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Re: Turbo cutoff at low ambient temperature Posted by Ari [Email] ![]() ![]() In Reply to: Turbo cutoff at low ambient temperature, Willy, Sat, 29 Dec 2001 07:19:49 Members do not see ads below this line. - Help Keep This Site Online - Signup |
You said it. Winter air is denser -both because it's cooler, and because it's dryer. This makes it easier to produce full boost, and boost comes in quicker.
The wastegate actuator doesn't care about outside temperature - it will limit based on pressure. But it's possible that with your particular engine (and all are different to some extent) the turbo can't produce quite the same boost on a hot summer day, so that's the limit, not the wastegate. Most turbos produce much more boost than the limit, so the wastegate kicks in to control overboost. But if you've modified the system, and the turbo was a little worn to begin with, it can only make full boost in cold, dense air conditions. So in reality, the wastegate is set too high, it's just that you don't know it in summer because the turbo doesn't kick in.
When you say 'jerking' - that doesn't sound like fuel cutout to me. When you overboost and hit the fuel cutout, the engine just plain shuts off for a second or so. Much more common is a feeling of 'missing' or hesistation, like some of the cylinders aren't firing, but the engine keeps running. That's usually due to an ignition problem. It's harder for the ignition to make a spark the higher the pressure (boost) in the engine. So any weakness in the ignition shows up at high boost as the spark plug actually not sparking, and the result is an engine that misses at boost. First off, make sure the spark plug gap is right. Too big a spark gap means it's harder to make a spark. If you DI cassette is weak, that can also contribute. If you're running higher boost levels than stock, any weakness in the ignition system will show up.
Good luck!
posted by 12.79.3...
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