phebbler
08-28-2012, 10:08 AM
I posted a previous thread concerning my misdeed of attempting to devise a blow through roots style super charger on my delorean on a excellent running and idling vehicle. (by the way this problem occurred over a weekend and I never drove the vehicle over 30 mph and never saw over about 0.5 psi of boost so I think the other side of the throttle body never really saw boost only mainly the intake components before the throttle body)
I am having an extremely lean idle issue (according to my AFR gauge. it starts on the lean side of idle and then drops steadily until extremely lean). Here is what the AFR looked like at idle before...
12774
One member suggested that I may have damaged parts and seals of the chamber before the throttle body since at idle this area is sealed except for the tube that supplies the idle speed motor. I was thinking that the idle speed motor may have been stuck too far open since the supercharger was trying to force a large volume of air through that 1" line and through the oscillation vane that meters the air during idle. I disassembled the air induction system and found the following:
1- The brass tube that goes from the underside of the intake body to the idle speed motor seemed to be a little loose in the o-ring. The oring was still intact... (I have an intake o-ring kit so I plan on replacing all of them anyway)
2- the rubber connector between the throttle body and the fuel distributor side of the intake has no damage or cracks. All of the other o-rings and seals seem fine.
2- I removed the idle speed motor and applied power in both directions and the vane snaps from all the way open to all the way closed just fine and hums when the ignition key is on. I shined a flashlight down the opening with the motor on and it seemed to oscilating the vane so that only about 1/5-1/6 of the valve was exposed.
3 - ****Prior to dissasembling the air intake the car would idle when cold (85 degrees ambient) but very lean and the metering plate is being pulled down a lot more than before.
This is the previous meter plate positon at 770 idle and at 1500 rpm steady speed. As you can see the opening is very small.
12770
12771
Now the opening is about 1/4" when idling and when I lift gently up on the plate (using the center bolt) to close the gap the idle seems to smooth out.
4 - Also prior to dissasembling the air intake the vacuum guage was only showing 10-15in at idle where prior to my stupidity it was idling close to 20in and even 22-23in when holding the engine at a higher rpm. Here it is before at 775 and 1500
1277212773
Can anyone give me any additional suggestions?
I am having an extremely lean idle issue (according to my AFR gauge. it starts on the lean side of idle and then drops steadily until extremely lean). Here is what the AFR looked like at idle before...
12774
One member suggested that I may have damaged parts and seals of the chamber before the throttle body since at idle this area is sealed except for the tube that supplies the idle speed motor. I was thinking that the idle speed motor may have been stuck too far open since the supercharger was trying to force a large volume of air through that 1" line and through the oscillation vane that meters the air during idle. I disassembled the air induction system and found the following:
1- The brass tube that goes from the underside of the intake body to the idle speed motor seemed to be a little loose in the o-ring. The oring was still intact... (I have an intake o-ring kit so I plan on replacing all of them anyway)
2- the rubber connector between the throttle body and the fuel distributor side of the intake has no damage or cracks. All of the other o-rings and seals seem fine.
2- I removed the idle speed motor and applied power in both directions and the vane snaps from all the way open to all the way closed just fine and hums when the ignition key is on. I shined a flashlight down the opening with the motor on and it seemed to oscilating the vane so that only about 1/5-1/6 of the valve was exposed.
3 - ****Prior to dissasembling the air intake the car would idle when cold (85 degrees ambient) but very lean and the metering plate is being pulled down a lot more than before.
This is the previous meter plate positon at 770 idle and at 1500 rpm steady speed. As you can see the opening is very small.
12770
12771
Now the opening is about 1/4" when idling and when I lift gently up on the plate (using the center bolt) to close the gap the idle seems to smooth out.
4 - Also prior to dissasembling the air intake the vacuum guage was only showing 10-15in at idle where prior to my stupidity it was idling close to 20in and even 22-23in when holding the engine at a higher rpm. Here it is before at 775 and 1500
1277212773
Can anyone give me any additional suggestions?