99 Turbo update - vroom vroom

Well, the beastie runs & drives. After building one good engine out
of two bad ones and more than a little creative merging of newer
parts in an older car, the '78 99 Turbo I've been working on is
driveable.

So, the inevitable questions. Where is the overboost sensor on
this thing? It seems to be cutting out the ignition just as I
get into the "red" on the turbo gauge, rather than up a ways as
I would expect. Where is that beastie, and/or might it be
something else like a stuck turbo bypass valve?

I still don't have a working alternator for it; can I use one from,
say, a 96 or Sonett? Those, I have. Otherwise, can I use
a later Saab 900 alternator, and which should I choose?

Thanks,
Dave Hinz

I still don't have a working alternator for it; can I use one from,
say, a 96 or Sonett? Those, I have. Otherwise, can I use
a later Saab 900 alternator, and which should I choose?

You could use a 95/96/97 alternator but those used in the US only go up to
35 Amp. Only from 1976 or so did they get a 55 Amp one. Both have an
external voltage regulator. You'd be better off using a 99/900: 55, 65 or 70
Amp and a voltage regulator integrated in the brush holder. If you do not
have many electrical accesories on at the same time (AC, heated seat, heated
rear window, fog lights, spot lights...) 55 Amp is more than sufficient.
Also, the 96 one rotates the other way round as a 99/900, so you also have
to swap the cooling fan. One more difference is the double pulley on (some?)
900 alternators (like my 900T).
--
MH
'72 97 '77 96 '78 95 '79 96
'87 900T8
http://go.to/saab96

Dave Hinz wrote:

Well, the beastie runs & drives. After building one good engine out
of two bad ones and more than a little creative merging of newer
parts in an older car, the '78 99 Turbo I've been working on is
driveable.

So, the inevitable questions. Where is the overboost sensor on
this thing? It seems to be cutting out the ignition just as I
get into the "red" on the turbo gauge, rather than up a ways as
I would expect. Where is that beastie, and/or might it be
something else like a stuck turbo bypass valve?

I installed a 900T engine in my 78 99 some years ago, but didn't get
any such luxury as overboost protection -- still I did experience the
symptom as you describe, I think it was the warm-up regulator that was
stuck, leaving too little fuel at high loads.

If you haven't already, try to increase the fuel/air ratio by turning the
adjustment screw 1/4 turn clockwise at a time and see what happens. Also
check the so-called "control-pressure". If it is too high, as I said, the
engine will run lean at high loads. more than 4 bar is too much. The Haynes
manual for the 99 is quite informative on this part. When cold, it is
approx. 1 bar, increasing steadily to around 4 when fully warm.

PS: Until you get the fuel mix mostly correct, you may find it convenient to
use a set of "hotter" NGK-s than specified, I think I still use BCP6's,
but then in Norway, continuous operation at highway speeds in hot summer
days is soo rare!

--
Frode

On Sun, 12 Dec 2004 22:25:21 +0100, MH <nomail (AT) nowhere (DOT) no> wrote:

I still don't have a working alternator for it; can I use one from,
say, a 96 or Sonett? Those, I have. Otherwise, can I use
a later Saab 900 alternator, and which should I choose?

You could use a 95/96/97 alternator but those used in the US only go up to
35 Amp. Only from 1976 or so did they get a 55 Amp one.

Right, looks like I'll fix up one of the two bad ones with the car then.
There's a Motorola that doesn't turn (but I'm comfortable rebuilding
motors so this shouldn't be bad), and the other one which is I think the
Bosch that seems to be missing parts - has the 3-blade connector on the back
of it that looks like where a voltage regulator should go. Or, can I put
a VR from a 96 onto those, with the right cable?

Both have an
external voltage regulator. You'd be better off using a 99/900: 55, 65 or 70
Amp and a voltage regulator integrated in the brush holder. If you do not
have many electrical accesories on at the same time (AC, heated seat, heated
rear window, fog lights, spot lights...) 55 Amp is more than sufficient.

Let's see. 99 Turbo - manual windows, no AC, not sure about rear window
defogger (I think yes), heated seat of course, no fog lights or spotlights.
So 55 should be reasonable if that older Bosch just needs a VR.

Also, the 96 one rotates the other way round as a 99/900, so you also have
to swap the cooling fan. One more difference is the double pulley on (some?)
900 alternators (like my 900T).

Good to know. Surprising though, since both are at the 'front' of the
engine?!?!?

About the Sonett ring & pinion set we were talking about,
I looked in the other place I could think of for that ring&pinion, it's not
there. The only other one I might have is still in the intact parts sonett,
and it won't be coming out of there any time soon I'm afraid. I'll keep an
eye out for them, but I wouldn't hold my breath.

Dave Hinz

On Mon, 13 Dec 2004 15:57:41 +0100, Frode <fh (AT) dynamica (DOT) no> wrote:

Dave Hinz wrote:

So, the inevitable questions. Where is the overboost sensor on
this thing? It seems to be cutting out the ignition just as I
get into the "red" on the turbo gauge, rather than up a ways as
I would expect.

I installed a 900T engine in my 78 99 some years ago, but didn't get
any such luxury as overboost protection -- still I did experience the
symptom as you describe, I think it was the warm-up regulator that was
stuck, leaving too little fuel at high loads.

It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter. Need
to try again tonight and see what RPM it's happening at; I was watching
the boost gage rather than the tach.

If you haven't already, try to increase the fuel/air ratio by turning the
adjustment screw 1/4 turn clockwise at a time and see what happens.

Which adjustment screw, please? This is a CIS fuel injected system, does
that change what you're saying?

Also
check the so-called "control-pressure". If it is too high, as I said, the
engine will run lean at high loads. more than 4 bar is too much. The Haynes
manual for the 99 is quite informative on this part. When cold, it is
approx. 1 bar, increasing steadily to around 4 when fully warm.

Sounds like I need a Haynes for the 99T then. My 900 manuals are good for
almost everything, but they're too new for some stuff, and my 99 manual is
too old for the turbo stuff. Ah well.

PS: Until you get the fuel mix mostly correct, you may find it convenient to
use a set of "hotter" NGK-s than specified, I think I still use BCP6's,
but then in Norway, continuous operation at highway speeds in hot summer
days is soo rare!

I put BCP6s in there, which I think is as hot as I should go, yes?

Dave

Dave Hinz wrote:

On Mon, 13 Dec 2004 15:57:41 +0100, Frode <fh (AT) dynamica (DOT) no> wrote:
Dave Hinz wrote:

So, the inevitable questions. Where is the overboost sensor on
this thing? It seems to be cutting out the ignition just as I
get into the "red" on the turbo gauge, rather than up a ways as
I would expect.

I installed a 900T engine in my 78 99 some years ago, but didn't get
any such luxury as overboost protection -- still I did experience the
symptom as you describe, I think it was the warm-up regulator that was
stuck, leaving too little fuel at high loads.

It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter. Need
to try again tonight and see what RPM it's happening at; I was watching
the boost gage rather than the tach.
The 99 fuel cutoff is really just the fuel-pump being switced off. I don't

know how that feels since I don't have that feature, but I would think not
quite as abrupt as total ignition misfire. The rev limiter is supposed to
cut in at 6000 rpm and as far as I can tell from design, it will stay out
until the rpms have dropped substatially. 6000 rpm is way beyond where I
shift up and I have never experienced that. It is a simple spring-loaded
centrifugal device in the distributor, quite easy to disable just for the
sake of ruling out that possibility. It could be that the spring is getting
old. Your original post indicates that it is boost related, not RPM.

If you haven't already, try to increase the fuel/air ratio by turning the
adjustment screw 1/4 turn clockwise at a time and see what happens.

Which adjustment screw, please? This is a CIS fuel injected system, does
that change what you're saying?
It is the green one here displayed at this page:

http://ncr-pca.org/tech/tech-cis.htm
An allen screw, buried deep inside the unit betwen the airflow meter and the
fuel regulator. It is accessible from the top. You'd really need a tool
like this:
http://store.autotoolexpress.com/assh4516.html

I have always used a long electronics-type screwdriver. Just remember to
keep a record on how much you turn it. 1/4 of a turn is maximum between
test drives. Also keep an eye on the spark plug deposits in the long run.

I'm sure the web is full of info on CIS / K-jetronic, it was/is used in
every kind of vehicles from the Golf to the 911 turbo and Lamborghini
Countach, Ferrari Mondial And that V- thing too...

Also
check the so-called "control-pressure". If it is too high, as I said, the
engine will run lean at high loads. more than 4 bar is too much. The
Haynes manual for the 99 is quite informative on this part. When cold, it
is approx. 1 bar, increasing steadily to around 4 when fully warm.

Sounds like I need a Haynes for the 99T then. My 900 manuals are good for
almost everything, but they're too new for some stuff, and my 99 manual is
too old for the turbo stuff. Ah well.
No big deal, I can take some photos of selected pages, and cite some key

figures if needed.

PS: Until you get the fuel mix mostly correct, you may find it convenient
to use a set of "hotter" NGK-s than specified, I think I still use
BCP6's, but then in Norway, continuous operation at highway speeds in hot
summer days is soo rare!

I put BCP6s in there, which I think is as hot as I should go, yes?
In the long run, yes!

Good luck with a fun engine!

--
Frode

There's a Motorola that doesn't turn

The 900 Motorola is 70 Amp

Bosch that seems to be missing parts - has the 3-blade connector on the
back
of it that looks like where a voltage regulator should go. Or, can I put
a VR from a 96 onto those, with the right cable?

Yes, that should work, The 96 has a short (+/- 20 cm - 8") triple cable for
that, also with a cable connection to the charge light spliced in - that HAS
to be connected for the alt to work ok!

Also, the 96 one rotates the other way round as a 99/900,
Surprising though, since both are at the 'front' of the engine?!?!?

yes, but the front of a 99/900 engine is facing the rear...

About the Sonett ring & pinion set ....
I'll keep an eye out for them, but I wouldn't hold my breath.

no problem, thanks for the effort.

--
MH
'72 97 '77 96 '78 95 '79 96
'87 900T8
http://go.to/saab96

On Mon, 13 Dec 2004 20:31:00 +0100, Frode <fh (AT) dynamica (DOT) no> wrote:

Dave Hinz wrote:

It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter. Need
to try again tonight and see what RPM it's happening at; I was watching
the boost gage rather than the tach.

The 99 fuel cutoff is really just the fuel-pump being switced off. I don't
know how that feels since I don't have that feature, but I would think not
quite as abrupt as total ignition misfire.

Probably not that, then.

The rev limiter is supposed to
cut in at 6000 rpm and as far as I can tell from design, it will stay out
until the rpms have dropped substatially. 6000 rpm is way beyond where I
shift up and I have never experienced that. It is a simple spring-loaded
centrifugal device in the distributor, quite easy to disable just for the
sake of ruling out that possibility.

This is the inductive sensor distributor, yes? I'm not actually sure if this
is the right dizzy for the car, it was just the only 99/900 dizzy I could
find with the right gear cog on it (course teeth rather than fine, to mesh
with the older-style countershaft in the engine). I should look at numbers,
and/or try another dizzy I think.

It could be that the spring is getting
old. Your original post indicates that it is boost related, not RPM.

I thought it was just as it crossed over into the red boost, but it may
have been also when I hit 6K RPM. I'll check tonight rather than second
and third-guess my second-guessing.

Which adjustment screw, please? This is a CIS fuel injected system, does
that change what you're saying?

It is the green one here displayed at this page:
http://ncr-pca.org/tech/tech-cis.htm

An allen screw, buried deep inside the unit betwen the airflow meter and the
fuel regulator. It is accessible from the top. You'd really need a tool
like this:
http://store.autotoolexpress.com/assh4516.html

Excellent. I've got pretty much that exact tool from my days as a
biomedical electronics technician.

I'm sure the web is full of info on CIS / K-jetronic, it was/is used in
every kind of vehicles from the Golf to the 911 turbo and Lamborghini
Countach, Ferrari Mondial And that V- thing too...

It's a delightfully elegantly simple solution. I'd love to refit one to
a V4 Saab.

Sounds like I need a Haynes for the 99T then. My 900 manuals are good for
almost everything, but they're too new for some stuff, and my 99 manual is
too old for the turbo stuff. Ah well.

No big deal, I can take some photos of selected pages, and cite some key
figures if needed.

I am likely to take you up on that at some point. Right now things seem
good aside from the above. I got a new cap for the expansion tank today,
because the other one was very scary looking, so hopefully I can bring the
system up to normal temperature and pressure to check for leaks. The oil
system seems intact, and the turbo sounds good. Still haven't heard the
bypass valve noise I remember, so I'm not sure what that's all about yet.

I put BCP6s in there, which I think is as hot as I should go, yes?

In the long run, yes! Good luck with a fun engine!

It's been a dozen years since I drove (a/this) 99 Turbo, until yesterday.
The steering is a bit heavy, but it's a _very_ fast/responsive rack.
Handles good, even on not so good tires. I plan to put on more than 3
miles tonight, but since it hasn't moved on it's own power in more than
a decade, I'm going gently and cautiously.

Dave Hinz

On Mon, 13 Dec 2004 20:33:31 +0100, MH <nomail (AT) nowhere (DOT) no> wrote:

There's a Motorola that doesn't turn

The 900 Motorola is 70 Amp

....and it seems to have the VR built into it, would that be the best
bet then do you think? I'm not intimidated at all by rebuilding it if
it's worth using.

About the Sonett ring & pinion set ....
I'll keep an eye out for them, but I wouldn't hold my breath.

no problem, thanks for the effort.

The annoying thing is, I know they're in the barn, but can't put my hands
on 'em, as they're not on the shelf I'd expect.

Dave Hinz

Dave Hinz wrote:

On Mon, 13 Dec 2004 20:31:00 +0100, Frode <fh (AT) dynamica (DOT) no> wrote:
Dave Hinz wrote:

It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter.
Need to try again tonight and see what RPM it's happening at; I was
watching the boost gage rather than the tach.

The 99 fuel cutoff is really just the fuel-pump being switced off. I
don't know how that feels since I don't have that feature, but I would
think not quite as abrupt as total ignition misfire.

Probably not that, then.

The rev limiter is supposed to
cut in at 6000 rpm and as far as I can tell from design, it will stay out
until the rpms have dropped substatially. 6000 rpm is way beyond where I
shift up and I have never experienced that. It is a simple spring-loaded
centrifugal device in the distributor, quite easy to disable just for the
sake of ruling out that possibility.

This is the inductive sensor distributor, yes?
Thats the one. In my car (taken from a 1980 or 1981 900 I think), the purely

mechanical RPM limiter is built into the high voltage (secondary) circuit
only and does not involve the low voltage parts at all.

I'm not actually sure if
this is the right dizzy for the car, it was just the only 99/900 dizzy I
could find with the right gear cog on it (course teeth rather than fine,
to mesh
with the older-style countershaft in the engine). I should look at
numbers, and/or try another dizzy I think.

It could be that the spring is getting
old. Your original post indicates that it is boost related, not RPM.

I thought it was just as it crossed over into the red boost, but it may
have been also when I hit 6K RPM. I'll check tonight rather than second
and third-guess my second-guessing.
As you may have noticed, the 99T has a quite unusual boost control system

that actually senses and controls the exhaust manifold pressure via a
rubber diaphragm regulator. At high RPM's, (max BHP is at 5000 remember), I
would expect that the added back pressure from the exhaust system will keep
the needle away from the red area. If the rubber diaphragm is in good order
and the wastegate valve isn't stuck, that is;-)

I dont have a tachometer and only a self made digital boost pressure gauge,
but my impression is that the torque while quite impressive at around 3000
rpm it rolls off quickly to just above adequate when I feel like it is time
to shift up. This is quite good for the limited cooling capacity of the 99
and quite contrary to the 2.3i I must drive when I need AC;-)

Which adjustment screw, please? This is a CIS fuel injected system,
does that change what you're saying?

It is the green one here displayed at this page:
http://ncr-pca.org/tech/tech-cis.htm

An allen screw, buried deep inside the unit betwen the airflow meter and
the fuel regulator. It is accessible from the top. You'd really need a
tool like this:
http://store.autotoolexpress.com/assh4516.html

Excellent. I've got pretty much that exact tool from my days as a
biomedical electronics technician.

I'm sure the web is full of info on CIS / K-jetronic, it was/is used in
every kind of vehicles from the Golf to the 911 turbo and Lamborghini
Countach, Ferrari Mondial And that V- thing too...

It's a delightfully elegantly simple solution. I'd love to refit one to
a V4 Saab.

Sounds like I need a Haynes for the 99T then. My 900 manuals are good
for almost everything, but they're too new for some stuff, and my 99
manual is
too old for the turbo stuff. Ah well.

No big deal, I can take some photos of selected pages, and cite some key
figures if needed.

I am likely to take you up on that at some point. Right now things seem
good aside from the above. I got a new cap for the expansion tank today,
because the other one was very scary looking, so hopefully I can bring the
system up to normal temperature and pressure to check for leaks. The oil
system seems intact, and the turbo sounds good. Still haven't heard the
bypass valve noise I remember, so I'm not sure what that's all about yet.

I put BCP6s in there, which I think is as hot as I should go, yes?

In the long run, yes! Good luck with a fun engine!

It's been a dozen years since I drove (a/this) 99 Turbo, until yesterday.
The steering is a bit heavy, but it's a _very_ fast/responsive rack.
Handles good, even on not so good tires. I plan to put on more than 3
miles tonight, but since it hasn't moved on it's own power in more than
a decade, I'm going gently and cautiously.
And double-checking that the wastegate is operational before you go all the

way could be a good idea. I am on my second tranny and third head! A
bicycle-pump will help you in revealing any leaks and perhaps you can hear
the shaft moving as well.

--
Frode