Weird 1.2 SPi problem

[novaguy08]

Hello guys,

I posted here resently titled "semi hessitant 1.2" and i was told that it was over fueling from to what i though was noisy tappets, i was told that it was pinking insted! However i have just pulled the plugs out and 3/4 are normal, peered through the hole and the piston tops seemed a bit black but other then that perfectly normal, the last one on the other hand (cyl 4) looked normal in colour however had a small amount of buildup stuck to the electrode, i checked the good ol' haynes and it says under heavy deposits "A Build up of crusty deposits lighty-grey sandy colour in appearance, Fault: Ofter caused by warn valve guides, excessive use of upper cylinder lubricant or idling for long periods" This has confused me somewhat as idling would cause all 4 to be like that, worn valve guides would mean that it would rattle like fook (i believe) constantly.

Now let me discribe whats going on properly

Whilst driving along normally usually at 3-4k RPM a get kinda of a rattle which i thought was noisy tappets people have said that its overfueling, i thought that it was as i can make it backfire out the inlet however looking at the plugs it is showing that its working fine??!! again reading through the haynes manual it saays that pinking can be a symptom of the engine needing to be de-coked, however i thought that current petrol with all sorts of detergants ect it didnt need that to be done anymore?! the only other relevent answers to the symptom are the fuel octane being too high, which unless tesco (yes TESCO there no other good petrol stations in my area!) are putting 95ron in their 99 ron tanks i doubt! and weak mixture however its EFI and not running lean (hot)

So im baffled:cry: !! Is it pinking or isnt it?!?:wtf: Ill try to get a video up of the engine doing it, but if anyone can help........... then please HELPPPP!!!:confused:

Ta guys :D:thumb:

[novaguy08]

Right, as no-one has got back to me i have been thinking about this and i believe that the valve guides are worn on cyl 4, which isnt good news for me as i not have to take the head off and that means a headset, and more than likley means im going to have to get some broken exhaust studs removed, head skimmed (going to cry :cry:)

[MK999]

Shouldn't backfire out the inlet as the exhaust valve opens after the compression stroke... would point towards bad timing usually, but all of those symptoms combined would point to No4 valve not seating properly? That would cause it to backfire through the inlet and possibly muck up the oil seal meaning you get oil in that chamber and the sooty deposits.

[novaguy08]

its not sooty, but if the inlet valve guide is not right and the valve isnt seating properly then that would be my best guess. Think ill be calling my insurace company tomorrow and seeing how much it will cost if i chuck an SRI lump in there or franenstein the engine with something i read earlier on.
Yes your right there normally if it was firing out the inlet first stop would be timing however when i put the new belt on i made sure that BOTH timing marks were on the money and seeing as there nothing happened that would suggest a tooth being jumped then i dont believe the timing is out. the only way oil would get in there is if the stem seals went

[MK999]

aye, both symptoms point to diff things but together say some kind of valve seating problem. Also, since you've timed up an engine before check out my project thread, first time I've done it and I want to be 100% before I try and fire it up lol

[novaguy08]

right well now need to figure out what im going to do....... get another head and get it reconned maybe polished or put up with it and try to bring my engine conversion plans forward?