General problems, please help

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General problems, please help

fizzell86

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Right where to start.

A while ago the car produced a wierd sort of missfire,it would do it at high speed and while accelerating, but also on idol it would vibrate a little. I thought it would just be plugs old or leads maybe. Put up with it for a while then another problem occured where I had to change the rad. Changed the rad and at the same time done the stat.

When I went to change the stat there was not one in there, obv probs then. anyway the HG ends up blowing so I do all that, whilst doing that I learn that the water pump was gone, hense the stat being removed. So all done new HG, bolts, water pump, timing belt and tensioner.

from there the car was very smokey, I thought this would clear but hasnt. I then work out now that the MPG is not going past 28.5? and the missfire is back with a vengeance. I was told maybe the timing was not right. So I check it and decide to drop it back a notch, as while looking at the mark on the head it can be deceving depending on what angle you look at it. then the misses takes it out and it drives fine. I think job done.

Then today the missfire is back, the mpg is the same and still smoking. I don't understand.

I would really apreciate help on this as much as possible as I'm so close to just doing an insurance job :)

it's a MK 2 8V btw
 
Right where to start.

A while ago the car produced a wierd sort of missfire,it would do it at high speed and while accelerating, but also on idol it would vibrate a little. I thought it would just be plugs old or leads maybe. Put up with it for a while then another problem occured where I had to change the rad. Changed the rad and at the same time done the stat.

When I went to change the stat there was not one in there, obv probs then. anyway the HG ends up blowing so I do all that, whilst doing that I learn that the water pump was gone, hense the stat being removed. So all done new HG, bolts, water pump, timing belt and tensioner.

from there the car was very smokey, I thought this would clear but hasnt. I then work out now that the MPG is not going past 28.5? and the missfire is back with a vengeance. I was told maybe the timing was not right. So I check it and decide to drop it back a notch, as while looking at the mark on the head it can be deceving depending on what angle you look at it. then the misses takes it out and it drives fine. I think job done.

Then today the missfire is back, the mpg is the same and still smoking. I don't understand.

I would really apreciate help on this as much as possible as I'm so close to just doing an insurance job :)

it's a MK 2 8V btw

I;ve never owned an 8valve petrol but I know from looking through here tht the 8valver will run a few teeth out on the cam / valve timing, but will do so just as you describe... Did you have the Head skimmed? Ideally you should use locking tools rather than depend on timing marks alone.
 
Thanks, I know what your saying but they were unavalible to me.

I don't understand though if this is the case why it was fine for a few miles
 
Can't lock the cam/crankshafts on the 8v and it runs very smooth even with teeth out. Mine was 3 teeth out and running smoothly.

First thing to ask is, is it using coolant? or oil?

If so one of them is still being burnt off so if head gasket is all okay you'll be looking at blown piston ring(s), cracked cylinder head. But that's IF it's still using the coolant or oil.

Otherwise is the system definately bled properly?
 
I'm sure its bled properly, not using any coolant, possibly burning a little oil but hard to tell, the thing that's wierd is that it's only doing the misfirng sometimes. Almost like when the car has warmed, it's worse uphill and it doesn't do it if you really reall feather the peddle. It stinks of fuel aswell.

any more advice greatly apreciated.(y)
 
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If its ok when cold its possibly the lambda sensor.

By default the engine runs rich. When it heats up the lambda is switched into circuit and the ECU reduces the fuel flow accordingly. If the sensor is faulty the fuel mixture stays rich and causes a missfire.
 
thanks,

would this cause the 28.5mpg issue though, and could this of worsened with the overheat at all?
 
Hello mate :)

I can help with your timing but as for your engine burning something, gonna have bit of a think on that one (y)

If your timing belt is a new/recent one then it'll most likely have two lines across its width in two separate places as well as directional arrows.

With the arrows showing the correct direction of rotation and the engine more or less at TDC on number 1 cylinder, fit the belt so that the first line is aligned up with the timing mark on the crank end timing belt sprocket. Loop the belt the way it should go on the motor and then the second line across the belt should line up with the timing mark on the cam sprocket.

The other way I know (please feel free to chime in guys) is to either use a long screw driver through plug hole number 1 and carefully determine TDC that way OR use the fly wheel timing marks using a torch through the square port hole in the bell housing more or less under the battery tray (remove rubber cover first).

That'll get your timing in order mate, not sure yet about the fluids its burning. Good luck with it though :)
 
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28mpg on an 8V is very poor then with a missfire under power it's all pointing towards a failed/faulty lambda sensor. The voltage output needs to be tested. See the guides.

Burning smells could be an oil leak from the rocker cover gasket. Easy to fix with a new rubber gasket - tighten the screws just enough to avoid squeezing the gasket out of place.

The cam belt might be out but on an 8V it wont cause damage. Do the easy stuff first.
 
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thanks, I will start by testing the lambda then, can't find any guides though mate?
 
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