Erratic boost C70 T5

Post 530353 by thad1 on 2012-08-13 14:25:08

Car is a 1999 ME7 C70 T5. I have been trying to trace a potential boost leak, have removed all the pipes from the BCS one by one and they seem fine, have also removed the intercooler pipes and checked them as well. Have checked the one to the inlet manifold as well. The car will boost nicely on 3/4 throttle but it's not hitting target boost properly, it's just slower than it used to be, feels like it's a few psi down on what it should be. If you change down at 40mph (suto box) it just does'nt boost up like it did, but if you apply the throttle gradually it's better but still not 100% power. I have pressurized the CBV and that is not leaking either. Is it possible to pop a bleed valve on it to see if it's the BCS? I thought if I kept the boost fairly low it should give me an idea if the inconsistent boost is being caused by the BCS? Just trying to avoid shelling out £50 for something I may not need!! Also the pipe that comes from the intercooler and goes under the inlet manifold could not be checked as I could not get to the other end of it, is it connected to the ETS/ETM? Thanks

Post 530354 by M-R-P on 2012-08-13 14:46:45

Yep, the Big hose under the inlet mani is connect to the throttle and can be a pig to undo. There's a good chance that the BCS has got tired, or the spring in the waste gate actuator has gotten weak. Have you thought about flushing the autobox? that might be holding you back. Also, reading and clearing any codes can make the car run better, as many ME7 owners will agree (myself included). I'm currently running an MBC as I also suspected my BCS was faulty. Just spend the money on a semi decent one if you don't want massive boost spikes.

Post 530356 by thad1 on 2012-08-13 14:59:12

O.k thanks, think i will pop the bleed valve on just to test the theory! If it is that then will get a MBC, had a MBC on my 944 t running 300+ hp and it flew, boost came on quicker as well!

Post 530359 by M-R-P on 2012-08-13 15:07:19

Be careful, ME7 engines (as I believe yours is) don't like MBCs/bleeders, I've been lucky - possibly something to do with plod tinkering about with it but there's no way I should be getting away with 16psi.

Post 530368 by thad1 on 2012-08-13 16:06:08

ok so I reset the ecu, plumbed in the bleed valve, gradually raised it but all I got was more and more hissing the more I increased the boost! So next question is where the hell could the boost leak be??? I cannot undo the lower intercooler hose due to the jubilee clip being rusted!

Post 530369 by thad1 on 2012-08-13 16:07:04

And no CEl with the bleed valve plumbed in either

Post 530374 by M-R-P on 2012-08-13 16:27:52

The hissing is probably coming from the bleed valve mate. You need a gated one that doesn't vent to atmosphere. Either that or you have a major leak somewhere, did you plumb the MBC(bleed) in correctly, sounds like you might have the pipes round the wrong way.

Post 530376 by Wobbly Dave on 2012-08-13 16:28:57

I have a 320bhp C70 (ME7 1999) - MBC will at best be ignored & at worst the ECU will put u in limp home. I would check all the hoses as you have been doing & also ensure that the actuator is properly set. Best to throw 300 quid ECU map at it & have done. If you actuator is a bit weak then you may be venting boost earlier than expected. ME7 is an on-demand system - you ask & it tries to deliver. This is very different to the manual cable systems which are reactionary

Post 530379 by Wobbly Dave on 2012-08-13 16:31:43

To set the pressure you will need one of these... http://compare.ebay.co.uk/like/270941685287?var=lv<yp=AllFixedPriceItemTypes&var=sbar&adtype=pla Actuator pressure is a scaled down version of boost pressure & IIRC should be set between 5 & 7 psi.

Post 530383 by thad1 on 2012-08-13 16:40:33

Hi Guys, Just to clarify I have already removed the bleed valve. The hissing sound is there with or without it fitted. I put a couple of turns on the actuator to see if it improved things but to be honest it's made no difference to peak boost, it just spools up quicker! I am certain it's a leak as it did not make the hissing sound a month ago and went like the clappers!

Post 530385 by Wobbly Dave on 2012-08-13 16:43:56

What about the sleeve on the top of the turbo? Sometimes the holes are not obvious.

Post 530388 by thad1 on 2012-08-13 16:50:07

Do you mean the turbo inlet? I had that off today and put it back on nice and tight, it's the soft pipe that connects to the hard pipe right?

Post 530415 by M-R-P on 2012-08-13 19:33:40

i think Dave means the outlet, the short rubber hose between the turbo and the plastic pipe that goes to the intercooler. They can split or leak when old. also, the intercooler may be worth investigating as they can split with age. Dave - not wanting to start anything, my ME7 is running an mbc at 16 psi with no warnings or boost cut and both my gauges have been calibrated. maybe this ME7 boost tying is a myth, maybe plod did something to my map, I dunno but my ecu is not ignoreing the mbc.

Post 530480 by Wobbly Dave on 2012-08-14 02:08:45

Yes indeed I was talking about the short sleeve on the turbo OUTlet - sorry! I raised my 2nd gear boost level just using the actuator alone. IMHO MBC has limited application in ME7 - though the debate will go on, I'm sure

Post 530482 by thad1 on 2012-08-14 07:31:53

ok well I had that off yesterday and it seemed ok, might be the ic or the throttle body end!

Post 530632 by Wobbly Dave on 2012-08-14 22:48:48

I have spares

Post 530669 by thad1 on 2012-08-15 08:48:20

Thanks mate! I am going to try and rig up a leak tester today, I have a compressor so might give the rubber glove method a go!

Post 531027 by thad1 on 2012-08-17 09:53:10

ok so the rubber glove exploded! nice idea in embryo form I guess!

Post 531184 by Wobbly Dave on 2012-08-17 23:47:54

You need a smokey leak tester. HLM have one & when ever I've had a leak they use that. Something like this..http://www.smokewizard.com/ or this... [ATTACH=CONFIG]16454[/ATTACH] most garages will carry one.

Post 533855 by thad1 on 2012-08-31 12:10:50

I have taken off the 3 hoses from the boost control valve and seem ok, except for the one that goes to the inlet manifold, it's a bit brittle so will replace it this weekend. I have removed the intercooler pipework from the top of the intercooler to the turbo and they all seem ok. Apart from the bottom hose which the clip is rusted on (will hacksaw that off this weekend) are there any hoses I have missed? Is there a diagram of all the boost hoses on the car anywhere? thanks guys

Post 535081 by thad1 on 2012-09-05 13:29:41

Update! Still cannot find a leak but I can Bl***y hear one lol What's the best way to pressurize the system? I have removed all the intercooler hoses and they are fine, checked all the other hoses coming off the Boost control solenoid and they are all fine as well! Are there some other vacuum hoses that would cause lower boost that I need to check? Thanks

Post 535083 by Wobbly Dave on 2012-09-05 13:45:31

As I said above whenever I have had a boost leak I went to HLM to use the smoke machine to pump pressurised smoky air into the whole system. I have spare pipework for the entire system if you need it - including the ETM plastic one.

Post 535109 by thad1 on 2012-09-05 17:00:08

Thanks Dave The only connection I have not checked is the one to the ETM, once I have checked this I will know what I am doing! Any ideas how to get the the jubilee clip on the ETM as I cannot see a thing under the manifold! I have a feeling it could be the intercooler but would like to check everything first! Money is very tight at the moment so don't want to pay a garage to test it unless it's a last resort! Thanks again for all the help!

Post 535110 by thad1 on 2012-09-05 17:00:53

Are there any other vacuum pipes that could leak under boost?

Post 535111 by thad1 on 2012-09-05 17:01:24

Dave also do you have a pair of front calipers from the C70 your breaking?

Post 535193 by Wobbly Dave on 2012-09-05 21:22:06

[QUOTE=thad1;535109]Thanks Dave The only connection I have not checked is the one to the ETM, once I have checked this I will know what I am doing! Any ideas how to get the the jubilee clip on the ETM as I cannot see a thing under the manifold! I have a feeling it could be the intercooler but would like to check everything first! Money is very tight at the moment so don't want to pay a garage to test it unless it's a last resort! Thanks again for all the help![/QUOTE] I usually use a combination of all the 1/4 inch drive parts I have (including the flexible one) to locate & undo the 7mm jubilee nut. Access is a little tight. Best to try to feel your way. If you are local to me I'd happily show you how. I have a spare FMIC if you need it - though you could use the opportunity (if it is a split FMIC).

Post 535194 by Wobbly Dave on 2012-09-05 21:23:05

[QUOTE=thad1;535111]Dave also do you have a pair of front calipers from the C70 your breaking?[/QUOTE] Yes

Post 535279 by glock19 on 2012-09-06 00:35:55

Have you thought of the hose to the brake servo pump ? After prolonged use, they're hardened and becomes brittle. Cracks or leaks under boost are possible but not under vacuum - so you don't heard it during idle. ME7 has also one-way check valves from the manifold to the servo and some models have extra vaccum pump for the servo.

Post 535303 by thad1 on 2012-09-06 10:11:16

Thanks, I will check this today! I have managed to get pressure into the intake but I am also pressurizing the crankcase as well! I am not sure if this is ok or not, can someone advise?

Post 535408 by glock19 on 2012-09-07 02:27:43

If that's the case, maybe your PTC is blocked. At the left of the intake manifold (Standing in front of the engine), there's an elbow connected to the intake tract (after the MAF). I don't know how you block up your IC during this test but any unreleased pressure along the PTC/PCV could cause the pressurised air to end up back in the crankcase through the oil catch tank. Since we are on this, maybe the boosted air leak is also coming from your PTC routes ?

Post 535436 by thad1 on 2012-09-07 11:43:32

Thanks for this However I have found the leak! The ets pipe was not done up properly, I managed to see the jubilee clip through the manifold and could just get the screwdriver on it, two turns later it seems ok The problem now is I think I have the pipes on the boost control solenoid the wrong way round because it boosted like crazy, i then swapped them over and it boosted hardly anything! I have the bottom hose on the bcs to the wastegate which i think is wrong! I think the side one goes to the intake and the bottom to the compressor but I can't really see properly!

Post 535441 by thad1 on 2012-09-07 12:36:48

quick update! Got the pipes on the right way round, the car now pulls hard initially then backs off a bit then pulls hard to the redline! However the hissing has started again! Not sure where to go from here lol