2.0 Turbo Timing Advance Mechanism - Maintenance and Repair Forum

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2.0 Turbo Timing Advance Mechanism
Monday, October 04, 2021 12:24 PM

89 Sunbird GT, 2.0 Turbo engine.

As of my previous post, I was having an issue where the exhaust system was running way to hot to the point where it was melting my fan. It was suggested that I was running too lean. To go along with that, I wondered if maybe my timing was the issue. The exhaust only seems to get that hot at higher speeds and therefore higher RPM's. Does this sound like an issue with the timing advance/initial timing? The crank is at 8-10 BTDC and the cam is at 0, but I had to turn the distributor a little to get it to idle low enough to be drivable.

If it is timing advance, what/where is that mechanism? How would I verify that it's working? My thought was that if that isn't working correctly, it would be allowing fuel to ignite with the exhaust valves starting to open, thus allowing combustion (think heat) into the exhaust. Does this seem logical?

All help appreciated!

Re: 2.0 Turbo Timing Advance Mechanism
Saturday, October 16, 2021 11:51 AM
To my knowledge, the advance is electronically controlled (I could be totally wrong so don't quote me). I doubt timing at your distributor is your issue however. Have you checked to make sure your cam timing is correct? How old is your timing belt? On my car, I had a newish belt that had been replaced by a PO. When aligning the timing marks on the engine, the top timing mark on the cam didn't line up exactly perfect. The engine ended up being one tooth off. The car ran, and ran well, but also ran LAVA HOT while feeling low on power. I had to experiment a little, which meant taking the belt off and adjusting the cam one tooth more than once. However, once I correctly timed the engine, it ran like it was designed to. The timing mark on the cam still doesn't line up EXACTLY perfect, but it's where it's supposed to be. I share this because it's VERY EASY to misalign the timing by one tooth on the belt and cause some fairly perplexing issues. I don't think this is your problem, but worth looking into if all else fails.

I would really look into the possibility of running too lean. If your engine is not compensating the boost with extra fuel, you can certainly run HOOOT! I'd also make sure you're getting the appropriate fuel pressures, that your injector isn't dirty or plugged, that your sock, filter and tank are clean or new, and that you don't have any vacuum leaks. I sure hope you don't have a warped head or intake manifold. That would be a bummer.
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