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Willys

OK boys and girls, lets talk turbos

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OK, I have questions.....our turbos are massive I know and should push as much air as a gas powered leaf blower I'm sure...lol.  Yeh right....the fins are about an inch in diameter so I can't see it pushing much...?   OR does it?  
I am having this over fueling issue and have been told that I am not getting enough air to fuel ratio...?  So I have started the hunt to see why or what is causing it.  I have swapped out all sensors, fuel rail, fuel pump, checked for blockages.....nothing out of the ordinary as everything is new so everything should work as it should. Even the turbo is new Chinese version, with a brand new manifold and came as a unit, that spins sort of freely like an old one does. It is a slightly bit stiffer imho due to the new oil seals on the shaft as the fins do not make contact with the sides etc. At least from what I can see or tell.  Also the wastegate is operating as it should, sealing when closed.
BUT, when I used my compressor to see how much air the turbo actually forces out it was almost undetectable.....yes I blocked off two of the exhaust ports and made the air intake a tight fit as not to loose any inward flow or pressure. The old turbo was at least twice the force of the new one...? Yes it spins slightly better but so little difference you seriously have a hard time judging it.
I have also pinned out the entire electrical harness for the engine bay searching for a short or break in a wire...nothing with a continuity check.  Next after checking the turbo I will be removing what looks like a very slightly used inter cooler radiator and checking to see if it is clogged in any way...? The intake is clear also. The muffler is a converted Honda CBR1000rr new take off muffler that has no CTT inside it. It flows extremely well. 

I started this thread to hear from those who have played with turbo's and can help guide me as to what I'm supposed to be seeing and feeling from our turbo's....any and all help and suggestions will be greatly appreciated as usual.  

The main issue is an over fueling which produces way too much whitish smoke which burns your eyes if you get into it too much. I am not driving the car so no worries about ruining the engine while it is having this problem. It idles perfectly but once you introduce your right foot into the mix at any amount the problem starts.

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Reducing it to round numbers.

 

16 PSI boost pressure is 1 atm so double normal pressure. That means that each rev it has to shift 800cc of air.

 

At 1000 rpm that is 800 litres of air. Not a huge amount. :)

 

Top of the head ball park stuff that. Not sure my brain is up to it but it's a start.

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Hmmm....so I changed turbo's from brand new to old and rusty.....lol....no difference at all.   So now time to swap it back to new once again.....oh what fun  we're having.   AUGH!!!!

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I don't think turbo faults make smoke on a smart unless it is the turbo oil seals. Nothing makes smoke quite like that..

 

I have not had a 450 diesel turbo go duff but I have had a petrol one go. No smoke just total lack of power. Same with my 451 diesel when the turbo went. No smoke just absolutely not enough power to set off.

 

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4 hours ago, Mjolinor said:

I don't think turbo faults make smoke on a smart unless it is the turbo oil seals. Nothing makes smoke quite like that..

 

I have not had a 450 diesel turbo go duff but I have had a petrol one go. No smoke just total lack of power. Same with my 451 diesel when the turbo went. No smoke just absolutely not enough power to set off.

 

I had to rule it out as a cause for the over fueling I'm getting. Made sense that if I wasn't getting enough air into the system it would over fuel...?  I have just stripped all insulation etc from wiring harness to check for any rubbed or burned wires, none, it all looks like new.  It is past frustrating at this point.....augh.....!  I'm open to all suggestions.....????  The funny thing is it idles perfectly but as soon as you apply any throttle it smokes ...?  It also measures out correctly when hooked to the STAR machine as in balance, fuel pressures, even the throttle peddle numbers match which I am to believe is correct. ????  There has to be something sending a signal to the ECU that isn't correct, but I have traded all sensors, fuel pump, computers, fuel rail,injectors, pressure tested intercooler and the hoses, now swapped turbo's, wastegate is correctly set, idle is 825rpms, air cleaner is new, no restriction on that side of it, fuel lines,  All of these parts are presently running perfectly on my beater, so I know they work correctly.  Thoughts..?
I am now thinking to get my mechanic buddy to hook up his extremely expensive shop scanner to it and see if it see's anything wrong...?  But that can't happen for another month, so I keep trying different things until then.

Edited by Willys

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The ECU will fuel according to how much air it is getting (and other factors).

 

If you have a hole in the air delivery then that measurement is wrong so the ECU thinks it is getting more air than it really is but, again, in my experience it does not smoke when there are holes in the intercooler because the exhaust lambda sensors correct for it. Does the 450 have lambda sensors?

 

Could it be insufficient back pressure on your exhaust?

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9 hours ago, Mjolinor said:

Could it be insufficient back pressure on your exhaust?

The car will run with or without an exhaust no and not normally smoke,  correct?  I have checked for holes in the intake side of things, none, no leaks or damage..?    I think it's electrical as in a sensor telling the ECU to deliver too much fuel...? but as I have said above, I have swapped out each sensor one at a time with my beater's sensors which don't run poorly so to speak...it runs perfectly so I know what I swap should run the same way....?   This is why I went after the wiring as in looking for a short or melted wiring causing a signal to be incorrect? The wiring looks like new after removing the protective shielding. Plus i have also checked for continuity using a volt meter a while back thinking the same, a broken wire or shorted wire somewhere in the engine wiring harness.
Am I correct in thinking that the SAM simply tells the ECU to operate and not directly control what the ECU does as in amounts of fuel etc..?  The only thing I can think of is the throttle foot peddle toaster wire could be damaged but it also was carefully examined in the process of rebuilding/restoring the car. What does the foot pedal actually control? The amount of fuel or the RPMs..? 

My final thought is to swap just the engines and see if it is the engine itself or a signal it is getting to cause the problem.  The only thing that has stopped me from doing this is it leaves me without a running vehicle. Hmmm...?   But this step would rule out the engine as a whole. But a load of work.....? I wanted to get any and all other possible reasons out of the way before going this far.

Again always open to suggestions why this is happening....thanks again.

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have you done a compression test on the intake side? pressure it up to 10 psi, listen for hiss.. boost leak is common

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Welcome to the club by the way and thanks for the suggestion.  No I haven't had a intake compression test done before.   I will now add that I have swapped turbos with known good working turbo and the issues are the same, so have sort of semi ruled out the turbo causing my problem....AUGH.....!!!!   
I am back to pressure testing the cylinders next after watching someone with similar issues on youtube, he had incorrect lifters installed new and as soon as he swapped in correct lifters his issues were resolved.  I have since checked to see if 451 CDI lifters are different to 450 CDI lifters and see that they are the same product number so the idea that I was given the wrong lifters has dwindled as in someone simply picking the wrong SmartCar model from the shelf by mistake...?  This is why I again am going after compression testing numbers...?  Just out of curiosity ....?  When I first installed engine it was getting 380psi and was told for a freshly rebuilt engine those numbers were good and would build after rings had seated to cylinder walls as expected.  I haven't run engine long enough to do this yet and don't want to until I figure out why it's over fueling as the fuel will wash the walls of oil and glaze over the surface which will prematurely ruin engine.

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