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LTX-12 Microtech 20B help

Old 05-20-16, 02:47 PM
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LTX-12 Microtech 20B help

So, today was the big day. My first trip down to the dyno to get a base map setting one low boost. After running into some issues with wastegate control having being sold a completely wrong spring we were able to really run in anger but got some half reasonable load runs done up to about 6k with around 7-8psi boost. Mostly the map so far seems pretty smooth and the car runs quite nice. However I have noticed a couple of things I am hoping I can get some help with solving.
First of all idle.. after cold start being super rich and taking out some fuel and compensation my tuner can get it to idle nicely warm. However it seems to sit idling for a couple of minutes and then just dye like someone turned of the ignition. I presume it is dropping into some other section of map causing this but don't know what? Either that or could it maybe cooling a couple of degrees in this time and dropping into a different water temp compensation area that is not yet tweaked and too rich or lean?Currently the idle valve is disconnected as when we plugged it in it seems to open and stay that way so the rpm was too high. Plan it to find out what is wrong with that and run it for a bit better stability on idle. Want to try and get the idle working nicely without first so the valve is just there for backup.

The other issue that I didn't like and we ran out of time with due to the boost issue was when you lift off after a load run there is a thick black puff of smoke from the exhaust for a second. This then turns mid grey but pretty thick and plumes from the exhaust pretty much until the revs have dropped right back down to idle. then it idles quite clean again? Is this a decelleration enrichment gone crazy or something? I am running premix and 1680 injectors all round for a bit of info. Strange that it predominently seems okay under load other than a few rich spots where you get a dark puff of exhaust. Also I should not it didn't breath at all during the runs and I gather this is something that 20B's are also quite good at!
Would be great if I can get some pointers or which screens I need to post for further help.

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Old 05-20-16, 07:51 PM
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need more data. like what was AFR before it died. also I would make sure there is no big leak anywhere by spraying some brake cleaner all around the manifold while the engine is running to see whether that can affect the idle. vacuum leak and faulty tps sensor can do many weird things. when it dies, you need to be looking at the microtech screen. make sure the tps is still at 0%, watch afr, etc.

I don't know what's going on with smoke. I wouldn't worry too much about smoke until you go through heatcycle a few times. new exhaust/wrap etc. can smoke initially. also make sure your turbo doesn't have oil leak by looking at the compressor side. good luck.
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Old 05-21-16, 04:07 AM
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Thanks for the reply.. Chees for the pointer. Cannot remember AFR's off hand. But I think idle was around 11.2 and I think it starts to climb before dying but didn't really get to check that. I was going to get a smoke machine and check the inlet side anyway. To check there are no leaks. So will make sure I rule that out.
Turbo is brand new and I am pretty confident it is not oil smoke too grey. Runner thought the black puff could be crap off the rotors on lift off? Wondering if the grey could be fuel and rubbish burning up in the exhaust still. Would have expected it to clear pretty. Soon though.that said we only had about 4 big pulls. I had an injector stick open before I got it all running and it filled up the engine and exhaust with fuel. Maybe ot is that burning up in the silencer still? It look like smoke from a bonfire?!

Will see if anyone else has thoughts on that or have to wait until I get back to the dyno.

If I get a chance I will run it up and see if I can get some more info for the idle stall issue.
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