LX470 Intermittent Prolonged Starts Only at first start up

[MONT470]

If the car always ran fine under load and didn't have fuel delivery issues (misfire) while running, the fuel pump was fine. When a pressure regulator leaks, it can bleed off the fuel left in the fuel rail while the car sits and then the pump has to work longer to re-prime the fuel rail on startup.
Normal operation of a regulator sends excessive pressure at the fuel rail back to the tank in a return line while the car runs, you just don't want it leaking fuel back to the tank while the car sits.
You could always just turn the key on for a couple seconds to prime, turn it off, and then on and crank. That will give it that little extra prime it needs.

I replaced the fuel pump because I thought it had a bad check valve in the pump itself...I couldn't find out for sure if there is a check valve in the pump, but I thought I'd give it a shot not being too expensive or difficult to install. Turning the key to "prime" has not worked in the past...I guess Toyotas are unique in that respect.

 

[Slotheye]

All the above is accurate except for the last two sentences. This is a common misnomer. Neither the 80 series or 100 series (if not modified) will 'prime' the fuel system UNTIL the engine is cranking. I know....that is unlike just about every other vehicle out there...but that is the way Toyota engineered it.

Jeez tough crowd here. What I meant was the fuel pump will turn on when the key is on and bring the pressure back up in the fuel rail. I was talking about the fuel rail pressure here and not an injector prime.

 

[flintknapper]

Jeez tough crowd here. What I meant was the fuel pump will turn on when the key is on and bring the pressure back up in the fuel rail. I was talking about the fuel rail pressure here and not an injector prime.

That's what we are talking about too. Fuel rail pressure. There is no such thing as injector prime. An injector is nothing more than an electric 'valve' that opens and closes, it does not prime.

You can continue to argue this if you like (at the expense of your credibility) or you can listen and learn (my suggestion).

We are not a 'tough crowd' here, quite the contrary but we strive to be accurate.

 

[flintknapper]

Again, the fuel does not (can not) prime with the key turned only to 'on'. It primes and provides pressure only when cranking the engine.

 

[Slotheye]

That's what we are talking about too. Fuel rail pressure. There is no such thing as injector prime. An injector is nothing more than an electric 'valve' that opens and closes, it does not prime.

You can continue to argue this if you like (at the expense of your credibility) or you can listen and learn (my suggestion).

We are not a 'tough crowd' here, quite the contrary but we strive to be accurate.

I don't care much about credibility on an online car forum. Thanks. I'm striving for accuracy as well. Most cars (not the LC) give an injector pulse as soon as the key is turned on. This is called a prime. The LC to my understanding turns the fuel pump on once the key is turned on. Correct me if I'm wrong (as I'm sure you will), but if the fuel pump is on, the fuel rail will have operating pressure so the injectors can pulse when cranking starts.

 

[flintknapper]

I don't care much about credibility on an online car forum. Thanks. I'm striving for accuracy as well. Most cars (not the LC) give an injector pulse as soon as the key is turned on. This is called a prime. The LC to my understanding turns the fuel pump on once the key is turned on. Correct me if I'm wrong (as I'm sure you will), but if the fuel pump is on, the fuel rail will have operating pressure so the injectors can pulse when cranking starts.

You've been corrected twice already. Is a third time really necessary?

Just WHERE and HOW did you come upon the 'understanding' that the fuel pump comes on with the key in the 'on' position.?

What do you have to offer that would support that idea? It DOES NOT do that on an 80 or 100 series Land Cruiser. I don't know how to be more plain about it.

We really don't give a damn what 'Most Cars' do or don't do. It doesn't apply to the Land Cruiser.

You may continue your insufferable position and plays on semantics if you like. Or....you can start anew, listen and learn. But you'll find yourself quickly ignored here if you continue to argue what we know to be fact.

It's OK to be wrong. Just correct it and move ahead.

 

[Slotheye]

Yeah ok thanks. A third time was necessary for my stubborn self. If the ECU controls the fuel pump and it isn't on when the key is on, that makes sense. And my apologies.
Hopefully the thoughts on fuel regulator operation is helpful though, since that was the original point. Sorry to derail the thread.

 

[flintknapper]

Yeah ok thanks. A third time was necessary for my stubborn self. If the ECU controls the fuel pump and it isn't on when the key is on, that makes sense. And my apologies.
Hopefully the thoughts on fuel regulator operation is helpful though, since that was the original point. Sorry to derail the thread.

Yes, first half of your post was spot on.

No apology necessary....these Land Cruisers (and some other Toyota offerings) are a different kind of cat.

Traditional wisdom and automotive engineering doesn't always apply. I can assure you....it trips us all up at some point.

Welcome to the forum. We aren't trying to bust your balls, I promise.

Flint.

 

[krispykritter]

Back on topic - I have seen where bad cam/crank sensors can drive this sort of behavior. Not usually just when cold, but occasional long start/no start situations followed by operating fine for extended periods, only for the phantom issue to return on a different start.

Maybe that's worth looking into, OP?

Back off topic here:

That's what we are talking about too. Fuel rail pressure. There is no such thing as injector prime. An injector is nothing more than an electric 'valve' that opens and closes, it does not prime.

Most cars (not the LC) give an injector pulse as soon as the key is turned on. This is called a prime.

Slotheye is correct here - most cars DO 'prime' the injectors. Adds some fuel to the intake to help with starting and to clear any possible air bubbles out of the injectors. I don't know if the LC does that. I also didn't know that the LC doesn't run the fuel pump for a couple seconds when you turn the key to 'on' though - strange they'd do that differently that virtually every other manufacturer on the planet. This was discussed in another thread recently with a no start/start then die condition going on.

 

[flintknapper]

Back on topic - I have seen where bad cam/crank sensors can drive this sort of behavior. Not usually just when cold, but occasional long start/no start situations followed by operating fine for extended periods, only for the phantom issue to return on a different start.

Maybe that's worth looking into, OP?

Back off topic here:


Slotheye is correct here - most cars DO 'prime' the injectors. Adds some fuel to the intake to help with starting and to clear any possible air bubbles out of the injectors. I don't know if the LC does that. I also didn't know that the LC doesn't run the fuel pump for a couple seconds when you turn the key to 'on' though - strange they'd do that differently that virtually every other manufacturer on the planet. This was discussed in another thread recently with a no start/start then die condition going on.

It doesn't. And show me documentation where Multi-Port Sequential Fuel Injection adds fuel to the intake 'primes' before starting. (Not direct injection, Sequential).

Almost all vehicles (Toyota excluded in most cases) prime the fuel rail when the key is turned to the 'on' position. This provides fuel under pressure to the injectors. I am not aware of any that go on to 'prime' (squirt an amount of fuel into the port) at the same time. Why would it?

Every time you turn your key on it would do this right? So if you just want to roll down your window with the engine off the fuel system primes the intake? And with Sequential Injection it is 'timed' per cylinder just like firing of the spark plugs (different from MPI which fires all injectors at the same time).

As for Toyota's design 'strange' or not....it is in fact that way. Perhaps for safety's sake....or some other reason, who knows, but that's how it works (fuel system does not engage/prime) until engine is cranked, then fuel pump runs (variably on some vehicles) after that.

 

[krispykritter]

It doesn't. And show me documentation where Multi-Port Sequential Fuel Injection adds fuel to the intake 'primes' before starting. (Not direct injection, Sequential).

Here's a link to where it's discussed on the megasquirt forums: MSExtra Forums

Here's a screenshot of the first post, you're welcome to read more as needed.

Also, if you google "fuel injection priming pulse" you get posts on any number of technical forums discussing this, including Megasquirt, Haltech, miata turbo, speeduino, etc.

No, toyota may not do it (and it makes sense they wouldn't given they don't run the fuel pump), but that doesn't mean no one else does. Since it seems to be incorporated in all the aftermarket ECU info, I infer that it's likely incorporated in many OEM ECUs as well. I'm not an OEM engineer, so I can't say for certain. I can say even the microsquirt we wired into our racecar includes this feature, and it's a pretty bare-bones ECU.

Agreed, full sequential is timed per cylinder. Semi-sequential fires a whole bank of injectors at once, alternating 360 degrees of crank rotation.

 

[flintknapper]

Here's a link to where it's discussed on the megasquirt forums: MSExtra Forums

Here's a screenshot of the first post, you're welcome to read more as needed.

View attachment 2685116

Also, if you google "fuel injection priming pulse" you get posts on any number of technical forums discussing this, including Megasquirt, Haltech, miata turbo, speeduino, etc.

No, toyota may not do it (and it makes sense they wouldn't given they don't run the fuel pump), but that doesn't mean no one else does. Since it seems to be incorporated in all the aftermarket ECU info, I infer that it's likely incorporated in many OEM ECUs as well. I'm not an OEM engineer, so I can't say for certain. I can say even the microsquirt we wired into our racecar includes this feature, and it's a pretty bare-bones ECU.

Agreed, full sequential is timed per cylinder. Semi-sequential fires a whole bank of injectors at once, alternating 360 degrees of crank rotation.

Again, I have asked you to demonstrate that the fuel systems in 'most' modern vehicles provide this function as designed from the factory.

You have referenced MegaSquirt which is an aftermarket electronic fuel injection controller that allows for tuning/functions by the user. How does this apply to vehicles without it? Then you seek to prove your point by 'inferring' that because it can be installed on a number of vehicles that the 'feature' (injector prime) is 'likely' present in most modern vehicles.

Surely the literature exists in the FSM's or other printings of the vehicles you propose? I am happy to concede if you can produce that, but I'm unwilling to make the 'leap' from MegaSquirt to OEM (on most vehicles).

I'm not trying to labor the point....but it assuredly does not exist on the Toyota's we are concerned with... and I doubt elsewhere with a few possible exceptions. I am willing to learn however.

 

[krispykritter]

Wrote up a bunch of words, then deleted it. Simple as this: it's trivial to prove your statement about not being able to 'prime' an injector wrong.

Enjoy your stay on Arrogance Mountain.

 

[flintknapper]

I am unwilling to spend hours searching for/downloading/reading FSMs to attempt to prove a point to someone who clearly knows more than anyone else on a toyota forum. I have exactly 1 FSM available to me (for the 100) and I wholly believe you when you say the toyota doesn't do that. I have no interst in attempting to spoon feed you this information. If it's of interest to you, feel free. If you are completely confident I'm wrong, then don't.

Either way, you come across rather arrogant and it's easy enough to prove yourr statement "There is no such thing as injector prime. An injector is nothing more than an electric 'valve' that opens and closes, it does not prime." wrong simply with a google search, which you clearly haven't done. Feel free to correct people, but also feel free to realize you don't know everything.

Not trying to sound arrogant (but perhaps I have failed). Just trying to keep the information here accurate so that in the future when someone searches they are not further confused.

It was you that stated:

"Slotheye is correct here - most cars DO 'prime' the injectors. Adds some fuel to the intake to help with starting and to clear any possible air bubbles out of the injectors.

Then when I asked you to provide documentation for that (most cars) you submit an obscure aftermarket example that makes it 'possible'.

So perhaps we are arguing two different things. I am saying I DO NOT believe that is what exists on 'most cars' and have explained what a typical injector does. The 'function' of an injector is precisely as I described.

WHAT an injector might be made to do (with aftermarket equipment) seems to be the point you are stuck on and the stumbling block of your argument IMO.

I suspect we will not come to an agreement about this...so lets not waste any more time on it and part amicably.

 

[huffer2]

I'm chasing the same thing in an 06 470 I recently bought. One owner always dealer serviced and it started to have the same problem. The dealer did 3k worth of diagnostics and work including cleaning the fuel tank. The owner gave up and sold it. I found a video by Googling lx470 intermittent start that shows a problem with the fuse box internal connections failing because of corrosion and then heat. The connections get hot and become loose, then cool and reconnect. Anyway, I found a new fuse box but haven't put it in yet because I haven't had the problem yet. See if you can find that video.

 

[flintknapper]

I'm chasing the same thing in an 06 470 I recently bought. One owner always dealer serviced and it started to have the same problem. The dealer did 3k worth of diagnostics and work including cleaning the fuel tank. The owner gave up and sold it. I found a video by Googling lx470 intermittent start that shows a problem with the fuse box internal connections failing because of corrosion and then heat. The connections get hot and become loose, then cool and reconnect. Anyway, I found a new fuse box but haven't put it in yet because I haven't had the problem yet. See if you can find that video.

Could well be an issue. More than a few people have experienced fuse box problems that caused various problems. Good suggestion!

 

[MONT470]

I'm chasing the same thing in an 06 470 I recently bought. One owner always dealer serviced and it started to have the same problem. The dealer did 3k worth of diagnostics and work including cleaning the fuel tank. The owner gave up and sold it. I found a video by Googling lx470 intermittent start that shows a problem with the fuse box internal connections failing because of corrosion and then heat. The connections get hot and become loose, then cool and reconnect. Anyway, I found a new fuse box but haven't put it in yet because I haven't had the problem yet. See if you can find that video.

Thanks. I had seen the video related to the fuse box, but thought it likely wasn't my issue...mainly because if I go to start and the prolonged crank/start occurs, I can shut it off and restart it immediatley with out the long crank time. I'm defintely not ruling the fuse box out at this point or even the EFI relay...updates to come!

 

[huffer2]

I'll keep you posted as well. I also have VGRS issues with the steering wheel 80 degrees off and that seemed possibly related to a power failure issue at the fuse box. I'm waiting for some techstream stuff to go after that one.

 

[MONT470]

UPDATE’ish. After a visit to my mechanic for a new exhaust manifold (passenger side) and brake flush... he wasn’t able to witness much of the prolonged crank start himself so could only go by my description. He did say he noticed a couple coils with cracks developing in them. He recommended I buy an 8 pack of denso coils and replace them myself to save some money. His cost to me would be about $150 per coil and the 8 pack is under $200 if he remembered correctly. I thought that was nice of him to suggest, however he didn’t feel super confident that it would solve the issue but still felt it was worth doing. He also suggested that I begin to use ethanol free gas. He has a 99’ 100 series with 500k miles which is his daily driver. He says running ethanol gas (10%) will prevent his rig from starting well. He also gave me a bottle of 44K gas treatment to try which I am running in my current tank of 91 octane (ethanol free). I’m trying not to get too optimistic about a solution in a bottle but I have read the 44k stuff is pretty great...I hope so at $30 a bottle lol. I’m considering replacing the efi relay...or looking into the fuse box as a possibility....but, I gotta say I’m also considering just living with it. It always fires up, it just takes a bit longer at times. Sucks it kinda gets in my head and tarnishes my confidence in the LX. That’s probably the hardest part of the issue for me. We’ll see how things play out in the next couple of weeks...

 

[huffer2]

I managed to get tech stream running and was able to center my steering wheel through the VGRS pretty easily. In the tech stream history I found some instances of ecus having a low voltage condition (including VGRS), so in my case I'm still thinking fuse box. I haven't had a problem so far and there are no error codes so I'll just wait and see what happens.