Assuming all hoses are ok, there are no vacuum leaks and the converter is not gunked up, then the home tune up process is as follows.

You have two tuning screws. An 8mm brass bolt which is the bypass screw and a 10mm brass bolt with spring which is the sensitivity screw.

To tune properly you should disconnect the ISC and place a 0.75mm feeler between the throttle stops. This will stop the ECU trying to throttle up and affecting the sensitivity tune.

Before starting the engine count how many turns to completely in both screws take. This is your backup in case you screw up. Warm up the car.

Turn the 8mm bypass screw all the way in. Turn out the 10mm sensitivity about 6 full turns. This should allow the car to start and run. If it stalls turn it out some more until the car runs.

Start to turn the sensitivity screw in. You want to stop when you get to the point where the car will 'just' run. You want it almost stalling here.

Now start to turn the bypass screw out. Keep turning until you get a nice idle. This could be anywhere from 2 to 4 turns. This one is quite sensitive, up to 8 times as sensitive as the sensitivity screw.

You have now tuned your car to idle on the bypass and supply gas as soon as there is a requirement by the sensitivity screw.

Connect the ISC back up and go for a run. If you think the car is running a bit lean, open the sensitivity screw 1/4-1/2 a turn.

Now of course the best way to tune is by dyno, but this should get you started.

cheers
Scott

^^^^^ This is for an OMVL system.

would it be the same for a LOVATO system? i want to stop mine stalling everytime i put the clutch in

You could try adjusting the idle speed screw on the throttle body. Try 1/8th of a turn in and go for a drive. It might be that you are just a bit lean or a bit too rich on off throttle applications and this will help stop you from stalling.

cheers
Scott

This may work on any other system that uses the same principle, ie an idle bypass and a sensitivity screw.

cheers
Scott

What Macgyver means is a system with a complex convertor and simple mixer (Not Impco).
What he's described is fairly basic for getting that kind of system running close, but you also have a power valve, that is the main feed between the convertor and mixer.
To get a rough tune on this, get the engine upto 2500 to 3000 rpm, make sure it's screwed out quite a few turns before doing so, get the revs up and turn the screw in slowly until you feel the engine start to drop, turn the screw back out around 1.5 to 2 turns, that will get you fairly close.
As stated above, you really need a Lambda unit which is wired through your oxy sensor to get it right, or to have it dyno tuned.

Best thing i've found is to get the car idling nice, then adjust the power valve, then go back and do the idle adjustment again to get it smooth as the power valve can throw everything out.

power valve? big bronze screw inbetween convertor and mixer ring?

i use this meathod, and car runs better, but keeps losing power, esp at stable highway speeds. any help would be GREAT as i have ~80km trip to uni each day as of tuesday.

That would be the one Marc, they're either a stand alone or they're built into a stepper motor, i'll get some pics to give you a better understanding.
If it's losing power, try opening up the power half a turn at a time, remember this is just an indication, if you have a unit that's wired via oxy sensors etc then you can get it spot on... That's how i tune mine and have done for the last 9 years.

did u get some pics?

Sorry blackone i've been busy prepairing for QLD, if i remember tomorrow i'll take some.
I've got a std power valve on mine at the moment but i'll be fitting the stepper motor back on by thursday and re-tuning it... I'll get pics of both on car.

Here are a cpl of pics i took today, one is a basic power valve and the other is a stepper motor with power valve built in (Some are not adjustable).

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Here are some pics of modifying an OMVL R90e, you only need to do this if you find it's running too lean as mine was, even after opening the power valve out to the max..
It's a 5 minute job, you remove the cover on the front and put a washer in between the cover and spring to give it more pressure.
This may come in useful for some, it certainly fixed my problem.

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To MacGuyver -- Thanks for the 'tune-up' advice, it worked!!!! But now I've lost 'overdrive'. Can you please look in the 'gearbox' forum at my problem, with a view to helping me further?
Thanks,
Top_Cat

The power valve/stepper motor as we're all calling it here.. is it best positioned close to the mixer as mine traditionally was very close to the converter..
I know i have opened another thread about this one but im looking for more opinion before I take the thing in to the gas shop on friday..

Can anyone atleast see any problems with this? as I needed to move the stepper closer to the mixer to protect it from exaust heat.


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Additionally , my lamba unit has two lights on it, green and red.. The instructions say rev to 3/3.5k and turn the brass screw until the red and green lights alternate. Seems to work well but then it goes on to say tune the converter in a similar manner at idle and I havent got any good results yet.

You turn the idle screw on the convertor until the red light just comes on mate, that's how i tune mine.
Is your lambda unit fixed to the engine bay? I have a little unit that plugs into my module under the dash, that way i can get it spot on as i drive it.