The Lack Of Power Over 3000rpm

[webbie]

Hi all, the rav has developed the 2nd biggest issue over the DMF. Loss of power over 3000rpm and the mil turbo over boost. It also has the exhaust noise that has been described in the other posts. To me its the turbo blowing off the pressure as its over boosting. Its like a steam train "chuffing” away. Looking through all the posts It seems its one of those issues that a lot of people have had but no ones has come up with a definitive "its that". Some have done the scv valves, fuel filter, good thrashing down the road, turbo replacement or a combination.

This is my story so far in trying to get to the bottom of the issue. Long post but it would be nice to get together and pin down this issue for future reference.

we hadn't used the rav for a few months took it out to get ready for the mot and tax it for winter. It would not pull at all over 3000rpm and had the chuffing and went into limp home.

1 changed scv valves (ouch how much). This made it pull better up to 3000rpm and the chuffing was not as bad but it still holds back over 3000 and chuffs higher up the rev range. But it is now drivable (in fact it pulls well) if you keep it below 3000, but still has a bit of chuffing and a flat spot over 3000. Does not seem to go into limp home though.

2 changed fuel filter no effect same as above.

3 cleaned out intercooler, pipe work, inlet side of turbo and the EGR no effect. The EGR was clean and moved freely.

4 checked out the vsv and valve pipe work. Looking at the download on a previous post VSV.PDF that describes testing out the vac valve that anchorman posted from the Toyota manual. Line 4 I think is incorrect as its says check air does not flow from port E to G, I think it has too as there is no one way system fitted, so power off it flows from E to G, power on from E to atmosphere via the filter. Has anybody else checked there's ?.

5 I have looked at the actuator that controls the variable vanes on the turbo, expecting this to be stuck or tight. Now this is free and the actuator moves up/down and the linkage moves ok. Having a closer look I think it moves too freely as I would expect the vanes and the mechanizm to take a little bit of moving, maybe its not connected at the other end ?. that would account for the symptoms as described if the vanes are stuck in the full boost condition, you would get good performance up to 3000 then the extra exhaust pressure would build up as its not venting down the pipe restricting performance and eventually it would go into over boost limp home. Before tackling a turbo removal I have run it with and without the vac pipe on the vanes actuator, as in theory if the vanes are stuck or the actuator rod is broke there should be no difference in performance. But with the vac pipe off it is a lot less responsive indicating that the vanes are moving (default no vac the vanes move to lowest boost). Connect it back and it pulls a lot better at lower revs.

6 is it just choked up ?. I have trashed it within a inch of its life up and down the motorway and its made no difference. Its running very clean out the exhaust you can mot test it and there is hardly any smoke from the back. But this seems to have worked for some on previous posts.

next steps

Has anybody ever split the turbo in place ?.

I would like to see if the vane mechanism is ok for myself and it looks just as easy to split the turbine part off the exhaust body 5 bolts around the turbo then remove the actuation ring and vane assembly out of the turbo exhaust body. Rather than try and remove the manifold/exhaust connections and take the whole lot off.

has anybody got a schematic of the later variable vane turbo they can post ?. There is one on a previous post but its a waste gate type.

has anybody got a PDF of removing the turbo ?

The turbo pressure sensor, has anybody ever changed one for any reason and did it cure the issue ?.

Kingo are they cheap ?.

you need equipment that normally is not around to check if its working, so it might be easier to fit a replacement.

Anybody want to list what worked for them in solving the issue. It may be that different things can cause the same effect, at least we can get it all in one post and pin it.

Any other comments help

Thanks

vsv.pdf

[anchorman]

Hi Webbie

I get involved with so many of these things that I can't always remember who has got what problem and whether I stuck my 2p worth in but I am just off to work and have to be brief.

Pulling the turbo apart would be the very last resort for me and only when it I think it is worth one more try or get another one.

There are no wastegated turbo's on RAVs unless someone has modified one. If you look at the turbo, the vac unit has a link to the variable nozzles, not a wastegate. The nearest thing to a wastegate is the VSV you know about as it indirectly does the same thing.

What you describe sounds like the EGR valve to me.

I can provide more info if you need me to but it will be tomorrow.

Cheers.

[bothwell_buyer]

always wanting to be different, my RAV does have a wastegate.... but thank goodness its petrol. Did manage to mangle a turbo thru extreme heat due to the exhaust system being partly blocked. Thats another story. Good luck on finding the cause of yours.

[anchorman]

always wanting to be different, my RAV does have a wastegate.... but thank goodness its petrol. Did manage to mangle a turbo thru extreme heat due to the exhaust system being partly blocked. Thats another story. Good luck on finding the cause of yours.

Your RAV has afterburners and a drogue chute but nobody elses does!

[igormus]

Hi all, the rav has developed the 2nd biggest issue over the DMF. Loss of power over 3000rpm and the mil turbo over boost. It also has the exhaust noise that has been described in the other posts. To me its the turbo blowing off the pressure as its over boosting. Its like a steam train "chuffing” away. Looking through all the posts It seems its one of those issues that a lot of people have had but no ones has come up with a definitive "its that". Some have done the scv valves, fuel filter, good thrashing down the road, turbo replacement or a combination.

This is my story so far in trying to get to the bottom of the issue. Long post but it would be nice to get together and pin down this issue for future reference.

we hadn't used the rav for a few months took it out to get ready for the mot and tax it for winter. It would not pull at all over 3000rpm and had the chuffing and went into limp home.

1 changed scv valves (ouch how much). This made it pull better up to 3000rpm and the chuffing was not as bad but it still holds back over 3000 and chuffs higher up the rev range. But it is now drivable (in fact it pulls well) if you keep it below 3000, but still has a bit of chuffing and a flat spot over 3000. Does not seem to go into limp home though.

2 changed fuel filter no effect same as above.

3 cleaned out intercooler, pipe work, inlet side of turbo and the EGR no effect. The EGR was clean and moved freely.

4 checked out the vsv and valve pipe work. Looking at the download on a previous post VSV.PDF that describes testing out the vac valve that anchorman posted from the Toyota manual. Line 4 I think is incorrect as its says check air does not flow from port E to G, I think it has too as there is no one way system fitted, so power off it flows from E to G, power on from E to atmosphere via the filter. Has anybody else checked there's ?.

5 I have looked at the actuator that controls the variable vanes on the turbo, expecting this to be stuck or tight. Now this is free and the actuator moves up/down and the linkage moves ok. Having a closer look I think it moves too freely as I would expect the vanes and the mechanizm to take a little bit of moving, maybe its not connected at the other end ?. that would account for the symptoms as described if the vanes are stuck in the full boost condition, you would get good performance up to 3000 then the extra exhaust pressure would build up as its not venting down the pipe restricting performance and eventually it would go into over boost limp home. Before tackling a turbo removal I have run it with and without the vac pipe on the vanes actuator, as in theory if the vanes are stuck or the actuator rod is broke there should be no difference in performance. But with the vac pipe off it is a lot less responsive indicating that the vanes are moving (default no vac the vanes move to lowest boost). Connect it back and it pulls a lot better at lower revs.

6 is it just choked up ?. I have trashed it within a inch of its life up and down the motorway and its made no difference. Its running very clean out the exhaust you can mot test it and there is hardly any smoke from the back. But this seems to have worked for some on previous posts.

next steps

Has anybody ever split the turbo in place ?.

I would like to see if the vane mechanism is ok for myself and it looks just as easy to split the turbine part off the exhaust body 5 bolts around the turbo then remove the actuation ring and vane assembly out of the turbo exhaust body. Rather than try and remove the manifold/exhaust connections and take the whole lot off.

has anybody got a schematic of the later variable vane turbo they can post ?. There is one on a previous post but its a waste gate type.

has anybody got a PDF of removing the turbo ?

The turbo pressure sensor, has anybody ever changed one for any reason and did it cure the issue ?.

Kingo are they cheap ?.

you need equipment that normally is not around to check if its working, so it might be easier to fit a replacement.

Anybody want to list what worked for them in solving the issue. It may be that different things can cause the same effect, at least we can get it all in one post and pin it.

Any other comments help

Thanks

hello

It is not good for the car to be stored without drive.. I deem this has resulted a chain of problems.

Your problem is not connected with turbo ,but somethis is stuck now giving no power above 3000 rpm.

You did not state how the engine is started? I am seriously think that after an idle time the HP delivery valve could be leak giving no sufficient pressure arter pump delivery stroke or injection timing must be re-checked.

CHeers/Igor

[bothwell_buyer]

always wanting to be different, my RAV does have a wastegate.... but thank goodness its petrol. Did manage to mangle a turbo thru extreme heat due to the exhaust system being partly blocked. Thats another story. Good luck on finding the cause of yours.

Your RAV has afterburners and a drogue chute but nobody elses does!

didn't want to rub it in, but the engines now running at optimum between 4000 and 7000RPM - bit far from a diesel turbo RAV? 13.4secs on the 1/4 mile today -best time yet. And no following wind, nor did I need the chute!

[Parts-King]

13.4secs on the 1/4 mile today -best time yet. And no following wind, nor did I need the chute!

I needed a "chute" to slow my underpants down when he gave me a blast in his RAV Inter Continental balistic missile last year

Kingo

[Ravmania]

Hi,

Did you get your chuffing sorted, was it the EGR valve?

[Brendy]

Hi

just joined the forum and looking for help!

same symptoms as webbie, accelerates fine up to around 3000rpm then chuffing noise/vibration starts behind the dash (sounds like turbo or cat vibrating?), lack of further acceleration and goes into limp mode.

has nayone found the problem?

[anchorman]

Look at the SCV write up pinned in the tech section.

[Brendy]

thanks for the response anchorman.

where do I access the tech section, can you send me a link?

[Parts-King]

Here you go

http://www.toyotaown...showtopic=87986

Go to Forums/ RAV club/ Technical info hints and tips in the pinned section

Kingo

[anchorman]

Do we know where the duff batch of diesel came from/went to? There seems to be an awful lot of SCV problems lately.

[Parts-King]

Prices for them have gone up shockingly too!

Kingo

[Tech01]

It also has the exhaust noise that has been described in the other posts. To me its the turbo blowing off the pressure as its over boosting. Its like a steam train "chuffing” away.

This is the sound produced when the front exhaust box (containing a ceramic honeycomb) has become badly blocked. My 2003 D4D 4.2 suffered all this some time ago. Replace the box (expensive) or remove its contents (not universally approved, but effective).

A blocked box strangles power at high throttle/revs, and the chuffing noise is the turbo letting off excess pressure.

To test all this out, simply remove the exhaust system from the front box onwards (leave the downpipe from the turbo), and test-drive the car. (It will be surprisingly quiet.) If power returns, then the front box is the culprit.

Chris

Please update your vehicle details (personal profile) so we know exactly what you've got!

[Brendy]

Thanks Chris

Do you mean the box located under the floor just about in line with the front seats?

[Tech01]

Hi Brendy . . .

Yes, that's the one: Order is turbo, downpipe, then the cat box. Uncouple the flange connection between downpipe and the box, and remove the rest of the exhaust. This will allow a test-drive without the suspect box.

Chris

[Brendy]

cheers Chris, I'll try this tomorrow and report back

[Brendy]

Well folks I removed the underfloor cat and it looked like it had melted in the centre. I made a hole through the centre of the honeycomb, flushed the cat out and put it back on. The chuffing noise has now gone and the car was revving freely but a bit sluggish then went into limp mode. I pulled off the vac hose to the turbo actuator and what do you know the car is absolutely flying, revving freely, good power through the revs and no chuffing noise!! I suspect I would have even better power if turbo was being properly utilised. I think the actuator and turbo vanes must be ok as the vanes appear to be opening (when vac line is disconnected) and closing (when vac line is connected).

Could it be a faulty N75 valve creating too much vacuum pressure at high revs or a faulty VSV? Is there an easy way of testing ( I do not have any vacuum testing equipment )

Also wondering if there is a risk rest of cat insides could now disintegrate and plug the back muffler box? If I removed the entire innards of the cat would it throw a fault code as pressure differential across cat would presumably be next to zero?

[anchorman]

Chris (Tech01) is the expert on these 4.2 cats so wait for him. He was the one that knew this strange noise was linked to a blocked cat.

Not sure what an N75 valve is but we have had VSVs piped backwards before now.

[Tech01]

Hi Brendy,

Melted innards - gosh! When all this happened to me, the innards of the cat box (a white micro-bore ceramic honeycomb, almost completely filling the box) was almost 85% blocked with soot, causing massive back-pressure. I had always used best-quality diesel, with plenty of motorway runs, so was very surprised to find this.

A diesel expert suggested simply removing the contents of the cat box (all of it), and this was done by poking the honeycomb repeatedly with a metal spike/coldchisel, until it disintegrated and fell out. The outer surface of the crumbly ceramic was wrapped in a flexible steel 'knitted' mesh. This was removed too, leaving an empty box. After all this, the car ran perfectly, with only a very slight increase in exhaust note, with emissions tests always v.low.

On my 2003 D4D, there isn't any pressure differential (or any other) sensor on the cat box - which is fitted to some later DPF systems, so no problems there. Anchs and others can advise on checking turbo etc.pressures - not something I've needed to do.

I think you are right to suggest getting rid of the rest of the box contents, to prevent further break-up. Whether you replace the box with new, or just leave it empty, is a personal choice. I have done the latter.

Several steps forward - well done, you!

Chris

PS

This emptying of a diesel oxidation cat box has been done many times before in the trade, and they therefore have experience and thoughts about it. I have been told that an empty box normally behaves perfectly well (just like an non-catted diesel), and increased exhaust note and emissions-testing is not a problem.

One remedy should noise or lowered back-pressure be a problem consists of making up a length of steel pipe to fit inside the emptied box, running from inlet opening to outlet opening, and a reasonably snug fit. The pipe should be blanked off halfway along its length (probably cut, blanked and re-welded), and the entire surface of this inner pipe peppered with small drilled holes (say 2mm diameter, and 2-3mm apart).

The action of this pipe will be to slow the exhaust gases down through the box, and lessen the shock wave, thus reducing the exhaust note. It will also provide a small amount of back-pressure, which some engines seem to need.

I've not personally felt the need to do this on the RAV, but this mod has been done elsewhere. I have done it once, admittedly, but only on our home emergency generator, run through a small Peugeot front box to the outside world, where we didn't want to annoy the neighbours!

C.

[Brendy]

Well I must admit to being pleased with myself to have made this much progress, thanks for the advice Chris.

In reply to anchormans post the N75 is the same as the VSV as far as I can find out, located above the egr next to the turbo sensor. Does anyone have the correct piping diagram between egr, VSV and vacuum modulator just to check that everything's piped correctly?

From other posts I've read the VSV seems to the one that gives the most trouble,

[anchorman]

Can somebody photograph it for him?

[yyaann]

I dont know if it is any help but it would seem very similar to a problem i have just had, if you look very closely to the two rubber pipes they apear to be different sizes and the two spigots on the valve also seem to be two different sizes.So in my case i have the pipe from the turbo diaphram connected to the front spigot (one nearest the front of the car) and the pipe from the vacuum pump below the valve connected to the rear spigot. There is a picture somewhere in the Haynes book which will confirm this if you have one,hope this helps or in fact makes any kind of sense.

[anchorman]

I dont know if it is any help but it would seem very similar to a problem i have just had, if you look very closely to the two rubber pipes they apear to be different sizes and the two spigots on the valve also seem to be two different sizes.So in my case i have the pipe from the turbo diaphram connected to the front spigot (one nearest the front of the car) and the pipe from the vacuum pump below the valve connected to the rear spigot. There is a picture somewhere in the Haynes book which will confirm this if you have one,hope this helps or in fact makes any kind of sense.

Thanks for this useful info. I thought the pipes crossed each other.