Hey guys.

recently had technical control of the car, it wasn't good on the emissions. i've managed to get the readings better, but they are still off a bit.

Now, first of all some info:
1500 ram 5.2l 2wd
290k miles
secondary LPG fuel system. ( living in Belgium it's way cheaper then gasoline. )

My car runs 80% of the time on LPG , which it did great. No issues at all, except i didn't have much power anymore last year half.
Due to some personal issues, i didn't take good care of the car in terms of maintenance. I've had 2 gasoline injectors failing for a few months, ignition system needed a tune up, and normal maintenance needed to be done.

i've replaced the airfilter, cleaned the air inlet etc. put on a new distributor rotor, cap & all new wires to the plugs.
after this, i had all my power back that was lost last year half. my emissions where way better as well. And the car drove perfect on LPG!

at this point i still needed to do the gasoline injectors and sparkplugs. i've ordered 2 new injectors to replace the failing ones. which where on cyl 2 and 7. Replaced them today and also replaced the sparkplugs. When putting everything back toghetter and starting up the engine, i expected a smooth running engine.. But oh no, it didn't. It misfires now all the time on cyl 1 , 5, 8. both on LPG and gasoline... i checked everything 5 times, each plug wire is connected to the right sparkplug and on the distributor cap. Injector plugs are connected as well... my injector failure codes are gone. only misfires ones now.

So i'm thinking.. if everything is connected right. and i suppose nothing is broken from the plugs or the wires ( always remove/install them carefully ), then what could be causing this?
i do get the feeling it's ignition related. i really checked everything a few times, and all seems good. Anyone suggestions on what to check? i'll recheck everything tomorrow. but im really sure everything is connected as it should,

Thanks in advance guys!

 

Is this a factory installed lpg system? I have heard of them but never seen one here in the states. What plugs did you use? Are the wires going to the correct cylinder?

 

It's all installed correctly 100% sure. I've rechecked every connector , wire , vacuum line onto intake. Can't seem to find the issue.

It's not a factory installed one, it's a after market one OMVL XIII i believe. Or something like that.

I've used DENSO QJ15HR-U removable 5018 plugs.
the bosch , champion plugs couldn't be delivered.

Cyl 1 , 5 , 8 continuous misfires on both fuel systems. Before it was injector failures on 2 , 7 on gasoline only ( replaced injector 2 and 7 and all spark plugs with denso ones , bosch FR8DCX+ was installed before.

 

Compression test?

 

Okay i made a error somewhere installing plug 1. must have dropped or smashed it somewhere , there wasn't a gap anymore. put in a old plug and now on LPG all 8 cyl's work fine.
It drives perfect on LPG , except i notice a small performance drop. is it possible the denso plugs cause this?

on gasoline, cylinder 5 misfires. it must be injector related, as it runs fine on LPG ( pulled the plug wire of 5 on LPG and immediately notice it runs on a cyl less)
I will check if i can get the 2 old injectors back to work, maybe clogged.. and swap out injector 5.

I need to do a compression test, i burn about 1,5 liter of oil in 1000km. i'm filling up often..
Gonna run a dry and wet test, hopefully its the valves...

Still need to get it through emission.. 2 years a new cat got put in, garage thinks its a bit a small one and might be clogged already due to excessive oil burn..
CO needs to be within 0.3 range , and its sitting at 0.4 ..

 

And seems like misfire on cyl 8 doesn't occur, checked the sparkplug and put it back in..

The plugs are a bit longer , the internal part going in the engine.. Garage told me it's OK.. but is it?
Or could piston 1 have hit the plug?

 

 

That's a big difference in length..... Think I would verify those are the correct plugs.

If the piston is hitting them, it will be obvious immediately.....

 

Well the engine runs with them... I will recheck for other ones. Any chance you got a pic of yours? Or part id?

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Don't use those plugs, try to find the correct ones, simple copper plugs not platinum or iridium. Worst case clean the old ones and check the gap. The super long electrode does have very different heat characteristics.

Edit: Here's a list of vehicles that use this plug: https://www.stockwiseauto.com/denso-5018-spark-plug