Timing / Variable resistor Question
07-29-05, 12:55 AM
#26
Chad Carson
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Originally Posted by HAILERS
Pull the intake duct off the throttle body, with the engine hot, and see if the throttle plates are CLOSED like they should be.
If it's series four throttle body it will have a thermowax device with fast idle cam etc. It's meant to keep the idle around 1100 when the engine is cold and as the engine warms up the cam moves and the idle drops down to an acceptable 750 rpm give or take..
If the engine is cold and you look at the primary throttle plate it will NOT be fully closed. It will be cracked open a touch due to the thermo wax device. You need to have water flowing thru the thermowax in order for the thermowax to expand and cause the roll pin to fall off the cam which causes the throttle plates to fully close.
See the free online fsm for the series four. The FUEL section. It shows the fast idle cam/fast idle screw/thermowax etc.
I'm betting that the throttle body does not have water going thru the thermowax which in turn means the throttle plates are staying cracked open a touch keeping the idle high.
If it's series four throttle body it will have a thermowax device with fast idle cam etc. It's meant to keep the idle around 1100 when the engine is cold and as the engine warms up the cam moves and the idle drops down to an acceptable 750 rpm give or take..
If the engine is cold and you look at the primary throttle plate it will NOT be fully closed. It will be cracked open a touch due to the thermo wax device. You need to have water flowing thru the thermowax in order for the thermowax to expand and cause the roll pin to fall off the cam which causes the throttle plates to fully close.
See the free online fsm for the series four. The FUEL section. It shows the fast idle cam/fast idle screw/thermowax etc.
I'm betting that the throttle body does not have water going thru the thermowax which in turn means the throttle plates are staying cracked open a touch keeping the idle high.
I can't remember if it is hooked up or not. I do know the tb mod was done to this tb so one of the throttle plates were removed if I remember right.
Thanks
07-29-05, 07:05 AM
#27
Chad Carson
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Originally Posted by 88IntegraLS
Air fuel ratio plays a big role.... my large street port purrs like a kitten at 5-600 rpm at times (BACV gone now that megasquirt is in) and it gets real rough if it is too lean or rich. Retarded timing generally idles smoother but kills the power, and the variable resistor should change your idling air fuel ratio enough to hear a change in engine smoothness at idle. As a last resort you can angle the air flow meter to change the effect of gravity on the flapper valve. Also have you checked your TPS? Don't want to be in closed loop (rich mode) at idle.
Sorry did not see this post,
QUOTE=88IntegraLS] the variable resistor should change your idling air fuel ratio enough to hear a change in engine smoothness at idle.[/QUOTE]
So if it don't do anything what could cause it not to work?
Originally Posted by 88IntegraLS
Also have you checked your TPS?
Originally Posted by 88IntegraLS
Don't want to be in closed loop (rich mode) at idle.
08-02-05, 10:58 AM
#28
Chad Carson
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Ok,
Everyone I have sloved the problem.
First I replaced every vac block off nipple with plastic ones instead of the rubber ones I had. THen I cjecked my throttle plates, they were closed all the way.
I checked all the bolts on the intakes (new motor with 2k miles) thinking maybe one came loose, but all were snug.
Well, then something told me to block off the vac advance on the dist., just to see how she would run. Well, I did that and checked the timing again. Well the Leading timing was off slightly so I adjusted it. Then I checked the trailing and it was off a great deal so I dialed it in on the mark. Then I rechecked my leading just to make sure it was on and it was.
At this time my idle came down to 800 rpms. Yes! Well, I tried to adjust the variable resistor since before it made no changes, and what do you know when I turned it all the way to the right the car wanted to die, and all the way to the left the car smoothed out, so this is where I left it.
(So how do I set it correctly? Or is that done while setting the TPS?)
So now my idle is 800 and engine is almost perfectly smooth, so I decide to run it down the road. It road good but lacked a little power so I came back and adjusted the leading to 10 degrees advance and left the trailing alone.
Now my idle is dead on 1k and motor is still somewhat smooth. Dove that and it had the power I was looking for so I came back home.
I hooked the AC belt back on and the rpms came down to 900. Nice!
So I am running 900 rpms with 10 degrees advance timing with ac, ps, wp, and alt pullies hooked up. The idle adjustment screw is 1/4 turn out and everything is like it should be.
I do have a small jitter in the motor but it is very small and is probally from the light weight flywheel but it is hard to see it unless you looking right at the motor. Before you could feel it sitting in the car.
So the problem that I was having that has stumped us all seems to be when I hook the vac advance back up on the dist. I think that problem there is that the two vac lince off the dist go into a tee to a single line back to a tee where it splits into two lines again. One line goes over to the oil injection and tees off again to run those two vacs and the other line goes over and plugs into the second runner off the intake.
I think the problem is that when hooked to the dist. it is pulling too much of a vac for the dist so it is advancing the timing at a idle instead of advancing it while under acceleration.
So I need to find a vac port to use that pulls hardly no vac at an idle for the dist. and leave the oil injection hooked up the way it is.
Man something so easy caused this much problem! Well at least we know now!
Anyone know where is a good vac to use that pulls little to no vac at an idle?
If not I will check all the ones I have blocked off to see if I can use onre of those.
Thanks for all the help guys. Glad this problem is sloved!
Need to know about the variable resistor for sure since it is set right now at all the way to the left.
Thanks
Everyone I have sloved the problem.
First I replaced every vac block off nipple with plastic ones instead of the rubber ones I had. THen I cjecked my throttle plates, they were closed all the way.
I checked all the bolts on the intakes (new motor with 2k miles) thinking maybe one came loose, but all were snug.
Well, then something told me to block off the vac advance on the dist., just to see how she would run. Well, I did that and checked the timing again. Well the Leading timing was off slightly so I adjusted it. Then I checked the trailing and it was off a great deal so I dialed it in on the mark. Then I rechecked my leading just to make sure it was on and it was.
At this time my idle came down to 800 rpms. Yes! Well, I tried to adjust the variable resistor since before it made no changes, and what do you know when I turned it all the way to the right the car wanted to die, and all the way to the left the car smoothed out, so this is where I left it.
(So how do I set it correctly? Or is that done while setting the TPS?)
So now my idle is 800 and engine is almost perfectly smooth, so I decide to run it down the road. It road good but lacked a little power so I came back and adjusted the leading to 10 degrees advance and left the trailing alone.
Now my idle is dead on 1k and motor is still somewhat smooth. Dove that and it had the power I was looking for so I came back home.
I hooked the AC belt back on and the rpms came down to 900. Nice!
So I am running 900 rpms with 10 degrees advance timing with ac, ps, wp, and alt pullies hooked up. The idle adjustment screw is 1/4 turn out and everything is like it should be.
I do have a small jitter in the motor but it is very small and is probally from the light weight flywheel but it is hard to see it unless you looking right at the motor. Before you could feel it sitting in the car.
So the problem that I was having that has stumped us all seems to be when I hook the vac advance back up on the dist. I think that problem there is that the two vac lince off the dist go into a tee to a single line back to a tee where it splits into two lines again. One line goes over to the oil injection and tees off again to run those two vacs and the other line goes over and plugs into the second runner off the intake.
I think the problem is that when hooked to the dist. it is pulling too much of a vac for the dist so it is advancing the timing at a idle instead of advancing it while under acceleration.
So I need to find a vac port to use that pulls hardly no vac at an idle for the dist. and leave the oil injection hooked up the way it is.
Man something so easy caused this much problem! Well at least we know now!
Anyone know where is a good vac to use that pulls little to no vac at an idle?
If not I will check all the ones I have blocked off to see if I can use onre of those.
Thanks for all the help guys. Glad this problem is sloved!
Need to know about the variable resistor for sure since it is set right now at all the way to the left.
Thanks
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