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Car Forum / Chrysler Cars / September 2006'86 EFCS (ESA) advance prob.
I'm having some weird things happening on my Electronic Fuel/Spark Control system on my 318. When the throttle body is at hot idle, a ground is put on the carb switch and the EFCS module is supposed to stop all vacuum advance...or at least the book says that! I'm getting instances when the module is providing vacuum advance at idle, even with a ground present on the switch lead. The module itself is seeing ground on lead N3, violet, which goes to pin 7, conn. 1 of the EFCS board on the air cleaner. Sometimes, I get advance, sometimes I don't. The manual states that there should never be vacuum advance whenever there's ground on pin 1-7 from the switch. Anything I'm overlooking here, except a bad board? This is a CA car, 7° BTDC @ 630 RPM, not the 49 state version. Does engaging AC cause the spark advance to come on, or is there another sensor in play here? If I just pull the hose off the transducer on the air cleaner mounted housing, I set the timing for 7°, and then...sometimes...I get a fast idle indicating advanced timing, and then it'll drop off. Hmmmm! >I'm getting instances when the module is providing vacuum advance at idle, even >with a ground present on the switch lead. The module itself is seeing >ground on lead N3, violet, which goes to pin 7, conn. 1 of the EFCS >board on the air cleaner. Sometimes, I get advance, sometimes I >don't. The manual states that there should never be vacuum advance >whenever there's ground on pin 1-7 from the switch. <snip> The EFC board is drawing current (around 80 mA) from Pin 7, Conn 1 when grounded and showing +12 VDC when open, so there's current draw there, but it's not stopping the vaccum advance at all. I haven't opened up the case yet, but I would think that this would strictly an electronic function and have nothing to do with the vacuum diaphragm. Anyone?? Help, as I have to pass Californai SmogChek II next week and this ain't gonna make it, UNLESS the diaphragm's feeder hose is supposed to be DISconnected when checking basic timing, in which case it'll pass fine. I already know it's cleaner than clean on the dyno, so no problem at 15 and 25 MPH. >The EFC board is drawing current (around 80 mA) from Pin 7, Conn 1 >when grounded and showing +12 VDC when open, so there's current draw >there, but it's not stopping the vaccum advance at all. I haven't >opened up the case yet, but I would think that this would strictly an >electronic function and have nothing to do with the vacuum diaphragm. <snip> It appears that the EFCS WILL allow more advance at idle only when the feedback circuit is operating open loop. Once the O² sensor's up to temperature and generating a signal voltage, it cuts off the advance at idle. I tried checking basic timing both ways...with open loop and vac. transducer disconnected, and with hot engine/good O² sensor signal voltage, and got the exact same results. So, if you get done with a job and just want to set the basic timing, if you take the vacuum off of the diaphragm on the EFC box, it'll give you the same results as if you drove around to get the sensor hot and then set the basic timing. You'd think they would've explained that in the manual! Make progress every day...duh. > I'm having some weird things happening on my Electronic Fuel/Spark > Control system on my 318. When the throttle body is at hot idle, a [quoted text clipped - 13 lines] > housing, I set the timing for 7°, and then...sometimes...I get a fast > idle indicating advanced timing, and then it'll drop off. Hmmmm! The best thing to do if you are still running a vacuum advance distributor, is disable all the switching crap- and run a straight vacuum advance line from manifold vacuum to the distributor. This will give you full vacuum advance at idle, and at all part throttle driving applications- and a lot more power and driveability. More importantly, the extra advance will give you 2-3 more MPG. That switching crap is only there so the car will pass emissions tests at the factory. It actually really hurts the engine's performance. Run a straight line to the vacuum advance, on at all times. On 1 Sep 2006 16:47:48 -0700, "duty-honor-country" aka Charlie Nudo of Drums, PA, who never even served in the military and who has had 17 Google Groups accounts banned as of yesterday and will have <dutyhonorcountry2@hotmail.com> banned tomorrow wrote: >The best thing to do if you are still running a vacuum advance >distributor, is disable all the switching crap- <snip> ...which is a Federal felony in all 50 states... > and run a straight >vacuum advance line from manifold vacuum to the distributor. <snip> 'Tard...these Chryslers haven't had distributor vacuum advance in YEARS. I'm not going to clue you in as to where it is, since you're a brainless moron whose life only consists of being a Usenet troll and attempting to destroy newsgroups you have no business even being in....as your plagierized comments about the supposedly non-existant 1955 270 HEMI would suggest. Suffice it to say that a simple diagnostic check of in and output signals to the EFCS showed me how this feature worked. My '77 Honda CVCC also supplies non-ported vacuum advance during warm-up through the "Thermosensor A" thermoswitch. |
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