1.8 turbo, hesitation when accelerating hard

[wixyw]

We bought a 1.8 turbo tourer a couple of weeks ago, no real problems so far, just one annoying niggle, on the rare occasions I put my foot down hard, the engine revs, cuts out then picks up again, sometimes it is just a hesitation other times a definite cut out for a second or two. Under moderate acceleration this does not happen, it's very smooth. Any thoughts on what the fault may be ?

Thanks,

Phil

[cossie dunc]

Sounds like it's over boosting

[Yorkshire GOC]

Hello,

My turbo did this a few years ago - turned out to be a failing ignition coil pack - stutters/cut outs when you put the pedal down hard - then recovers - and no problem at gradual load.

[wixyw]

thanks for the above suggestions, I will get two new ignition coil packs fitted, that should sort that, if that is the cause, but if not and it is the turbo over boosting how can that be altered, and what causes the over boosting in the first place?

[impvan]

Over-boost is a natural characteristic of a turbo. There's other gubbins attached to the turbo circuit to control the tendency to overboost.

1) Overboost due to the pressure not being sensed: look for split sensing pipes, or the rubbery bits on the end of the pipes, or the pipes not connected at all. If they've already been changed for silicone ones, check along their whole length for teeth marks...

2) Overboost, where the pressure IS being sensed, but it's not being reacted to: Boost solenoid not operating or blocked, one of the three pipes come adrift, wastegate actuator pipe off, or linkage sticking at the 'hot' end. (the linkage can corrode here, and the circlip jams on the rusty bits..)

[Sheraton]

first check boost control hoses are connected

it's likely a failed electronic boost control solenoid - the bit on the side of the air box with the 3 vac hoses connected - common failure and causes overboost which will result in fuel cut

if you locate the 2 vac hoses coming from the turbo to the boost control solenoid - (check they are connected obv) - if not then there is your issue - if they are connected disconnect them both from the turbo end, remove the smaller vac hose from boost solenoid to air intake and use to connect the 2 sides of the turbo directly - this gives wastegate boost pressure and will eliminate overboost - if you still have an issue - then i'd check spark plug gap 0.60/0.50 mm is best for the 1.8t


Paul.

[wixyw]

Many thanks for both replies about the Turbo boost ! they answer all my questions and have pointed me in the right direction ! Much appreciated, never owned anything with a turbo before, know nothing about them, so this really helps.

cheers Gents,

Phil

[Arryhall]

I asked the same question when I got mine as it was doing the exact same thing. I was told it was "a pipe come off the turbo" which it may have been.

Then the head gasket failed and I had the engine rebuilt. Now it's doing the exact same thing again, but all the pipes are connected. What I'm going to do is take it to a garage I know, with this thread, and tell the mechanic dude to fix it, because it's pigging annoying when you want to accelerate onto a motorway or duel carriageway, and it feels like the engine is about to fly out of the car or blow up!

[T-Cut]

It's also reckoned to be better if the 1.8T spark plugs are gapped to 0.5 - 0.7mm rather than the book value (1mm I think).

TC

[Sheraton]

Originally Posted by Arryhall

I asked the same question when I got mine as it was doing the exact same thing. I was told it was "a pipe come off the turbo" which it may have been.

Then the head gasket failed and I had the engine rebuilt. Now it's doing the exact same thing again, but all the pipes are connected. What I'm going to do is take it to a garage I know, with this thread, and tell the mechanic dude to fix it, because it's pigging annoying when you want to accelerate onto a motorway or duel carriageway, and it feels like the engine is about to fly out of the car or blow up!

the "electronic boost control solenoid" on these cars are known to fail - i've replaced mine twice in 2 years

http://https://www.worldcarparts.co....g-7-22908-03-0

buy yourself a new one and plug it in - it's too easy not to
most folks I've read about with this issue who have taken the car to a garage have wasted a lot of time/money replacing all the ignition parts for the problem to still be there

while you wait you can bypass the solenoid and connect the turbo compressor side to the wastegate - i'll look for an image to show this
http://http://postimg.org/image/mxyxba445/

Paul.