cylinder down on mk iv turbo

[mikeyh]

hi there had a missfire all week trying to find what the problem was but no luck until today when i did a compression check.i found that all cylinders were running around 170 apart from one which was only a hundred.is this most likely to be a valve burnt out?do the supras suffer with cracked heads or piston failure,rings etc etc. also who do you reccomend to carry this work out would like someone who knows what there doing to take a look.

[michel lane]

supras are know not to go wrong in the engine area's i think you have just had a bit of bad luck . try some of the southern traders to sort you out . sometimes when you pull the engine apart , it may be cheaper to buy a second hand engine , then repairing the old one. well look at the good side , forged pistons and head work aswell, which means more boost !!!!!!

[mikeyh]

yes true but a bit low on funds at the mo hopfully wont be too bad lol

[eyefi]

get a leakdown test done, that will show where you're leaking. anyone should be able to do this. then choose your engine builder.

 

sounds like a valve because your not describing any other symptoms, but who knows.

 

good luck

[mikeyh]

its not overheating its not burning oil loosing water etc and only misses on idle although it did begin to miss or hold back on high boost set at 1.1-1.2 its fine on 0.7-0.8

[eyefi]

might just be plugs then and a dodgy compression reading (bad meter seal or something)

 

try new plugs and another compression test

[mikeyh]

the plugs havnt even done 100 miles yet i put ngk bcpr7es in plus it was a mac tools compresion tester might be worth ago though do you know of any good garages that you can reccomend

[s crane]

ring 01206861791 g b h motor sport colchester tell steve crane told u to ring he will look after u best of luck m8

[eyefi]

sounds like your plugs should be ok. maybe coilpacks??

[JohnA]

One cheap thing to try is going through half a tankful of fuel after you've added a bottle of STP's "Total System Cleaner" (at half of a supra's tank it will be at high potency)

This will clean most carbon deposits under your valves.

Then do the compression test again.

IF you're lucky, it will be better, IF it was a dodgy valve not closing properly. Never seen that sort of cylinder pressure variance from deposits, but hey, for £15 it's worth a try, I'd think.

[michel lane]

eyefy is right here , it sounds like your plugs . get some ik24 this should solve your problems . spark plugs can be doggy when new.