saespyder

So, after the timing chain debacle of a few weeks ago, the car is back in the shop and they have no idea what is happening. The car is running rich at idle.

Compression reads 175 across all cylinders, so it doesn't look like a repeat of the timing chain issue, although there are two cam-related codes coming up: Cam timing implausible signal and Camshaft exhaust signal sensor. They are stored though, there are no active codes to read (which seems odd).

Other notes are:

1. Some sort of interruption between the emu and fuel rail
2. Passed the smoke test, so it doesn't appear to be a loose hose anywhere
3. The car has already been through the cam sensor recall and there is no oil showing where the usual leak would be
4. Fuel sensor 2 is jammed, though I'm not sure that's related to what's going on now.

They're going to start checking the bypass actuator and related components next, but they're just fishing at this point. They've contacted other shops and haven't received any help with these specific symptoms.

Any ideas?

Glyn M Ruck

I'll bet they have fitted the timing chain 1 tooth out on the cams. Tell them to check the cam timing. PROPERLY!

saespyder

It seemed to be running fine for the two weeks between the repair and the new issue. Wouldn't a chain adjustment have surfaced as soon as they started it up right after the fix?

Glyn M Ruck

Then why are they getting a cam timing implausible code. Also possible that one of the cam adjusters is damaged. They should check the basics first. Then they can chase down possibilities like a clogged Cat, MAF etc.

saespyder

So, it turns out the timing chain skipped AHEAD two teeth. No bent valves, but that's why I was losing power and passed the compression test. The head mechanic said he was able to slip the chain back two teeth without even taking it off, so they're putting a new chain on today. We'll see if that cures the problem.

If this was the only issue, what else should I look out for? The tensioners were replaced a month ago during the top end rebuild and the cam sprockets don't look worn.

Glyn M Ruck

If the chain is the correct length & they have assembled things properly then they don't understand the use once tensioner.

saespyder

I expect to hear from them tomorrow about the old chain length, but there are a lot of fishy things about this. I'm curious to see what they say tomorrow morning. Will report back. Thanks again Glyn.