leonardo advice needed

[demonicwillow]

I used to run a tartarini tec 97 and omvl r90e on my jeep and to begin with had a fair few problems, ironed out most of the problems by installing the omvl vap, on average was getting 180 miles to 60L of gas, a few m8t's claim around 220 to 230 miles from 60L but the 180 was about the best I could get, I had the chance to swap in a Leonardo and being a faster newer system this is what I have done, only swapped the loom and ecu, everything else stays the same, the system fired up first time but what im noticing is that no matter how closed off the vaporiser is it defaults to around 70, with the tec 97 if I closed the vaporiser off a bit its default would increase which is what you would expect but with the leo it defaults to around 70 no matter what and it runs perfectly except it wont idle of course, the default lock is not set in the software options, would there possibly be a problem in the vap or should I change the mixer on the throttle body for the one off the jeep which donated the leo system, I read in the leo installation manual that the default should be around 50 to 60 but read elsewhere that its best around 100 give or take a few steps, I have the vap set slightly lean on idle so its operating above default fine but runs bang on for normal driving, still getting the not so good mpg's though and yet my jeep isnt any different to anyone elses, any ideas ?? or is it a case of thas the best you can get.

Tim

[Tubbs]

Ok back to basics to start with, whats the lambda doing ? Is it slow ? If you take the stepper motor out of the loop and replace it with a power valve does it run better manually. Are you getting a TPS reading ? How much have you been fiddling with the reducer ? Did you reference the idle and main mix screw ? Or don't you know where you are now.
70-100 i would say as the default. Have you tried locking the default. And then closing the idle bar down so it sits on the default rich as it returns to idle and then starts to toggle the voltage after a few seconds.

[demonicwillow]

Everything is as it should be O2, tps, rpm etc, the o2 is toggling fine, the stepper is reacting as you would expect, I would have expected that when I closed up the main mix on the vaporiser the default to increase, but no matter where it is even fully closed up it defaults around 70 when driving, obviously it wont idle with everything wound in which is why I was wondering if a nearly newish vaporiser may be at fault, there must be enough vacuum to draw gas in the out of idle condition, on the tec 97 if I had closed evrything off then the default would have gone off the scale but the leo defaults to always around 70, the only other thing I can think of is that the car suffered quite a serious overheat just before I changed the system so wondering if this has damaged the diaphram at all, I know where it was set to before and is really rudimentary now as the manual preset configuration of the tec 97 stepper motor has been taken out of the equation and the one supplied with the leo dont need to be preset, and it didnt require the opening of the idle bleed as it isnt now, just a bit baffled really

[demonicwillow]

But thinking about the diaphragm if it was split then I guess it would just suck are thru the balance vent and not allow much gas to flow, so maybe thinking that the main mix jet/orifice has an obstruction or something preventing the gas flow to be reduced, sometimes I think that this particular jeep will never produce good results with a single point no matter what the system, or perhaps its my right foot causing the trouble

[Tubbs]

Could be the old concrete left foot i suppose
Try this, power up the solenoids with the feed pipe connected, obviously you would need to keep all the wires on if they are both connected together. Have a listen down the pipe. You should hear gas, a steady scwoosh (technical term) as you turn up the idle screw (lets call it that) it should go to a SCHWOOSH over about 1/4 to 1/2 a turn. ScHwOoSH should be enough for a ticking over jeep.
Now you haven't said wether the leo is a second hand unit or not. Ive seen a few strange issues with stepper motors in my time. Generally due to people crushing the ends with too tight a jubbly clip. If you can get hold of a power valve, open loop it and watch the stepper motor. Make the car run rich and watch the stepper shut, make it lean and make it open. If it just hovers and you can feel it clicking then you may have a dodgy stepper. Always worth giving it a clean if its gummy.

[demonicwillow]

The concrete foot cant help itself especially at the lights when boy racer in his lil zinger is left behind wondering how on earth an old cronker like my jeep showed em up like that no but seriously thinking about it more the tec 97 stepper is a power valve and stepper all in on, being adjustable mechanically as well as being electrically managed, had the thought to pop that in but I remembered that I sold it so I think its a case of re-set up the system and leave it be cos it does work fine, where the confusion lies is that I dont understand why when I restrict the gas mix from the vaporiser the stepper always defaults to around 70 under driving conditions, when I close the gas mix down the stepper will climb up to compensate at idle, but even with the idle bypass closed and the gas mix wound right in it drives perfectly opening and closing around the default 70, I expected the default to increase with the restriction of gas mix when the pedal was down and its in its learning/adapt to changed conditions phase ie 2nd/3rd box in the tps display on the laptop, just had me thinking that there was a problem within the vaporiser.

[demonicwillow]

Just thought I would post a few pics of the said lpg installation, probably not the best but I think its quite neat, ignore the grey flexi tube as its owt to do with the lpg, its for the screen wash bottle which had to be moved out of the way while I was messing about installing stuff

removing the old and tidying up





This is what was left over from the acquired leo setup after I had to tidy up the loom and remove a few bits of unwanted @!##



Finished install



Been out this morning and very quickly set the vap and software settings to how I had them set for the new install, default went to 70 drives nice around the default, the idle mix is above default a few steps and I shall just now leave it for a few tank fillups and see how it goes

[SimonHobson]

What do you mean by "closed off the vaporiser" ? Presumably you screwed in an adjuster - which one ?

Assuming your were adjusting the idle screw (the smaller one on the side), then this will have very little effect out of idle - and the Leo doesn't adjust the default value at idle.
The larger screw next to it adjusts the bias springs on the main diaphragm.

Assuming were talking about the same type of reducer - see the one on the right, 3rd picture down in this article.

This is explained in the first of my tuning articles.
Tuning a system with a Leonardo is described in my second tuning article.

[demonicwillow]

I have read all your articles Simon and always refer back to them when my brain goes into confusion mode, yeah its an omvl r90e around a year and a half old now, the system is working fine, but as it is a much more responsive system than the tec 97 I was hoping for slightly better mpg results, closer to what my other jeeping friends achieve, I average 180 miles to 60L of gas so its not too bad but not as good as the 220/230 average for a 4.0L Jeep that others achieve, Reading the leonardo install instructions it reckons on 50/60 steps as the default average, but reading your article you say it should probably be more close to 100, forget the smaller idle by pass screw, just assume it is fully closed (wound in) which it is, when I first fired up the leo after the install it defaulted to around 70 steps without any adjustment to my vap so I assumed that by winding in the larger bias screw (making it work harder for the gas) and a reset the default would have been higher as in a higher default step value, (this was simple to achieve with the tec 97, just wind in the bias a bit so the default would learn a higher value ie move from say 80 steps up to 85 or 90 or whatever) but with the leo winding in the bias screw makes no difference to the default value under normal driving conditions, obviously it wont idle with the bias wound right in so i wound it out enough so it would idle but i would have expected a higher default value, this was making me think that there may have been something broken or stopping the bias valve in the vap from closing off properly or a spring broken inside so the diaphragm doesnt return fully closing off the gas, I guess ultimately I will have to pull the vap apart and check its all ok which it probably is, with the tec 97 stepper motor you could close or open the aperture with a 10mm nut a bit like a power valve and it was controllable electronically, might try n wangle it back off my m8t actually n swap it for a universal jobby as if the system packed up I could switch on the solenoids seperately, shut off the injectors and still be able to use the system, but I doubt that will happen

[demonicwillow]

just been doing some maths after reading about a saab mpg's, on 60L I get an average of 180 miles, 60/4.5 = 13.33, 180/13.33 = 13.5, average mpg for a 4.0L jeep on petrol is 18mpg, so 18 - 20% = 3.6 = 14.4mpg theoretical gas mpg, actual is around 13.5mpg on gas, I have noticed a misfire on steep hills recently throwing the check engine light, so guess the plugs are probably shot (havent checked them in around a year or so since newly fitted) so working on those figures I havent got tooo much to complain about at 65.9p a litre, 85/90 quid a full tank of petrol will return about 300 miles, 40 quid a tank of gas returns around 360 so not a huge difference but its still a saving plus greener emissions, ill look at the plugs tomorrow, bet they have about 300mm gap or even worse no anode

[SimonHobson]

so I assumed that by winding in the larger bias screw (making it work harder for the gas) and a reset the default would have been higher as in a higher default step value

So you didn't actually fully read and comprehend what I've written then.

The actual value of the default doesn't matter that much - except that if it's below around 50-60 then you probably have a mixer that's putting a bit too much gas in, and vice-versa if it's very high (above 150-200). That's still OK as long as it's tuneable.

What does matter is that the stepper position stays roughly the same across the power band. If the stepper stayed put and never moved, that would be the equivalent of having a manual power valve. All it should have to do is move a little to fine tune the system.
Large stepper movements are bad. If (for example) the stepper has to open up a lot going from idle to power, then you'll get a momentary weak spot (and hesitation) when accelerating.


Adjusting the bias screw will have different effects at different rates of gas draw. In particular, it will have more effect at low rates (low power, little "suck" from the mixer) than at high rates when there is more "suck" from the mixer and the offset on the bias will be less in proportion.
So, if your stepper is steadily opening more and more as you increase power, your bias is wrong (pressure too high). If your stepper is steadily closing more and more as you increase power, your bias is wrong the other way (pressure too low).
If you get it right across most of the power band, but can't get it right at idle (too rich, even with bleed screw fully in), then you'll need to compromise a little and adjust the bias a little to get the idle right at the expense of a little more stepper movement.

So ignore the default value - it really doesn't matter much. Just watch what the stepper is doing.

[demonicwillow]

I have read your info on quite a few occasions, mainly when I installed the tec 97 system and I have returned back to them as your 2nd article is based around the leonardo, which is brilliant for me, I do understand in general all the principles of what your saying but dont forget I have been used to a system which was alot older, less responsive, less tweekable software options wise and also had a mechanical adjustment on the stepper as well as being ecu controllable, so how the tec 97 responded was slightly different to the leo, my system is working fine and as it should be, im not having any problems with it idling or running rich or lean and I have set the bias screw so at idle the stepper is working around the default value with no problems and the idle bypass (little screw) is closed, so its all working fine, the confusion on my part was in the leo install info they recommend the default to be between 50 to 60 steps, when I read your article you wrote ...

"What should the default position be ?
Well general opinion seems to be that anywhere around 100 to 150 is ideal, even a fair bit outside that is OK. If it’s over 200 or under 50 then the mixer is probably the wrong size for your engine"

So I was only trying to get it to default closer to the 100 mark, but if 70 is ok then thats fine, its doing what it shud be, I was hoping for slightly improved mpg's over the tec 97 but I guess my jeep is what it is and Ill have to live with that until I can get my hands on a donor jeep already fitted with multipoint, (so it can donate its pre drilled manifold to save me asking bucket loads of questions on here ) one which I missed out on yesterday but as im moving this week and should use the cash for the new house I chained my arms to the wall preventing me from going higher than my original bid so got outbid, there will be others

I assumed that by winding in the bias screw a little the system would default to a higher value allowing the correct amount of gas to draw past the stepper from idle and up, because the tec 97 stepper motor has to be mechanically adjusted prior to initial start up (I was advised to set it to between 7/8) the stepper is partially closed before anything else happens (much like a power valve) which is why it would default to a higher value.

I suppose it would have been easier to ask what the best default position was as mine was 70 ish and if that was ok to leave it set as is, rather than try to explain all the tweeks I been doing and confusing everyone

[Super Dragpack]

I also have a Jeep 4.0 Auto with a Tech 97 system. If it makes you feel any better, I'm getting around 12mpg around town, but have managed as much as 27.7mpg on a run (although normally no more than 20mpg).

Mine runs fine, but I don't have anything to compare it with. I may find one at a local garage to compare my performance but I have nothing to make me think it isn't running perfectly.

I've recently fitted a new vaporizer due to a leaking seal, but this failed to improve the MPG massively.

The only fault I have is a less than perfect idle, but this is on petrol or lpg.

[demonicwillow]

I wish I hadnt swapped it over now tec 97 system was achieving around 180 miles from 60L, Leonardo 100 miles from 60L whats all that about then ?? nothing else has changed apart from the engine bay loom and the lpg ecu and emulator, oh and a back fire flapper that I robbed off the donor jeep and have fitted to the airbox which is sealed down nicely, the stepper operates around its default setting on idle and when driving, and the o2 sensor is working just fine so where is just under 30L of lpg going ?? because there isnt any leaks and it aint going through the engine The only setting I changed on my pc was to unlock the default position as the Grand Cherokee's default position was locked to 120 steps, I suppose it be worth a try, but I would have thought it better to leave it unlocked and allow it to manage itself.

And would swapping over the mixer ring that was fitted to the donor jeep which is different to mine make a difference or should they both perform and do the same thing ??

[rossko]

Don't overlook simple causes of lower MPG, like a binding brake or a repaired aircon system. If autobox, does the torque converter lockup at 52mph?

If you're convinced the Leo achieves 60% mpg of a Tec97, put it back. But it is the the same control principle using the same components, so clearly something is wrong.

It might pay to take it to a pro for a tickle, if consumption is that heavy.

Or we can talk you through it, but it takes time.

Start over with something simple - allow to idle hot on gas. Observe with your laptop. Tell us what the lambda signal and the TPS signal does. Tell us what the step value figure does. Go to the tailpipe and sniff, any smells? Put your hand close to it, any pops or puffs, or an even pressure?

[SimonHobson]

Was the TEC system actually working properly ?

And then there are other parts that have been changed - mixer and cat-flap. In theory the mixer should do the same thing, but in practice it may (together with the catflap) alter the air/gas flow and change <something>.

But I wouldn't expect to see that much difference in consumption.

[demonicwillow]

Thx Rossko Im determined to see it through to getting at least the same as the tec 97, assume everything Jeep side is working correctly because there are no mechanical problems, no brakes binding, no aircon to worry about and the torque converter locks up at around 40mph in comfort mode and 50 ish in sport mode so its doing what it is supposed to do, cars been serviced recently, checked the plugs this morning, gaps were not too bad and no significant wear in them, I had noticed a misfire a few weeks ago on a steep hill which has never happened before but put that down to the emulator that came with the leo, so swapped that for my original which is an AEB so its all matched now and it hasnt happened since.

(1) Allowed to idle hot on gas for a while, o2 sensor is switching correctly, the step value (default currently 68) is moving up and down around 5 or 6 steps maybe 10 either side of the default,.

(2) The TPS jitters around 0.75 volts at idle, I did suspect the TPS for a while but after some jeep research and much as a lot of other make vehicles its because of the iac valve, but to be satisfied in my mind that it wasnt a TPS fault I have swapped the TPS for numerous TP sensors which I have from my jeep breakers and a new one as well and they all basically respond the same, so after a few drive trials have set the TPS hysteris to 0.12 to allow a cleanish switch from box one to box two in the TPS display box on the laptop (it was set to 0.14 when it was on the grand cherokee)

(3) The cat is ok and is not blocked either, pressure is consistent at idle and various throttle positions, but during idle I have noticed that it does pop a small amount and the idle gets very slightly uneven each time the stepper allows more fuel (richer) its always done this on lpg even with the tec 97.

(4) I have the laptop setup in the car mounted just right so I can see it and use it as a satnav for green laning (memory map) and can observe what the lpg system is doing for an entire journey whether it be a long or short one, the system shows everything to be working correctly apart from on the overun when the o2 sensor will show a high reading until the stepper is virtually closed which in stepper speed time takes a little while, by then the car has slowed down and the stepper has gained control of what the o2 sensor is doing (its always done this even with the tec 97 but it doesnt do this on petrol) and I have always suspected that its this brief deceleration period when its consuming large amounts of fuel which is why I feel the problem is unique to this particular jeep, everything before and after the mixer is airtight with no leaks and although the car has a snorkel as most offroaders do I spent quite sometime ages ago setting and modifying the air intake so that there is no ram air effect on the induction side, as I have said the setup is no different to other jeep offroaders but yet it consumes more gas.

Was the TEC system actually working properly ?

And then there are other parts that have been changed - mixer and cat-flap. In theory the mixer should do the same thing, but in practice it may (together with the catflap) alter the air/gas flow and change <something>.

But I wouldn't expect to see that much difference in consumption.

Simon yes the tec 97 was fine, in the beginning it was down to a worn out vaporiser and incorrect spark plugs which were corrected and 180 miles from a modified jeep is not too bad, but as previously said I only did a front end swap (leo, emulator, loom and stepper motor, I havent changed the mixer) and consumption has gone up drastically, the backfire flapper was only fitted the other day and hasnt made consumption worse or better and the system still shows the same as before, I am quite stumped with this one tbh

[rossko]

on the overun when the o2 sensor will show a high reading until the stepper is virtually closed

Now you have everyting working, you can play with fuel cutoff. The TEC97 didn't implement that at all, but you can set it up on the slightly cleverer Leo.
Use the options to set cutoff step value at say 70% of the normal idle value, then drive around and see if behaves the way you want. If you overdo it, you'll get stalls or fluffing when it returns to idle - typically this is pulling up at roundabout.

The stepper must be close to the mixer to get this working well, your looks okay there. It is not going to make a huge difference in consumption.

Personally I think you're chasing shadows and there is a calculation error or expectation mismatch somewhere or other. I would have a careful sniff around below tank and filler on a windless day though.

[demonicwillow]

The tec 97 did have a cut off option but I didnt use it, the reason was because of engine hunt at whatever the option rpm was set too whether it was accelerating or decelerating, the same has happened with the leo, so have disabled it, mind you for a while it behaved then the next day started to hunt so turned the option off, although I may have had it set to close the stepper too much now that you mentioned 70%, im going to see if I can do a video screen capture of what the software displays and then post it here so you can see exactly whats going on, I have checked all around the tank area and with the airtight box lid off for leaks, also checked the entire pipe length from front to back for damage and everything is ok.

[SimonHobson]

Yeah, setting the cutoff option is even more of a black art then setting up a system
You don't want to set it too deep, or you tend to go through "weak but ignitable" periods which promote backfires - especially during those "foot down, lift off and change up, foot down" sprints when trying to join moving traffic from a junction (but it does wake up any nearby pedestrians ). When it's active, I can hear mine sort of "woofling" in the exhaust as it's on the weak side (reduces power) but not so weak as to give backfires.

As for cutoff revs, it needs to be high enough that it's above the normal idle speeds (even under cold start conditions) of the engine management. I haven't quite got that on mine - I settled at 1500 rpm which is a bit high to get the best use of it, but still at a level where I get hunting as the engine (EFI) and gas ECUs fight each other until the EFI system settles down.