1992 740 turbo wagon 150k miles sending smoke signals...

Thanks in advance for any help diagnosing this problem, long time lurker to
this group and have had tons of good advice in repair of my stable. I did
read historical posts for several days now and cannot find the problem with
what I have been reading.

My 740 suddenly started to smoke badly from one drive early in one day to
starting it that evening.
Its a weird smoke, in that it seems to roll out not really related to engine
speed.
In fact when first started, there was no smoke and then a few seconds later
it sort of rolled out at idle.
It doesnt seem like an air mass sensor, because [my 82 would not start with
a bad one unless placed in limp] that smoke was ?thinner? but always smelled
rich.
This smoke smells like bitter diesel, and isnt blue or black, but white [no
coolant loss that I can tell]
Here is what I know:
bosch lh jetronic 2.4 system
battery was slightly low on volts 12.2 [charged now]
oil was weird, thin , not milky replaced it and filter
Pulled harness off AMS and slightly corroded, cleaned, replaced = smoke
Pulled the air cleaner and found that a piece of deteriorated foam from the
cover was blocking 1/3 of the intake of the AMS. removed all foam, replaced
=smoke
pulled oxogen sensor connector, slightly corroded terminals/wires, cleaned,
replaced=smoke
pulled each FI wireset, no corrosion, replaced=smoke
pulled fuel pressure reg vacume line, no fuel in line, replaced=smoke
pulled/checked flame trap hoses, not clogged at all, replaced=smoke
pulled other vacuum lines and checked all i could reach/see, no
missing/unhooked/holes,,. still smokin
slightly corroded ground straps to firewall from valve cover,, only surface
corrosion not at lugs, replaced=smoke
pulled outlet to intercoller line from turbo, not too dirty.
pulled intake to turbo, not too dirty, turbo spinns freely, no play/wobble
tested AMS [kinda] did not know [ala chiltons manual] which was the signal
ground of the bl/g bl/r bl/w wires..
Ignition=on, connector =on: had 12v on bl/y and br =grnd other wires to
ground varied among millivolts, but definetly had a reading on all, none in
the .1 volt range all lower
did not test ox sensor, afraid to warm up engine [only run for movement of
car since that evening and testing...] dont wanna blow the cat. or ??

Error codes pin 2 test "1"
got a 1-2-1 =AMS absent/faulty [rember the foam chunk?] did not reset to
recheck
got 3-1-2 no knock enrichment from "DI system" [what is DI system?]
got 2-3-1 adaptave fuel mix too lean or rich
then pin 6 test "1"
got [forgot code] EGR temp or flow error

I have read posts about Y shaped vapor lines near the turbo/under the
turbo.. all I have are oil and coolant lines
the turbo is mitsu because the ss band in the middle [right?]
I have not checked the oil lines to the turbo [chicken for now]
I have not checked the sp plugs [REALLY] tight/hard to turn out, afraid to
strip and create more problems...got plenty now
I have not checked the knock sensor [again chicken for now to pull off the
intake]
I have not checked the injectors for spray pattern [not a gradual smoke, a
sudden smoke]

I dont want to go replacing the turbo or AMS as tests..but do not know where
to go next..
Any ideas?

Thanks
Dave Simon
92 740 turbo wagon 150k
82 240 dl 250k

 

Check the rubber hoses, particularly those right at the intercooler, a leak
will cause it to run very rich.

 

Remember that for every litre of petrol burnt in the engine, more than a litre
of water is produced. White smoke is usually water (steam) caused and it may be
that the coolant flowing through your Mitsubishi turbo's cooling jacket may have
sprung a leak or blown a gasket or washer, or even corroded the jacket and is
dripping coolant into the turbo. This is the one problem with water cooled
turbos.

Cheers, Peter.

: Thanks in advance for any help diagnosing this problem, long time lurker to
: this group and have had tons of good advice in repair of my stable. I did
: read historical posts for several days now and cannot find the problem with
: what I have been reading.
:
: My 740 suddenly started to smoke badly from one drive early in one day to
: starting it that evening.
: Its a weird smoke, in that it seems to roll out not really related to engine
: speed.
: In fact when first started, there was no smoke and then a few seconds later
: it sort of rolled out at idle.
: It doesnt seem like an air mass sensor, because [my 82 would not start with
: a bad one unless placed in limp] that smoke was ?thinner? but always smelled
: rich.
: This smoke smells like bitter diesel, and isnt blue or black, but white [no
: coolant loss that I can tell]
: Here is what I know:
: bosch lh jetronic 2.4 system
: battery was slightly low on volts 12.2 [charged now]
: oil was weird, thin , not milky replaced it and filter
: Pulled harness off AMS and slightly corroded, cleaned, replaced = smoke
: Pulled the air cleaner and found that a piece of deteriorated foam from the
: cover was blocking 1/3 of the intake of the AMS. removed all foam, replaced
: =smoke
: pulled oxogen sensor connector, slightly corroded terminals/wires, cleaned,
: replaced=smoke
: pulled each FI wireset, no corrosion, replaced=smoke
: pulled fuel pressure reg vacume line, no fuel in line, replaced=smoke
: pulled/checked flame trap hoses, not clogged at all, replaced=smoke
: pulled other vacuum lines and checked all i could reach/see, no
: missing/unhooked/holes,,. still smokin
: slightly corroded ground straps to firewall from valve cover,, only surface
: corrosion not at lugs, replaced=smoke
: pulled outlet to intercoller line from turbo, not too dirty.
: pulled intake to turbo, not too dirty, turbo spinns freely, no play/wobble
: tested AMS [kinda] did not know [ala chiltons manual] which was the signal
: ground of the bl/g bl/r bl/w wires..
: Ignition=on, connector =on: had 12v on bl/y and br =grnd other wires to
: ground varied among millivolts, but definetly had a reading on all, none in
: the .1 volt range all lower
: did not test ox sensor, afraid to warm up engine [only run for movement of
: car since that evening and testing...] dont wanna blow the cat. or ??
:
: Error codes pin 2 test "1"
: got a 1-2-1 =AMS absent/faulty [rember the foam chunk?] did not reset to
: recheck
: got 3-1-2 no knock enrichment from "DI system" [what is DI system?]
: got 2-3-1 adaptave fuel mix too lean or rich
: then pin 6 test "1"
: got [forgot code] EGR temp or flow error
:
: I have read posts about Y shaped vapor lines near the turbo/under the
: turbo.. all I have are oil and coolant lines
: the turbo is mitsu because the ss band in the middle [right?]
: I have not checked the oil lines to the turbo [chicken for now]
: I have not checked the sp plugs [REALLY] tight/hard to turn out, afraid to
: strip and create more problems...got plenty now
: I have not checked the knock sensor [again chicken for now to pull off the
: intake]
: I have not checked the injectors for spray pattern [not a gradual smoke, a
: sudden smoke]
:
: I dont want to go replacing the turbo or AMS as tests..but do not know where
: to go next..
: Any ideas?
:
: Thanks
: Dave Simon
: 92 740 turbo wagon 150k
: 82 240 dl 250k
:
:
:

 

Update: for future refrence.

Thanks to all who posted suggestions.
Here is what I did. [in addition to way below...]
I changed all visible vacuum hoses.
I pulled the fuel rail and checked the spray, and operation [on=on
off=off]
[was fine]
Changed out all orings after cleaning intake and rail.
Left battery off to 'reset' computer

Started it [has always started]
Smoked badly, ran it anyway for a good 15-20 minutes to allow the
computer to renormalize the settings.

When I got home, No smoke, No stink. runs better than before.

My thought is that the foam liner caused a confusing airflow problem
the computer couldnt solve, went really rich on old oil with old
vaccuum plumbing.
Dont think it was turbo related.

Just needed some tlc I guess.

So far so good.

Cheers,
Dave

 

This may be a reach, however. Check your cam gear. The stationary pin that keeps the cam gear from moving may be sheared off and cam timing is off. Strange but it happened to me. Once corrected it ran fabulous again