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Re: ARI, here are the results from your sugestions Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 25 Nov 2008 22:46:14
In Reply to: ARI, here are the results from your sugestions, James, Tue, 25 Nov 2008 08:00:50 Members do not see ads below this line. - Help Keep This Site Online - Signup |
By taking the hose off of the W line on the BPC and getting boost into the red, it shows the turbo is working well. It doesn't say much about the wastegate.
We kind of backed into this problem based on a question about fixing the valve way back at the beginning of October. So let's start at the beginning. This shouldn't be a treasure hunt - information is power.
You've got a '92 Turbo, TCS. I noticed you said 98 octane fuel - where are you located? I'm guessing Europe, so that's a RON rating about equivalent to the 93 R+M/2 we get in the US.
You're not getting full boost. Did you always have this issue, or has it come on recently?
Does the Cruise Control work? Oldsaab's point is very good. You'll only have a switch on the brake pedal, but it can mess things up.
Brown spark plugs is interesting. What kind of brown? Spark plugs should be grey; brown is usually a sign of running rich or maybe some oil in the system. But color can be subjective - grey is like a leaden sky. A poor spark plug will be brown like the color of tobacco. Replace the spark plugs - they're not expensive, and color isn't something they should have.
Is there anything else to know about the car? How long have you had it? What maintenance has or hasn't been done? When was the air filter last replaced? Was anything associated with the boost loss, or was it always that way?
Find a nice uphill, or merge onto a highway where you can really get into the throttle. See the boost in 2nd and 3rd gears - up to about 65 mph where it'll shift into 4th even with a very heavy foot. Do you get near full boost there?
When the car is off, where does the boost gauge needle sit? It should be in the gap between white and yellow.
Do an adaptation run. The Trionic system adjusts to engine components, and you can speed things up with an adaptation run. This is for an auto tranny car:
Warm the car up, and make sure you've got good fuel.
Find a long hill to go UP. You need to get the engine to go through the rev range of 3750-4250 RPM under full (or nearly full) throttle for more than 3 seconds.
Accelerate as hard as you can between 3000 RPM to 4500 RPM without dropping a gear. 3rd gear is good for this. Watch the maximum boost.
Repeat until the boost doesn't increase.
Lack of full boost can be due to a lot of things. Yes, it could be a weak wastegate spring or a mis-adjusted wastegate rod. Never adjust the wastegate rod unless you know that's the problem. It might work in the short term, but if there is some other issue, the engine will drop the boost back down, and now the rod is mis-adjusted. Wastegate springs do get weak, but it's not the likely candidate.
The most common reasons for base boost (not getting full boost) is the APC system thinks there is a good reason not to provide it. The APC cuts back boost if it detects knock (via the DI), if the cruise control is on, or if the brake pedal is pressed. Or if it thinks any of that is happening, due to worn spark plugs, weak DI, bad switches, etc.
If the car feels like it is strong but the gauge doesn't respond as it should, it can be an air leak to the gauge or a weak gauge. With a sample of one, it's hard to know if a car is boosting fine but the gauge reads wrong, or the car isn't boosting right.
Next comes the BPC valve itself. A sticky BPC can give strange boost results. It can be the valve, either mechanically or the coils (electrical), wiring, or the drive circuit in the APC.
Last comes the wastegate and the turbo. Turbos usually give plenty of boost or none at all. The usual problem with a wastegate is that someone adjusted the rod length when they didn't get full boost, figuring that was the issue when it actually was something else. Wastegates do fail, but it's low on the probability list.
So let's start at the beginning. Please try to give background on the car, when the boost went away, and if the CC is working. And where you're located, as different markets had different systems.
posted by 76.252.197...
, Tue, 25 Nov 2008 22:46:14 <-- Viewing This Message
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