As for the voltmeter, no need, you are using an afr meter, this will give you an indication as to whether it is working correctly.
Forgot about the melted piston, better change the plugs too.

As for the cossie pistons... Forged pistons arent always worth it...They may be stronger, but when this happens, it really makes no difference what they are made of!! valve seats came out, and pulled the heads off the 2 valves, at 6000rpm...OOPS!!


[Edited by ustolemyname??stevieturbo - 9/8/2002 2:32:53 AM]

 

the engine is jerky when driving along. im only using light throttle as ive just rebuilt it.

it idles fine and smooth, doesnt smoke, and sounds really nice.

however, when driving, is quite jerky. could it be the plugs? as ive used the old ones again, was going to replace them after the run-in period.

i replaced the fuel pump too.

any ideas?

thanks
ian

 

anyone??

i just want to drive it now

 

o2 sensor..???

Dan

 

better bl**dy not be!

 

Try unplugging the lamda and it will resort to the fixed map which will probably be a bit on the rich side. It may be that the oil from when the piston failed damaged it ?
Having seen your piston I would be surprised if the plug on that cylinder wasn't u/s ??
If your o2 sensor is OK it would be worth monitoring it closely, would hate to see any damage to those lovely cossie pistons

 

andy, your the 3rd person to mention the lambda sensor (stevie turbo also).
steve mentioned that it would affect light throttle, and that is all ive been doing to run it in.....hmm ?

if its duff, i'll be playin footy with it

 

so if i unplug it, apart from being a little rich, it should run smooth if the lambda is faulty?

 

As far as I'm aware My one did, it will show a CEL when disconnected.
Try a voltmeter across it to find out if it's duff.

 

where do i put the voltmeter? and what voltage should i see

cheers

 

how much did you pay for a lambda?

 

ah, i can see the voltage with my afr guage cant i, should go up and down at idle.
thinking about it, it only works now and then recently, and didnt work before

i'll have a gander tomorrow eve when home from work, off to bed now, early morning tomoz

cheers, ian

 

Yes, your AFR should be cycling up and down at light loads if it's the wide range reading type ? Some AFR's only monitor 800mv upwards (dawes type) and may not pick up the hunting.

Voltmeter should swing between 100 - 800 mv somewhere during closed loop (light load) running. Measure across the pair of wires sharing the same colour insulator (usually a black or white pair) the 3rd wire is the 12v heater supply. (NB it needs to be hot to work)

I paid £50 for one from halfords and it has been fine up to 850 C exhaust temp Although others have not had the same success with them for some reason ?

 

Is that recent?

Michael's engine?

ouch indeed

 

is it like beef jerky?

Maf sensor (unlikely on old car) or lambda sensor (more likely, replacement can be v.cheap from PartCo, circa £35)

Paul

 

My old 3.9 Rover V8 engine. The heads were in a similar state, and the pistons had also managed to punch a hole throufgh the side of the liner into a waterway. They were Ross forged pistons from the US, made to roder, which only cost about £600 for 8, which makes the subaru ones quite a ripp off, at well over that for only 4 pistons.

 

thanks for the replies

steve, dont be showing me piccies like that mate

right, i think ive eliminated the lambda. unplugged it, drives the same, still jerky.
dont think its the maf, as it starts and idles perfect, and idles perfect when stopping at junctions too, so i think i can rule that out??

checked all connectors, no luck there, all fine.
checked all boost/vacuum pipes, all fine.

what next....replace the plugs?

ian

 

Hi.
I have just had a pistonfoult like yours and iam sure that it is the plugs.
I put in the old ones too and it just dosent work til you change them.
They have been covered in oil from the piston foult.

Skassa

Ps:good luck

 

yes i think its the next step, my mate is going to get me a set of ngk PFR 7B (iridium tip) for cost price tomorrow, so i'll soon find out. driving it before, its starting to feel more like a bad spark.

thanks
ian

 

Ian, forgot to mention!

WHen piston/cylinder has been detting, you can end up with aluminium deposits on the plug that short the insulator.

Also do a diagnostic check, as some faults don't show a CEL but will log an error code.

Paul

 

aha, so it may not be visible damage to the plug then. im getting some plugs tomorrow, and i just hope it will cure it

failing that, the diagnostic check you mention, is that where the two under dash connectors are plugged in, then count flashes etc or is it a garage job, sun machine etc?

ian

 

just got some NGK PFR 7B's.

going to fit them in a minute, will report back later....fingers crossed this works!

ian

 

changed the plugs earlier, and it drives perfect!!

however, about ten mins after driving, it went a bit jerky for a few minutes, but is now fine again.

i'll give it a good go tomorrow, absolutely lobbing it down here now!

cheers
ian