mk3 Astra - not boosting

[DavidB]

I bought the Astra TD 1.7 (Isuzu engine) in February of this year for £200 (no tax and a bit of MOT).
I can't ever remember it having any factors which would lead me to believe the turbo is boosting at all. Receipts show it had a new engine about 5 years ago, and a new turbo more recently than that.

I finally took the turbo off (with manifold) and checked everything was as it should be - the turbines is fine with no play (and spins freely), and the wastegate opens OK on the actuator. Did 130 miles last night, I can not get the thing to boost. I checked before and the most I could muster was 1 bar on a gauge. It has no pull whatsoever, and up hills isn't fun. I have a-framed three cars in the past month and it couldn't pull the skin off a rice pudding. There are no air leaks, etc. Every turbo diesel has the 'pull' when they boost - this has none of that.

I'm stumped now, I heard these were quite rapid, what could be wrong?

[bortaf]

If it wasn't boosting at all i cant see how you could tow anything let aloan get just the car up a hill? they boost at 1 bar standard so tahts right ?
there are 2 version with high and low boost, maybe you have the low boost one?
is there any black smoke? the fueling could be low, maybe check the fuel enrichment device on the pump pr it's control pipe for leaks.
Have you changed the fuel and air filters recently, allways the first port of call on a low power diesel or TD.

[DavidB]

Thanks for the reply.
It's definitely the hi-blow version - the speed is bearable, but I bought the car so I could tow occasionally. I had to sack off towing a mk1 Micra (!) because it was really struggling. If there's any incline involved, forget it. There is the normal amount of black smoke out of the exhaust. It becomes totally gutless at about 4000rpm, I doubt it's ever seen the redline.
I revved the balls off it last night just before I put everything back together at standstill and could hear the turbo spinning with the intercooler/exhaust off.

[Dez]

It should be gutless by 4000rpm. That engine in Stock form will make all its power in the 2-3000 range, maybe even lower as the turbo is quite small. There's little point revving diesels over 3500rpm anyway tbh. It's not what they're about.

Are you towing with a trailer then a car on it? I think thas wildly optimistic for a standard Astra anyways, but if you are you should be using the low down torque characteristics of the engine, not revving it high.

[indyz12]

change the MAF and tubing to the boost and egr solenoid. If that doesnt work, change the boost solenoid.

[welshpug]

Nov 3, 2014 16:44:48 GMT indyz12 said:

change the MAF and tubing to the boost and egr solenoid. If that doesnt work, change the boost solenoid.

on a mk3??

[rodney]

I'm sure they a fully mechanical pumps like a p100 , so firstly check the on fuel boost as no td will pull if that isn't working , then once you know that's working turn the fueling up on your pump , td engines work on fuel rather than extra boost , also make sure the boost control pipe that normaly goes from inlet or turbo to the compensater , cos if that isn't on or working then it give you the extra fuel for on boost

[DavidB]

Dez, it is gutless through the whole rev range!
How do I check the fuel boost - this is my third TD - first was a Corsa van with the same engine, then a Peugeot 405 GLDT which was rapid, and now this!
I've done the 'washer' mod on the fuel pump btw (not related to this problem).

[welshpug]

82 bhp @ 4400 rpm and 124 lb/ft @ 2400 rpm.

not surprised the 405 felt quicker, they're 92 bhp and 145 lbft, and they peak at 4000 and 2250 respectively.

[Dez]

when you did the 'washer mod', did you make sure you put the diaphragm back in the right orientation? the boost reference pin wont work right if you didnt. it is marked as stock, but doesnt usually sit in its optimum position. you want the most agressively cut away side of the pin facing towards the front of the pump.

also, as has been mentioned above, id check the boost referencing is working at all, if the diaphragm is damaged, it wont lift the pin and increase the fueling as it comes on boost.

[DavidB]

I did the washer thing not too long ago, this was after 'the problems'. It did run better though. Do you mean the rotation of the pin in the hole, I know it's indexed - I may have another look at it, but I did put everything back in order.

[Russ]

Does it still have the 'cat' fitted? I had a Corsa TD with this problem and removing the partly blocked cat restored its full power. I now have an Astra TD and again removing cat released more power even though it was mostly clear from soot.

IMHO, the Isuzu engines aren't as quick as most people will have you believe and the wide ratio gearbox fitted the Astra's make them more sluggish. My Astra is sluggish up to around 2200rpm, then the boost kicks in until around 3200rpm, where it drops off. They do require a fair bit of gear stirring to make them shift along well.

[DavidB]

Russ, I think you're right about the power of these things - I hear loads of feedback about how fast they are, but I'm not sure that sub 100bhp they really are that fast anyway.
The journey home it literally stopped producing power at about 2000rpm in second, it wouldn't graduate above that.
It does have a cat, as it's an M-reg, may take it off to see if it changes things.
I love old Vauxhalls, but I sold my 405 for this. 405's are much better cars.

[Russ]

I'd definitely look at removing the cat if it's not producing power above 2000rpm. In my Astra, in 2nd gear, you can start to feel the boost come in at 2000rpm and will fairly quickly pick up and take you to 3500rpm/45mph, with your foot flat down on the pedal.

Also check if the throttle cable has any slack in it at the fuel pump end. Get someone to press the throttle pedal whist you're looking at the pump end connection, you'll see if the cable has slack as the cable won't pull the pump 'lever' all the way.

[Colonelk]

Hmmmm, looked to see if here are any splits in the boost reference pipe to the fuel pump? Is the rubber diaphragm split free?

Turned the max fuel up just to see what happens? If you have done the boost and fueling you should feel a very decent surge as the boost kicks in around 2k and it should pull to 3500-3750 then tail off as the governor kicks in.

1 bar is fine, I run mine at 15psi which is a smidge over. The standard turbo's lifespan plummets if you run higher boost than that.

Sounds more like it isnt fueling right.

Another thing would be to get a clear bit of fuel pipe and replace the feed to the pump to look for air leaks in the rest of the fuel system.

They aren't rocketships, especially as standard, but yours doesnt sound right at all

[vaughant]

Had this before on a series one rs turbo and it was a tiny spilt in the boost pipe on the crossover inlet pipe just under the jubilee clip. Showed full boost on the gauge etc yet no pull at all.
Check all that stuff first, they do feel like a nippy car as well, obviously not a flyer but they really move along pretty well.

[DavidB]

It's possible I may be over rating the car - I came from a VTEC CRX, Impreza and MR2 to this. I'm going to have a look over it anyway, but I'm coming to terms that this may be normal! lol

[DavidB]

Car is much improved since taking the manifold off. I sealed all the gaskets and gave the actuator rod a good going over, and it slowly improved through the week.
Not sure what fixed it, but it seems much better now (or is it all in my head lol).

[DavidB]

Was driving to Cov tonight, noticed a high pitched whistling, building in pitch. Pulled in (after about 100 miles ) and the pipe had come off the intercooler (hadn't tightened the worm drive clip). At least the turbo works.

It is better, but I'm not thinking this is something as simple Russ's suggestion that that cable to the throttle isn't 'maxed out'. As I said, it's missing something, and I don't think the pump is opening fully!

[indyz12]

Nov 3, 2014 17:24:35 GMT welshpug said:

Nov 3, 2014 16:44:48 GMT indyz12 said:

change the MAF and tubing to the boost and egr solenoid. If that doesnt work, change the boost solenoid.

on a mk3??

sorry, didnt read correctly, thought it was a mk4 Haha