P0401 Defeated - with pics (1 Viewer)

[scharpestguy]

Flank,

How difficult were the repairs that you performed? The most difficult things I have done lately were spark plugs in a 1991 V6 4Runner and a new starter in the LX450 including an oil change and filter. Is this a doable repair for a very shade tree one banana owner?

Second how long did the repairs take? I'm trying to think how long the downtime would be if I performed the repairs which I would like to as it feels great to repair it and learn about the truck / engine. I do have some spare vehicles so the wife and boys will be fine with the truck being down for a little bit but she loves her truck.

Thanks Flank,

Scharpe St Guy

 

[Flank]

Flank,

How difficult were the repairs that you performed? The most difficult things I have done lately were spark plugs in a 1991 V6 4Runner and a new starter in the LX450 including an oil change and filter. Is this a doable repair for a very shade tree one banana owner?

Second how long did the repairs take? I'm trying to think how long the downtime would be if I performed the repairs which I would like to as it feels great to repair it and learn about the truck / engine. I do have some spare vehicles so the wife and boys will be fine with the truck being down for a little bit but she loves her truck.

Thanks Flank,

Scharpe St Guy

I had never done any engine work past changing batteries and plugs before this, and I now feel much more comfortable getting into it. I also am much more familiar with the engine components than I was. Lastly, I committed to the cost of the job and to having the stuff to do it right on hand - saving frustration of trying one part, trying another, etc. Nothing here is rocket science, I was not calibrating, adjusting, or redesigning. I was just disassembling, cleaning, and re-assembling. The next most important thing i think, is having a write up on it, FSM handy, and using a digital camera to document EVERY INCH of what you touch. It is easy to think "I will remember that". Trust me, you won't. Pictures from every angle before disassembly and especially of all of the vacuum hoses were critical to my success.

The biggest thing in doing this is the desire. I have small children, so spending 8 hours in the garage in one stint in not an option, I have to section it out, often, in several sessions. I probably put, with tear down, cleaning, and reassembly, about 10 hour into this. I would probably cut that by 1/3 or 1/2 when I do it again just do to knowing what I am doing and lack of fear. If you try to do everything from the top, you will take longer and be VERY frustrated, the easiest way to get to the intake plenum bolts is to be on your back working up . Goes very quickly.

So in answer to the question, if you are adventurous, have the time, you will gain the knowledge on the job. Have fun, I did.

 

[scharpestguy]

Just what I was hoping to hear, will be ordering the parts from CruiserDan this week. Thank you for the reply and inspiration Flank.

Scharpe St Guy

 

[jlg32281]

Does anyone know a way of cleaning the port with just the throttle body off? I had the throttle body off and that gave me enough room to get to the VSV and I was able to clean the port to the left hand turn. I couldn't figure out a way to make that turn with anything that would be stiff enough to scrape the carbon off. Any ideas? At this point I have a new EGR modulator, VSV, and a partially cleaned port. I haven't driven it enough since to know if this cleared my code, but I'm thinking that the port needs to be cleaned.

 

[redeye]

X2

I would also like to know this.

 

[skibob]

There is a way to clean the blockage without disassembly.
It might be a little scary for some of you, and some of you will undoubtedly flame me for even suggesting it, but it works great, I've done it with chebbies, dogs, fjords, dottsuns, and the occasional yoda.
First, pull the throttle body, look for blockage.
It will be obvious if it's there.
If blocked, get your oxy acetyline torch with the smallest tip you have.
Don't even think of using the cutting torch for this, it will slag your entire manifold.
Set your torch with a very small flame, suitable for welding thin sheet metal.
carefully position the flame to heat the very center of the blockage. It will start to glow like a cigarette.
When it gets hot enough that it is glowing, turn off the acetyline but leave the oxygen running right on the smoldering plug.
As it burns it will crackle and pop, you need to keep your safety glasses on, shield the area with maybe a piece of sheet metal or other noncombustible.
As it burns, the smoldering mass will disappear in the hole but keep happily popping and crackling until the port is open, all foreign material is burned away.
You will want to stick your torch tip right into the hole, maybe turn up the oxy a little in order to push it deeper into the port before it is forced out by exhausted gases/spatter.
Again, be very careful to keep the torch flame away from the aluminum or you will suddenly have an opportunity to buy some really expensive aluminim bits.
Don't do this until you buy or have a very small torch tip.
Don't do this if you have a really dirty engine compartment, oil leaks that haven't been cleaned up.
Don't do this inside of a closed room, it will stink you out.
When it is cleaned out, put all the bits back together and if your only problem was a blocked port, you should be back in business.
Happy days.

 

[MSGGrunt]

If the upper intake manifold is separated from the lower section there is access to what looks like a plug on the backside of the manifold (area circled in red). Is this a plug that can be bought through Toyota? If so, it looks like removal of the plug would provide straight access to the area that tends to clog. Then you could possibly use a wire shotgun bore brush in a drill with some fuel injection cleaner to give the inside a good scrubbing.

I too am about to fix a P401 code and want to make sure that ALL areas that could lead to this code are addressed and ALL parts that could lead to the code are replaced.

 

[jlg32281]

If the upper intake manifold is separated from the lower section there is access to what looks like a plug on the backside of the manifold (area circled in red). Is this a plug that can be bought through Toyota? If so, it looks like removal of the plug would provide straight access to the area that tends to clog. Then you could possibly use a wire shotgun bore brush in a drill with some fuel injection cleaner to give the inside a good scrubbing.

I too am about to fix a P401 code and want to make sure that ALL areas that could lead to this code are addressed and ALL parts that could lead to the code are replaced.

With the upper intake pulled, it would be easy to clean. Even without pulling that plug, you could uses all kinds of things to get in there an unclog the port. I was trying to figure out a way to do it with just the throttle body removed. Mostly, I don't want to have to remove the egr valve, but I guess it's inevitable.

 

[skibob]

I got the 0401 code.
Decided to look at the plugged port problem.
Didn't want to pull a bunch of stuff apart just to look at it, so in order to check for a plugged egr port as shown in the pictures from Flank above, I just pulled the sensor and started the engine. No massive vacuum leak from that, so I pulled the throttle body. Port was plugged, so I dug it out with a pick, cleaned up the mess, plopped the throttle body back on, started it again.
Massive vacuum leak now, maybe it's fixed, put the sensor back in, cleared the codes, waiting for cdl to pop on again. fingers crossed for now.

 

[scharpestguy]

Today I purchased the full compliment of parts listed by Flank along with the VSV for EFI and the Air Temp Sensor mentioned by Flank. I figured since I'm in there and the truck has 230k it might as well be replaced now rather then later. I think I'm also going to pull the fuel injectors and send those out for cleaning.

Obviously we love the truck! We also love CDAN and Ownr at American Toyota!

Scharpe St Guy

 

[skibob]

You can test egr valve open/close, port flow, etc by applying vacuum to the egr while the engine is running. There is a good source of vacuum at the little black vacuum port shown in the pic by msggrunt above. just start the motor, put a vacuum hose from the vacuum port to the egr. if the egr is working, and your intake port is unclogged, the engine will die. if this doesn't happen, pull the vsv, start the motor, if there is a massive vacuum leak, your egr is most likely dead. I haven't worked out simple tests for the rest of the system yet, but they will be coming soon.

 

[scharpestguy]

Ok, I am deep into this repair with the truck up on ramps, hood taken off (really helped accessibility to the parts), and the fuel injectors removed ready to be cleaned and adjusted if need be. I purchased a few additional parts from CDAN that were not on Flank's list such as the water temp sensor and VSV for EFI. I figured while I'm in there and since the truck has 230k I might as well.

My port looked and appeared 100% clogged it was actually worse than Flanks appeared bulging out of the inside hole and the hole that comes around where the gasket sits was clogged 100% as well. It puzzles me why I have not received the P0401 light prior to this due to the extent of the clog.

I'm anticipating paying approx $15 per injector to have cleaned down the road from my house or if they cannot do it then I found a fuel injector shop in Austin who provides fast turnaround times.

I will note that I went out and purchased three 10 inch 1/2 inch extensions and I should have purchased the 3/8 size but never the less the bolts are not all that tight and the 1/2 inch socket worked just fine removing each bolt although I now have an adapter that will allow me to use the proper 12mm socket. I have not yet started replacing the hose but I have a fear that I may not have purchased enough. I followed Flanks suggestion and purchased ten feet of the 5/32 ID Vac hose, and ten feet of the 1/4 ID Gas line, and five feet of the 5/16 ID Vac hose.

Removal of the Fuel Injectors was pretty painless except for removal of the last electrical connector on the fuel injector closest to the fire wall. I found a long grip and my hand wedged in did the trick finally.

I will post another update next weekend on my adventure reassembling everything! All in all I'm very happy that I have gotten this far and am undertaking this repair even with my novice skills. I'm learning a great deal about the truck and am repairing to my specifications and standards which I have to believe are a little higher than most mechanics.

All the best,

Scharpe St Guy

 

[stonehenge]

Did this to my LX450 today and what a huge difference. My port was plugged and bulging out by a 1.16th of an inch. I also had a lot of carbon and oil built up in the intake and runners which took the better part of 2 hours to clean to my satisfaction.

I found that three cans of carb cleaner and then i switched to this really great oil eater stuff i got at costco worked best. i sprayed and then used a bong cleaner brush (very stiff) and kept at it until it was broken up.

i flushed with warm water until it ran clean, used a air sprayer to clean/dry the water and then began the tedious task of buttoning everything back together. Thanks for the writeup, armed with the list of parts i didnt have to go running around once i got started.

Andy

 

[Flank]

 

[Dan2722]

Performed this maintenance over the weekend and so far no more P401 and the truck is running smoother. I had a slight rough idle sitting at a stop light before that is now gone.

Thanks for the write up.

 

[Solid Taco]

Did this too a couple of weeks ago even though it wasn't the problem causing my P0401 . Glad I still did it though. I recommend cleaning and calibrating the fuel injectors and changing the fuel filter if doing this. Thanks for the tips and pics. Helped a lot.

Cary

 

[tqcruiser]

My LX450 only has 103,000 miles but it is not running as smooth as before. I am suspecting the EGR port to throttle body is somewhat clogged as well. If I just want to take the EGR valve off for a cleaning what tools are required? I looked at this area before but it appeared an open wrench larger than 27mm would be required. What tool did you all use to break loose the EGR pipe nut?


Tan
'97 LX 450 103k miles
'87 Mercedes 190D 2.5t
'91 Mercedes 300D 2.5t

 

[Solid Taco]

I used a 1 1/4" open end wrench to loosen EGR pipe union nut. IIRW, to loosen would be towards the driver side so, righty loosy? in this situation The size 32 was mucho $$ but the standard size worked for me. I then used large pliers to loosen it all the way. Having the hood out makes it easier. HTH.

Cary
P.S. Be careful with the wire loom. Remember to take it off its base so it would be more maneuverable and later on wrap it with heat tape.

 

[Atoyot1031]

10-4. I did this yesterday by just pulling the EGR and the SC intake cone. BTW, a 4mm socket worked for me to remove the EGR studs. I'll post back up in a week after a road trip to Boise to see if this rectified my PO401. I tested EGR, VSV, EGR actuator, and all passed FSM tests. The only other thing it could be would be the gas temp sensor, which I seem to remember Cdan said once upon a time that these fail and are overlooked. The FSM test requires testing resistance in various pots of water with known temperatures.

 

[MikePL]

I have also defeated my EGR problems. I hate this system so much that I had to cut the hell out of it. Who invented this? First you use filters to clean intake air and then you let the EGR pollute it all. It's like breathing your own farts or eating your own... nevermind.

So it's 1:0 for me EGR defeated and resistor installed