Erradict Ignition Timing
Posted 30 July 2006 - 09:17 PM
My main question is What could cause this erradict jumping of timing according to the timing light?
Posted 30 July 2006 - 09:20 PM
if you pull the knock sensor loose at idle it should drop about 5 degrees of timing
i bet if you disconnected it the fluctuation would stop and be dead on 5 degrees at idle.
Posted 30 July 2006 - 11:15 PM
id go ahead and replace it im sure its in need as most are
oh and your checking the timing with the vac adv. hose unhooked and plugged correct?
Posted 31 July 2006 - 01:43 AM
Posted 31 July 2006 - 10:29 AM
the exactly 5 degrees is why i went towards the knock sensor..
i check mine by disconnecting it as it runs (ive added 6 inches of wiring to get the connector where i can reach it though)
Posted 31 July 2006 - 10:42 AM
If it moves around........your Dist has a problem with the mech. a**. PERIOD! :wink: Like......strechted out the springs? or WRONG springs.
There should be NO VACUUM at idle from THAT HOSE .........at all. :wink:
PJ's Manual for Newbies: http://starquest.i-x.net/viewforum.php?f=12 or http://forums.kdmperformance.com/forumdisplay.php?f=26
Posted 31 July 2006 - 10:57 AM
Posted 31 July 2006 - 11:53 PM
The ECU commands this extra +5 degrees of timing for:
* cold engine startups
* operating at high altitudes (just a couple thousand feet)
So a bad ECU coolant temp sensor or a bad barometric pressure sensor (inside the airflow sensor assembly on 87-later cars, on the firewall for earlier cars) can confuse the ECU. You can actually jumper those two wires together to force your car into "low alt" mode and kill that +5 degree timing advance. See if your timing stabilizes - probably at only 5 deg BTDC now... I'll bet your base timing is 5 degrees off due to this bug.
Posted 01 August 2006 - 10:29 AM
im going to install a junction block for the ignition and fuel pump test leads
1 dead end terminal for fuel pump, the ignition test , and a 12v keyed sample.all close to make troubleshooting a simple use of jumpers and voltmeter.
I already bought the box to enclose them in.
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