turbo ls boost problems?
04-14-2013, 05:22 PM
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turbo ls boost problems?
So, its a b18b with a t3/t4 .50 trim turbo cast manifold, greddy bov, tial wastegate, 440cc
injectors, tuned at 10 psi with chrome. made 221whp 198tq. So after the tune, went
on a couple freeway pulls. 10 psi consistantly. after the 3rd pull, boost started to taper down,
so i thought it was some sort of boost leak or exhaust leak. So, next day pressure tested it
at 25 psi, no major leaks found besides bov flange, so i rtv the flange and rechecked, no
leaks. Inspected exhaust system. full 2.5 in exhaust with a resonator, no leaks/cracks.
inspected wastegate. replaced wastegate gasket. test drove vehicle. car still boost around
3-4 psi. thought it was a bad wastegate, swapped it with my friend's brand new in box
wastegate with new fire ring, same thing. swapped turbo with same size turbo, same thing.
swapped bov, same thing. smoked tested system to make sure no leaks are present, no
leaks. checked my spark plugs ngk 7's, they look nice and dark brown. Prior to this problem
car was boosted for 9 months at 6 psi no problems. I'm running out of ideas. as of right
now, car won't boost over 2 psi. engine starts up fine, idles fine, no smoke, no rough running, does not misfire at high rpms or anything like that. it just feels like i'm boosting at 2 psi.
last thing i can think of is engine damage even though no symptoms of it what so ever. I shall do a compression check tomorrow and maybe leak down. but if anyone has some sort
of idea that can help me, that would be much appreciated. I also have a wideband installed. it's running slightly rich which is o.k but it tapers around 11 to 12 at high rpms.
injectors, tuned at 10 psi with chrome. made 221whp 198tq. So after the tune, went
on a couple freeway pulls. 10 psi consistantly. after the 3rd pull, boost started to taper down,
so i thought it was some sort of boost leak or exhaust leak. So, next day pressure tested it
at 25 psi, no major leaks found besides bov flange, so i rtv the flange and rechecked, no
leaks. Inspected exhaust system. full 2.5 in exhaust with a resonator, no leaks/cracks.
inspected wastegate. replaced wastegate gasket. test drove vehicle. car still boost around
3-4 psi. thought it was a bad wastegate, swapped it with my friend's brand new in box
wastegate with new fire ring, same thing. swapped turbo with same size turbo, same thing.
swapped bov, same thing. smoked tested system to make sure no leaks are present, no
leaks. checked my spark plugs ngk 7's, they look nice and dark brown. Prior to this problem
car was boosted for 9 months at 6 psi no problems. I'm running out of ideas. as of right
now, car won't boost over 2 psi. engine starts up fine, idles fine, no smoke, no rough running, does not misfire at high rpms or anything like that. it just feels like i'm boosting at 2 psi.
last thing i can think of is engine damage even though no symptoms of it what so ever. I shall do a compression check tomorrow and maybe leak down. but if anyone has some sort
of idea that can help me, that would be much appreciated. I also have a wideband installed. it's running slightly rich which is o.k but it tapers around 11 to 12 at high rpms.
04-15-2013, 05:51 PM
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04-16-2013, 06:18 PM
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Re: turbo ls boost problems?
I am using stock ignition coil. Rich would be black wouldnt they? Plus the wideband showing me stoich under boost. Maybe a little rich. But i was running way richer than this before my tune. I dont think i'm having ignition problems. I would start sputtering if i did. I just check compression. 150 psi across. I heard an unbalanced turbo can cause this symptom. Can anyone relate to this?
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