EGR needs my help, and I need yours!! (1 Viewer)

[StressPuppy]

I have been having an issue with my EGR valve on and off for some months now on my 97 LC. I get the engine light coming on now and again and when it does, it has the code P0401 - EGR Flow Insufficient. At first it would reset itself after a bit, but then I reset it myself and things would go for some time. Now, if I reset it, it comes back rather quickly.

I stopped by the dealer today and they said it would be $300 or so to do the service to clean out the carbon that is causing this.

Is this something I can do myself? What is involved? Is it a matter of cleaning things, or replacing things? How big of a pain is it?


(On a side note, I saw a new Cruiser on the lot while I was there. I love my LC, but $65k???!?!?!? Yikes, not that much!)

 

[IdahoDoug]

You can have your EGR valve in your hand in about an hour if that's of any use in your consideration. I don't know how much a new one is or what Cdan would say is likely to fail, but it's not rocket science to remove - 2 studs and a large union nut. Here's a quicky:

Lay a plank across from the right fender to the forward engine lift eye. Remove the hood support strut bolts from the fenders and somehow prop the hood up as high as it will go.

Remove the two bolts holding the plastic wire bundle box on the firewall above the heater valve. Remove the two bolts holding the heater valve to the firewall. These are optional, but help with swing room.

The EGR valve is held onto the intake manifold with two Torx studs (you'll need the female socket in size E7) and a nut (12mm?). Loosen the nuts - don't remove. Put serious pressure against the studs while twisting as you DON'T want to let it slip/strip it while breaking them loose. Smart shoppers hit the bolt on the stud with penetrating oil daily for a couple days.

Remove the studs, but being sure to get the metal gasket between the valve and the intake manifold while getting the second off (you can flex the valve away to pull the gasket out) as dropping it will put it in No Man's Land down there.

Now comes the fun part. There's a large union nut connecting the EGR pipe to the valve. A very VERY smart shopper would have also put PB Blaster penetrating oil on these threads also. The nut is larger than anything I had around and I had to borrow a fairly large adjustable crescent wrench for this. You'll have limited room to swing it and it's frustrating as once loose it still requires the wrench almost all the way off. DON'T round this off while trying to break it loose - get serious about tightening the crescent wrench onto it. You can remove the bolt you keep hitting the wrench against that holds the metal heater pipe on the manifold - it's worth the 2 minutes to get the extra swing as you won't believe how many turns the big union nut takes with a crescent wrench.

Once the union nut is loose, you can push it back down the pipe a bit to get it out of the way. Then a couple gentle twists, a single vacuum line simply pulled off an the valve is in your hand to be cleaned and looked at. Use a vacuum cleaner with a jury rigged piece of rubber hose duct taped onto it to clean out the pipe end you just exposed, then clean up the valve's openings and the opening on the intake manifold. Put a dab of anti-sieze on the union threads so you can easily hand spin it back most of the way on instead of the tedious crescent wrench deal.

They used studs because you have to pull them in order to get the valve off the union pipe. It will be clear when you're doing it, but you MUST have the Torx socket and remove the studs.

DougM

 

[Beowulf]

StressPuppy,

Sorry to hear that you've got the dreaded P0401 but don't fret too much as it is fixable and, as you already know, it is OK to drive the vehicle until you finally get the problem resolved.

We've had numerous posts on how to attack the P0401 problem. There is also a FAQ on this topic.

Basically, there are 4 components plus some interconnecting wiring and hoses. There is the EGR valve, the EGR modulator, the EGR temp sensor, and the VSV for EGR. I know you have an FSM so read the section on troubleshooting the P0401. This will give you suggestions on how to test each component. Some are easier to test than others.

Many have resolved their P0401 problem by replacing the EGR modulator. A very few were able to "clean" the EGR modulator but that doesn't seem to help the majority. If your EGR modulator has a lot of carbon then clean it up and clean the connecting hoses. There have been a couple of reports where a passage through the intake manifold was clogged.

I pulled and cleaned the EGR valve 2 or 3 times. Each cleaning would appear to give me a month or two without the code but I don't believe it really helped anything. A new EGR valve helped for about 4 months. A new modulator didn't make any difference on mine. Cleaning the EGR temp sensor has helped very few and 1 guy reported he had a bad temp sensor.

Many of us have solved the problem by replacing the VSV for EGR. It's in a hard to reach spot under the intake. You have to remove it to test it so most of us hold this one off until the last because it's hard to remove. You can get to it from underneath with a long extension, then pull it out from above. More details are in the FAQ.

Good Luck and keep us posted!

-B-

 

[MikeB]

First cut the problem domain in half by seeing if EGR is working when the valve is activated:

Disconnect the vacuum hose from the modulator to the EGR valve and put a long piece of hose on the valve. With the engine idling, suck on free end of the long hose. If the engine dies, then you know that the EGR valve is working and the passage is clear enough to flow exhaust gas. At that point you can flip a coin as to whether to try replacing the modulator or the VSV first. If the idle doesn't stumble badly when you activate the EGR valve, then that indicates that the valve itself is bad or a passage is so clogged that exhaust gas can't flow.

Mike

 

[StressPuppy]

<whack> <whack> <whack> <whack> <whack> <whack>

(sound of ruler hitting my knuckles for not searching first!!)

:whoops:

Thanks for the input. I did do a little reading some time back, but got a little lazy last night. Sorry.

I'll give the tests you mention a try and see how things come out. How expensive are the components we are talking about (modulater, VSV, EGR Valve)? Seeing that I plan to keep this truck for some time, is it worth considering replacing all 3 components or is it just a waste of $$ ?

I guess my next call will be to C-Dan (what would we do without him?!?!?!?)....

 

[Beowulf]

I guess my next call will be to C-Dan (what would we do without him?!?!?!?)....

I threw parts at it and replaced good parts with new parts. I don't recommend doing that so go through the tests if you feel comfortable.

If the EGR valve passes (including the test MikeB mentions) and the EGR modulator passes and the EGR temp sensor passes, then order the VSV and swap it or test it; your choice.

From memory and prices 3 years ago...
Modulator ~$60
EGR Valve ~$150
VSV for EGR ~$50

-B-

 

[StressPuppy]

I started reading over the threads here and the stuff in the FSM. In the FSM, it describes procedures to diagnose what is wrong when you get that code. But it keeps mentioning the Toyota code reader and info I don't get on my code reader. So how can I go through each of these steps and diagnose what is wrong?

(Are these expensive? As I plan to have my LC for some time, I'm up for buying if not outrageous!)

 

[Beowulf]

The Toyota tool is over $3k. Drexx is the only DIY guy that I have heard of buying one and he found a deal on his. There is another section in the FSM that tells you how to do the tests without the Toyota tester.

-B-

 

[cruiserdan]

Over 4 thousand actually.

 

[StressPuppy]

Ok, so I must have been smoking crack on that idea!!

I'll dig into the manual a little more and see if I can find the section you are talking about.

Part of me wants to do it to save on the labor costs, to learn and to make sure it is done to my perfectionist standards. The other part of me says "Screw it, you don't have time!" Ah, the eternal inner struggle of the cheap-skate and the guy with no free time!

 

[Beowulf]

Part of me wants to do it to save on the labor costs, to learn and to make sure it is done to my perfectionist standards.

In an effort to help you with your 2nd goal...

This is a cut-away of a typical EGR valve. You can see that it either lets the EGR flow or it doesn't (insufficient flow.) So if the valve will open (test is in the FSM) then you don't want to pull the EGR valve.

-B-

 

[MikeB]

I haven't had great luck in diagnosing the modulator or VSV through FSM tests on any recent Toyota. They seem to always pass the tests. Go ahead and test them, but don't completely eliminate them if they seem to pass the test. Just replace the other if the code comes back after your first guess. Anyway, it is cheaper to replace both rather than pay someone to attempt to diagnose which it is.

You can also test the resistance of the EGR temperature sensor. I don't think that anyone has reported one failing though.

Mike