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Chasing Leaks and Tuning Idle



Well, one good thing about getting the motor running, it does provide some quick feedback on if you have any leaks.  After going through the mis-adventure of the leaking heater core, (turned out to be just the hose clamp to the heater core on the driver's side), I did identify 3 leaks while running the motor.  I had an oil leak at the oil filter housing, a coolant leak at the thermostat and a transmission leak at the back of the transmission (output shaft seal, shift selector seal, or both).  Two leaks I have successfully fixed and one remains until I have enough motivation and help to complete the task.


The oil and the coolant leak were first on my list.  I started with the oil leak at the oil filter housing by pulling that part and inspecting all the connections (oil filter, AN fittings to the oil cooler, oil pressure sender for the aftermarket gauge and the oil pressure switch for the oil light on the dash).  My inspection uncovered my mistake pretty quickly, I used the wrong type tape to seal the threads on the AN fittings and the oil dissolved it and started leaking.  Cleaned up the threads and decided to use a proper thread sealer (Gasoila) to prevent future leaks.  I had a "while I was in there" moment and decided to replace the electric oil pressure gauge with a mechanical one.  Not because it was leaking or not working, but because it seemed to be always near pegged at 80 Lbs, the limit of the gauge.  I found a 52mm mechanical oil pressure gauge from Dyno Racing on Amazon that reads up to 150 Lbs and bought it and the Dorman Universal installation kit.  When it arrived, I thought I would just use the original M12 to 1/8" NPT fitting I had for the electric oil pressure sender to install it.  I pulled the original adapter from the oil filter housing, coated the threads in Gasoila and screwed it back in.  As I was snugging it up, I suddenly snapped in two, leaving the threaded section in the housing.  Turns out, it was cheap aluminum and many people had the same issue.  I did manage to find a stainless steel version and installed it instead.  With all the fittings installed, I reinstalled the oil filter housing, ran the oil hose through the firewall and installed the gauge in the console.  


Now the coolant leak.  I never liked how some of the hose connections to the thermostat fit, lots of strange angles and hose clamps that didn't quite fit square on the fittings.  For good measure, I reworked the lower hose from the thermostat to the radiator (longer) and the hose from the thermostat to the water pump (also longer).  I replaced some of the clamps that weren't tightening properly with new and that seemed to correct the issues.  The thermostat has two M14 fittings for sensors.  I had one fitted with the sensor for the 52mm water temp gauge in my console, the other had a plug that I tapped for a ground wire for the other sensor.  Well, this arrangement was not leaking, but when I was running the motor, the water temp gauge never seemed to register anything.  I decided to replace the electric water temp gauge with the matching Dyno Racing mechanical gauge to see if that would solve my issue.  When the gauge arrived, I found 2 issues, the probe was larger than the hole in my M14 adapter and that the connector for the probe was 1/2" NPT.  I ended up drilling the M14 to 3/8" NPT hole larger so the probe fit through and then adding a male 3/8" NPT to 1/2" female NPT adapter to secure the temp probe.  After everything was installed, I started the car and brought it up to temp (170 F out of the head).  This equated to about 155F in the thermostat where cooler water from the bottom of the radiator mixes with hotter water from the head which was now showing on the new gauge.  The old electric gauge was probably working, but the scale was such, that 150F didn't move the needle much.  I completed the cooling system repairs with the correct radiator cap.


After firing up the motor after these repairs, no more oil and coolant leaks, but the motor still idles very high during the warmup cycle.  After warm up enrichment is off and the idle control valve is closed, it should idle around 850 - 900 RPM.  My motor idles around 1200 RPM when warm and nothing I have done seems to change it significantly.  My theory is that I have too much air entering the motor which requires more fuel to get a decent AFR, which drives up the RPM, which increases the advance, which drives up the RPM.  Here is a list of things I have done to work on this issue.


1. Verified the duty cycle of the IVC (20% closed, 85% open)

2. Restricted the air flow on the input side of the IVC (rubber stopper with a hole in it)

3. Cleaned the Air Bypass Screws, changed the O-Rings, reinstalled and adjusted with Carbtune (see video)

4. Turned in the idle speed screw (no change)

5. Modified the ignition map to run 3 degrees at idle (did drop the idle slightly)

6. Modified VE table at idle to produce 14.0 - 14.5 AFR

7. Performed smoke test on ITB vacuum ports and noted air leaking from throttle plates (Don't know if this is excessive, but will reset throttle plates at .1mm)


Things left to do


1. Pull throttle levers and verify proper length

2. Remove current TPS and adapter (Massive)

3. Reset throttle plates to .1mm

4. Reinstall throttle levers

5. Replace Massive TPS adapter with VAC Motorsports version (adjustable to remove signal delay to ECU)

6. Check and recalibrate Air Bypass screws with Carbtune (if needed)


Hopefully, getting me to a reasonable idle speed will be the end result of these changes so I can move on to other tasks, interior, suspension sitting too high, transmission leaks.


Thanks for reading!











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