87 Honda Accord lxi (hatch back) !!

1) My honda is having a pinging sound from my engine at low speed ~ 25 rpm but sound goes away at high speed. Any idea, is that EGR ? i tried to adjust the timing but no luck. Also, no breaks as break pedals is going all the way down to the floor and almost no brakes at all. Any suggestion would be much appreciated.
2) where does the temperature sending unit harness comes from as i found out that there is nothing attached to it(plug missing) to the temperature unit ( temperature sensor.sensor is about center of intake near firewall). my car has a history of overheating and rough idle now i think that must be the reason (nothing is attached to it) and can not located any free/hanging wire harness that suppose to go to this unit.
Picuture would be more help ful .

Thx

hey there,

i actually wanted to ask if you could tell me tha timing spec's for this vehicle model.

thanks,
-taF

cant help with the sensor but over heating can be caused by the thermostat being old, and not functioning properly, which isnt to hard to replace, and if the system was bled incorrectly, now for brakes, you either dont have enough fluid in your master cylinder causing the problem of no brakes, check your fluid levels, if the levels are at maximum or minimum, then you need to replace you brake pads and rotors, and probably even the rear drums, rough idle could be cause by dirty fuel filters, dirty fuel injectors, change your fuel filters, one is located near the rear left wheel well, take the wheel off and you would be able to see it, its a little cylinder looking thing with two lines hooked to it, second one is in the engine bay, sits near the wiper motor, to clean your injectors you need to by a good fuel tank treatment, they arent to expensive, also, its a good idea to change your spark plugs, they could not be giving the full spark, which will make the engine run poorly, i recommend NGK plugs, they are very good, also check your spark plugs wires, see if they are cracked, if they are, then replace them ASAP