Black deposit in intake of TB48DE

[Scottyc]

Hi guys, I can report that the issue with mine is resolved through much trial and error. Big thanks to Robo for his advice during the process.

1. I pulled the reducer/regulator out - my system is called a Lambda Control System 2 which uses feedback from the 02 Sensor to control the flow of gas via two stepper motors. The Idle one is on the SE-81 reducer, the other high speed one is on a valve in the hose between the reducer and the mixer in the inlet system.
2. I bought a repair kit from ebay and found it was missing most of the parts required for the repair so bought another from the Landi Renzo distributor, Apollo Gas, in Sydney. Price was the same so call them first and save the headache, they were very helpful.
3. I disassembled the SE-81 reducer. The large diaphragm was punctured and it was full of hardened oily deposit - I will try to get some pics up. The smaller diaphragm was also caked in oily crap. I cleaned everything with carby cleaner, taking Robos advice to use stuff that was safe for rubber parts. Replacable parts in the kit were the two diaphragms, the two valves - one is a metal see-saw assembly, the other is just a rubber disc and then numerous O-rings for the various inlets and outlets for gas and coolant.
4. I re-installed the reducer in the car and replaced the coolant. After checking for gas leaks with soap and water I switched it over to gas and found that my efforts had come to nothing. Still stalling once the RPM's went above 1000 and were then allowed to fall back below this.
5. My mechanic suggested I check for oily deposits in my mixer. This was in the rubber tube between the filter/MAF assembly and the throttle body. I found that this was installed with the outlet holes facing back toward the filter end of the tube and while it is a ring, it was sitting at about 45 degree angle in the tube and also caked in oily crap. I couldn't find info on how to install it correctly but took a guess that the holes should be facing toward the throttle body, cleaned it and re-installed it. I also changed the plugs while I had the inlet manifold apart. That number 6 is a bitch. Put it all back together - again had to top up the coolant as there is a line through the throttle body. Warmed it up, went over to gas and she was perfect. Back to Normal... for three days and then started stalling again.
6. I gave up had my mechanic take it to his gas specialist - the same people reccomended by Landi Renzo. They had it for three days and after replacing the low speed stepper and giving it a tune, it's back running as normal. Idle is still a bit rough but this is the case on both fuels. Suspect it might be the plug gaps but it's not bad enought to go through the ordeal of getting them back out - I will live with it and am just glad it's back in action.

[beaST_01-dell]

Glad it has all finally worked out for you. Now, i will get stuck into mine :-)
I have a zavoli mixer, so just need to find a retailer that sells kits....

[beaST_01-dell]

Just to add, i adjusted my timing today, about 6mm?? Engine is running alot smoother, and i have driven on gas today, without indecent. Which is awesome!!!!! Still have to service mixer, but at the moment i have a little smile!!!

[Scottyc]

Well here's a couple of images of the inside of mine... The large diaphragm had a puncture in amongst the muck. The regulator/reducer functions with two chambers with the large and small diaphragms. Small one is normally open controlling flow of gas into the regulator, held by the spring you can see in the second pic. The large one is normally closed with the diaphragm pressing on the large lever in the second pic as suction from the engine increases and thus increasing the volume of gas delivered. The chambers are heated by coolant, assisting in the vaporisation of the liquid gas delivered from the tank. The small tube leading from the center of the regulator to the outlet at the top delivers gas to the engine when the large lever is in the closed position - ie when at idle. The stepper motor that had failed on mine controls the flow of gas through this tube based on feedback from the O2 sensor in the exhaust.

[beaST_01-dell]

Wow, thats some black gunk, eh??? Thanks for the pics :-)

[BearGUST]

Have any of the gas places suggested a tar filter on the gas system?

[beaST_01-dell]

Have any of the gas places suggested a tar filter on the gas system?

What is a tar filter????

[BearGUST]

What is a tar filter????

Some new cars on gas have a tar filter that gets changed every service, might be able to be retrofitted???

[Scottyc]

Have any of the gas places suggested a tar filter on the gas system?

Actually not heard of this until you mentioned it (outside smokers circles, anyway). To the right In the second picture I posted is the cutoff solenoid with a filter underneath. The filter inside is a little paper one like an air filter and it was perfectly clean. There was a couple of o-rings for the filter in the kit but not the filter itself. Obviously the oil is released from the gas when it converts from liquid to gas - the tar filters I can find info on work with the gas in its gaseous phase so maybe only work on the injected systems?