Egr Valve - Where Is It - Exactly?!

[CanadaCraig]

Hi Guys!! :)

I did a 'search' and I'm still confused. Where exactly IS the EGR VALVE?! Some cartoon drawing [that I found here at LOC] seemed to indicate the the EGR Valve is near the throttle body. And some messages seemed to suggest that it's way down below and very difficult to get to.

If you know - please tell me. And is the EGR Valve expensive?!

I own a 1993 LS400.

Thanks,

Craig!! :)

[maniek_LS]

Hi Guys!! :)

If you know - please tell me. And is the EGR Valve expensive?!

Craig!! :)

EGR Valce in LS400 is here (right side of the engine if you facing your car)

[CanadaCraig]

Hi maniek_LS!! :)

Thank you very much. I appreciate it.

But I'm curious. Is there more to the EGR than just the VALVE? IS there an EGR PIPE? [or whatever] Quite a few messages [here a LOC] seemed to go on about how difficult it is to change the EGR [something or other] and takes up to 5 hours to do.

If I'm confusing you - good!! I won't feel so alone then!! lol

Craig!! :)

[Leadfoot]

But I'm curious. Is there more to the EGR than just the VALVE? IS there an EGR PIPE? [or whatever] Quite a few messages [here a LOC] seemed to go on about how difficult it is to change the EGR [something or other] and takes up to 5 hours to do.

Oh yes, there is so much more. To reduce nitrous oxide (NOx) emissions, part of the exhaust gases are recirculated through the EGR valve to the intake manifold to lower the maximum combustion temperature in the cylinders. The gas is taken from the exhaust system near the cat, up the back of the engine bay through the EGR pipe, which is notorious for leaking, and is a complete beyotch to replace (which is why mine is still leaking!!) to the EGR valve, which is in turn controlled by the VSV (vacuum solenoid valve) and the Vacuum modulator.

Basically the system monitors coolant temperature, throttle valve angle and engine speed through a combination of ECU control and vacuum levels to adjust the EGR valve settings. The exhaust gas is allowed into the plenum chamber of the intake, which is why the backs of our throttle bodies get so caked up with crap over time. Over 4000 rpm or below 55C coolant temp the system doesn't operate, other times it operates as it pleases.

Bet you wished you had never asked!

Also I don't know about cost, but your local Lexus Stealer will.

[CanadaCraig]

Bet you wished you had never asked!

Hi Leadfoot!! :)

Actually - I'm VERY glad I asked. [although I'll admit - the idea of a 'simple EGR valve' problem doesn't seem quite so simple any more!!] BUT it's good to know these things!! lol So thank you very much!!

In your opinion - could an EGR related 'thing' cause my car to accelerate poorly when 'floored' from a dead stop?! AND cause a surging sensation?! Everything else seems to have been inspected, adjusted, cleaned and/or replaced.

Thanks!!

Craig!! :)

[Leadfoot]

In your opinion - could an EGR related 'thing' cause my car to accelerate poorly when 'floored' from a dead stop?! AND cause a surging sensation?! Everything else seems to have been inspected, adjusted, cleaned and/or replaced.

Thanks!!

Craig!! :)

OH....MY......GOD. I just read the entire "please do me a favour" thread of yours and I had no idea how much torment you have gone through for such a long time. Dude, you have the patience of a saint.

Lets try and step back and look at your problem from the fundamentals.

Your customer complaint is

"my car is really VERY nice if driven only semi-aggressively. But after an hour or so, especially if I floor it from a dead stop, it begins to hesitate and surge and the gear changes become more abrupt. This is especially true when 'red-lined'. In fact - the entire 'feeling' of the car changes. It goes from being quite pleasant to quite frustrating and annoying. The idle also becomes erratic, like the engine is trying to clear its throat. It's noticeably worse at 1400 RPM's and 1800 RPM's."

A perfect engine will;

1) suck in the right amount of air and fuel

2) compress it

3) ignite it

4) get rid of it and start again, making lots of torque

a) Your problems may lie in the amount of fuel being delivered. I saw that you have had the fuel pump and filter cleaned and the pipes "fully checked out" by a doorknob. The interesting fact is that the fuel injection cut rpm is 1800 and the fuel return rpm is 1400. Hmmmmmm, a strange coincidence? ( I don't know what this means yet, I have to do some background reading on the EFI system)

b ) Lets say you had an airleak that was sucking extra air into the manifold, thereby reducing the proper fuel to air ratio. Well I think this is out since the ECU calculates the burnt gas ratio using those lovely new O2 sensors you bought it, and if it was out of spec it would tell you with engine fault codes 25 or 26 (but we will check soon anyway).

c) The EGR system could have a malfunction and be allowing recirculated gas into the intake, diluting the mixture and robbing you of all those glorious horses that you know live in that block. The ECU will only produce fault code 71 if the EGR gas temperature sensor is reading <65C when EGR should be occuring (i.e engine warmed up, below 4000 rpm)

d) compression should not be an issue on a motor as young as yours, and as you know its history you know the engine hasn't gone without oil for a couple of weeks during a drive through the baja desert. So lets discount this one.

e) Lets face it, you have done virtually everything to your ignition system. The car sounds good on the videos too, no complaint of a misfire as such. I want to discount this one too.

f) the exhaust system, if choked will prevent the flow of gas through you motor. But you say it does occasionally "run free", which is not a typical characteristic of a clogged cat. Lets ignore this one for now.

g) nobody has mentioned the gearbox. Maybe the engine is making making lots of power, but its being robbed by something in the gearbox. Is redlining good for them? The torque converter is fine though as that passed the "smoke the rear bags" test. When was the toyota "T-IV ONLY" oil last changed? I am going to assume you have serviced it at the correct intervals, but had to mention it as its part of the "powertrain".

Therefore;

Even though you only have OBD1, it has a highly sensitive diagnostic setting that it can be placed in that is used for tracking problems. Lets use it to eliminate some of the above items, namely b & c (air/fuel ratio amd EGR function).

Do you know how to read the OBD codes from your instrument cluster? if not please check some of my previous threads, I have rattled on about it quite a bit in here (click on my name and look for my previous posts).

What I propose is that we work together to eliminate the possibilities above till the culprit is found, and not spend any money on replacement parts (you have done enough of that already). Your car is working smoothly when taking it easy, so nothing is seriously wrong. It is obvious to me that you have the patience and determination to get this sorted, you just need some technical guidance to help locate the problem. I have the ability to read instructions (i.e. the factory manual), so we should be able to find where your variance from normality resides. Hopefully.

My old 92 also gets ropey around 1800 rpm, and I have a leaking EGR pipe. Maybe we have the same problem, which is why I responded initially to the EGR question. Hopefully we can both cure our frustrations and learn a bit about the wonderful engineering that is the LS400.

So bone up on my posts on reading fault codes and I will see you back here when you are ready to start or have some questions.

[CanadaCraig]

OH....MY......GOD. I just read the entire "please do me a favour" thread of yours and I had no idea how much torment you have gone through for such a long time. Dude, you have the patience of a saint.

Hi Leadfoot!! :)

THANKS!! I greatly appreciate the fact that you obviously read the entire "please do me a favour" thread!! I think that's great!! I'm not so sure I'm 'patient' as much as I can't afford to buy another car. [unless I get rid of both of my cars] PLUS - so much has already been done to my LS that it would be a shame to get rid of it when it's probably just ONE THING that's causing all the problems. It's trying to FIND that ONE THING that has been driving me NUTS!! On a few occasions - I've actually stopped the car - got out - and paced back and forth because I was so frustrated. It should also be noted that the Lexus dealer hasn't charged me for everything they've done. In fact - I still haven't paid the last two bills [on their insistence that I 'try it - and let them know if it's any better'] and the one before that they simply said, 'no charge'. [and that was for over $800] So I can't say that they're trying to cheat me or anything like that.

a) Your problems may lie in the amount of fuel being delivered. I saw that you have had the fuel pump and filter cleaned and the pipes "fully checked out" by a doorknob. The interesting fact is that the fuel injection cut rpm is 1800 and the fuel return rpm is 1400. Hmmmmmm, a strange coincidence? ( I don't know what this means yet, I have to do some background reading on the EFI system)

Just so you know - both the fuel filter and fuel pump were replaced with new. As for the rough spots at 1400 and 1800 RPM - it might be more like 1400 and 1600. [but that was last night - I'm sure it was 1800 at other times]

b ) Lets say you had an airleak that was sucking extra air into the manifold, thereby reducing the proper fuel to air ratio. Well I think this is out since the ECU calculates the burnt gas ratio using those lovely new O2 sensors you bought it, and if it was out of spec it would tell you with engine fault codes 25 or 26 (but we will check soon anyway).

Apparently - the last time they had it - they checked for codes AND attached a computer to whatever and drove it at varying speeds. Nothing came up as 'error code' worthy. But who knows. He did say [as I've posted here a LOC] that my car was unable to go faster than 118 MPH. [if that means anything - diagnostic wise]

c) The EGR system could have a malfunction and be allowing recirculated gas into the intake, diluting the mixture and robbing you of all those glorious horses that you know live in that block. The ECU will only produce fault code 71 if the EGR gas temperature sensor is reading <65C when EGR should be occuring (i.e engine warmed up, below 4000 rpm)

But what IF it's getting stuck [sometimes] in the 'occurring position' [which I assume means, 'when it is OPEN'] at RPM's above 4,000 RPM. My car often takes it's time reaching the redline.

Points d, e and f noted.

g) nobody has mentioned the gearbox. Maybe the engine is making making lots of power, but its being robbed by something in the gearbox. Is redlining good for them? The torque converter is fine though as that passed the "smoke the rear bags" test. When was the toyota "T-IV ONLY" oil last changed? I am going to assume you have serviced it at the correct intervals, but had to mention it as its part of the "powertrain".

Since I've owned my LS [bought in October of 2003] both the transmission fluid and the differential fluid have been changed twice.

Even though you only have OBD1, it has a highly sensitive diagnostic setting that it can be placed in that is used for tracking problems. Lets use it to eliminate some of the above items, namely b & c (air/fuel ratio amd EGR function). Do you know how to read the OBD codes from your instrument cluster? if not please check some of my previous threads, I have rattled on about it quite a bit in here (click on my name and look for my previous posts).

It will be interesting to try all that. But I'm not quite sure what to use. In one of the responses to one of YOUR messages - someone suggested using part #SST 09843 18020. Is that necessary OR can someone simply use a paper clip? [or something like that] Am I at risk for an electrical shock and/or ruining some electrical component by shorting 'things' out?! [i'm a worry wart - just so you know]

What I propose is that we work together to eliminate the possibilities above till the culprit is found, and not spend any money on replacement parts (you have done enough of that already). Your car is working smoothly when taking it easy, so nothing is seriously wrong. It is obvious to me that you have the patience and determination to get this sorted, you just need some technical guidance to help locate the problem. I have the ability to read instructions (i.e. the factory manual), so we should be able to find where your variance from normality resides. Hopefully.

That sounds wonderful. It would be GREAT to finally OWN a Lexus LS. [which was - at one time - one of my dream cars]

My old 92 also gets ropey around 1800 rpm, and I have a leaking EGR pipe. Maybe we have the same problem, which is why I responded initially to the EGR question. Hopefully we can both cure our frustrations and learn a bit about the wonderful engineering that is the LS400.

It would especially great if we could BOTH find a 'fix' for our cars. I love driving. I find it relaxing. So it's no wonder I find it frustrating to own a car that makes me MORE stressed out!!

Take care of yourself. And THANKS AGAIN!!

Craig!! :)

PS I posted this response at about 4 AM. So if it doesn't make sense - forgive me!! :)

[blake918]

In your opinion - could an EGR related 'thing' cause my car to accelerate poorly when 'floored' from a dead stop?!

I think it could. The ES300 that I had before the LS had EGR problems, and it was a snail (well more of a snail than usual. LOL) when the EGR was out of whack. I would not pull out in to heavy traffic because I knew the car wouldn't be able to keep up--it was very slow and shifted erratically. I certainly think it would be worth while to have the egr system checked.

I know there is a different egr pipe design between GenI and II, but my car has a cracked egr pipe, and it accelerates as it should only louder than normal.

[Leadfoot]

The ES300 that I had before the LS had EGR problems, and it was a snail (well more of a snail than usual. LOL) when the EGR was out of whack.

Thanks for the input Blake, the evidence is stacking up for some sort of vacuum leak/egr problem. The reason I want to go through all the error code diagnosis is that the manual says to do that first. If the ECU finds nothing then the troubleshooting matrix is used.

This matrix lists causes for the malfunction in rank of probability (one benefit from having the Lexus LS400 development program's 450 prototypes tested to death, thats a nice statistical sample!), and looking ahead a vacuum leak is listed higher than egr. The surging and poor power are typical symtoms of a open hole to atmosphere somewhere. Trouble is there are so many parts to weed through. That's where patience and a methodical approach will work.

Craig, the #SST 09843 18020 can be as simple as a paper clip, but I will take a photo of the device I made and show you where to position it. It is wise to have it insulated just incase you touch another terminal by mistake. SAFETY FIRST!! You are right hand drive too so it should be pretty close to my UK spec. My wife gets back from holiday in an hour so I will get the camera back, but will have to spend some family time this weekend so you may not hear from me for a few days. Have a nice weekend, as over the next few weeks I am going to work you like a dog.

You are going to need

1) a voltmeter,

2) ideally a spare 12V battery and some leads

3) some hand tools to remove some of the egr bits so we can test them.

Are you happy to pull bits off and get your hands dirty? If you can type an email then I believe you posses enough dexterity to get the job done, also is this car your daily driver?

Also can you please confirm that your gas tank hisses (i.e. sucks air) when you open the cap. The emissions control system is designed to have the fuel tank run under vacuum.

[maniek_LS]

Craig!,

paper clip is enough to check OBD1 codes. Just connect two points TE1 and E1 after you put key to ON position (don't crank engine !) In many mails on this forum you will find detailed procedure HOW TO. If you will encounter any problems - send me PM - I can share my photos from this operation. I think prefered diagnostic connector is under hood - it is easy to access.

SECOND - important also to me...

Guys ! When I read your mails I feel like reading STORY about my LS :-( (1992, EU). My LS do the same - IS SLOOOOOW - from full stop to 60mph needs about 12 seconds !!. On the highway accelerates better (e.g. from 70 to 110MPH), but car not gives me satisfaction from driving. I feel like my LS will have trailer with 2 tons on the back when I depress gas pedal.

I have NO any error codes in ECU (checked several times). Replaced time belt (it is set properly for 100%), new sparks, new wires, new filters (all parts from dealer), checked compression (strong and constant on all cylinders) . In Poland I can't find no ONE dealer/garage with big experience in Lexus and no one can diagnose why my car is slow like snail.

I made Oxygen sensor tool to check them - 10 LEDs which are moving in 'rhythm' of reach/lean and observed strange thing. On idle for 6 seconds on O2 sensors is LEAN mixture, then O2 start working normally (Lean/Rich/Lean/Rich for 6 cycles) and then LEAN for next 6 seconds. I performed check of O2 sensor according to service procedure 2128_codes_diagnostic_procedure (with shorted terminals TE1 and E1) and it seams O2 sensors are OK.

Last thing to check is EGR, but I don't know how to check this system ? I read several times EFI part of LS manual and when I look under hood of my LS parts are located differently (e.g I can't find EGR temp.. sensor in place where manual is showing it -engine from European LS is different than in US ?). Can I simply DISABLE EGR ? Just for check ..

Additionally - I borrowed MAF sensor from friend LS (which is fast like a thunderbolt :-) ). I drove car with his MAF (also reset of ECU) for two days - my LS still WAS SLOW...

What do you think - can any temperature sensor (water, oil) cause poor performance of LS ?

It doesn't matter if car is just started (cold) or is hot (after 200km way) - NO ACCELERATION from start at all :( Especially there is a problem to go to redline on the first gear (take a lot of time). Tranny was/and is serviced - changed oil, filter.

I love this car, but I start thinking to sell it - I don't see a change to repair it and be happy own LS..

Maybe you - LOC guys - can help me ?

(Here SLOW you can see how slow car accelerates from 75 - 130MPH - as you see on the beginning - kick down but speed SLOWLY increases from 75MPH to 85MPH, next point on gear 3 when redline is meet after long time..

[CanadaCraig]

Hi Leadfoot!! :)

Yes - PLEASE - enjoy your weekend. I'm still not sure how daring I am. I'm definitely NOT mechanically inclined. In my imagination - I keep seeing things blow up whenever I'm 'trying' to fix them!! lol As for the gas tank - YES - it does hiss [like opening a big can of nuts] when taking off the cap. So something is working fine. That's good!! lol Off to bed now. Talk more later. Thanks!!

Craig!! :)

PS Thanks blake918!! :D

[CanadaCraig]

Hi maniek LS!! :)

Thanks for the reply.

I saw your video. What I'm about to say will [probably] make YOU feel better and ME feel worse!!

When comparing our two videos [i made one of MY LS going from ZERO to 160 km/h] I took note of how quickly our cars get from 120 to 160 km/h.

YOUR LS takes half the time. [8 seconds vs 16 seconds]

Something to think about.

Off to bed I go. Take care of yourself. AND thanks again.

Craig!! :)

[swordfish]

The ES300 that I had before the LS had EGR problems, and it was a snail (well more of a snail than usual. LOL) when the EGR was out of whack.

Thanks for the input Blake, the evidence is stacking up for some sort of vacuum leak/egr problem. The reason I want to go through all the error code diagnosis is that the manual says to do that first. If the ECU finds nothing then the troubleshooting matrix is used.

This matrix lists causes for the malfunction in rank of probability (one benefit from having the Lexus LS400 development program's 450 prototypes tested to death, thats a nice statistical sample!), and looking ahead a vacuum leak is listed higher than egr. The surging and poor power are typical symtoms of a open hole to atmosphere somewhere. Trouble is there are so many parts to weed through. That's where patience and a methodical approach will work.

Craig, the #SST 09843 18020 can be as simple as a paper clip, but I will take a photo of the device I made and show you where to position it. It is wise to have it insulated just incase you touch another terminal by mistake. SAFETY FIRST!! You are right hand drive too so it should be pretty close to my UK spec. My wife gets back from holiday in an hour so I will get the camera back, but will have to spend some family time this weekend so you may not hear from me for a few days. Have a nice weekend, as over the next few weeks I am going to work you like a dog.

You are going to need

1) a voltmeter,

2) ideally a spare 12V battery and some leads

3) some hand tools to remove some of the egr bits so we can test them.

Are you happy to pull bits off and get your hands dirty? If you can type an email then I believe you posses enough dexterity to get the job done, also is this car your daily driver?

Also can you please confirm that your gas tank hisses (i.e. sucks air) when you open the cap. The emissions control system is designed to have the fuel tank run under vacuum.

hey leadfoot

you might have noticed i have the same symptoms as craig down here, on your point about vaccum leak

i notice a hose its a 18 or 19mm diam.,going from inlet pipe of the throttle body to the cam cover, presumably

for crankcase venting, mine didnt seem to have a valve in it, thought this might have some bearing on things??

[Leadfoot]

hey leadfoot

you might have noticed i have the same symptoms as craig down here, on your point about vaccum leak

i notice a hose its a 18 or 19mm diam.,going from inlet pipe of the throttle body to the cam cover, presumably

for crankcase venting, mine didnt seem to have a valve in it, thought this might have some bearing on things??

It may do if the valve thats missing is the positive crankcase venting valve.

Thanks to Carl we have some pictures...

http://www.lexls.com/tutorials/emission/pcv_valve.html

The workshop manual says

INSPECTION OF PCV VALVE

1. REMOVE PCV VALVE

2. ATTACH CLEAN HOSE TO PCV VALVE

3. BLOW AIR FROM CYLINDER HEAD SIDE

Check that air passes through easily.

NOTICE: Do not suck air through the valve.

Petroleum substances inside the valve are harmful.

4. BLOW AIR FROM INTAKE MANIFOLD SIDE

Check that air passes through with difficulty.

If the PCV valve fails either check, replace it.

5. REINSTALL PCV VALVE

Basically the PCV valve is a variable throat device held down against its seat by a spring. Under idle or deceleration the high vacuum in the intake lifts the valve off its seat, but the flow area is actually small. A heavier engine load means less vacuum, and the valve is not lifted so high and actually has more flow area.

If you did not have a PCV valve at all but the hose was connected then the flow would be high at idle, which could suck in a lot of oil mist into the intake chamber which would probably cake things up beautifully over time.

If your valve was stuck shut with gunk then the crankcase pressure could increase, but no where near the levels required to steal noticeable power. It's merely an emissions device.

Thanks to your question I have discovered that fresh air is actually sucked into the cam cover under the throttle body (check the pictures in the http://www.lexls.com/tutorials/EFI/throttlebody.html tutorial) by the crankcase vacuum created by the PCV, which recovers this air mixed with blow by from the pistons and burns it up in the cylinders. My last car was a 1978 MGBGT so this hi-tech stuff is all new to me. Its cool but complicated.

Can you post a picture of the cam cover end of this hose for us?

It would be nice if it was a simple $10 part causing the problem, lets see.

[swordfish]

its not the pcv system, thats on the other bank-its RH drive- will have to remove air clnr and inlet piping to get fotofor you -give me a few days.

swordfish

[AzHotLS]

oops. deleted.