BMW Werkz banner
1 - 20 of 46 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter · #1 ·
first post so here i go..

i recently bought a 95 bmw 740i. it has an aftermarket LPG-g3 lpi installation in it.

when i bought the car it already didnt sound nice but i thought it would be an easy fix.(but its not i guess)

when the engine is cold (after 8 hours) it starts direct but sounds like it runs on 5 or 6 cilinders. then when its hot when i turn the key it takes about 10 seconds before it starts.. still only 5 to 6 cilinders..

i dont know if the lpg has anything to do with it. it runs just the same on gasoline as it does on lpg.

the dealer has looked for any fault codes but it doesnt have any??

anyone has a suggestion?

im getting a new CPS in a day or 2.. but dont think this will fix it.

also the car just died after startup this morning.. tried it a couple of times. the rpm stays around 400..
 

·
Help from over the pond
Joined
·
3,239 Posts
It could be your MAF, but that would show a code, I would say its to do with the LPG system, I have come across a lot of problems conerning 5 & 7 series with an LPG system fitted, your best option would be to take it to an LPG service centre. However if there's a way to isolate the LPG try that first.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #3 ·
i have checked with the lpg install removed by just disconnecting the power going to the lpg control module.

the problem remains..

also a couple of days ago when i was comming home from work it showed "getriebenotprogramm" this was the transmission running at safemode..

the next day i started it was running normal again and i havend had it anymore.

that day it was very cold outside. maby thats what triggered it ?
 

·
Help from over the pond
Joined
·
3,239 Posts
Hmmm... I know its not what you want to hear but LPG and V8's just don't go together, get rid of the gas then with help from here she will run as she should...she never will on gas....or should I say may for a while...

It was designed by engineers to run on petrol not gas...I will say no more, apart from don't buy a V8 and then worry about the running costs !!! false economy?
 

·
42, The meaning of life
Joined
·
2,405 Posts
Did the previous owner give you any insight into the history of the problem?

Have you looked at the spark plugs to establish if it is consistent in which cylinders are not firing, it might have something to do with the iginition system if two or three of the plugs are showing signs of being unignited. Given that the problem is consistant on LPG and Petrol, I'd look at the common systems first, plugs, leads & HV packs.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #6 ·
i got some details from the last owner but i dont believe the bills he gave me ar from this car.. i have a bill of 4 new spark plugs.. seems kinda weard on a 8 cil car..

but tomorrow i wil have a look at the sparkplugs and i will look if i can check the MAF..

iim thinking to just dissconnect the MAF when its running to see if te computer does indeed detect the faults..

i

thanks for all the help and tips you guys have given me

ill let you know if i find the problem
 

·
42, The meaning of life
Joined
·
2,405 Posts
I am not sure if it applies to the more modern injected LPG conversions, but the old mixer style units required a different spark plug to the petrol only engines, so it may be worth checking that the "correct" plugs are installed.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #8 ·
i have now changed the CPS.. the car doesnt die anymore but still it doesnt run smooth..

the RPM shakes around 400 to 600.

i also disconnected the MAF while the engine was running.. the engine didnt change in rpm. also no check engine lights came on..

it seems it doesnt respond to any errors at all

i also did the obd test nr.2 to check all the lights in the dash.. the check engine light doesnt work?? is this normal ? all the other ones work in the test..

i also got 8 new NGK spark plugs..

i think i will fit them tomorrow to see if there is any improvement.
 

·
42, The meaning of life
Joined
·
2,405 Posts
Maybe the Check engine light is burnt out (if it was on a lot)
Good luck.
 

·
Help from over the pond
Joined
·
3,239 Posts
At this point I would have a diagnostics done, as it sounds like someone has messed with check engine light or it has burnt out like Brettski has mentioned, when the MAF is unplugged it should run like a pig...it maybe that its on 02 sensor, diagnostics would put you in the right direction or you could be messing about for ages and spending money on parts that are not required.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #11 ·
is there a way i can trigger the check engine light? to make sure ist busted?

witch sensor could i dissconnect to make it light up?

would the CPS do this?
 

·
Help from over the pond
Joined
·
3,239 Posts
Where do you live as Ive just notice you had "getriebenotprogramm" come up are you in Germany?, the reason I ask is that older european 7 series dont have the EML light fitted!!
 

·
Help from over the pond
Joined
·
3,239 Posts
Ok, The SES light indicates an engine fault that will cause raised emmisions, such has a misfire, air-leak etc. In certain countries it is called the OBD (On Board Diagnostics) indicator and has the same function as the SES light. If it doesnt come on then you dont have a problem with the above...

What I would do next is clean the throttle body and MAF, also for any air leaks even though the light is not on,,,there is a gasket that sometimes fails between the throttle body and intake manifold check this if its hard or cracked it will let air in the system..
 

·
42, The meaning of life
Joined
·
2,405 Posts
Were the old plugs able to indicate that some of your cylinders weren't firing properly?
Did the new plugs make any difference to the problem?
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #16 ·
i havent changed the plugs yet.

i have been to a friend of mine who works at a bmw garage..

he thinks by listening to the engine that one of the head-gaskets is leaking.

it looks like he's right becouse there is also comming a lot of white smoke from the exhaust.

anyway. he told me to wait with the plugs becouse he wants to do it so he can look at them.. and he also wants to do a compression check of the cils..

next week i hope to know more...
 

·
Help from over the pond
Joined
·
3,239 Posts
Ah....you never mentioned white smoke, we may have got to the problem earlier.....
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #18 ·
i never noticed the white smoke.. ist been realy cold outside so all cars smoke now.. i just noticed it when it was running in a garage..

so didnt know it..

stupid me :rolleyes:
 

·
Help from over the pond
Joined
·
3,239 Posts
So is there any mayo gunk on the dipstick or under the expansion tank cap or oil fill cap?
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #20 ·
no there is nothing but the thermostat has just been replaced and the car is filled with new water..

but next week i will know for sure if any of my cilinders is loosing compression.

als i noticed a tube sticking out of the back of the engine witch has been cut of and a bolt is put in it to close it up??

doest look like a dealer fix to me.. anyone knows what this is?

its in the center of the engine. at the back. when im standing in front of the car i can just barely see it with the cover removed offcourse..

if needed i can take a picture of it tomorrow.. or even post a short movie of my problems on youtube..
 
1 - 20 of 46 Posts
Top