OK, so here's a new one...low idle, help me please!, also timing questions |
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OK, so here's a new one...low idle, help me please!, also timing questions |
porsche735 |
Sep 8 2003, 10:39 AM
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#1
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Member Group: Members Posts: 189 Joined: 10-January 03 From: Los Altos, CA Member No.: 127 |
We just finished rebuilding our engine and it started right up the first time...
We set the timing at 27 degrees with both hoses removed at 3500 rpm. After the engine had warmed up and the aux air valve shut (even tested by plugging air inlet to valve), we tried to set the idle. The idle is way too low, about 500 rpm max. The adjustment screw is making almost no difference. I played with the mixture screw on the ECU both directions (refresh my understanding, it is backwards, right? CCW is leaner, CW is richer). Adjusting this did not make a huge difference. I adjusted this to achieve highest rpm and richened one click (CW). We cleaned out the air bypass hole to make sure it was not plugged. We also played around with the TPS by shutting the butterfly valve all the way to make sure the ECU "thought" it was in idle mode. I also have another question about advance. I have been told that we should see a total advance (with hoses on) of around 33-34 degrees. We checked our's after setting the 27 degrees the normal way, it was around 39 degrees. Does anyone have any specs on the mechanical advance and vacuum advance (retard as well, I guess)? My understanding is that at WOT that vacuum advance should be close to nil. We should basically only see the mechanical advance. However, we are seeing about 12 degrees advance due to the vacuum advance (39-27=12). Does this make sense? We played with the advance all over the place and were not able to get the idle to go higher. Please help me with these questions.... Your help is much appreciated. Chris |
Bleyseng |
Sep 8 2003, 11:00 AM
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#2
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Aircooled Baby! Group: Members Posts: 13,035 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Sounds like you have the vacuum/retard hoses hooked up wrong- switched. The vacuum advance hooks up to the port that is above the throttle plate. The retard hooks up to the lower port.
The air bleed should increase the idle cuz it adds air into the engine bypassing the throttle plate. Only if the timing is off have I seen this, so recheck the timing. ie-if you add air to the engine rpm should increase right? something is goofy here. Make sure the marks are the right ones (use the Pelican tech article for the template) 27 degrees BTDC @ 3500 rpms with hoses off and plugged (means take them off the dizzy and plug em) Geoff (IMG:style_emoticons/default/confused24.gif) |
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