY0720]

I'd really like to hear what gap on the spark plus are. Hard to see in picture above. But some look eaten away, which increases gap. That could over heat multiple coils.

I see multiple misfires and some air intake issue. A good tune up from air box, MAF, battery clamps & post, sparks plugs, coils, vacuum lines leaks, coolant, etc is in order here.

I compared the old and new, and the clearance seems to be the same

 

[OEMGUY0720]

Seems like this is a known issue of most 2006-2007 LCs and LXs. The fuel line is close to the catalytic converter and when weather gets too hot plus the heat of the exhaust then that causes the stalling affecting the fuel pump, and all other parts like coils, spark plugs, charcoal canister..

This now is telling me a bit that this is a probable case of temperature-dependent symptom, it only happens when temperatures soar, I will be trying first @1meancruiser ‘s simple approach to address it: lower the temp down using a heatshield between the fuel line and the catalytic converter.

UPDATE: I went on a fishing trip in early august. The temperatures were 90-110 the entire way. It's been an early and hot summer this year in s. california. I filled up the land cruiser with a full tank half way through the trip. There were no symptoms whatsoever. No vacuum when opening the gas cap, no hissing, no gas boiling or even smell of gas when driving. This trip had the high temp and elevation gains which has consistently caused the symptoms mentioned previously, but the LC experience no such symptoms.

I believe there are two problems on these LC's, one is a charcoal canister and fuel tank vent which caused the engine to sputter and die. The second are the fuel lines run near catalytic converter causing to fuel to overheat.

Lastly, i added a heat shield near the catalytic converter to block radiant heat which caused the gas to get hot, taking off the previous temporary heat wrap i had wrapped the fuel lines in. The heat shield is 24 gauge sheetmetal, 23" by 3.5", riveted to the existing cat heat shield. I added thermotec heat shield to the sheetmetal, only because i had it laying around, i believe it is NOT necessary...

I'm posting detailed work and results on this topic because, frankly, this was a huge PITA for me and had me considering selling the LC but i believe it's solved once and for all...

View attachment 1776206

View attachment 1776207

 

[OEMGUY0720]

Update:

New 8pcs of spark plugs are in, all bolts are tight, plugs seated tight.

I was able to start the truck on one click this morning, no problems at all, decided to clear the error using techstream, it did that.

Ran a quick errand more or less 45 minutes of driving on 97F outside temperature. As I was headed back home the CEL, VSC TRAC and VSC OFF lights came up on the dash again. I was able to drive it home safely, no stalls. Plugged in techstream and this came up:

Now I beleive P0430 is referring to the catalytic converter. Probably the cat O2 sensor? How do I know which side? Or is it safe to just replace both sides bank1 and bank2? I recently replaced the O2 sensors on the exhaust manifold 2 months ago if that would help. Does anyone know if Autozone or O'rielly have these?

Thanks in advance gents

 

[FxFormat]

P0430 is bank 2, down stream on the passenger side's cat. You could try and replace the O2 sensors first since they're much much much cheaper than replacing the cat. If that doesn't work then you're gonna have to replace the cat, the VSC lights are tied into any check engine light so as soon as that's fixed those will go off too.

 

[OEMGUY0720]

P0430 is bank 2, down stream on the passenger side's cat. You could try and replace the O2 sensors first since they're much much much cheaper than replacing the cat. If that doesn't work then you're gonna have to replace the cat, the VSC lights are tied into any check engine light so as soon as that's fixed those will go off too.

Thanks. Was able to pull it out and marked them accordingly.

I got these engraved on the side O2 sensors, are these the part numbers?

 

[OEMGUY0720]

Another update for today:

I got 1 downstream O2 sensor and will put this in now. Got it from O'Reilly for about 98 bucks. Will get the 2nd one in a couple of hours as it will be delivered in their branch later.

The guy said (who seemed more knowledgeable than the one I was talking to at the counter) that both side O2 sensors (banks) are interchangeable? Is this true, that I can put in the downstream O2 sensors (btw it's Denso but w/o the TOYOTA engraving on the side) on ANY side and will work? Can anyone confirm this?

 

[2001LC]

Either side (bank 1 or 2) are the same. Fronts (A/F) and Rears (O2) are different.

 

[OEMGUY0720]

Update today:

I got both downstream O2 sensors installed BANK1 and BANK2. Properly seated and tightened with anti-seize grease on both. I started it up and CEL, VSC TRAC and VSC OFF lights were still on. Hooked up techstream and cleared the error codes. Went to a dinner, going there it was a 20-minute drive on 100F temperatures, no stalling no CEL VSC TRAC VSC OFF lights. But on my way back, same outside temperatures 100F, the CEL VSC TRAC VSC OFF lights came up again coming off a stoplight.

Got home, ran techstream and P0430 again.

Clearing DTC:

Checked upstream and downstream O2 sensors, none loose all seated and torqued tight like before.

Night time came and I decided to re-create the problem, I went out for a drive 2-3 blocks from the house (thinking if the CEL would come up again however this time outside temp is different at 86F), and I was flooring it up to 4,000 rpm until i hit neighborhood speed limits at 45-50mph! But no CEL at all!! I even stayed idle with aircon in front of the house trying to wait if CEL will show up -none, no DTCs.

Weird?! Or it can be the temp conditions? Or is it just placebo?
Could it be really similar to the other thread that is symptom is temperature-dependent? So if this is the case then it could be the fuel pump?? P0430 caused by fuel pump or high temp?

I'm a bit lost at this point..

 

[2001LC]

I'm close (when I get time) to diving into one with similar codes.

First is gas tank; Was it ever over-top (handle at gas pump squeezed, after fist auto shutoff). This will cause charcoal canister issue.

Second; is gas cap OEM and in good working order.

I am suspecting fuel pump:

There are threads on this issue of this and bank 1 CAT and or o2 codes. That replacing cats, does not help. Some found R&R A/F sensor (front O2's) fixed issue others replaced all four. But most times codes come back. I think we may be damaging sensor due to running lean for to long. That bank 2 indicates bad more often than bank 1 (at first) because fuel comes in a bank 1. So Bank 1 may take down fuel pressure, which may be low to begin with. As bk1 uses fuel before it get to bank 2, which may be dropping pressure slightly in bank 2 fuel rail. FPR would normally compensate, that, and injectors themselves. But a faulty fuel pump just weak enough that it doesn't trip a code and passes all pressure test, may be at play.

Fuel pump is believed to be two speed. That during high RPM it in high. Then letting of gas dropping RMP fuel slows. It during the slow speed that pressure may drop to point were mixture runs lean.

After clearing codes. Try running in lower gears so you can keep RPM up for longer, say 3 minutes or more. This should keep pump running in high mode. Then shift up to "D" and let RPMs drop way down even take foot off the gas peddle for as long as you can. Then drive normal. Repeat this 3 times. See if code comes back.

 

[2001LC]

Here's a test for coils. While hooked to tech stream, load engine That is: Hold foot brake on, shift into "D" and raise RPM to ~1,700 or more. Watch for misfire while you have under load.

 

[OEMGUY0720]

Here's a test for coils. While hooked to tech stream, load engine That is: Hold foot brake on, shift into "D" and raise RPM to ~1,700 or more. Watch for misfire while you have under load.

I will try this too. Basically press and hold the foot brake and press gently the gas pedal too and increase RPM upto 1,700rpm?

I'm close (when I get time) to diving into one with similar codes.

First is gas tank; Was it ever over-top (handle at gas pump squeezed, after fist auto shutoff). This will cause charcoal canister issue.

Second; is gas cap OEM and in good working order.

I am suspecting fuel pump:

There are threads on this issue of this and bank 1 CAT and or o2 codes. That replacing cats, does not help. Some found R&R A/F sensor (front O2's) fixed issue others replaced all four. But most times codes come back. I think we may be damaging sensor due to running lean for to long. That bank 2 indicates bad more often than bank 1 (at first) because fuel comes in a bank 1. So Bank 1 may take down fuel pressure, which may be low to begin with. As bk1 uses fuel before it get to bank 2, which may be dropping pressure slightly in bank 2 fuel rail. FPR would normally compensate, that, and injectors themselves. But a faulty fuel pump just weak enough that it doesn't trip a code and passes all pressure test, may be at play.

Fuel pump is believed to be two speed. That during high RPM it in high. Then letting of gas dropping RMP fuel slows. It during the slow speed that pressure may drop to point were mixture runs lean.

After clearing codes. Try running in lower gears so you can keep RPM up for longer, say 3 minutes or more. This should keep pump running in high mode. Then shift up to "D" and let RPMs drop way down even take foot off the gas peddle for as long as you can. Then drive normal. Repeat this 3 times. See if code comes back.

Thanks for the insight, I will do a road test later this afternoon and do what you suggest basically run at 2nd or 3rd gear and leave it there. will report back later for results.

• Original Gas cap recently replaced about 2 months ago (dealership)
• Downstream bank1 and bank2 O2 sensors replaced with Denso yesterday (O’Reilly)
• Upstream bank1 and bank2 O2 sensors replaced 2 months ago with Toyota Denso (dealership)

Additional info: if it would help, when I took out the spark plugs, one of the coil packs looked dirty like it has some sort of brown dirt on it. I have a probable feeling the coil packs haven't been replaced yet since it rolled out from the dealership.

 

[2001LC]

I will try this too. Basically press and hold the foot brake and press gently the gas pedal too and increase RPM upto 1,700rpm? Yes! Watch for misfire in tech stream as you do this.


Thanks for the insight, I will do a road test later this afternoon and do what you suggest basically run at 2nd or 3rd gear and leave it there. will report back later for results. No! Run in low gear high RPM for about 3 minutes. Then shift to "D" and let off gas peddle. Do this after clearing codes. Repeat at minimum 3 times. See how it behaves and if codes come back. Watching fuel trims as you do this can be useful.

If you could climb to 12,500 ASL up a mountain pass that would be better. It would take a heavy foot on gas until summit reached, then coast down hill. The atmospheric pressure would drop as you climb the pass. This seems to have and affect on these bad fuel pumps, resulting in engine shutting down. Often it's though of as vapor lock, it not. Vapor locks and boiling gas seem to also happen at high altitude. But this we believe is from over filling gas tank in 03-07 wherein charcoal canister was moved to the rear. Toyota & Lexus OM have warnings about not topping tank since 2003. I've not heard of engine shutting down at your elevation of near sea level. But worth a try to see what if anything happens.

One other test is done, when engine is tuned and 'should be' running a peak. Get on HWY ramp and floor it and keep it floored. You should feel very stead and strong acceleration. If you feel minor hesitation or just not smooth acceleration. New set of coils does wonders at that point.

• Original Gas cap recently replaced about 2 months ago (dealership)
• Downstream bank1 and bank2 O2 sensors replaced with Denso yesterday (O’Reilly)
• Upstream bank1 and bank2 O2 sensors replaced 2 months ago with Toyota Denso (dealership)

Additional info: if it would help, when I took out the spark plugs, one of the coil packs looked dirty like it has some sort of brown dirt on it. I have a probable feeling the coil packs haven't been replaced yet since it rolled out from the dealership.

Dirty coil appearance was likely a loose spark plug. Gasses escape combustion camber and cause that. It is a sign coil ran hot. Also loose plugs draw more current from coil, heating coil more than normal. Excessive heat does damage coils. Sometimes all that is needed is a Denso coil kit. Comes with seal, boot and spring. These kit help stop sparks from firing around in spark plug tube.

A bad coil will show as a DTC (code). But a buggy or weak one will not through a DTC. A poor running engine can cause CAT issues long term. But with all you've replaced and codes keeps coming back. The problem must be up stream, cause and effect!

Expand for reply

Here's one thread you may have seen. P0420 and P0430 - 2006 LC Fornt O2s (A/F) have worked the best. But I think we have more than one 'cause' to this issue in the VVT. One being fuel pressure.