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Old 05-07-2010, 09:43 AM   #30
ARModen
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Join Date: Oct 2009
Location: New Orleans
Posts: 146
I believe people are directing you to the intake/maf based on the O2 sensor errors. These are more likely caused by the misfires. Gas that's not completely burnt in the cylinders when they misfire ends up partially burning in the exhaust manifold. This gives the O2 errors and can lead to cat failure.

I think the misfires can either be caused by incorrect timing, or an electrical/computer issue. If it was a timing chain issue, you'd probably just have errors on one bank. If it was an IMS failure (both chains) you'd hear your valves high fiving your pistons. So probably electrical/computer related. Of course that's 90% of the car!

For fuel, I'd check and make sure you have pressure at the test connection when the car is cranking. A pressure tester at autozone is only about $20. It connects to a test connection on the passenger side fuel rail. You can position it so it's visible from the drivers seat while you're cranking the car over. You can rent a set of "noid lights" for free ($20 deposit again autozone) and check the fuel injectors at the same time in almost the same location.

Electrical problems usually have lots of symptoms in cars that are so dependent on electronics. Have you had issues with any of the following not working: alarm, remote, windows, top, radio, lights? Dirty battery terminals or a failing ignition switch can cause your problem, but usually come with a dozen other issues.

Computer issues can be checked with a durametrics or shop tester. If you're able to read codes with a regular OBD2 scanner then the DME is probably working. It may still be the cause of the problem if it's getting bad inputs. A bad MAF should cause it to run like crap, but shouldn't throw off the timing because it affects fuel/air ratio not timing. Failed cam/crank sensors are more likely to cause misfires because they are timing inputs.
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