Is there a fix to TII rough idling?
08-17-09, 11:58 AM
#1
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Is there a fix to TII rough idling?
Good Day all,
I have read soooooooo many threads on this(Rough idle) and there dont seem to be too many completed successes. I assume people fix their issue and dont post the resolution or havent fixed their issue. My car:87 TII s4 stock with walbro and RB DP(nothing connected to it yet), idles at like 1100 then jumps up to 1800 back down then back up.
I have tested the resistance on my bac,cas,port air sol,water thermo, air thermo, tps and variable resistor(round thing that adjust rich/lean). i have removed the TMIC sprayed everywhere for vaccum leaks nothing found and my boost gauge is showing -5@1100 then when it bounces to 1800 its between -8 to -10psi. from what i was told that is normal. is it?
I have removed and reinstalled the cas to ensure correct timing good fuel pressure and everything. funny thing is when i unplug the bac nothing changes. from what i have read there should have been a change, but the bac had good resistance.
i read on here that the BAC connection inside the ecu could be bad thus not signaling the BAC. anyone had that issue here.?
I have read soooooooo many threads on this(Rough idle) and there dont seem to be too many completed successes. I assume people fix their issue and dont post the resolution or havent fixed their issue. My car:87 TII s4 stock with walbro and RB DP(nothing connected to it yet), idles at like 1100 then jumps up to 1800 back down then back up.
I have tested the resistance on my bac,cas,port air sol,water thermo, air thermo, tps and variable resistor(round thing that adjust rich/lean). i have removed the TMIC sprayed everywhere for vaccum leaks nothing found and my boost gauge is showing -5@1100 then when it bounces to 1800 its between -8 to -10psi. from what i was told that is normal. is it?
I have removed and reinstalled the cas to ensure correct timing good fuel pressure and everything. funny thing is when i unplug the bac nothing changes. from what i have read there should have been a change, but the bac had good resistance.
i read on here that the BAC connection inside the ecu could be bad thus not signaling the BAC. anyone had that issue here.?
08-17-09, 12:41 PM
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HAILERS
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Unplugging a BAC will not show a difference in rpm unless the ldle is under 700 rpm (approx).
This link might help some: http://www.teamfc3s.org/info/articles/idle.html
You might unplug the tps and see if that makes a difference.
See if the throttle stop screw is keeping the throttle linkage open. Or even better, when the engine is fully hot, look at the throttle stop screw and see if it is TOUCHING the linkage. IF there is a gap b/t the screw and linkage, and the idle is as high as you say, then lift up on the fast idle screw and see if that will make the idle drop down. It could be the thermowax piston is keeping the throttle open (if you see a gap b/t the stop screw and the linkage this applys).
TID ducts with cracks on the part that attaches to the turbo itself can cause your type problem.
You know where the throttle stop screw is???? It has a 8mm wrench size nut holding the TINY scew in place.
I attached about four jpg of the throttle stop screw on a turbo car. I did that because it's not too clear in all those jpgs but that's the general area.
Try making a PCV piping arrangement as shown in the attached jpgs. Then the intercooler can be removed and you can make adjustments to the screw..tps ...whatever. with the engine running.
This link might help some: http://www.teamfc3s.org/info/articles/idle.html
You might unplug the tps and see if that makes a difference.
See if the throttle stop screw is keeping the throttle linkage open. Or even better, when the engine is fully hot, look at the throttle stop screw and see if it is TOUCHING the linkage. IF there is a gap b/t the screw and linkage, and the idle is as high as you say, then lift up on the fast idle screw and see if that will make the idle drop down. It could be the thermowax piston is keeping the throttle open (if you see a gap b/t the stop screw and the linkage this applys).
TID ducts with cracks on the part that attaches to the turbo itself can cause your type problem.
You know where the throttle stop screw is???? It has a 8mm wrench size nut holding the TINY scew in place.
I attached about four jpg of the throttle stop screw on a turbo car. I did that because it's not too clear in all those jpgs but that's the general area.
Try making a PCV piping arrangement as shown in the attached jpgs. Then the intercooler can be removed and you can make adjustments to the screw..tps ...whatever. with the engine running.
08-17-09, 01:41 PM
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Unplugging a BAC will not show a difference in rpm unless the ldle is under 700 rpm (approx).
This link might help some: http://www.teamfc3s.org/info/articles/idle.html
You might unplug the tps and see if that makes a difference.
See if the throttle stop screw is keeping the throttle linkage open. Or even better, when the engine is fully hot, look at the throttle stop screw and see if it is TOUCHING the linkage. IF there is a gap b/t the screw and linkage, and the idle is as high as you say, then lift up on the fast idle screw and see if that will make the idle drop down. It could be the thermowax piston is keeping the throttle open (if you see a gap b/t the stop screw and the linkage this applys).
TID ducts with cracks on the part that attaches to the turbo itself can cause your type problem.
You know where the throttle stop screw is???? It has a 8mm wrench size nut holding the TINY scew in place.
I attached about four jpg of the throttle stop screw on a turbo car. I did that because it's not too clear in all those jpgs but that's the general area.
Try making a PCV piping arrangement as shown in the attached jpgs. Then the intercooler can be removed and you can make adjustments to the screw..tps ...whatever. with the engine running.
This link might help some: http://www.teamfc3s.org/info/articles/idle.html
You might unplug the tps and see if that makes a difference.
See if the throttle stop screw is keeping the throttle linkage open. Or even better, when the engine is fully hot, look at the throttle stop screw and see if it is TOUCHING the linkage. IF there is a gap b/t the screw and linkage, and the idle is as high as you say, then lift up on the fast idle screw and see if that will make the idle drop down. It could be the thermowax piston is keeping the throttle open (if you see a gap b/t the stop screw and the linkage this applys).
TID ducts with cracks on the part that attaches to the turbo itself can cause your type problem.
You know where the throttle stop screw is???? It has a 8mm wrench size nut holding the TINY scew in place.
I attached about four jpg of the throttle stop screw on a turbo car. I did that because it's not too clear in all those jpgs but that's the general area.
Try making a PCV piping arrangement as shown in the attached jpgs. Then the intercooler can be removed and you can make adjustments to the screw..tps ...whatever. with the engine running.
okay so i have the pvc piping done. there is a gap on that stopper, didnt really want to mess to much with that as i have read of people royally screwing themselves up with that. with the TID duct to the turbo i seems to be in good shape(sprayed like half a can of carb cleaner in that area, that shyt tastes awful).
oh and check this out, when i press in the TPS the rpms climb quickly, if i unplug it the rpms rise quickly. the fuel pump resistor relay has be taken out of the loop (it bad) as well, would that be a issue?
Last edited by OriGiNaL TyPe R; 08-17-09 at 01:42 PM. Reason: oh that link in ur reply, i tried that to.
08-17-09, 02:25 PM
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one more thing when i try and hold the gas pedal to try and balance the idle, the rpms go up and it still pulses at 500 intervals i.e. 3000-pulses to 3500; 4000-pulses to 4500. if i pump the pedal it responses rather quickly.
08-18-09, 09:40 AM
#5
See the following s4 FSM pages: 4B-80 to 4B-82 (Fuel and emissions control--turbo model, idle speed section)
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
I put a box around the fast idle cam and a green arrow indicating that it can rotate. You can reach behind the TB and, if you're creative, zip tie this thing completely up. That will effectively disable the fast idle cam on a temporary basis. You will see TPS voltage drop and TPS resistance increase as the linkage rests on the throttle stop screw. Start the car and warm it up. It may struggle to stay alive now (at least when cold), so somebody may have to keep a foot on the gas.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
I put a box around the fast idle cam and a green arrow indicating that it can rotate. You can reach behind the TB and, if you're creative, zip tie this thing completely up. That will effectively disable the fast idle cam on a temporary basis. You will see TPS voltage drop and TPS resistance increase as the linkage rests on the throttle stop screw. Start the car and warm it up. It may struggle to stay alive now (at least when cold), so somebody may have to keep a foot on the gas.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
08-18-09, 10:26 AM
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See the following s4 FSM pages: 4B-80 to 4B-82 (Fuel and emissions control--turbo model, idle speed section)
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
I put a box around the fast idle cam and a green arrow indicating that it can rotate. You can reach behind the TB and, if you're creative, zip tie this thing completely up. That will effectively disable the fast idle cam on a temporary basis. You will see TPS voltage drop and TPS resistance increase as the linkage rests on the throttle stop screw. Start the car and warm it up. It may struggle to stay alive now (at least when cold), so somebody may have to keep a foot on the gas.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
I put a box around the fast idle cam and a green arrow indicating that it can rotate. You can reach behind the TB and, if you're creative, zip tie this thing completely up. That will effectively disable the fast idle cam on a temporary basis. You will see TPS voltage drop and TPS resistance increase as the linkage rests on the throttle stop screw. Start the car and warm it up. It may struggle to stay alive now (at least when cold), so somebody may have to keep a foot on the gas.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
thank you. i will try this as well.
08-21-09, 07:35 AM
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See the following s4 FSM pages: 4B-80 to 4B-82 (Fuel and emissions control--turbo model, idle speed section)
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
You need to verify that the fast idle cam is fully released. Hailers mentioned this but I'll try to further clarify.
With the engine at operating temperature, jumper the initial set coupler. The initial set coupler sets the BAC valve to a fixed duty cycle of 20% so that it does not interfere with any idle adjustments. Now adjust the BAC valve air screw to set the idle speed near 750-800 or whatever. You may also have to adjust the throttle stop screw. Now put your timing light on there and verify timing again.
You may have to adjust the variable resistor a little bit too, and finally verify that the TPS is still in spec. Once the warm idle is set, you can cut the ziptie. If the idle rises, you need to fiddle with the cam adjusting screw in the pic above, I would try loosening it first. When everything's done remove the jumper on the initial set coupler.
my question about the bac is with it not working, when i accel the gas and hold it would it effect it not holding the rpms steady at lets say 4k?
pls anyone chime in.
Last edited by OriGiNaL TyPe R; 08-21-09 at 07:36 AM. Reason: typing error.
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08-21-09, 10:51 AM
#9
I'll add some info in case it will help.
This is actually a TII swap into a GSL-SE (1st gen), so there is a possibility that there is a wiring issue, something unplugged, etc.
We checked the ECU voltages and everything looked pretty good. The strange thing is we couldn't get the code checking lights to work. I have done this many times in my GSL-SE as well as for S5 cars, etc..but we got nothing out of either code checking output, nor the pin that would go to the "check engine" light. Any ideas on what could cause this?
It is possible that the fast idle cam was not disengaged when we set the TPS. I helped him before this thread getting the car started. Once it started, it did this boucing idle. It really behaved like a TPS out of whack. So, we reset the TPS, got one light on, and tried it again..same thing. The engine should have been fully warm, but I don't know for sure as the water temp gauge was not working at the time.
It tends to bounce like this even if you hold the throttle open a bit. The frequency of the bounce is about once per second.
Unfortunately, I do not live close to him, so it is hard for me to help out.
This is actually a TII swap into a GSL-SE (1st gen), so there is a possibility that there is a wiring issue, something unplugged, etc.
We checked the ECU voltages and everything looked pretty good. The strange thing is we couldn't get the code checking lights to work. I have done this many times in my GSL-SE as well as for S5 cars, etc..but we got nothing out of either code checking output, nor the pin that would go to the "check engine" light. Any ideas on what could cause this?
It is possible that the fast idle cam was not disengaged when we set the TPS. I helped him before this thread getting the car started. Once it started, it did this boucing idle. It really behaved like a TPS out of whack. So, we reset the TPS, got one light on, and tried it again..same thing. The engine should have been fully warm, but I don't know for sure as the water temp gauge was not working at the time.
It tends to bounce like this even if you hold the throttle open a bit. The frequency of the bounce is about once per second.
Unfortunately, I do not live close to him, so it is hard for me to help out.
08-26-09, 07:46 AM
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UPDATE:
I have not been out to the car as i am moving and dont have the time to get out there(the car is like 20 mins from where i live). I got my camcorder ready to record this event. To give a visual of the matter.
Addict thanks for adding to the stew
I have not been out to the car as i am moving and dont have the time to get out there(the car is like 20 mins from where i live). I got my camcorder ready to record this event. To give a visual of the matter.
Addict thanks for adding to the stew
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