High searching Idle - Page 4 - ZR-1 Net Registry Forums

Demps · 02-10-2018

Permatex 2 is your friend.

Ted

XfireZ51 · 02-10-2018

Quote:

Originally Posted by Demps

Permatex 2 is your friend.

Ted

It certainly is for the coolant passage between the IH and cylinder head.

jss06c6 · 02-11-2018

Got it done without pulling plenum. Pulled TB, which gave me just enough room to get the hose fitting back onto the end of the pipe nipple. Made a wire hook with coat hanger wire and pulled it into the pipe. Put a tie wrap around it and cinched it up.

I'll be changing out the throttle set screw while the TB is out.

When i get the plenum and injector housings I got from Constantine ported, I'll pull the top end down, including the valve covers and get everything powder coated gloss black with red lettering. Going to re-plumb everything under the plenum when I build it back up.[ATTACH][ATTACH]

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Demps · 02-12-2018

Sweet. I wrongly assumed it was the other end. It will come loose at the purge solenoid connection sometimes if you raise the front of the plenum.

Glad you fixed it.

Ted

jss06c6 · 02-12-2018

I should have known to look here first since the PCV connection at the PCV valves was popped up. These two connections are right next to each other at the front of the plenum..

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jss06c6 · 02-15-2018

Got the TB reinstalled and fired up the engine. It settled down to about 900 rpm, cold and in open loop. Let the engine warm up and it dropped down to my "normal" 750 rpm in closed loop. Got the laptop, launched TunerProRT and began to log the engine. I replaced the throttle set screw with a hex head and lock down nut. Installed it the same offset distance as the original one I removed. IAC sits a 0, versus previously at 4 with a hot engine. Have not set minimum air yet, but will get that done with a warm engine.

Took the car out for a drive. Each time I came to a stop, the engine would idle down to about 700-750 rpm and IAC would return to 0. Throttle position at 0.53 volts.. all good. After about a 5 mile test drive, I noticed the idle was again about 1200 and hunting again. AFR was swinging from about 13 to 15.5, not quite same frequency as normal dithering. Let it sit in the driveway for about 5 minutes, idling, no change.

I pulled the bellows and got a piece of cardboard to block off the TB. Took about 5 seconds before the engine began to bog down. I let it get to about 400 rpm and then pulled the cardboard off (difficult with that much suction!). The engine RPM came back up and the AFR was now swinging pretty hard from 12.5 to about 16.5, but the idle was now back to 750! Repeated the sequence two more times with the cardboard, with same results. IAC still at 0 at idle and TPS still at 0.53 volts.

I'm going to try to set the minimum air this afternoon while I've got good weather. I looked very closely at the TB when it was out and I cleaned it. There was virtually NO light coming past the TB blades. Only spot was near the shaft on one of the blades and this was extremely small. There is no DAG in this TB. Makes me wonder if this TB has been worked over in the past, possibly by Marc and prior owner had it with him..

So, I've either still got a small vacuum leak under the plenum, or the TB is allowing some air to pass through at idle. The fact that after the TB was blocked off caused the idle to return to 750 causes me to think that a vacuum hose connection may have been leaking slightly and the increased manifold vacuum "pulled" the connection in enough to re-establish integrity?? Don't believe the TB was sticking, it was clean and free. I put a very small amount of oil on the shafts where they come through the outside of the TB casting..

jss06c6 · 02-15-2018

Reset minimum air and TPS to 0.55 volts. Got it good and warm. Throttle was sticking slightly. Cleared that. Idles at 725. IAC still at 0 when hot and at idle. Three pulls to 7250. Smiles all around!

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mike100 · 02-15-2018

These throttle bodies and the pcv vent bypass too much air an it is hard to get a positive IAC number. I was able to get a value of 10-20 on the iac counts after I restricted the diameter of the pcv hose to the manifold. To make up for the pcv flow at high rpm where it needs the full tube, I tee'd off to a mini filter atmospheric vent.

Ccmano · 02-15-2018

Quote:

Originally Posted by jss06c6

Reset minimum air and TPS to 0.55 volts. Got it good and warm. Throttle was sticking slightly. Cleared that. Idles at 725. IAC still at 0 when hot and at idle. Three pulls to 7250. Smiles all around!

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Your going to want the IAC around ~10 or so. Otherwise you will run the risk of stalling as the car comes to a stop. Zero means the system is out of adjustability to compensate the idle speed. I’m going through that right now in the tuning process with Dom. Mine is dialed in pretty well now, IAC went to Zero and I started getting isolated stalling issues. Dom might be able to pipe in with a more detailed explanation.
H

jss06c6 · 02-15-2018

Hans,

Yes, ideally this is the case. I run my idle at 700 rpm. If I move up to 850, IAC will be at 10-15. When I set minimum with the IAC pintle fully closed, I set it to 600 RPM. Then reset the TPS to 0.55 volts. Plugged the IAC back in and it settled in and slowly walked back to 0. Can't get the idle any lower with the IAC disengaged. If I moved my idle speed up, no problem holding 10.

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02-10-2018	#31
Demps Join Date: Jan 2006 Location: Niceville Posts: 998	Re: High searching Idle Permatex 2 is your friend. Ted

02-12-2018	#34
Demps Join Date: Jan 2006 Location: Niceville Posts: 998	Re: High searching Idle Sweet. I wrongly assumed it was the other end. It will come loose at the purge solenoid connection sometimes if you raise the front of the plenum. Glad you fixed it. Ted

02-12-2018	#35
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: High searching Idle I should have known to look here first since the PCV connection at the PCV valves was popped up. These two connections are right next to each other at the front of the plenum.. Sent from my XT1585 using ZR-1 Net Registry mobile app

02-15-2018	#36
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: High searching Idle Got the TB reinstalled and fired up the engine. It settled down to about 900 rpm, cold and in open loop. Let the engine warm up and it dropped down to my "normal" 750 rpm in closed loop. Got the laptop, launched TunerProRT and began to log the engine. I replaced the throttle set screw with a hex head and lock down nut. Installed it the same offset distance as the original one I removed. IAC sits a 0, versus previously at 4 with a hot engine. Have not set minimum air yet, but will get that done with a warm engine. Took the car out for a drive. Each time I came to a stop, the engine would idle down to about 700-750 rpm and IAC would return to 0. Throttle position at 0.53 volts.. all good. After about a 5 mile test drive, I noticed the idle was again about 1200 and hunting again. AFR was swinging from about 13 to 15.5, not quite same frequency as normal dithering. Let it sit in the driveway for about 5 minutes, idling, no change. I pulled the bellows and got a piece of cardboard to block off the TB. Took about 5 seconds before the engine began to bog down. I let it get to about 400 rpm and then pulled the cardboard off (difficult with that much suction!). The engine RPM came back up and the AFR was now swinging pretty hard from 12.5 to about 16.5, but the idle was now back to 750! Repeated the sequence two more times with the cardboard, with same results. IAC still at 0 at idle and TPS still at 0.53 volts. I'm going to try to set the minimum air this afternoon while I've got good weather. I looked very closely at the TB when it was out and I cleaned it. There was virtually NO light coming past the TB blades. Only spot was near the shaft on one of the blades and this was extremely small. There is no DAG in this TB. Makes me wonder if this TB has been worked over in the past, possibly by Marc and prior owner had it with him.. So, I've either still got a small vacuum leak under the plenum, or the TB is allowing some air to pass through at idle. The fact that after the TB was blocked off caused the idle to return to 750 causes me to think that a vacuum hose connection may have been leaking slightly and the increased manifold vacuum "pulled" the connection in enough to re-establish integrity?? Don't believe the TB was sticking, it was clean and free. I put a very small amount of oil on the shafts where they come through the outside of the TB casting.. Last edited by jss06c6; 02-15-2018 at 05:32 PM.

02-15-2018	#37
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: High searching Idle Reset minimum air and TPS to 0.55 volts. Got it good and warm. Throttle was sticking slightly. Cleared that. Idles at 725. IAC still at 0 when hot and at idle. Three pulls to 7250. Smiles all around! Sent from my XT1585 using ZR-1 Net Registry mobile app

02-15-2018	#38
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	Re: High searching Idle These throttle bodies and the pcv vent bypass too much air an it is hard to get a positive IAC number. I was able to get a value of 10-20 on the iac counts after I restricted the diameter of the pcv hose to the manifold. To make up for the pcv flow at high rpm where it needs the full tube, I tee'd off to a mini filter atmospheric vent.

02-15-2018	#40
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: High searching Idle Hans, Yes, ideally this is the case. I run my idle at 700 rpm. If I move up to 850, IAC will be at 10-15. When I set minimum with the IAC pintle fully closed, I set it to 600 RPM. Then reset the TPS to 0.55 volts. Plugged the IAC back in and it settled in and slowly walked back to 0. Can't get the idle any lower with the IAC disengaged. If I moved my idle speed up, no problem holding 10. Sent from my XT1585 using ZR-1 Net Registry mobile app