More fluactuating Tem Gage AND now pinging real bad

[ernzo]

...I have burped the motor several times. Temp gage still fluctuates wildly alomst to red, then falls rapidly back etc. Seems worse when I accelerate uphill.

Replaced Radiator cap, water pump, t-stat.

Mechanic friend says he thinks the timing is too advanced, says there is a small sensor behind the battery that controls the timing advance and when it fails it goes to full advance.

He reaches in and pulls out this VERY small plastic piece / plug with 2 male connectors and unplugs it. I go for a test drive, and no ping! And it *seems* to run cooler.

WTF? Am I being worked? Anyone know what this is?

[surf]

If the piece he pulled out is gray plastic I think it is called the octan shorting block and removing it retards the timing. You want to clean your maf to see if that cures your ping and if not you might want to check for vacuum leaks. As for the fluctuating temp gauge you may want to check the temp sensor.

[Robert Nick]

I agree with Surf regarding the Sensor for the Temperature Gauge. You could also check the Gauge Function by testing it with the Sensor uplugged. This should give a full Cold Gauge Deflection. In addition, Short the wire at the Sensor to the Engine Block and the Gauge should read full Hot Gauge Deflection. Drive the vehicle in both conditions and see if the Gauge deflection stays consistent.

[ernzo]

Yes, it is the octane shorting plug that was pulled, and yes it did eliminate the (very bad) pinging and also helped the EX to run cooler.

I read that doing this will harsh the performance (limited as it is) and also wreck my mileage, so I do not want to keep it off. Maybe cleaning it?

I did test the wire / temp sensor all good.

I will (again) clean the MAF and try to figure out WTF is happening.

[ernzo]

pulling the octane plug did change the way my ex ran - cooler, more stable and zero pinging....VERY sluggish though and gas mileage seemed to tank...(pun)

yesterday, i put it back in as a control - would the ex start running hot, swinging temp gauge, pinging?

And the answer is it did. not at first, but after about 10 miles, back to the same old thing. Power did return though! VERY noticeable...

Initially, the temp gauge ran down to below the N and that was an indication to me , as with the octane plug out, the gauge really stayed in the middle.

So....WTF? I know that removing the plug retards the timing (about 3 points I read) but while I can understand an over advanced engine running hotter and pinging, why does the gauge swing so much?

one other thing....I have had ongoing trouble with a 'knock' from my motor - when hot, mostly noticeable at idle with my foot on the brake and revving the motor to about 1000. I have been on this forum many times trying to figure it out - not lifters, not the "typical ex knock, have had several good mechanics listen and all say front of motor, lower down but no a rod, does not really sound like a bearing. Harmonic balancer checks out fine. All are stumped.

I am checking again, but I believe that with the plug out, the knock is gone. Zip, nada, evaporated! So......the knock is the kind of thing that one hears when one (in the old days) would jack a dizzy way over. Car would idle up, but also car would kind of knock due to the timing being so advanced!

I will report back as this AM I am disconnecting the battery and re-connecting to set the computer again. Will drive with the plug in and see if things change. I will also remove it a little later and check the "weird engine knock"...

[SavaX]

I replaced my temp sender unit and had to bend the connecting boot so it made good contact with the sender. Just something to try since your gauge seems to be working.

[Roadrunner777]

I'm saying this as a just maybe because it does not fit all of your symptoms precisely, but I had similar experience. And I hope I am very wrong. I had a vehicle do this wild temperature thing, and it ended up being a minor leak in the head gasket from cylinder to water jacket.The part I cannot quite connect is why the timing would effect it. But, I thought I would mention it as a distant thought. A hydrocarbon test on antifreeze would hopefully disprove this. Hope I am wrong!!!!

[ernzo]

..ok so when I did pull the octane plug and re-set the computer (which i 'thought' stopped the heating and pinging...) I also turned off the hot water to my heater (i had installed a heater hose shut off valve) as it was getting warmer and I thought I did not need heat. I did not think this had any effect on the temp gauge / heating and pinging...

I was wrong..

Yesterday, it cooled down, I turned the valve on and after 5 minutes of driving all symptoms are back!!

So, turn off heater hose valve, car runs correctly (a little gauge swinging) and does not ping.

Turn on heater valve allowing hot water to circulate through the heater core and all hell breaks loose!

How can that be? Did my brother in law screw something up when he installed the new water pump? WTF??