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Chasing my loss of performance problems, I'm down to two suspects, both of which appear to be faulty- the Trionic ECU (it's going back to Maptun again...) and the head.
I thought maybe cracked head or failed gasket as the plugs were not all the same colour (although that could be caused by poor fuelling due to faulty ECU). I also have traces of oil in the coolant, although I now suspect that may be a leak from the auto rad I fitted. A block test proved negative.
Anyway, I carried out a compression test on Friday and got the following results:
Cold 12.6 11.0 11.4 12.0
Hot 13.0 11.2 11.6 12.2
Oil 16.8 14.0
The "good" range according to the gauge is 10-14 bar.
I put a teaspoon or so of oil in two cylinders to see if I had a major problem with ring wear (I wasn't expecting it, they were only done about 30k miles ago).
I'm a bit of a numpty on this stuff, but according to Haynes, there shouldn't be a variation of more than 2 bar. I've got a difference between #1 & #2 of 1.8 bar (2.6 with oil added), which is close to the limit.
Haynes lists the following symptoms/faults:
A low reading on adjacent cylinders suggests a blown head gasket, but the block test was negative.
If adding oil does not improve it substantially, then leaking or burnt valves, or a blown head gasket are to blame- observe the relative difference between #1 & #2 3.8 vs 2.8 bar
If one cylinder is 20% lower (16% between 1 & 2)and the engine has a slightly rough idle (it does), a worn camshaft lobe is suspected.
And just to add insult to injury, having done all this and swapped out the ECU and injectors, I now have a misfire under more than about 0.5 bar of boost . I tried another DI (admittedly faulty itself, but only above 1 bar last time I used it) and the same result. I can't believe it's chewed another DI- this will be 3 in 4 months if it has!! Or has the demise of the DI been caused by the faulty ECU (I don't see how myself)
Any ideas gang, other than a can of petrol and a match?
posted by 193.133.23...
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