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4.6 lpg issues

6K views 21 replies 11 participants last post by  jsp 
#1 ·
Well i wondered how long it would take for a problem to appear, lol

driving home from Yorkshire Dales, and doing about ! hmm well lets say a spirited drive, and i noticed a misfire and thought i run out of LPG rather early, only to find it took only 45 litres and the misfire still present.

Its OK on petrol, not perfect but drivable so we did the last leg on petrol, i changed plugs but its still there, it stutters when revved, gets worse the nearer 2000 RPM it gets then at around 2000rpm it clears and revved the rest of the way fine, on petrol it seems fine, i thought it may be an ignition issue being highlighted on LPG but it seems related only to LPG, seems to run fine on petrol!!

Tartarini etagas multi point system if anyone has any ideas? HELP.......... lol
 
#2 ·
I forgot to mention i have checked for fault codes and have P1176 and P1178 P1178 i know is due to running lean when nearly out of lpg, P1176 i think is similar??

AND i have Magnecor HT leads! i got them new and they probably no older than 2 years! coil pack anyone?????
 
#4 ·
How old is the etagas system also is yours a Bosch or Gems motor? The later Bosch motors really don't like this type of system it doesn't react quickly enough and I found the Motronic system would switch to default mode as it took this as being an O2 sensor fault. If I used the inbuilt emulation to fool the Motronic system it still wasn't happy with this.

This system doesn't use injectors it will have 2 distributors which can get a little gummed up. ?You can carefully strip these down and clean them. They also seem to fail at moderate age (the reason I ripped mine out and replaced with a sequential system.)

This could also be a problem with the vapouriser not giving enough pressure and possibly a failing diaphragm in the vapouriser.

Do you have the lpg software and lead to connect to check for errors and calibration? Do you have an OBD reader or Rovacom etc to monitor live O2 sensor outputs?
 
#5 ·
Its GEMS system (1996), the Etagas system was fitted in 2003, its been running absolutely fine with no problems at all untill yesterday when i noticed hesitation and thought i run out of lpg i hadnt!

i was going to fit a new coil pack as mine is prolly the age of the car BUT at £130 a go im not eager to replace it just because, lol although i may benefit in other areas from this.

on close inspection of the coil pack i see only 4 coils but 2 leads from each one so i assume its wasted spark??? if this is the case and its a coil failing i would expect to have a miss fire on two cylinders, if this is the case il be happy to fit new... i wonder if i can notice a lack of spark using a timing light ???
 
#6 ·
Right, i checked for spark at all 8 leads using a timing light, i know this isn't the best way of doing it but its all i got for now! i noticed a miss in the light strobing on some cylinders in time with the engine missfire, it was more noticeable on number 4, its there whether its on LPG or petrol so i would assume coil pack? anyone else think the same? i doubt it the leads as they only two year old Magnecors AND could two or more suddenly need changing at exactly the same time? also it made no difference weather engine was hot or cold either....
 
#8 ·
As you have GEMS engine the following test is easy :D

Remove HT lead number 1 and measure the resistance. Divide this figure by the length of the lead in inches. Write down the answer.

Repeat for all leads.

Study the results. They should all be SIMILAR. Any lead that has a higher than average reading is on the way out.

I do this with new leads and have occasionally rejected the odd lead. Just because it is new does not mean it is good :naughty: .

Also, when did you last clean out / replace your under bonnet LPG filter / filters? 12 months or 12000 miles minimum is required.

Ray
 
#9 ·
Ray A said:
As you have GEMS engine the following test is easy :D

Remove HT lead number 1 and measure the resistance. Divide this figure by the length of the lead in inches. Write down the answer.

Repeat for all leads.

Study the results. They should all be SIMILAR. Any lead that has a higher than average reading is on the way out.

I do this with new leads and have occasionally rejected the odd lead. Just because it is new does not mean it is good :naughty: .

Also, when did you last clean out / replace your under bonnet LPG filter / filters? 12 months or 12000 miles minimum is required.

Ray
Underbonnet lpg filters? not seen any! hard pipe supplies the vaporiser from the rear and then goes into flexy pipe to the distributors and on to injectors jets! no filter to be seen!!!

i know this is good advice but the prob happened all of a sudden, so even though il look for a filter to change or fit one if there isnt i dont think its the fault at this time, also the fault is present on petrol too but not as severe....i suspect coil pack, but at £129 for new one???? prolly a good thing to change regardless, just hope it sorts the problem as well
 
#10 ·
There is normally a filter in the round bowl under the front gas solenoid - which is a normally ignored service item,along with vaporiser rebuild kits,etc,etc.
Before you buy a new coil pack see if you can move the misfire around by swopping over leads/plugs and then the individual coils on the brackets themselves.As Rich said scoping is the best way to diagnose the HT circuit,but is not always easy to get done.Also make sure the injector/emulator connectors are good,I've seen a few where the sealing grommet has been lost and the connectors corrode badly.
Be aware that if the misfire is allowed to continue the ecu will start to modify the fuel trims to compensate for the unburnt fuel and make the other cyls on that bank run leaner - not good.
 
#13 ·
Mark,

I'd probaly leave it until it was dark, open the bonnet & start it up.

You might see all sorts or arching coming from your leads especially just above the coil packs.

Without diagnostics you need to take the ******* approach.
 
#14 ·
Rick-the-Pick said:
Mark,

I'd probaly leave it until it was dark, open the bonnet & start it up.

You might see all sorts or arching coming from your leads especially just above the coil packs.

Without diagnostics you need to take the ******* approach.
Hi Rick, thats a brilliant idea but at the mo although it may be dark i had enough to drink that i reckon il be seeing sparks everywhere, lol Certainly good advice for tomorrow night though, if i can remember this conversation? lol

wil call you soon about comin down again...
 
#15 ·
I found when my leads were going and it was missing that occasionally the BECM would get upset too as the arc to earth is enough to spike the electricals and cause all sorts of wierd issues like loos of headlamps - doors locking etc.
 
#17 ·
Selby P38 said:
G'day Red Range,
A mate of mine has a 1996 .6 HSE with sequential lpg around a year old,it has been playing up just recently runs fine on petrol ,took it back to the dealer and they say its done a head gasket between 4 and 5 :crybaby2:
Is this likely?
It's not just unlikely - it's impossible :lol:

Cylinders 4 and 5 are on opposite banks of the engine.

Might be better too get some more info and start a new thread
 
#18 ·
AMcK said:
Selby P38 said:
G'day Red Range,
A mate of mine has a 1996 .6 HSE with sequential lpg around a year old,it has been playing up just recently runs fine on petrol ,took it back to the dealer and they say its done a head gasket between 4 and 5 :crybaby2:
Is this likely?
It's not just unlikely - it's impossible :lol:

Cylinders 4 and 5 are on opposite banks of the engine.

Might be better too get some more info and start a new thread
Sorry your right there 3 :doh: and 4
 
#19 ·
still impossible - 3 and 4 are also on opposite banks of the engine.

cylinders 2,4,6 and 8 are on the right bank and 1,3,5 and 7 are on the left bank looking forward.
 
#20 ·
Thanks AMcK, :doh:

Forgot about firing order,just picking numbers side by side , :oops: i new it was Cylinder No 5 was one and something ,so 3 and 5 or 5 and 7 was his dianosises But at the end of the day a leaking head gasket between two cylinders is the given reason why his car runs crap on gas and ok on petrol .

So Redrange have you sorted it out yet :?:

Whats the update.
 
#21 ·
I have exactly the same fault codes and the same single point lpg install. How did you sort it out?
 
#22 ·
Selby P38 said:
Thanks AMcK, :doh:

Forgot about firing order,just picking numbers side by side , :oops: i new it was Cylinder No 5 was one and something ,so 3 and 5 or 5 and 7 was his dianosises But at the end of the day a leaking head gasket between two cylinders is the given reason why his car runs crap on gas and ok on petrol .

So Redrange have you sorted it out yet :?:

Whats the update.
Hmm I am no mechanic but I still don't understand this, can someone put it into layman's terms?

I would have thought running crap on one fuel compared to another was either a timing or supply issue? I know both my rangies have had different spark plugs put in to ensure a better spark and the dizzy on my classic was retarded a bit to aid the mix as well. Only time my rangie runs crap on petrol is when there's an air leak somewhere on the intake or a breather hose, then it chugs like buggery, whereas on LPG it seems to go a bit better.

I guess the only thing I can think of is on LPG it might pressurise the cooling system faster if its that type of leak as lpg is slightly higher compression? I believe? Or is it how the lpg reacts with coolant if the leak is in the opposite direction? If its that bad wouldn't the car chew fluid like mad and be off the road anyway?
 
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