Lanos 1.4 - Breaks and fixes itself alone

[tepih78]

Hi all,

I have a strange problem with my car. It's 1.4 lanos '98 without any kind of special electronics equipment like immobilizer, airbag, ABS or similar. Car also has LPG installed. It has close to 300 000km
Sometimes when I start the engine, the car is running but it severly lacks the power. It will go up to 40km/h in 2nd gear and giving more throttle will simply make it choke (rpm falls down). If I stop and turn off the engine and later start it again, the car would start either again in bad mode or in good mode where it behaves healthy. So the only difference is in shutting it down and starting it again.
I did diagnostics and besides one error with speed sensor, nothing else was wrong. Car is regaulary serviced.

Car also has LPG and switching between gasoline and LPG make no difference when car is running in bad mode.

Service guys told me that it could be ECU. Could?! Not sure...

Replacing an ECU is not a problem, the problem is replacing the ECU and not fixing the problem.

Any idea what could be bad with my car?

[benzino]

i thought you should always start the car on petrol and then switch to LPG?
it makes no difference?

Mr G on here has experience with LPG, maybe ask him

[tepih78]

This is not an issue with LPG. I just noted that the car has LPG but the LPG is disabled because when car starts in bad mode, it runs somewhat better on gasoline than on LPG and there are no risk of LPG detonations. So now I run completely on gas all the time.

Yes, I do start the engine on gasoline. Just disregard I ever mentioned the LPG so that we don't discuss about it unneccessary.

I start the engine, sometimes its ok, sometimes its not ok. The symptoms are as described, engine severly lacks power (2nd gear up to 40km/h) with lazy acceleration. More throttle appears to choke the engine, exaust appears to be warmer than usual, engine sounds different (humms in lower frequency), when giving throttle at idling it will spin up and when releasing the throttle one can hear slight bangs in exaust.

Diagnostics guy says that is probably ecu because it breaks and fixes by itself.

I haven't got time to go under the passenger seat and take a look at ECU. Is there a way to reset the ECU or someting like that? Is disconnecting the battery enough? I have no immobilizer, abs.. it's plain simple car without any electronics comfort packages.

[benzino]

ok mate.

if it's the ecu, it should throw a code... should

it could be a loose ground somewhere or a sensor intermittently shorting out

could it be a head gasket failure?

[tepih78]

Hi benzino,

thanks for trying to help.
This week it works almost well. I only had one incident and it fixed itself till morning when I could drove normaly again.
I am waiting for OBD diagnostics that I ordered on ebay to arrive so that I can connect with my laptop on ECU and save parameters when it works bad and when it works ok. Then I will check to see if there are any suspicious differences.
If it is a head gasket failure, then it wouldn't fix by itself. It would remain broken once it breaks. This is at least how I see it.

[tepih78]

My car is now finaly fixed.

Replaced head gasket, Lambda sensor, exhaust and intake pipe gaskets... works perfectly.
I had a broken screw on one exhaust pipe so the exhaust was leaking or air comming in. This all affected ECU runtime parameters.

[RichieOzzie]

Sounds like the problem I had/have to me.

Starts, runs well from cold, no probs. Set off too soon, and it backfires, bangs, hesitates, feels like fuel has been cut. Stop, allow 5 mins, and it runs great, no probs.

I did notice if I gave it a boot-full, occasionally, when I came to a stop, it idled really rough.

It turns out the oil viscosity is very important in the 1.5 sohc engines.

The valve lifters can over-fill, and leave the valves half open if the viscocity is wrong.

Did some fooling around, until I got the right grade, and presto..!!, no more problems at all.

I got Mobil 2000 5w/30 in there now, and this lets the lifters ease sufficiently at cold, and perfectly at warm.

I was all set to pull the head off, and have a look in there too!!

[MMamdouh]

what was the viscosity of the wrong oil you were using before the Mobil 2000?

MMamdouh

[RichieOzzie]

Could be wrong, as like a fool, I lat a garage do it for me in a moment of madness. I negotiated with the ministry of war and finance (The wife)at the time, and she was pushing to get it done, so off she went... paid $$'s for problems as most garages will give!!

I tend to be able to spot good from bad oils, and I feel it was 20w/50. I learned many years ago that 10w/40 was max for hyd lifter based engines with the Ford CVH engines!!, they rattled like crazy when first started on a cold day. You warmed them up, stopped, let it stand for 5 mins, came back, started, and presto, rattle vanished. Actually you can get oversize lifters for them if the bores were wearing. Trouble with these engines was the lifter was moved up and down with the cam, and the surface hardening started to wear as they were a heavy mass to move. the Woo ones are just the pivot tips, which do not move with the cam. They just pressure themselves up too much, and will lift/open valves.... which is not good for the seats nor the valves.

Put min 10W/40 or 5W/30 in at all times.... no multigrade 20W/50... its too thick an oil for them. i got the Mobil 2000 for under $30 for 5L, which is good for a oil such as this, and, there is an added benefit of lower viscosity when warm, which help reduce engine working to slosh the oil around=RPM & economy, albeit slight, everything will help.

[RichieOzzie]

This is the stuff I used.

http://www.mobil.com/Australia-English/ ... _2000.aspx