Hi everyone,
Its been a long time. I'm now encountering really bad problems.
Firstly, for all who don't know, I drive a bifuel-CNG Aveo. Here is the chronology of the problem.
Since the beginning of this year, I have been getting rough idle and misfires at start up. The usual pop, pop. Clears itself after the car warms up. It starts on gasoline. Not natural gas.
Since last month, the problem got so bad, it registered a flashing CEL. Analysis reveals misfire. This is using gasoline. No worries. I force start with natural gas. No problems. Idle is smooth, there is power on natural gas. I figured it might be a gasoline injector issue. The analysis also revealed that it was cylinder 2 that is giving the misfire.
Now, I'm out of options. The car has rough idle and misfires on natural gas. Ooops! Guess it is not an injector issue anymore. Apparently gasoline is pretty much intolerant of the mechanical fault and natural gas is not. Highly likely it is carbon buildup on the valves which gave the car "higher compression" which natural gas found comfortable then but not so now.
Someone suggested that an overhaul is required. I'm hesitant that this will solve the problem. Coolant levels have not dropped. Oil levels are still maintained. I most likely need decarbonizing and the odd tappet adjustment. The 1.4L Aveo notchback uses mechanical tappets. I should have them adjusted when I hit 70k km and the car is now at 157k km. I was suggested that intake tappet should be 0.015in and exhaust at 0.020in since I am using CNG.
Rough idle, misfire
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PrecisionBoost
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Mechanical tappets?????
That is really strange..... I had no idea there were still engines running non hydraulic self adjusting tappets.
Burning off the carbon shouldn't be too hard.... one trick is to pour in a small amount of transmission fluid (ATF ) into the engine while running.... it smokes like crazy but removes every single bit of carbon.
You must be careful how you do this so that you do not damage the engine..... do a search on google and find a couple of sites with instructions.
I'd tell you how to do it myself but it's been about 4 years since I did that to a vehicle.... so I don't remember the exact procedure.
Also keep in mind most of the procedures are for big V8 engines..... you may have to spray the ATF into the cylinders to make it work correctly.
That is really strange..... I had no idea there were still engines running non hydraulic self adjusting tappets.
Burning off the carbon shouldn't be too hard.... one trick is to pour in a small amount of transmission fluid (ATF ) into the engine while running.... it smokes like crazy but removes every single bit of carbon.
You must be careful how you do this so that you do not damage the engine..... do a search on google and find a couple of sites with instructions.
I'd tell you how to do it myself but it's been about 4 years since I did that to a vehicle.... so I don't remember the exact procedure.
Also keep in mind most of the procedures are for big V8 engines..... you may have to spray the ATF into the cylinders to make it work correctly.
2010 BMW 335D
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
1994 Opel Calibra 4X4 turbo ( C20LET 2.0L Turbo )
2002 Daewoo lanos
Actually, I know how it should be done. It is the good old water decarbonizing technique. I just need to find either the PCV or brake vacuum hose to do the job.
I have the option of using ATF or water. Not exactly easy since I need the RPMs to be kept at 3000 for maximum effect. Two man job.
Yes, it is strange that my car is using mechanical tappets. Says so on numerous tech articles for the 1.4L DOHC Aveo. The notchback is the only one using them. The 3dr and Aveo5 uses hydraulic automatic ones. Funny. Same engine but different tappet system. The engine management systems are different as well. Mine uses the Delphi MT80ECM. The Aveo5 and 3dr hatch using the same 1.4L DOHC engine uses the Delphi MR-140ECM.
Got it from here:
http://media.gm.com/eur/chevrolet/en/do ... 4dr_en.pdf
I have the option of using ATF or water. Not exactly easy since I need the RPMs to be kept at 3000 for maximum effect. Two man job.
Yes, it is strange that my car is using mechanical tappets. Says so on numerous tech articles for the 1.4L DOHC Aveo. The notchback is the only one using them. The 3dr and Aveo5 uses hydraulic automatic ones. Funny. Same engine but different tappet system. The engine management systems are different as well. Mine uses the Delphi MT80ECM. The Aveo5 and 3dr hatch using the same 1.4L DOHC engine uses the Delphi MR-140ECM.
Got it from here:
http://media.gm.com/eur/chevrolet/en/do ... 4dr_en.pdf