[amitverma]

Originally Posted by extreme_torque

Isn't a closed loop kit better? How about an closed loop kit with TAP and Lambda Sensor?

i want to know this too as i have a lambda installed

[abhik]

Originally Posted by extreme_torque

Isn't a closed loop kit better? How about an closed loop kit with TAP and Lambda Sensor?

Closed loop kit is any day better than an open loop kit. Simply because the Lamda does all the work of regulating gas flow and thus minimal or no periodic setting is required. A closed loop kit will always have a Lamda Controler but a TAP will not be of much use as in a closed loop kit gas in-flow is regulated and controlled by the Lamda which decides the amount of gas to be introduced into the combustion chamber according to the RPM. So timing does not need to advanced to burn unburnt gases as the amount of unburnt gas left in the cylinders is lesser, however there are hybrid loop designs in which a TAP might be used with a Lamda controller to further enhance combustion by adjusting timing. The difference in performance is lesser as compared to an open-loop kit in which the difference is very noticable.

[abhik]

Some cars are better off with an open loop kit simply because in a closed loop kit wires conneting the ECU with sensors have to be cut. Specifically the ones sending AFR signals. As like a piggyback ECU would fool the ECU into reading wrong signals as correct to enhance performance, similarly the Lamda control sends AFR signals to the ECU to operate on CNG as the IAC valve needs to be controlled in conjunction with the Stepper Motor which regulates gas in-flow. But some cars like Opel, Fiat, Ford etc with slightly sophisticated ECUs or lack of knowledge about them, are better left alone as it might hamper running in petrol mode or even other problems.
The TAP in my car is connected to the crank sensor, so again a wire connecting to the ECU was cut but its an open-loop system so the AFR was left to stock readings. But the open-loop system requires periodic settings to regulate R.P.Ms at idling as the gas flow is only regulated by a power valve which is manually set to a single setting allowing gas to constantly flow at a particular rate.

[amitverma]

i converted to cng last year and have come across all sorts of issues.
as it turns out the ecu is totally against cng and gave up after a couple of months. the car used to jerk and misfire on petrol but ran fine on cng. so i continued on driving.
i used to start on petrol then switch to gas and go. but last month, the ecm refused to idle and the engine went off immediately after starting up. so i have to do a cold-CNG start every now and then to get moving. i guess there is no other option but to look for a new ecu. anyone has an idea where can i find an old one. i dont want to go for an authorised part as they say it wont carry warranty as i am running CNG.

also would it heavily affect the engine if i continue to run on like this, i mean, only on CNG?

also, the most important part, I need to get some new engine oil, please suggest some?
thanks a lot

[ask77]

The problem may be with choked injectors and/or stale fuel . Also is the Check engine light coming on ? if so have you got the ECU scanned ? what error codes are being thrown up ? Italian cars like Fiat are suited for LPG/CNG conversions since duel fuel cars are popular there. Most good conversion kits are italian .

[amitverma]

i'd believed it to be true. but sadly it isnt. the scanner doesnt show any error. errors are only shown if some sensor or part is going bad. for the ecu itself, there is no error code. thats what the A.S.S guys told me.

the car jerks on petrol. interistingly, there is a cable, close to the wall (far side of the bonnet). if we take it out it runs fine on petrol. some MAC sensor or something.

also, please suggest which engine oil to put (mineral)?

[saintsinner]

i think that would be the MAP sensor. seems like you need a head job. you might have a valve leakage. nothing to do with the ECU. it WILL NOT fry if you use your car on CNG

if u use CNG, use it responsibly. on cold starts, run the car on petrol until the engine reaches optimum temperature. don't drive your car on CNG for more than 80 kms or so at a single go. switch over to petrol for a while.

[Deeps]

I have a Xeta CNG. I've had ECU problems after CNG installation with the same symptoms as yours. This meant a multiple ecu change. Dig up my thread on it in the archives. But the replacements were covered under warranty. Nowadays, the TATA guys just erase all the values/data on the ECU through the laptop and its as good as a new ECU. See if such an alternative exists for a Palio. Mine was always done under warranty but it costs around 300/- for resetting the ECU otherwise.

@saintsinner: Why can't we run on CNG for more than 80km? I've made multiple runs to Agra and back on CNG alone without any issues.

[amitverma]

but the issue is the car doesnt idle on petrol. it turns off immediately after starting up. its starts up fine.
@saintsinner: also the A.S.S guys replaced my ecu with a standby unit and the car functioned properly. thats when i realised that the ecu was the issue

[abhik]

@amit- contact the following:-

Kar Scanners
011-29219915

Contact them, they are located at G.K, at the place was Savitri Cinema existed earlier, right opposite Maketing Times(i believe) showroom. They should give your current ECU a scan and fix whatever issues there are related to it, i believe they also have a guy who is pretty good at tuning CNG settings too.
I believe its a sensor related issue rather than ECU, but error codes should show up in that case.
As far as engine oil is concerned try Castrol Magnatec, its 15W40 semi-synthetic and should help the engine run better. If you can spend more then switch to fully synthetic Mobil 1 5W40.

[Deeps]

@Abhik: What oil drain interval do you use? I too use magnatec nad drain at 10K.

[abhik]

I always use 5K drain intervals even with semi-synthetic, my driving style is a little aggresive.

[Takumi-san]

IMHO, there are no issues if you run the car for more than 80 kms. Its just the fact that the gas is a dry one , and using petrol periodically helps in prolonging the life of the engine. I am sure someone can explain the technicalities, but I do belv this is the underlying issue.

[saintsinner]

^^ its the valves that go first. valve seat recession is a common phenomenon in cars on gas. it's a dry fuel. the valves run dry. why i don't advice driving at one go for long distances say 80kms or more is because you are running your engine dry. it wouldn't hurt to run the car on petrol for 2 kms or so in between. use a good coolant and engine oil, use a colder spark plug too. it's a personal experience.

About the ECU thing. i always thought ECU's can be reset. in my xeta, the tata ECU started giving problems and it was reset. then the BRC ECU wasn't switching over, it was reset too. car works fine.

[Deeps]

Which kit do you have? I dont think its the Bedini kit fitted by Shrimankar (which I have). In the initial days of my ownership in early 2007 th ecu was always changed because there was no software available at TASS to reset it. Later when it was aquired, they would reset it rather than change it.