Which injectors???

[BYD1380]

Lambda seems to be fine, if I have adjusted the gas map badly, the engine light comes on and it throws rich/lean errors straight away.
I have replaced the intake pipe on the car also and had a good look for leaks etc.
Now I do see a completely different injection time on VAGCOM compared to gas ECU. I didn't check that time, but it reads a lot less.

Ivan

[Tubbs]

What's your maf reading ?
So let's get this straight. You are looking at the times on petrol. No gas on a fully warmed up engine with no load. Lights / aircon / blowers off etc.
I (and I'm sure every other converter here) have done a lot of Vw's. I run a Vw beetle, skoda octavia and even have a ford galaxy Vw. They all run sub 3ms injection times at idle. 3.4/3.6 on load. Air con on. Lights etc.
something's up with that.

[BYD1380]

What's your maf reading ?
So let's get this straight. You are looking at the times on petrol. No gas on a fully warmed up engine with no load. Lights / aircon / blowers off etc.
I (and I'm sure every other converter here) have done a lot of Vw's. I run a Vw beetle, skoda octavia and even have a ford galaxy Vw. They all run sub 3ms injection times at idle. 3.4/3.6 on load. Air con on. Lights etc.
something's up with that.

OK, I will check a few things today, but yes thats how the test was carried out.
I will check MAF and also injection time on VAGCOM too.

Ivan

[BYD1380]

Hi, Just in from a quick run, car fully up to temp and nothing on. I'm still waiting on my new injectors coming from lpgshop, ordered 10 days ago... I'm currently running the OMVL's with the 2.5mm nozzles removed. I know this sounds stupid, but the more pressure and more gas I give the car the better it drives. I have carried out a full gas remap, reset the fueling with VAGCOM.
Petrol only : 3.75
Gas on : Gas : 3.41 Petrol : 3.53
VAGCOM : Petrol on 2.06ms MAF : 2.84 g/s (changing fine when revving etc.)

Why is the VW ECU seeing a totally different injection time, surely they should be roughly the same?

Ivan

[LPGC]

Why is the VW ECU seeing a totally different injection time, surely they should be roughly the same?

Ivan

Probably because on the KME system you'll be looking at the average (average of all 4) petrol injector times and you have wired up one of the injector breaks incorrectly! Look in the diagnostic screen, you 'll be able to see individual petrol injector duration.

Simon
www.Lpgc.co.uk

[BYD1380]

Hi Simon,

Not sure what you mean "you have wired up one of the injector breaks incorrectly!" could you elaborate a bit please.
I have also checked the injectors are in phase too. This was a proper conversion, carried out at alternativefuelcompany just before Christmas. So I'm not that familiar with the exact wiring etc, but am happy to play about with it. I have spoken to peter about the issues, but he is over 100miles away from me, and I haven't got alot of time to head down at the minute.

Ivan

[LPGC]

Hi Simon,

Not sure what you mean "you have wired up one of the injector breaks incorrectly!" could you elaborate a bit please.
I have also checked the injectors are in phase too. This was a proper conversion, carried out at alternativefuelcompany just before Christmas. So I'm not that familiar with the exact wiring etc, but am happy to play about with it. I have spoken to peter about the issues, but he is over 100miles away from me, and I haven't got alot of time to head down at the minute.

Ivan

If the vehicle has run correctly on LPG before then my last post is unlikely to be relevant - There is still the chance of a wiring issue (injector breaks / bad constant positive / bad earth, but it is beginning to look more likely to be an LPG ECU issue... I thought this was a new conversion that you'd fitted yourself.

If the vehicle has never run properly on LPG then what I said in the last post would explain your symptoms. You have 4 petrol injectors, they each get a constant 12v feed when the engine is running, each has it's own individual earth that is switched on to energise the petrol injectors and make them inject petrol. When the LPG system is installed, each petrol injector's switched earth wire is cut and from the LPG ECU loom a wire goes to each half of each wire that has been cut - You have 4 petrol injectors, one wire gets cut to each injector (4 wires cut), 8 wires go from the LPG system loom to each half of the cut wires. If the installer incorrectly cuts the positive wire to a petrol injector (instead of the negative) or gets the wires that goes to each half of the cut wire the wrong way around then the LPG ECU may read very high petrol injection duration at low loads and lower petrol injection duration at high loads. The KME ECU normally shows average injector duration on screen, so if it reads 3 injectors OK but reads one of the injectors as being a very high duration, this will pull the average injection time up. You can see individual injector duration in the diagnostics screen, this would tell you if there was a problem on any specific injector channel and enable you to more or less go straight to and check the wiring that is likely to be at fault. But first check the voltage that the ECU is measuring on screen, check the main LPG system battery + connection and main LPG system battery earth connection.

Just to confirm - Does the engine idle nicely on petrol with no check engine light? Does the check engine light come on at first when you turn the ignition on?

Simon
www.Lpgc.co.uk

[LPGC]

Vagcom shows 2ms petrol duration? LPG ECU shows 4ms petrol duration? There's an issue right there.

Which model Passat is this?

Simon
www.Lpgc.co.uk

[Tubbs]

I think it's a 1600 passat.
Maf looks higher than if should be. Rule of thumb you expect to see somewhere around 1g per 1000cc.
So somewhere around 1.6/1.8 g/s would be what I would expect to see. It being higher than expected certainly wouldn't cause the issue your describing.

[BYD1380]

Sorry for the delay, been super busy at work.

Its a 2.slow.... Its a 2001 2000cc 8 valve. 115bhp AZM engine code, 100k on it, it was my brothers wifes car, never had a hard life. bought it before Christmas, did 1200 miles on petrol, average 36mpg. Converted by Alternativefuelcompany the week before Christmas, average 27.3mpg over 2800 miles.

Have done about 200 miles since removing the nozzles completely. It's a different car... It drives really nice. still not 100% but 95% at the minute. I filled with gas yesterday, so will fill again on Sat to check MPG.

Chased up my magicjets at LPGshop, weren't even in stock, so no show from them, will try the current setup for the next week or so before buying another set.

Ivan

[LPGC]

You need to find why the LPG ECU is showing idle duration at 4ms. Did you try checking individual injector duration?

Simon
Lpgc

[BYD1380]

Checked the injector duration in the diagnostic screen, all pretty much the same. I have reduced the pressure to 1.1bar and re-calibrated it, seemed to be driving well. Last tank with no nozzles and 1.3bar was 27.45mpg.

Ivan

[LPGC]

Checked the injector duration in the diagnostic screen, all pretty much the same. I have reduced the pressure to 1.1bar and re-calibrated it, seemed to be driving well. Last tank with no nozzles and 1.3bar was 27.45mpg.

Ivan

You can't rely on the fuel computer mpg figure, you could probably make the fuel computer reflect mpg's within a range of about 50% just by calibrating the LPG system differently! Actual mpg will probably remain pretty much unchanged while-ever the lambda flicks properly...

I converted an L322 Rangerover with BMW4.4 V8 and OMVl injectors the other day. This engine has 550cc cylinders. With the OMVL's nozzles removed the best pressure was 1.1 bar. OMVL SL's flow pretty well with the nozzles removed! The BMW V8 idles when warm at around 3ms on petrol, it has variable valve timing etc so draws a good vacuum at idle whilst giving a bit more oompf at the top end. Your engine idles at 4ms on petrol (and I still find this very high for your engine, I would really look into why the high Pinj times at idle, I'm sure it should be closer to 3ms especially on a normally aspirated VAG car, Vag usually do everything to Bosch type specs!)... Really you want the LPG injectors to be pulsing for longer than the petrol injectors. If your engine idles at 4ms on petrol then you should have the LPG injectors pulsing for at least 4.5ms at idle with a warm engine (they will pulse for less duration during warm-up with cold gas due to temp correction). You will need to check full throttle gas injection times if you do what I imply next, but all the above facts imply you may need to reduce the pressure still further. In fact I would compare high load gas inj duration to high load Pinj before messing with the pressure either way.

Simon
www.Lpgc.co.uk

[BYD1380]

Sorry for the long delay in update. I have playing with the vaporiser pressure and running no nozzles, pressure is between 1.05 and 1.1 seems best. I'm now getting 28/29mpg. Not great but I'll live with it. Can't justify 70quid on new injectors if these ones are working. Car is up for MOT next week, i'll have a good look for intake leaks etc.

Ivan