G wagen won't start / misfires

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rkl786
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Location: Germany
1991 230ge 463 model with lpg system installed. Back in March I made a thread about my Gwagen misfiring and not being drive able. I was unable to find the cause of the problem and decided to take it to a mechanic, unfortunately this was three months ago and now I am on my third mechanic. The only diagnostic I got from my mechanic was that I need a new engine, but I don't believe that the case. Background: Back in march I took a 2 hour trip to Frankfurt, driving on lpg. The trip went well and I came back home with no issues. The following day from that trip I changed the rotor to see if it would fix a issue in which once hitting over 140kph/ 40k rpm the gwagen would stop and lower it self to under 4k rpm. After changing the rotor I took the gwagen to the store on lpg. Once coming back I ran out of lpg and switch to petrol, just right before I got home my gwagen died and after that wouldn't turn on. I am grateful it was kind enough to drop me off home before it did that. The following day I check the rotor as I figure that might be the problem but it was set correctly. Problems: The Gwagen currently doesn't turn on. Turning the key give the usual sound of the engine trying to crank but never does and only drains the battery. The gwagen use to turn on and could idle, but then any attempt to push the throttle over 20k rpm would cause the gwagen to misfire and shut off. Trying to put it in gear would also cause the gwagen to turn off as it seems to push the rpms to low.Unfortunately as I said it use to be able to idle but I made the mistake of messing with the idle timing and now it does not turn on. Other thing I notice was that when pushing the throttle a little, it looks like a little bit of fuel would get out of the exhausts. Whats been done: I was thinking it was a ignition problem. So far I changed the cap, rotor, coil, spark plugs, and leads. I checked the fuses and they are fine. I check the ovp rely and its good as well as changed the fuel pump rely with a spare that I know works. Possible solutions? I was thinking it may be the distributor. Other ideas are that it may be a crank position sensor that went faulty. Lastly I was thinking it could be the ignition control module though I hope not after seeing the price on those things. Look forward to hearing any other ideas on the matter. Thank you
rkl786
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Joined: 24.06.2015
Location: Germany
Re: G wagen won't start / misfires

1991 230ge 463 model with lpg system installed.

Back in March I made a thread about my Gwagen misfiring and not being drive able.
I was unable to find the cause of the problem and decided to take it to a mechanic, unfortunately this was three months ago and now I am on my third mechanic. The only diagnostic I got from my mechanic was that I need a new engine, but I don't believe that the case.

Background:
Back in march I took a 2 hour trip to Frankfurt, driving on lpg. The trip went well and I came back home with no issues. The following day from that trip I changed the rotor to see if it would fix a issue in which once hitting over 140kph/ 40k rpm the gwagen would stop and lower it self to under 4k rpm. After changing the rotor I took the gwagen to the store on lpg. Once coming back I ran out of lpg and switch to petrol, just right before I got home my gwagen died and after that wouldn't turn on. I am grateful it was kind enough to drop me off home before it did that. The following day I check the rotor as I figure that might be the problem but it was set correctly.

Problems:
The Gwagen currently doesn't turn on. Turning the key give the usual sound of the engine trying to crank but never does and only drains the battery. The gwagen use to turn on and could idle, but then any attempt to push the throttle over 20k rpm would cause the gwagen to misfire and shut off. Trying to put it in gear would also cause the gwagen to turn off as it seems to push the rpms to low.Unfortunately as I said it use to be able to idle but I made the mistake of messing with the idle timing and now it does not turn on.
Other thing I notice was that when pushing the throttle a little, it looks like a little bit of fuel would get out of the exhausts.

Whats been done:
I was thinking it was a ignition problem. So far I changed the cap, rotor, coil, spark plugs, and leads. I checked the fuses and they are fine. I check the ovp rely and its good as well as changed the fuel pump rely with a spare that I know works.

Possible solutions?
I was thinking it may be the distributor. Other ideas are that it may be a crank position sensor that went faulty. Lastly I was thinking it could be the ignition control module though I hope not after seeing the price on those things.

Look forward to hearing any other ideas on the matter. Thank you

Pistonhead
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Re: G wagen won't start / misfires

If I am not confused, I thought I had drafted you a lengthy reply as to your issues. Did you follow these? As I have had no feed back from that posting. 

Now do you do your own repairs or are you relying on mechanics largely?

When you say one of the mechanic's claim that you need a new engine; on what basis is he claiming this?

You have one of two or probably three plausible problems or a combination of these; electrical, fuel or both and maybe mechanical. 

Before you go around changing this, that and the other please find out what your issue is and it is not simply change items and it is not easy to put a finger on it. 

If you wish to take advise, firstly, are you able to verify if there is spark at the spark plugs?

If yes; as you have mentioned that the ignition timing may be out, did you follow the set of instruction I post on the last thread to check the ignition timing?

Please respond to these questions first before I commit my time to giving you more.

 

Arnie
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Re: G wagen won't start / misfires

 

Hello,

I think you should follow a logical process of diagnosis as suggested by Rakesh, above.


Firstly, turn-off the LPG and focus on running on gasoline.

Then, ensure that the fuel pump(s) are running. You will hear a noise for 3 secs after turning-on ignition, as the fuel-pump primes the system.

Check you don't have any air leaks.

Remove one spark-plug and with the lead re-connected to it and the body of the plug touching some metal of the engine, see if you have a spark when cranking the engine. If not, check camshaft sensor at rear of engine.

If you have a spark, at the plug, then the problem could be air or fuel, so check fuel pressure when cranking.

Check also for air leaks, for example, from brake servo vacuum pipes etc. and check idle control valve is not stuck open.

Find a good mechanic who will do compression and leak-down tests before suggesting you need a new engine !

 

 

 

rkl786
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Joined: 24.06.2015
Location: Germany
Re: G wagen won't start / misfires

Pistonhead wrote:

If I am not confused, I thought I had drafted you a lengthy reply as to your issues. Did you follow these? As I have had no feed back from that posting. 

Now do you do your own repairs or are you relying on mechanics largely?

When you say one of the mechanic's claim that you need a new engine; on what basis is he claiming this?

You have one of two or probably three plausible problems or a combination of these; electrical, fuel or both and maybe mechanical. 

Before you go around changing this, that and the other please find out what your issue is and it is not simply change items and it is not easy to put a finger on it. 

If you wish to take advise, firstly, are you able to verify if there is spark at the spark plugs?

If yes; as you have mentioned that the ignition timing may be out, did you follow the set of instruction I post on the last thread to check the ignition timing?

Please respond to these questions first before I commit my time to giving you more.

 

First off I want to apologize, its never my intent to have someone waste time especially when they are offering help. Again I am sorry about that.

I do most of the repairs, but for the jobs I don't have the tools for I have the mechanic take care of it. He claims the engine is faulty is due to past working on my gwagen, and also he doesn't want to diagnose the problem.

Unfortunately the gwagn is with the mechanic and I won't be able to give you a 100% answer until later but from the last time I check the spark plug did have a spark.

I will check the ignition timing, what I messed with was with the idle.

 

rkl786
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Joined: 24.06.2015
Location: Germany
Re: G wagen won't start / misfires

Arnie wrote:

Hello,

I think you should follow a logical process of diagnosis as suggested by Rakesh, above.


Firstly, turn-off the LPG and focus on running on gasoline.

Then, ensure that the fuel pump(s) are running. You will hear a noise for 3 secs after turning-on ignition, as the fuel-pump primes the system.

Check you don't have any air leaks.

Remove one spark-plug and with the lead re-connected to it and the body of the plug touching some metal of the engine, see if you have a spark when cranking the engine. If not, check camshaft sensor at rear of engine.

If you have a spark, at the plug, then the problem could be air or fuel, so check fuel pressure when cranking.

Check also for air leaks, for example, from brake servo vacuum pipes etc. and check idle control valve is not stuck open.

Find a good mechanic who will do compression and leak-down tests before suggesting you need a new engine !

Yes LPG is currently off and they fuel pumps are running. I checked and they do turn on.

Last I checked I didn't find any air leaks but I will check again. When I go the mechanic this Tuesday I will check the spark plugs again, though I am pretty sure they did have a spark. By chance would you happen to have a picture of where the camshaft sensor is located? My mechanic will do a compression test on Monday.

 

Arnie
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Joined: 12.04.2004
Location: London
GWOA Groups: Committee, Members
Re: G wagen won't start / misfires

On the 300, M103 engine (6-cyl version of your engine), the cam-shaft sensor is on the rear of the cylinder head. Its cable goes straight to the EZL ignition unit. Should be the same on the M102, 230e.