1.8 is in the 1990

Mikkels · Post by **Mikkels** » Mon Sep 15, 2003 6:41 pm

Many thanks to all who have given me advice and
encouragement on this very successful project. A couple of
things to be going on with but the car is finished and runs
brilliantly.

Take a look at the photos

http://www.mx5club.org.nz/gallery/dons1800ina1990

Don

SLYDIT · Post by **SLYDIT** » Tue Sep 16, 2003 6:48 pm

Hi Don,
If you're looking for a better intake than the stock
airbox then check out my website...
http://miata.cardomain.com/id/supasparky
The intake is cheap to make up, and made a huge
improvement over the stock air box.Its inspired by the
racing beat intake. Ive got a vented headlight lid to
get a bit of flow to the new fabricated cold air
box.The lid did make a difference in intake temps as
measured with my K type thermo couple. Cost was about
$50 for the donut(makes 2 intakes) and i think $100
for the K&N filter. The sheet aluminium and other bits
were scrap offcuts from a sheet metal workshop.
FREEBEE, ZIP , NADA!(for those who love monster
garage).
Cheers
Glenn "SLYDIT" (Maybe not On my new 16"
wheels!!)

Mikkels · Post by **Mikkels** » Wed Sep 17, 2003 8:22 am

Glenn - Nice work

My immediate problem though is that I cannot install one of
the fans on the radiator because of the resonator on the
cross over pipe. I could remove the resonator or modify its
angle or get a slimmer fan. Any ideas here?

I'm keen to do a cold air induction system at some stage but
first I want to get the install all sweet. I have a AFM
from a 1.8 Astina which looks like it will go on my machine
and should flow more air for the bigger engine. Apparently
you can install same year bigger AFMs. Will need to get the
mixture checked afterwards. If it is lean apparently a
higher rail pressure can be obtained with a higher pressure fule regulator.
Any experience or ideas here. I plan to get the current
engine setup checked out by performance tuning in Hamilton
to see what or if there are issues with mixture etc.

Don

Don
[...]

Rex Johnston · Post by **Rex Johnston** » Wed Sep 17, 2003 8:52 am

On Wed, 2003-09-17 at 08:22, mikkels@ihug.co.nz wrote:

I'm keen to do a cold air induction system at some stage but
first I want to get the install all sweet. I have a AFM
from a 1.8 Astina which looks like it will go on my machine
and should flow more air for the bigger engine. Apparently
you can install same year bigger AFMs. Will need to get the
mixture checked afterwards. If it is lean apparently a
higher rail pressure can be obtained with a higher pressure
fule regulator.

You are better off NOT mucking about with the fuel pressure
unless you are cranking up lots of boost pressure.

It's a spring flap AFM right ?
Run a knife around the seal on the plastic cover, loosen the
screw and adjust away.
Loosening the screw richens the mix, tighening leans the mix.
You ideally want to adjust for slightly rich at WOT, so you'll
need a meter on your O2 sensor at least (typical sensor pokes out
about .9v or so right, but are none too accurate). At part throttle you
can rely on the closed loop nature of the system to correct subtle
imbalances (and keep the mix around stochio), and at idle, well, who
cares, as long as it idles OK, and doesn't inject so much fuel that it
washes the oil off the bore.

Cheers, Rex

SLYDIT · Post by **SLYDIT** » Wed Sep 17, 2003 7:13 pm

Hi Don.
I have a funny feeling that the 1.8 fans are swapped
from the left to right as one is thinner than the
other??? (Too wet to go and look under the bonnet at
the mo.) You may try getting a 1.8 aircond fanThe
larger airflow meter mod has had only limited success
. The part throttle drivability has been rather poor.
I think theres a write up on this site.
http://members.aol.com/solomiata/CheapHP.html
Hope this helps.
Glenn "SLYDIT"

Mikkels · Post by **Mikkels** » Thu Sep 18, 2003 7:35 am

Rex

Thanks for te great info. I will take a look on the
weekend. I need to have a good look at the Astina AFM. If
it fits right on then it should be perfect as it is set up
for the BP 1800.

Don

[...]

Mikkels · Post by **Mikkels** » Thu Sep 18, 2003 7:40 am

Hi Glenn

It would be good to know about the fan. I'm not in a panick
but want to sort it by summer. I'm goung to see Ross this
weekend to return the throttle body he lent me. I'll take a
look amongst his wreckage.

Thanks for the link about AFM. I'll have a good look on the
weekend.

Don

[...]

Rex Johnston · Post by **Rex Johnston** » Thu Sep 18, 2003 10:45 am

On Thu, 2003-09-18 at 07:35, mikkels@ihug.co.nz wrote:

Rex

Thanks for te great info. I will take a look on the
weekend. I need to have a good look at the Astina AFM. If
it fits right on then it should be perfect as it is set up
for the BP 1800.

The only guarantee is that it will flow aqeduately for a BP motor.
Your ECU has a base map that is highly non-linear and that will vary
between motors. Don't let that concern you too much, they are pretty
tolerant. I'm not sure if the old MX5 ECU is a learning computer but
some will actually adjust their base map according to how much
correction the O2 sensor indicates. This can be hastened by unplugging
the battery for long enough to drain the caps in the power supply, which
is usually a couple of days or so. The ECU then has to start again from
the factory defaults.

Even if the ECU can do this, it will only do it at part throttle. At
wide open (WOT), or idle, the oxygen sensor is not used by the ECU. You
can use it to determine if the mix is rich enough, but little else.
Typical narrow band O2 sensors are not really good enough for real fine
tuning, no matter what anyone tells you. They can indicate that the
motor is not in the danger zone (lean-high load), but can't really be
used to extract max power.

It's a spring flap AFM right ?
Run a knife around the seal on the plastic cover, loosen
the screw and adjust away.
Loosening the screw richens the mix, tighening leans the
mix. You ideally want to adjust for slightly rich at WOT,

Slight correction, loosen the set screw, turn the spring base, tighten
the set screw. You'll see what i mean when you open it.

Cheers, Rex

Mikkels · Post by **Mikkels** » Thu Sep 18, 2003 5:57 pm

Hi Rex

I have no info on the ability of the 1.6 ECU to adjust the
mixture and over what range this can be done.

When (if)the adjustment is made is it an alteration to the
length of the injector pulse?

I have driven abot 15k around town since the 1.8 went in so
if the adjustment can occur would it have by now?

My plan was to get the thing on a dyno and get the mixture
measured at various throttle settings. From the data I
should be able to decide what to do.

The new engine is very nice, smooth and more civilised than
the 1.6 but at the moment no noticable seat of the pants
boost which I would have expected with the extra capacity
lightened flywheel and extractors. I only get to the car on
the weekend as i work in Auckland so will have a go at
sorting it out this weekend.

Cheers

Don

[...]

Rex Johnston · Post by **Rex Johnston** » Thu Sep 18, 2003 6:10 pm

On Thu, 2003-09-18 at 17:57, mikkels@ihug.co.nz wrote:

When (if)the adjustment is made is it an alteration to the
length of the injector pulse?

That's right. The fuel pressure is held at a constant pressure above
the intake manifold to ensure that there is a linear relationship
between injector pulse length and the amount of fuel injected.

I have driven abot 15k around town since the 1.8 went in so
if the adjustment can occur would it have by now?

Yep. Would have been better if you disconnected your battery for a
couple of days, then drove around it.

My plan was to get the thing on a dyno and get the mixture
measured at various throttle settings. From the data I
should be able to decide what to do.

Make sure then, that you disconnect your O2 sensors and force the car to
go into open loop mode, otherwise you'll get a nice typical
lean-rich-lean-rich oscillation (except at WOT).

Cheers, Rex

SLYDIT · Post by **SLYDIT** » Fri Sep 19, 2003 6:00 pm

The 1600 ECU has no learning function. It operates off
hard maps in the ECU based on temperature and a very
crude air flow meter signal at Wide open throttle, and
also when not yet up to operating temp. The AFM signal
IS NOT linear to revs at WOT, it sort of snaps open
and is nearly fully open throughout the upper end of
the rev range. ONce the car is warmed up it goes into
closed loop mode and "chases" the oxygen sensor
voltage (optimium is around 0.45 volts at cruise from
memory)to acheive the right mixture at cruise and
idle, You can go up to around 15-20% bigger injectors,
or the same increase in fuel pressure before the range
of adjustment in closed loop can no longer cope with
the increase in fuel. if you feel that the car isnt
getting enough fuel at WOT, then the best thing to do
is hard wire in a resistor in the air temperature
sensor circuit. this will fool the ECU into thinking
the car is cooler than it really is and inject more
fuel at WOT. Turbo guys have been using about a 10,000
ohm resisor but youll only need probably a 2 to 3 K
ohm resistor (GUESS). Your cruise and idle will still
be ok because the O2 sensor will pull the injector
pulse width back down to acheive the correct mixture.
Personally id stay away from adjustable fuel pressure
regulators and different AFM's for your application as
the cost and tuning hassles will be getting to about
in line with a DIY turbo kit, which is better bang for your buck.
Hope this info helps
Glenn "SLYDIT"

Mikkels · Post by **Mikkels** » Sun Sep 21, 2003 9:08 pm

Hi Glenn

Thanks for the info

The car is going MUCH better after a bit of driving around. Great pull
down low and is screaming out to the red line nicely. This is without
touching anything except getting the idle right. (the cheapest tune up
ever). I have set the timing at 14 degrees and have now done about 150k
since the engine went in. I'm really stoked with the conversion now.
The thing I like the best is that it all worked without a hassle once I
had all the information and put it together on the day. The mounts on
the 1.6 must have been really tired as the 1.8 feels much more cushioned
from the body. The 1.6 was harsh cold and at moderate to high engine
speeds.

Looking for the next mod now which will be forced induction of some
sort. I want to do some cosmetic things to the car first though and
enjoy the car.

The engine from Any Mazz was just brilliant. The oil is clear golden
honey colour - I have yet to change it from the delivered engine. No
smoke, no funny noises, smooth as silk. Very cool.

Don

lou Girardin · Post by **lou Girardin** » Mon Sep 22, 2003 8:22 am

On 1.6 FI running a stock AFM, running 1.8 injectors (230cc) will give either
a lean top end or rich elsewhere or vice versa depending on fuel pressure.
They need an RX7 AFM with the flapper spring adjusted to compensate for this.
Or another ECU.
Lou

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