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Old 13th September 2007, 23:38   #1
yuv
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Default Urgent CNG Query... Wierd

Hi All,

I recently converted my lancer to CNG... BRC, Closed Loop.

Everything seems to have gone well since then... but yesterday while driving, all of a sudden the engine accelerated hard by itself and switched back to petrol. It revved hard for 3 seconds, then back to normal. I thought it was one-off and since almost immed it switched back to CNG and ran normally.... I didnt bother much about it.

But today... it did its wierd "ghost act" again.

All of a sudden the engine revs-up, as if I have pressed hard on the accelerator(which i dont)... and then almost immed comes back to normal... but on petrol(red light). I then have to switch back to CNG.

This happened twice today and 2nd time it revved up real hard... for like 10 seconds and then switched back to petrol and back again everything normal.

Im afraid, it may happen all of sudden when in-motion and cause an accident or something(although it has always happened between changing gears so I do have the clutch depressed)... and/or it may damage the engine itself.

Im suspecting the stepper motor, which maybe malfunctioning and providing a sudden burst of gas... leading to the sudden acceleration.
Is this a correct synopsis??

Also, all 3 times it has happened after the car has run 50-100kms ...so maybe heat has something to do with it???

Pls help!!!!!!! Thanks in Advance.
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Old 14th September 2007, 16:54   #2
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40 views and not a single reply??

Wolfi, Ajo and all you alternate fuel experts out there... any idea whats going on here? Thanks
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Old 14th September 2007, 17:49   #3
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As far as I know your car cannot switch back to petrol without you manually doing it. Its controlled by a switch. Right?
I think this is something to do with the changeover switch or perhaps the emulator. The stepper motor just regulates gas flow, but get it checked, you never know.

I had a problem where the revs were not dying down when you release the throttle like on petrol mode. Keeps coming up once in a while.
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Old 14th September 2007, 18:02   #4
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Get your mechanic to check the solonoids of CNG and Petrol. If any of them malfunctions, you might have cut off supply. Probably you CNG kit has auto switch to petrol incase of CNG becoming empty.

Dwarak
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Old 14th September 2007, 19:08   #5
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Quote:
Originally Posted by dwaraka View Post
Probably you CNG kit has auto switch to petrol incase of CNG becoming empty.
I havent seen Yuv's kit, but from what I know about BRC's kits, this mechanism is not available. The system is designed to start in petrol even if CNG is selected and then switch over to CNG.

I have seen a Lincoln with CNG in US with this mechanism.
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Old 16th September 2007, 14:56   #6
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Thanks alot Ajo & Dwaraka.

Kit is BRC, closed loop and it starts in petrol mode. I have 3 settings available on the switch..... (1) Petrol only (2) Auto and (3) CNG.

Mine is set to Auto... so as soon as I start the car on petrol(RED), i need to accelerate on idle for it to switch to CNG and the indicator on the switch goes GREEN.

Now im on CNG and the car runs like a beauty... until after 50kms and then all of a sudden she will rev-up hard for few seconds and switch back to petrol. Then again, im back to same position as if I just started the car... again give it a bit acceleration and she switches back to CNG as if nothing happened :(

Dwaraka - There is no auto switch-back to petrol... u still think it could be the solonoids?

Ajo - Switch is a good suspect... I will surely have it checked. Could you throw some more light on the emulator? Do you suspect some programming failure or something...

I still wanna know why it happens only after it has run 50kms or more.... never in the morning.... something to do with a hot engine?

Thanks Again!

Yuvi
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Old 20th September 2007, 19:03   #7
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bump! . . . . . . . . . . . . .
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Old 24th September 2007, 00:11   #8
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hi... got this sorted today.

The acc cable was getting hindered by a pipe from the CNG kit.

A bit of mod job and she's back to her former glory.

Thanks All.

Yuvi
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