Idle tuning issues.
08-30-2017, 01:13 AM
#1
2nd Gear
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Idle tuning issues.
I own a 86 auto and am having fun setting up idle after performing some mods to improve performance. It now runs a Howards 275/275 cam , MSD cap rotor and coil , BBK 58mm TB , live wire leads and Delco rapidfire plugs , and a PCM chip set for the cam. My problem is as such , I went through the usual process for setting idle. My car has had a right hand conversion and there is no ECT plug. After looking for some time , I put in my own plug. I used a clip in the socket under the dash , waited 30 sec and unplugged the IAC . Then removed the clip and started the engine and set idle . It seemed high on the TB but ran and idled perfectly. I then set TPS voltage at 0.60 as instructed by PCM. As soon as I plug in the ECT and IAC , the idle goes high to about 15- 17oo revs. Why cant it run like when they are disconnected , it sounded spot on. Any advice , I live in Australia and rely on forums such as this one . CHEERS
08-30-2017, 10:27 AM
#2
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TPS spec should be 0.54V, try that.
08-30-2017, 02:17 PM
#3
Team Owner
Is the ECM set up for that cam? It might be trying to get stock idle when the cam seems to run things differently.
08-30-2017, 07:50 PM
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PCM chip is set for cam with stock throttle body and port matching ect. I have found more info on this , ECS is over compensating timing and going too high . This can be for many reasons. Vacuum leaks the major , blocked injectors , knock sensor , and wires running parallel with secondary ignition wires can all cause issues. I have replacement Bosch style injectors on the way and a BBK adjustable fuel pressure regulator. I sprayed starter fluid around the vacuum hoses and found there may be a small leak or leaks around the vacuum canister area. I will check and clean all this and get back to you all. Once the injector swap has been done , all vacuum leaks should be over. I found an easy fix for the ridiculous heavy return spring on BBK throttle bodies as well , just get a small screw driver and flick the return spring off of where it is holding at the TB end and let it catch about a half turn looser. This made the pedal much more bearable and made driving at low speed better. Anyway will keep you posted.
08-30-2017, 08:31 PM
#5
Team Owner
PCM chip is set for cam with stock throttle body and port matching ect.
I have found more info on this , ECS is over compensating timing and going too high . This can be for many reasons. Vacuum leaks the major , blocked injectors , knock sensor , and wires running parallel with secondary ignition wires can all cause issues. I have replacement Bosch style injectors on the way and a BBK adjustable fuel pressure regulator. I sprayed starter fluid around the vacuum hoses and found there may be a small leak or leaks around the vacuum canister area.
I will check and clean all this and get back to you all. Once the injector swap has been done , all vacuum leaks should be over. I found an easy fix for the ridiculous heavy return spring on BBK throttle bodies as well , just get a small screw driver and flick the return spring off of where it is holding at the TB end and let it catch about a half turn looser. This made the pedal much more bearable and made driving at low speed better. Anyway will keep you posted.
I have found more info on this , ECS is over compensating timing and going too high . This can be for many reasons. Vacuum leaks the major , blocked injectors , knock sensor , and wires running parallel with secondary ignition wires can all cause issues. I have replacement Bosch style injectors on the way and a BBK adjustable fuel pressure regulator. I sprayed starter fluid around the vacuum hoses and found there may be a small leak or leaks around the vacuum canister area.
I will check and clean all this and get back to you all. Once the injector swap has been done , all vacuum leaks should be over. I found an easy fix for the ridiculous heavy return spring on BBK throttle bodies as well , just get a small screw driver and flick the return spring off of where it is holding at the TB end and let it catch about a half turn looser. This made the pedal much more bearable and made driving at low speed better. Anyway will keep you posted.
What is the IAC count?
What has the injector swap got to do with anything? Has that been addressed in the chip program or has it been adjusted already and these are the same size as before?
09-01-2017, 02:50 PM
#6
Safety Car
I own a 86 auto and am having fun setting up idle after performing some mods to improve performance. It now runs a Howards 275/275 cam , MSD cap rotor and coil , BBK 58mm TB , live wire leads and Delco rapidfire plugs , and a PCM chip set for the cam. My problem is as such , I went through the usual process for setting idle. My car has had a right hand conversion and there is no ECT plug. After looking for some time , I put in my own plug. I used a clip in the socket under the dash , waited 30 sec and unplugged the IAC . Then removed the clip and started the engine and set idle . It seemed high on the TB but ran and idled perfectly. I then set TPS voltage at 0.60 as instructed by PCM. As soon as I plug in the ECT and IAC , the idle goes high to about 15- 17oo revs. Why cant it run like when they are disconnected , it sounded spot on. Any advice , I live in Australia and rely on forums such as this one . CHEERS