Short T/E1, timing skipping/changes

Q&A regarding engines, turbos, and intercoolers and power upgrades

Short T/E1, timing skipping/changes

Postby CodingParadox » Tue Nov 09, 2004 12:16 am

So, my car's in the garage now, waiting to cool down so I can change the knock sensor. However, I did notice a few things. I tossed a timing light on while it was still parked on the street, and noticed the following:

1. The timing light seemed pretty consistent, maybe skipping one pulse in 20 or so, during a good idle. If I then pulled on the throttle cable a bit to rev it, it would start skipping pulses at higher rpms, and when i released the cable, it would skip the majority of pulses until it got back to idle.
2. When it was having a rough idle (what it does before I rev it a few times,) vacuum was at ~8, and the timing was pulled all the way back to like -2 or something. Why would the ECU pull timing enough to make a crappy idle...?
3. Confoundingly, with T/E1 shorted, the ECU would still change timing. The above observation re: rough idle was noticed with the service ports shorted. Also, even after I got it to idle well (by revving a few times), it would still pull and advance timing when I touched the throttle. I thought this was supposed to be hard-locked base timing so you could set it to somewhere that the ECU knew about..?

Also, a question: I have a ticking noise that I'm pretty damn sure is an exhaust manifold crack/leak. Would this be setting off my knock sensor? I'm probably going to replace the exhaust manifold in the very near future, but if this could be setting it off, then I'm even more likely to.
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David - Former owner of multiple Alltracs. Have moved on to yellower fields...
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