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Problem With Turbo Engine


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#1 Peteh

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Posted 08 September 2016 - 09:41 PM

Hi all,

I have recently had my metro engine rebuilt, after fitting it back into the car it will only run on tick over and cuts our when throttled up to around 4000rpm
It was working before with the same setup last year but started burning oil so went for a full rebuilt at a local specialist.

It is a standard spec engine, with an induction pipe and k&n filter, facet square fuel pump, fuel filter and pressure reg.

Things checked or tested
Fuel pressure 3psi on tick over rising to 6psi ish at 3000psi
Gasket to carb plenum
Fuel pipe connections
Balance pipe blocked off
Timing ok

The engine builder has a rolling road and offered to se it up for me, it won't boost up. When they throttle it up either on or off the rollers the fuel mixture leans off and the engine cuts out as if it it running out of fuel.
Fuel mixture is ok on tick over, it has a standard needle fitted.

I have spoken to SU today and they have suggested changing the needle to one the will run a little richer up the rev range. We have tried all the obvious things and running out of ideas.

Any help would be great

Pete

#2 sledgehammer

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Posted 08 September 2016 - 10:00 PM

I'm not to great on turbo's , but here are my guesses ...

 

is the float chamber vent fitted correctly or restricted ? - float chamber should be pressurised ?

 

if not as turbo pressure rises fuel will be pushed away from needle / jet & engine will stall / run rough at revs

 

carb to plenium gasket should have all the holes - if dashpot vent hole is missing , it will make mix very weak at rev's

 

blockage behind float needle , restricting fuel flow - enough for low revs - not enough flow for higher revs 

 

as I say - these are wild guesses


Edited by sledgehammer, 08 September 2016 - 10:04 PM.


#3 Turbo Phil

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Posted 08 September 2016 - 10:22 PM

If you've tried the above try putting a T-piece in line on the pressure sensing pipe from the plenum to the reg and run the extra leg to the float chamber venting pipe to pressurise the float bowl externally.
This will bypass the internal pressure feed to the float bowl incase there is a blockage etc

Phil.

#4 Peteh

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Posted 09 September 2016 - 07:29 AM

i thinks the engine builders have tied that but iam going next week so will check, they rang me yesterday and said they had it running great on the rollers, boosting and revving great. turned it off went back to it later o the double check before they rang me to say it was done and it was playing up again........ i have read a couple of threads where people are having the same problem but unfortunately no conclusions.

 

its a bit frustrating as it was running last year with exactly the same set up?????



#5 Turbo Phil

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Posted 09 September 2016 - 09:38 AM

Sounds like it could be a ignition fault then, possibly. It could be showing up as lean on the lambda due to a misfire. What are you using for ignition and what plug gaps ?

Phil.

#6 Peteh

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Posted 09 September 2016 - 01:01 PM

I have ordered a new fuel pump a BCA BCF an BCH needle to see if this sorts it out........ it is defiantly a fuelling problem, the Lamba sensor shows the fuel mixture leans off to almost zero before it cuts out. linking the pipe from the Plenum to the vent pipe did cure it for a bit and then it was crap again. reading other threads it suggest the Facet square pump may provide the pressure but not the flow????? I have ordered one for the Metro Turbo. going to the engine builders on Tuesday to fit them and have a try.

 

i will let you know how I get on.

 

Pete



#7 Turbo Nick

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Posted 11 September 2016 - 04:05 PM

facet pump will definitely be your main problem. you need an efi type pump that's capable of supplying at least 4psi more than your intended boost pressure.



#8 Peteh

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Posted 12 September 2016 - 06:05 PM

Fitting new one tomorrow hopefully......got new needles as well and a lambda sensor kit to so fingers crossed...

#9 phil hill

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Posted 13 September 2016 - 02:33 PM

Another thought - the gasket between the carb and plenum has an extra hole in it on the turbo - so the carb can "sense" the plenum pressure.

I've been caught out by this one before........... Car will idle fine but won't rev as the carb doesn't "sense" any increase in airflow and leans out.

Phil.

#10 Peteh

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Posted 13 September 2016 - 02:43 PM

Right...... Fitted new hi pressure performance fuel pump, and change the needle for BCA one. Ran up on the rolling road and it was still lean at about 4K Rpm.... and no boost. so removed the plenum and induction pipe...... Guess what.... the gasket was a normal one and not a turbo...... so changed that and put it back together. Engine ran okay and the fuel was now a little rich a 4-5K rpm but turbo still does not boost.

 

you can hear it spool up but the pressure guage shows 0.2bar at 5k rpm, if I take the pipe off the actuator I get about 0.6bar and the dump valve in the plenum blows off..... i refitted the pipe and the actuator moves a around 5k rpm but only getting 0.2bar of boost?????

 

its like the preload on the actuator is wrong???? and it is not opening the wastegate at the right time.... how can I check.

 

 

Any Thoughts

 

Pete



#11 Turbo Phil

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Posted 13 September 2016 - 06:39 PM

Replied to you on FB mate.

Phil.

#12 Peteh

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Posted 13 September 2016 - 08:49 PM

Got it thanks Phil.
I have done a bit of research..... A standard actuator on a metro turbo opens the wastegate at around 4psi ( 0.2) bar the ecu on the metro bleeds the air from the actuator at 4000rpm to increase to boost 7psi then closes a valve and the wastegate opens and boost drops off...... So connecting the actuator directly to the turbo means you can only get a maximum boost of 4psi (0.2) then the wastegate opens and boost drops off?..

So things i will try on Thursday. Connect a bike track pump to the actuator to see if the rod moves and at what pressure to see if the spring is ok, reset the preload to 6mm??. Fit a pressure control valve (ordered today) and set for 0.6 bar 8psi ish.

Does any one know what pressure it should move at.? Any other ideas would be great.

I will let you know how I get on..

Pete

#13 Peteh

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Posted 15 September 2016 - 07:00 PM

Thought I would give you an update......adjusted the preload on the actuator the hole was about 2-3mm from the pin so adjusted it to 6mm ish. I also fitted a pressure control valve. Unfortunately I had to go back to work, but the engine builder was going the change the needle for the original BDD and set it up on the rolling road.

So fingers crossed that its sorted out now.

#14 Peteh

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Posted 16 September 2016 - 11:05 AM

Still having problems, I shortened the actuator so the hole was 6mm from the pin and fitted a pressure control valve. is seems if its made things worse, we ran it up on the rolling road last night and it would only boost to 0.4 bar (5.8psi)

adjusting the control knob made no difference. 

we removed the pipe off the the actuator and tried again, and it still would only boost to 0.4 bar (5.8psi). before i adjusted the actuator it boosted to 0.9 (13psi) and it blew the dump valve in the plenum, this time it didn't.

 

So thing that are different are new pressure control valve fitted and shorten the rod. The pressure control valve came with a t piece with an arrow one of hose tails has a 1mm hole in it and the other 2 have a 3mm hole in, I have put the small hole hose tail to the turbo side and the lager one to the actuator then a hose from the top one to the tail says feed other says vent has nothing.

 

what could be wrong?????/ fuel pressure reads 13psi at full chat, timing is spot on just the boost. or the lack of it 

 

Regards

 

Pete 


Edited by Peteh, 16 September 2016 - 11:20 AM.


#15 Peteh

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Posted 20 September 2016 - 04:23 PM

After much head scratching and tyre kicking, I think we have sorted it....... Not quite sure what it was but....We tinkered with the actuator a little more and ran it up on the rolling road and it worked. The BDD was running to lean at the top end

and the BCA was running to rich so we fitted the BCF and this was running about right till about 4000RPM and leaned off to much so we modified the needle so at 5500+ rpm it was about 12.

 

we adjusted the boost control valve so we got 0.6 bar (8.4psi ish) at 5500rpm but the valve is blowing in the plenum at around 0.5 so I might blank it off? It is producing 103BHP 122ft bl of torque at 5500 rpm bearing in mind the engine is brand new although they have ran it in on the rollers it probably could do with a few road miles now.

 

So it was a combination of the wrong gasket between the carb and plenum and the actuator adjustment , fuelling and **** happens...... but it is all up and running now!!!! 

 

thanks for the advise and thanks to Turbo Phil for the input on facebook as well....I am picking it up on Thursday and taking it back in a couple of week to roller it again.

 

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Pete 


Edited by Peteh, 20 September 2016 - 04:27 PM.





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