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[zuluf]

Last 2-3 months I've been having problems, it all started with:

1. Firstly my camshaft sensor went dead. Lamp was on, the error was there. Tried poking around to make sure it was not some false info and in the end we were 100% sure it's dead. New one was fitted and off we go.
2. After fitting new camshaft sensor things were normal for few days and then started the idling problems. You could start up the engine and it worked perfectly. You could rev it up and let it go and it went to idle rev speed. But!
Put it in gear and try to move the car and then press the clutch and release the gas pedal and it wouldn't always went to normal rev speed. It went from 800ish to 1500. It was a random case. It didn't stop after few days and was so annoying I've decide to clean the throttle body again (did it last year around the same time). All was in great condition but I've cleaned it anyway. There were slight improvements but nothing much.
After that I've decided to go to a local garage that (sort of) specialize in Opel cars and explained the problem. Everything was checked. No errors, no misfires, no vacuum leaks. Nothing. The guy told me that he suspects maybe a false info from a sensor or clogged up injectors but didn't have the time then to poke around my car so I gave it a rest then.
Everything was like that for a month or so and last 2-3 weeks (I think) another problem occurred.
When the engine is cold it had troubles starting up. This went to trying to start it up until my battery is near dead. Cables did the trick but next day I've talked to a friend who repairs cars and explained all above and told him that it might me dirty injectors.
He cleaned the injectors (with some professional stuff machine) but the problem still persisted.
After that we've checked everything. Injectors are cleaned (look like brand new), new spark plugs, no spark plug cable problems. New ignition gizmo was borrowed from the store (dunno the english word for it) but same stuff. Also the new MAF was tried on, same problem. No vac leaks. Engine compression is great. New battery is fitted. Temp sensor is ok. NO ERRORS! (he has some high tech diagnostic stuff for Opel cars).
The car still sometimes struggles with starting up and revs don't act normal as they should be but there is a lot of improvement from the above text. When engine is cold and fired up if you rev it up it chokes a bit. After some time it switches to LPG and then you can do what you want with it its perfect but switch it back to gas (when its not on working temp) and it chokes again if you rev it up. Back on LPG and it acts perfect. When working temp is achieved the choking problem is gone (or if it appears its 1 out of 100 i guess). Again if rev'd up in place it goes back to normal idle. If driven or moved few meters mostly idle rev will be elevated a bit and then after a sec or 2 go back to normal.

Wall of text. I've explained the best I've could. Maybe I got lost in explanation and missed some details so point them out
Ive been poking around the net and came to a conclusion either crank shaft sensor or ICV is giving me headache.

Anybody has any experience with this kind of problems (or similar)?

Thanks for your time.

P.S.
Opel Omega, X20XEV on LPG, 1997.

[Michael2.6]

Does it work better on petrol or LPG

[TheBoy]

Do you have facilities to read the Coolant Temp sensor?


To clarify, when the engine is not up to temp, it runs OK on LPG, but poorly on petrol? Or have I misread?

[Andy H]

In the absence of diagnostic kit I would highly recommend pulling the plug on the coolant temperature sensor, squirting it with contact cleaner (or WD40 ) and plugging it securely back in place.

I used to have a 2.0 Carlton (Omega A) where the sensor is exposed on the front of the engine. It used to run well in wet weather but like a pig in dry weather. I eventually discovered corrosion on the pins in the CTS connector. WD40 fixed it

[zuluf]

Does it work better on petrol or LPG

Work is the same when engine is warm aka achieved working temp. When cold it chokes a bit when when reved up on gasoline.

Do you have facilities to read the Coolant Temp sensor?

To clarify, when the engine is not up to temp, it runs OK on LPG, but poorly on petrol? Or have I misread?

It was read twice with diagnostics. When it was read is showed temp same as it was in the air (+/- 1 or 2 deg)
For the rest read up above.

In the absence of diagnostic kit I would highly recommend pulling the plug on the coolant temperature sensor, squirting it with contact cleaner (or WD40 ) and plugging it securely back in place.

I used to have a 2.0 Carlton (Omega A) where the sensor is exposed on the front of the engine. It used to run well in wet weather but like a pig in dry weather. I eventually discovered corrosion on the pins in the CTS connector. WD40 fixed it

Will try that tomorrow just to double check it. I think my friend did inspect the connector but just to be sure.

[TheBoy]

It was read twice with diagnostics. When it was read is showed temp same as it was in the air (+/- 1 or 2 deg)
For the rest read up above.

Was this when the engine was hot?

The symptoms would point to a coolant temp sensor giving wrong values to ECU (has LPG installed purposely modified it?)

[zuluf]

It was read twice with diagnostics. When it was read is showed temp same as it was in the air (+/- 1 or 2 deg)
For the rest read up above.

Was this when the engine was hot?

The symptoms would point to a coolant temp sensor giving wrong values to ECU (has LPG installed purposely modified it?)

Temp was read when it was cold. As for LPG I don't know. It was installed by previous owner so I don't know every detail. As said, I will try to check the temp senor connector tomorrow though its in a pain-in-the-ass location. It is somewhere below the EGR valve right?

[zuluf]

I've checked CTS connector today. It was clean and shiny as if it was new. Anyhow gave it a bit of wiping and sprinkled a bit of contact spray in it. I've also checked the connector on the radiator near the cooling fan because it was suspicious but also all in good condition.

I've poked a bit around the net again and stumbled upon www.topbuzz.co.uk on some forum and there's a how to about the CTS. Is there any chance that the diagnostic tool can misinterpret information or any of those conditions/errors mentioned in the guide are easily spotted with it?
Again today the same experience. When cold (after aprox 12hrs not running) I had to crank the engine for 4-5 seconds and then it "caught up" and started. Again some chocking when running on petrol cold and after switching on LPG runs like a charm. When not completely cold the engine starts immediately.

[zuluf]

Another update.

I've checked the fuel tank because something bothered me and I've found out that some incompetent expert didn't fit the lid and gasket on the tank when they closed it aprox month ago when they measured fuel pump pressure. This surely caused a air leak in the system and I guess that it affected the pressure within the system. (that explains engine could start when left alone and tried restarting after few minutes). Also I've been poking around with fuel itself and I think it also added to the problem because after all this I can start the engine normally but to be sure the problem is gone I'll have to wait few days and time itself will tell if the problem persist because for now it seems like I've fixed it.

Although, the idle rpm still gets elevated from time to time and I can only guess that ICV or TPS is feeding false info to the ECU on those moments and to be sure I'll check (or quadruplecheck this time) for vacuum leaks. Any opinion on that would be appreciated

I hope this info can help someone

[cem_devecioglu]

Another update.

I've checked the fuel tank because something bothered me and I've found out that some incompetent expert didn't fit the lid and gasket on the tank when they closed it aprox month ago when they measured fuel pump pressure. This surely caused a air leak in the system and I guess that it affected the pressure within the system. (that explains engine could start when left alone and tried restarting after few minutes). Also I've been poking around with fuel itself and I think it also added to the problem because after all this I can start the engine normally but to be sure the problem is gone I'll have to wait few days and time itself will tell if the problem persist because for now it seems like I've fixed it.

Although, the idle rpm still gets elevated from time to time and I can only guess that ICV or TPS is feeding false info to the ECU on those moments and to be sure I'll check (or quadruplecheck this time) for vacuum leaks. Any opinion on that would be appreciated

I hope this info can help someone

the solenoid behind the dual ram caused that on my 2.5 V6..

[zuluf]

Well, that doesn't help much because as said above mine is 2.0l 16v (x20xev)
Although one thing I've noticed when you "went out the engine" e.g. shift gears on 4-5k rpm with pedal to the carpet (not metal ) afterwards it drops to idle speed with no problems and hesitations and stays that way until driven normally for some time or shut off.