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Rolling Road


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went to rolling road yesterday had a few problems main one was didnt think i would make it car was gradually getting worse driving on the motorway was a problem heavy traffic doing 55 to 60 mph was just at the right revs and speed to give me problems on a neutral throttle it would sound and feel like you were decelerating from high revs so to avoid this i either had to be accelerating or decelerating once off the motorway it got worse it would stall at junctions and roundabouts and was reluctant to restart anyway got to steves and had to find and sort the problem turned out it was the vvt which had somehow decided to stay at full advance permanently couldnt understand why cos it had been fine for weeks so after a long time of finding and correcting the problem the RR session could finally start so after many hours the results were very disappointing whilst the engine is running really smooth i have had the plugs out today and they are a perfect colour power is lacking i am suspecting i have the wrong head gasket compression to low about 145psi and maybe vvt not working correctly maybe the solenoid maybe the vvt map but trying to get a map to compare to is impossible

so left scratching my head

and because of steve having a few problems with his computers i dont have a bhp figure :bad:

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Don't assume low compression figures mean actual compression is wrong. Mis timed cams will make a big difference...my XE went from 210 to 130 gradually for no obvious reason, plus lost all low down power. It turned out that the vernier on the inlet cam had come slightly loose & ended up 5 degrees advanced over the correct figure. Get the VVT sorted first then check compression figures again

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ST170 engine does have shockingly low cranking compression figures. I had my head skimmed and ground flat. I know I have 10.5 : 1 CR by chamber volumes but don't manage more than you on cranking cylinder pressures. It's because the cams are far retarded at cranking speeds. (These engines are also heavy breathers!)

I would run the VVT Pro to control cam advance. It does what it says on the box (once you master the blasted clunkiest software in the world.)

 

Nigel

 

Basic 2D VVT map is in the paperwork. You can always wire up, write the map in and save it to the VVT Pro ECU. Stupidly you can't save a map to the laptop.

Edited by Longboarder
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