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Hi, I reported last week of a warped head on my b230ft 760 due to water valve failure at 100km/h. Decided to go the route of a rebuilt head. Well, now, we have a case of a car that runs great when turbo spools up past 5lbs, but the car is just a dog off the line from standing start. This was not the case at all before overheating the engine. The best way to describe it is that it bogs down, and takes three times as long to get going, and then hits its stride once the boost gauge reads 5 lbs or more then off to the races. nothing else was changed other than the head, and all new gaskets, all vacuum checked. On an unrelated note (perhaps) the car has been running lean and still is after the injectors were benched and are flowing as new. This was done when the car was in for the new head. The lean condition existed before the head got warped, and in pulling the old head, it was clean as a whistle (too clean) showing that the car has been running lean for a while. A recently installed A/F meter brought this to my attention when i installed it about a month ago.
So my problem/question is two-fold. Any suggestions on why changing a head with a good rebuild would cause such a performance problem (car bogs down off start, then comes alive once 5 lbs boost reached) when nothing else was done at the same time, other than having the injectors bench cleaned. Second question, i have a nagging lean burn issue and all the usual has been checked including:
Both fuel pumps recently replaced, and double checked (unrelated to this issue)
Injectors bench cleaned
ECT changed
O2 Sensor replaced
No vacuum leaks (smoke test done)
All new turbo hoses allround
AMM tested, and three other known good AMM's swapped in to no avail
ECU swapped for lack of any better suggestions
I have installed a Dawes, running 10 lbs, with a A/F meter
Sincerely,
Stumped in Hamilton, Ontario
Peter
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