Losing Acceleration And Going Into 'limp Mode'

[Kina]

We have a 2004 diesel which keeps losing acceleration and going into limp mode. This always seems to happen either accelerating down a specific hill or up a specific hill- always at about 2,900 rpm. If you turn the engine off and restart, everything is fine again! It doesn't always happen in these 2 places but if it's going to happen - that's where it happens for some reason!

We also have an occasional (but happens most days) jerking when accelerating through 2,600 to 2,800 rpm.

Also, we have had very slow acceleration from stop (ie like when wanting to pull out onto the A303) almost to the point of crawling out for 2-3 seconds then acceleration catches up and you whizz off! (scarey!!)This has only happened about 3 times in 2 years!

Garage thinks that this could all be connected. When they looked at it they said that it was running fine and that their best guess was a turbo boost sensor, which they changed. This doesn't seem to have made any difference at all - we have gone into limp mode 3 times in 8 days since the new sensor was fixed. They now say that unless they see it actually happening they don't know what to suggest.

Any ideas anyone?

Thanks

Kina

[Kina]

We have spoken to the garage again and they now suspect that its the ECM.

Can anyone agree or disagree with this assessment?

Kina

[Parts-King]

Sounds to me like you need a set of SCV valves, you might like to read this thread

http://www.toyotaownersclub.com/forums/index.php?showtopic=87986

If you do need a set, PM me, we can provide them for you, we keep them in stock

Kingo

[anchorman]

If its been in limp mode it will have stored some fault codes. Ask the garage to read them then let us know what they are.

BTW - welcome to the club!

[Kina]

Hello,

IF I remember rightly, I think I was told the code was P502 which they said was not a standard listed error code, but they said after a few phone calls they found someone who said it was indicating the turbo boost which is why they changed the turbo boost sensor!

This garage has now said that the believe the problem may be the ECM? and have asked us kindly to go somewhere else!

It went again on Tuesday evening, this time on a different road but still accelerating up an incline!

If the car 'stores' the error codes we should now have 4 more on the car since they were last cleared!

[anchorman]

They have gone for the part that sounds right but the one that causes problems is the VSV (vacuum sensing valve). It can sometimes be recovered by taking the pipes off and squirting some WD40 in the connectors.

Valve layout.pdf

[Kina]

Hello again .

Took the car to the garage today - the error message is P1251.

Kina

[anchorman]

Turbo overboost. Either squirt some WD40 in those connectors or change the valve. I would try WD40 first!

[Kina]

Hi. Back again.

Firstly thankyou for your replies! We are not DIY ers when it comes to cars but your advice does stop us from looking completely clueless when we go to a garage!

So we took the Rav to a Toyota garage about 6 weeks ago where they 'followed their flow chart' and told us that the turbo needed replacing - 'That will be £1745, please!' They said it would definitely fix the dying at 3000 revs and engine light coming on but could not guarantee that the juddering at 2600 revs or (very) occasional sluggish starts would be cured as they had no evidence of them.

Well, we didn't have the money at the time and so we said we would limp on for the time being! And also we were slightly miffed that a turbo should need replacing after only 55,000 miles! Is this normal?

Anyway. Since that day we have not had one single 'limp mode/engine light' - no matter how hard I try! We are still getting the juddering at 2600 rev though.

So my question is - does a turbo go through periods of behaving if it needs replacing? Or could they have inadvertantly 'fixed' the problem when messing around in the diagnosis? We are now in limbo, waiting for the problem to reoccur.

Any comments?

[anchorman]

Welcome back!

The turbo doesn't fix itself and you can see that the garage would have wasted quite a lot of your money. There are several small and relatively inexpensive control units that can cause these issues but to be honest I wouldn't start throwing money at it unless it starts playing up. The best thing is forget it and don't worry until you have something to worry about. It is either those little switches shown above or the SCVs as Kingo says. You CAN change both yourself or a friend who knows a little about mechanics.

The vibration could well be the DMF so that needs watching. If it gets worse it could fail.

[Kina]

Thank you for your reply Anchorman.

It is not so much of a 'vibration' - more like a cold engine judder 2 or 3 times!

Also we now have an annoying 'irregular beat like' noise when playing CDs ( we have tried a cleaning cd!)I have noticed that the noise is in time with the lights around the stereo dials flickering! Never with the radio! Very annoying but once again intermittent! Any suggestions?

I am fast losing patience with this car now!

Kina