Thanks, but in this case my problems do show up with tranny in park.
8Mud,
What about the AC issue, question I have raised. I know you have a lot more AC experience than I do.
I did have some pinging a month or so ago, but it was Valero gas, stopped when I went back to Citgo gas. Also I ran some FI cleaner through it the last tank. No more pinging at all.
What do you mean by checking plugs hot versus cold? Why, what do you see different?
You mentioned a litmus test, I heard that once before, does the excess CO2 in exhaust turn the coolant acidic, carbonic acid?
How much does your coolant bottle (football) liquid level change from cold to hot?
Mine stays the same, cold to cold, morning to morning. Maybe changes a little hot to cold, 1/2" at most. and hard to view or use unless you are on level ground each time, but never enough to alarm me like a leaking cap does when it boils over.
I have good flow through the football. I have no heater valve, it was not used in 87.
Right now, turning my AC seems to be the trigger, but I have hot wired the e-fan to keep it cool with AC off.
I sure don't know 134a like I do R 12 (I have the sliding scale coolant pressure/temperature curves etched in my mind for R12). The best way is to check low pressure at 70F-80F (in the morning) with all the doors open and the fan on high, compare your low side number to a known good system (I haven't done enough 134A systems to know the preferred number, likely 30-35 PSI, just a guess) (it's right around 25 PSI for R 12). Other than that, by weight , is the best method. The pressures are constantly changing, hard to get a good fill or constant value with a pressure gage.
I've never had any pinging in either of my Renix's (the 87 or the 88), in 20 some years. European gas is notoriously low octane. Even with a malfunctioning EGR valve or the EGR disconnected. Coolant soaked knock sensor?
Though I do seem to remember a very little valve rattle once when my O2 sensor was acting up, it was causing way more trouble than pinging. Loss of top end and mid RPM range bucking.
I was taught to get a true plug reading, you have to pull them after a run up the interstate with as little idling as possible before you get the plug out of there and check the color ( I generally keep the RPM's up and coast into a rest stop). It's called a true reading and may be an old wives tale, but something I typically do if there is any sign of odd plug color. Not the most pleasant thing to do, you need gloves. I usually have an extra plug available also, I've broken more than a few trying not to get burnt or blistered pulling the plugs on a hot motor. Can be helpful finding very small vacuum leaks, the plugs closest to the leak are often much lighter than those away from the leak. Also comparing plug color to the compressive for that cylinder can be helpful, you expect the plugs out of the higher compression cylinders to be a little lighter. Check the piston top, I've tracked down vacuum leaks that way. A significant clean (shinny) spot is unnatural, especially after an extended idle.
The auto parts store near here offered a litmus (type) paper test for coolant. It was supposed to change color if exhaust gases were present. It may work, but maybe the batch I used was old, I could smell the exhaust gas in the coolant, the test stripes never changed color.
My surge tank level rarely changes much, sometimes about a quarter of a tank in level from cool to hot. I typically only fill to around half, to allow for expansion. But it has expanded to above 3/4 on numerous occasions when I sit and idle for extended periods above 80F ambient and
high humidity. Though it has been years since I've had a significant spew.
I do game census and use my XJ, a lot of time spent at idle looking through binoculars. Game seldom pays attention to automobiles, I creep around an area with the XJ and do my counts.
If you can idle for an hour on a hot day without it going above 240. I'd call it good. Mine will typically start creeping up after 15 minutes of idle (two row radiator, strong fan clutch) and I'll switch on my aux fan. It typically lowers my temperature quick, if not I rev to 2000 RPM for a minute and the temperature gage needle falls.
Have you inspected the radiator with a flashlight? Pollen and dust gets in there and can cause partial air flow blockages. I've pulled significant amounts of pollen and fuzzies from between the A/C condenser and the radiator on numerous occasions.
From the sound of it you may have numerous things going on that add up. Possible restricted air flow. Hard to have significant air flow blockage (that you may not notice) in a single row, except at the A/C condenser. I got in the habit of shinning a flashlight from the back side of the radiator toward the front and following the light with my eyes in multi row heat exchangers, you'd be surprised how much dust, pollen and other junk can get caught in there.
I've had little trouble with my radiators plugging with deposits internally since I've been using distilled water to fill. Cheep coolant may cause deposits internally, I'd guess.
I'm about out of ideas Bro, keep us posted.
With the A/C on, the aux fan comes on and the pulse width for the injectors increases. Higher idle and slightly rich. Unplug your magnetic clutch connector and turn the A/C on and see what happens. I'm not exactly sure if it's possible to interrupt the "A/C on" signal to the ECU and still have the aux fan come on? I've occasionally wondered what the results would be if the diode failed, separating the normal aux fan system from the A/C aux fan on signal?
