Warm or cold engine and what figures should i be looking for?

 

Also, i found i have champion spark plugs, that have very sooty deposits, ive put in 4 NGK plats so far, need to get the balance bar off tomorrow and do the rest, but while im there, id like to do a Comp test.

 

So again

 

Warm or cold engine, and what figures for a TT

142-186 PSI with no more than 14 PSI between cylinders

 

online manual here:

 

http://300zx-twinturbo.com/cgi-bin/manual.cgi

Thanks Si, Forgot about the service manual.

what would cause sooty spark plugs? wrong type? gap? crap ones? over fueling?

140-160 is a realistic figure

what would cause sooty spark plugs? wrong type? gap? crap ones? over fueling?

Have you drove the car,they will never burn off the soot at idle after a cold start.

Have you drove the car,they will never burn off the soot at idle after a cold start.

 

no tax/mot so limited to in and out the garage at the moment, but going to be booking it in for a mot and taking it for a spin before hand.

 

replacing the last two champion plugs tomorrow anyway for the ngk one's

 

also going to be checking the condition of the passenger side pcv valve / hose tomorrow as that side of the plenum feeds the drivers side exhaust.

OK im am confused as hell, yesterday, ok admittedly i did the compression test cold, and also with the CAS plugged in, and with fuel still getting to the system (completely the opposite to how it said to do it in the service manual lol), i recorded a reading of

 

140 across cylinders 1 to 6

 

Just did it warm, with no fuel getting to the system, and the CAS unplugged, and im reading 100 across all cylinders? surely i shouldn't loose compression when the engine is hot, due to expanding parts.

 

is that a balls'ed engine? idle seems fine, and engine sounds good? Argghhhh!

 

**EDIT**

Oops, missed a step, "Depress accelerator pedal completely to allow throttle bodies to remain wide open" i suppose trying to suck air past them would definitely cause a low reading, ill go check again, and make sure. ugh, i hate doing pistons 5 and 6 :(

Edited April 16, 201015 yr by vodkashots

Ok, did the test properly, still reading 90psi per cylinder, on the passenger side bank, and 110 on the drivers side bank, now it could be a dodgy compression tester, as when i did cylinder 3 yesterday, it gave me a reading of 100, then i tapped it and did it again, and it shot up to 140.

 

God I'm confused. so new engine time? or dodgy compression tester?

 

anyone got one i can borrow for a day or two and send back to them?

 

Thing i did notice, was that it was dead on 90 on the passenger side, and dead on 110 on the drivers side, on all 3 cylinders per side.