Vx commodore melting plugs

[Tplunk]

Hi All
I have a problem with a 3.8 series 2 Vx engine i put this motor in my ford transit motor home reconditioned the engine fitted all new sensors etc
Took if for a run 58ks it was driving fine then started missing and backfiring loss of power
Got home pulled plugs out three had melted 1&3 on left bank and number 2 on right
Compression test nothing on number 1 pulled heads off all of those cylinders inlet valves had gone concave with number one being the worst hence no compression now fixed this problem ran it for about 90ks and it’s started to miss I’m worried that it might be the same thing pulled plugs out and they all look like the are running lean with two a lot leaner than the others
Any help would be appreciated oh and with the first time the muffler had a hot band around it near the baffle plate looks like it got very hot yet engine temp gauge normal

 

[Not_An_Abba_Fan]

It is leaning out a lot if it's melting plugs and valves. It may have a vacuum leak that will cause an uneven distribution of fuel to the cylinders. Is it running the VX ECU?

 

[delcowizzid]

Blocked injectors maybe or bad lower orings on the injectors leaking vacuum bad or is it possible the wrong plugs are on the wrong injectors

 

[Tplunk]

Thanks for your replies
I am using the vx ecu I even borrowed another to try but still the same
I did think of an air leak as when I rev it I can here a sucking sound that appears to becoming from the rear of the cover of the plenum chamber but I sprayed around the seal and nothing changed it does have a manifold insulator and a spacer on it so figured that was the noise
I took the injectors out and got them tested as I was told because they were bought on eBay for $100 they would be no good but surprise surprise they tested fine for a cost of $165 to test them grrrrr
Tomorrow I have it booked in for a scan and a sniffer up the exhaust as it’s running very rough again and I’m worried about valves
Oh it does have hi lift roller rockers has anyone had trouble with these ???

 

[delcowizzid]

There's some serious heat to get that plug hot all the way to the porcelain and heat that valve so hot that it could deform like that.ive never seen a valve do that or a plug get hot all the way to the porcelain.its like there's no water going round the heads does it run the heater hoses that normally goto the heater tap its the bypass hose to allow water to circulate before the thermostat opens.are the head gaskets correct and around the right way .is it a factory wiring harness or fully wired from scratch something is very wrong .does it have a bcm simulator to allow it to run with security still on in in the tune as a vx ecu shouldn't run the engine with security turned on

 

[EYY]

Jesus.. even if the cheap China injectors tested ‘ok’ i’d Replace them anyway.

If it were THAT lean it’d be almost undriveable tbh...

 

[losh1971]

Are they Autolite plugs?? Once you sort the problem bin the Autolite's get some Bosch ones.

 

[delcowizzid]

If they are aftermarket Chinese yeah bin them lol

 

[Tplunk]

Jesus.. even if the cheap China injectors tested ‘ok’ i’d Replace them anyway.

If it were THAT lean it’d be almost undriveable tbh...[/QUO

Jesus.. even if the cheap China injectors tested ‘ok’ i’d Replace them anyway.

If it were THAT lean it’d be almost undriveable tbh...

There's some serious heat to get that plug hot all the way to the porcelain and heat that valve so hot that it could deform like that.ive never seen a valve do that or a plug get hot all the way to the porcelain.its like there's no water going round the heads does it run the heater hoses that normally goto the heater tap its the bypass hose to allow water to circulate before the thermostat opens.are the head gaskets correct and around the right way .is it a factory wiring harness or fully wired from scratch something is very wrong .does it have a bcm simulator to allow it to run with security still on in in the tune as a vx ecu shouldn't run the engine with security turned on

Thanks
Yep it has bcm simulator and wiring harness from v6 conversions the temp gauge stayed at bit above normal which is strange for the amount of heat it must of generated
It doesn’t have a heater tap the water is circulated all the time thru the heater and is controlled by a flap inside yep gaskets with arrows facing front mmm it is a puzzle I have been to heaps of workshops and nobody knows what it is or wants to find out I have a booking tomorrow for scan etc so hopefully I can catch it before the valves go again although it’s running very rough now so that’s a bit scary

 

[losh1971]

Yeah probably worth getting some second hand Bosch injectors and getting them recoed as they can be expensive when new.