idle speed problem....

As you can see from the subject I have solved all my problems with engine except idle speed. My engine vibrate in idle, and I'am still dealing with it...I have new plugs, wires, air filter, timing belt is finally adjusted ok... I assume that it's result of lower compression on that 4-th cylinder, but I am not sure. Is it most common result of low compression or something else? Also I have noticed that when I disconnect injector plug from that conector engine works almost the same but when I disconnect any other injector engine stops...is that due to 'not working' injector maybe? Car is driven on natural gas and gasoline and idle speed problems are same

thx in advance Tomac

Reply to
Tomac
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Year and model? Auto or manual?

Reply to
Nobody U. Know

sorry, I totally forgot... it's Lancer 1.8 16v Gti, '91, 100 kw, manual transmission

Reply to
Tomac

natural gas ? You mean CNG ? And not LPG propane ? Never ever seen a lancer on CNG but on LPG there is a chance for the valve /seats to burn causing vibration on both lpg and gasoline. Check the valve clearances.

Reply to
Jonny

You could bump the idle up with the idle set screw and let it be. However, I would start with a good carbon clean and hope it's just gunk on one of the

4th cylinder valves or ISC. Just get some carb cleaner and follow directions. If compression goes up, you definitely have a caked valve problem. Another simple fix it to check vacuum hoses for cracks. Pull each one off and check them completely. You'd be surprised where rubber cracks.
Reply to
Nobody U. Know

sorry, it is LPG, my mistake

Reply to
Tomac

during holidays I had progressive oil consumption, so I am prepeared for the consequences, probably it will go on some major rapair procedure...I will not know until engine is opened... I have also spotted that I have oiled air intake, when I clean that idle is better for some time but then again it starts to make troubles, engine stops when I release pedal completely

Reply to
Tomac

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