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Old 26th December 2012, 23:08   #1
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Default Santro LPG - Engine Stalling in 2nd & 3rd Gear

Posting on behalf of a friend:

Hi All,
I own a Hyundai Santro which i converted to a LPG sequential kit 6 months back. The car was running fine till a couple of weeks back. Now I experience jerking at 2nd and 3rd gear and sometimes the engine just turns off while on the move at these lower gears or sometimes when the car encounters a pothole(I then have to restart the engine ).So far, I've changed the ignition coil(6 months back) and spark plugs(1 week back) but I still experience the problem.

The Hyundai mechanic says that it could be a problem either with the wiring to the ECU( since soldering instead of couplers have been used) or with the injectors. He says the cord wires and ignition coils are just fine.
The Lovato authorized mechanic who fitted the LPG sequential kit says that it could be a problem with the spark plug cord wires or the ignition coil.
The reason I am not convinced with the Hyundai mechanic's argument is that the car has been running perfectly for 7 months. Initially , when the car was fitted with the LPG sequential kit, there was a slight jerking problem but was gone once I got the ignition coil replaced.


The reason I don't see a rationale with the LPG mechanic either is that the ignition coil is just 6 months ( 4k kms ) old.


I've been struggling with this problem for a while since each mechanic is giving his own version of the problem. I might be wrong in my rationale above.


Appreciate your advice/pointers to get the problem rectified.
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Old 27th December 2012, 09:13   #2
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Default re: Santro LPG - Engine Stalling in 2nd & 3rd Gear

Your injectors may be clogged. The clogging occurs when the petrol in the tank gets stale & all the other chemicals which give petrol it's octane number evaporate. So, you are left with a fuel that does not evaporate easily, even in the engine cylinder heat. Therefore you get rough running & stalling. The injectors' small holes also clog up due to the 'thick' nature of the remaning petrol in the tank.

The solution is to remove the injectors, get 'em declogged & put fresh fuel in the tank. Do keep the car on petrol mode longer, to keep your injectors in good functioning condition. You should finish the fuel in the tank atleast every 2-3 months.

Last edited by 1self : 27th December 2012 at 09:16.
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Old 27th December 2012, 09:43   #3
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Default re: Santro LPG - Engine Stalling in 2nd & 3rd Gear

The problem can be identified easily, there was a similar problem in my cousin's i20 after he converted the vehicle to LPG. The problem was with clogged injectors(LPG) and rich air-fuel mixture. The injectors had got clogged because he used domestic gas, sequential injection kits cannot run on domestic gas. Check on these points

1. What LPG you are using, domestic gas or Auto LPG? Many people ignore this, Lovato kits use solenoid injectors, because of high impurities in domestic cylinders it gets clogged easily and wear out very soon.
2. Run your vehicle in petrol mode only for some kms and check for the problem.
3. Is automatic switch over happening from LPG to petrol when LPG gets empty?
4. Ask the Lovato mechanic to check the air-fuel mixture again and re-tune the ECU.

Last edited by deehunk : 27th December 2012 at 09:45.
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Old 28th December 2012, 18:22   #4
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Default Re: Santro LPG - Engine Stalling in 2nd & 3rd Gear

Thank you 1self and deehunk for the insights.

@deehunk: 1) I run my car on auto LPG
2) I've the problem with both petrol as well as LPG modes
3) Yes the switch to petrol happens after some beeps once LPG is emptyI took the car to the Hyundai service center again. The mechanic at the Hyundai service center had run the diagnostics and he confirmed that there was no problem with the codes.

Now comes the interesting part: He then gave a direct line to the injector from the original EMU bypassing the ECU of the LPG kit. When we drove the car now, the engine didn't stll or jerk. When he now reverted the connections to now include the ECU from the LPG kit, the engine as expected started stalling.

He informed me that this is a problem with either the ECU or the connections to the ECU. He ran some tests and confirmed that the injector isn't pumping fuel enough fuel. I am not sure what this means.

Should I now take it to the LPG service center guy and what should I ask him to check(clogged injectors or wiring to the ECUs)? I think he is facing this problem for the first time and hence he is sticking to the traditional ways of getting the spark plugs, ignition coil and plug wires replaced of which I have done the first two.
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Old 28th December 2012, 21:49   #5
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Default Re: Santro LPG - Engine Stalling in 2nd & 3rd Gear

Hi Foxbat, thanks for sharing your experience at HASS, even I am learning by experience, thanks to Pandian Sir also for spending his valuable time to our never ending questions. If the vehicle is running fine in Petrol mode with OEM ECU/ECM and not so when it is connected with ECU of LPG kit, I doubt it will be the solenoid valve which controls the fuel flow( LPG and Petrol). If there had been a issue with ECU wiring vehicle would have not run in LPG mode first and then auto switch over would have not happened so that is fine, just ask the LPG mechanic to reset the ECU by doing a test ride and switching between 2 fuels. This should solve your problem. Meantime I will talk to Pandian Sir and understand what may have gone wrong?
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Old 31st December 2012, 07:45   #6
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Default Re: Santro LPG - Engine Stalling in 2nd & 3rd Gear

Foxbat, if you are not getting enough fuel, it means the air-fuel ratio is all wrong. That means either the oxygen sensor or calibration of the LPG kit ECU with the OEM ECU, when in petrol mode is wrong.

To eliminate these issues one at a time, i would suggest you get the injectors cleaned. After that, i would strongly suggest that you consult another installer who installs the kits you have in your car.
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