[Diy_efi] Final tuning and adjustment for conversion

[gngrbrd_man]

----- Original Message -----
From: "Roland L Maynard" <fjdog at lycos.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, May 07, 2003 8:11 AM
Subject: [Diy_efi] Final tuning and adjustment for conversion


| Hello all,
|
| I wanted to tap the collective knowledge to solve some troubles that I am
having with a recent fuel injection conversion I did.
|
| For background, I put a tbi fuel injection system from an automatic 1.3 L
1993 suzuki swift on my suzuki samurai 1.3 (5 speed). For the conversion, I
used all of the swift parts except for the fuel filter (off of an early fuel
injected nissan, because it had straight connectiions) and the distributor.
For that I used the stock distributor that I modified by removing the
module, but wiring the existing crank angle sensor to generate the signal
for the PCM. I also disabled all of the advance mechanisms in the stock
distributor since the swift distributor does not have these. I set the crank
angle sensor to be located at tdc. This engine still has the stock cam, but
the bore, stroke and compression are the same as the swift. Not sure if the
cam is different,  but suspect it is.
|
| Anyhow, now to the troubles I am having...
|
| 1. The first problem is that when the timing is set properly, the engine
idles high for about 5 seconds (at 1600 rpm) and then drops to the specified
800 rpm after that.

This is typical behavior for noth of my factory TBI vehicles.

| 2. Next, the engine lacks power at speed. It is impossible to maintain 65
mph with any sort of grade or headwind.  I can get it up to 65 mph with the
pedal to the floor on level ground with no wind. Also, engine seems to lack
power below 2500 to 3000 RPM compared to the old carb.
|
| 3. The check engine light comes on for brief periods when traveling at a
constant 55 mph. As soon as I wiggle the throttle pedal (either increase or
decrease) it goes away.  This condition is worse (ie happens more
frequently) if the headlights are on. The PCM stores trouble code 13 (o2
sensor).
|

Not sure of the significance of the headlights, although I'll venture a
guess at the end of this.
I suspect that your timing may be off.  Way off.  This would account for the
lack of power, and the O2 code (retarded would run as if rich, and with
dirty combustion products in the exhaust, fouling the sensor.  Wiggling the
pedal knocks the computer out of cruise mode, and changes momentary
operating conditions.)
It sounds to me like you did most things right, but what I don't know is how
the 'zuk computer expects it's crank angle sensor.  I do know that it is not
uncommon for the crank sensor to be located somewhere other than TDC.  If
memory serves, Ford EDIS uses a sensor 90degrees BTDC.  The ford also TFI
also uses an sensor prior to TDC, and a 10* base timing for the Distributor.
Perhaps it would be worth finding a knowledgeable 'zuk mechanic who could
give you some advice on the location and timing for these signals?  I
haven't been around suzukis in quite some time, but the last time I was, I
found the local dealer's mechanics to be well above average for their
knowledge of these types of details.
If nothing else, put a timing light on it, and have a buddy kick the
throttle, and see what sort of timing you get.
Re. the headlights: Perhaps the added electrical load is taking just enough
off the spark to prevent much combustion from occurring in the later, lower
pressure chamber?  Going out on a limb, but this would also contribute to
partially combusted fuel in the exhaust.

Dunno if any of this will help, but good luck.

Keith

You know you've achieved perfection in design,
not when you have nothing more to add,
but when you have nothing more to take away.
-- Antoine de Saint Exupery



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