Hi everyone,

I have a yellow saloon T5-R Auto here in New Zealand (originally a Singapore model brought into NZ in 1999).

Just recently I have noticed that it has developed an issue under hard acceleration (i.e. accelerator flat to the floor). It will be pulling hard (as you would expect) then it will have a lull in its acceleration that lasts about half a second then it will be back to hard acceleration again - it kind of feels like a rough gear change on a bad auto (drop in revs while the box changes then harsh reapplication of power) but it isn't changing gear when this happens and, given the variety of speeds that it can happen at/gears that it can be in when it happens, I don't think it's anything to do with the gearbox.

So - to recap - it doesn't do it unless you are accelerating really hard (pretty much full boost) - it doesn't always do it - sometimes it just has one lull then it's fine - other times it will do it several times in one burst of acceleration (i.e. 3-4 seconds (ish) acceleration, half a second lull, 3-4 seconds (ish) acceleration, half a second lull etc. - When it does it like this the lulls are evenly spaced).

Now to a second issue which may or may not be related. The lambda/check engine light cam on on the way home on Friday, was on throughout Saturday, I didn't use the car Sunday but then today the light was off again. I was at the auto electricians anyway this morning (checking a suspect brake switch) so mentioned the light and he checked for fault codes. It came back with only one - 414 on A2. I've searched this online and come up with a description of the fault but it means nothing to me and I can't seem to find an explanation anywhere. Can anyone tell me what 'Boost pressure reduction from TCM' means? I would like to know what it is, what causes it, how serious it is and how to fix it. Also, is it likely to be linked to the 1st issue I have described above?

Has anybody got any ideas please?

If you need any more information or a better description please ask...

Thanks in advance for any help you can give me.

Cheers,

Duncan

 

Sounds like a Vacuum hose to the turbo might have broke and you are running full boost and hitting fuel cutoff.

 

Thanks for that - can you give me a heads up on the routing of the vacuum hose/s to the turbo so I can check this without having to give it to the NZ Volvo thieves over here masquerading as dealers?!!

Also, do you think my lambda light issue is related - any more info on what that fault code means please?

Cheers.

 

See if this helps:

http://www.matthewsvolvosite.com/for...hp?f=1&t=20229

I found other diagrams, but thought they were hard to follow.

 

Thanks for that - I'll see if I can trace these hoses and check them out - hopefully I'll find a nice big obvious split on one of them that's easy to get to.

Anybody with any suggestions on that diagnostic code and it's explanation?

Cheers.

 

I will be the code is from the vacuum line being bad.

 

Ok - thank you all for the good advice. The link to Matthews Volvo Site with the diagrams was very helpful and saved a lot of messing around on my part. I found that the green line was split (completely separated) right by it's connection to the unit next to the air filter. I was able to cut of the end to make it square and refit it without too much difficulty and this does seem to have cured the problem I described. I haven't done a reset yet to see if this cures the code issue but I expect that you are right about that too. So - all good so far...

However... the car is now considerably slower and I would say I am only getting about two thirds of the boost I was getting before the repair. Watching the turbo gauge on the dash during maximum acceleration in Sport mode, the needle only gets to about a third of the way (possibly halfway) between straight up and the top of the scale whereas before it was going up to the top of the scale.

Is this how it is supposed to be? If so, it must have had some degree of this fault since I have had the car (almost 3 years) as it's never been this boring before! What can I do to bring back some of the fun without taking this hose off again?!

Once again, thanks in advance for any advice you can give me.

Cheers,

Duncan

 

First thing I would do is get an aftermarket boost gauge and see exactly what the boost level is now. Then you can go from there. Before you were over boosting. Yes it will feel boring now after driving it in over boost for a while. But see exactly what the level is then you can decide your options from there.