Turbo problems

[bernie at innovative.iinet.net.au]

justin ivan tapped away at the keyboard with:

> I have a question regarding a BOSCH Digifant car that I have turbo'd.  Upon 
> startup the car idles fine. Regular O2 based AFR meter rapidly cycles from 
> rich to lean and everything seems normal. After the car warmed up I took it 
> out and tried some hard acceleration runs. Car behaved pretty well, that is 
> didn't see any rich or lean spots that were worrisome. After 5-6 pulls I let 
> the car idle down to cool the turbo. At this point the car started running 
> real rich, (Blowing black smoke) and rough. I pulled the plugs and they were 
> completely black. I am running Bosch Platinum WD-6 plugs.

Which Digifant ECU did you employ? One with MAP sensor? (e.g. from a
supercharged G60 or G40?)

> My question is: Do you think this is a problem with the EFI set-up or is 
> something wrong with the car (ie sensor bad, bad coil or plugs?)

Could be fuel-pressure related - The high reference pressure (what
sort of boost are you running?) may be causing too much fuel to be
injected; the minimum opening time of the injector is the limit.

That's only a _guess_.

You may have to look at the injector flow rates and the programming
to make sure.

> I understand that once the plugs start to foul then the condition is just 
> going to get worse and worse in a never ending loop.
> Is this something that I could remedy by changing the heat range on the 
> plugs?

6-range plugs should be OK... especially given the type of engine.

> Thanks in advance for any info.
> Justin

[It'd be great if you didn't attach the whole digest when sending a
message to the list.]

-- 
Bernd Felsche - Innovative Reckoning
Perth, Western Australia
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