4AGE 16V engine overheat when at high speed

[jondee86]

Found a reasonable explanation...

Quote:Retarded will over heat it most quickly. The burn occurs over about 80
degrees of crank rotation, when started late, there isn't time for the the
flame temps to be reduced by work against the crank. This combined with
the reaction still occurring when the exhaust valve opens conspires to
dump really hot gases into the exhaust passages. This greatly increases
the valve temp and the amount of heat picked up by the cooling system
thru the structure of the head and exhaust port.

This statement didn't have any hard evidence but it does seem plausible.
With the correct timing more heat is extracted in the form of mechanical
work. This likely lowers the temperature of the gases in contact with the
cylinder walls before they hit the exhaust valves.

With retarded timing combustion is still taking place when the exhaust
valves open and high temperature gases contact the head, valves and
exhaust ports. This increases heat transfer to the cooling system.

So yeah... severely retarded ignition timing could push the engine
temperature up at constant load, and your engine will lack power. The
exhaust manifold and down pipe (or headers) will be really hot. Upside is
that your engine should be easy to start and idle nicely

Cheers.... jondee86

[totta Crolla]

In an effort to find more low down torque I messed around with camshaft timing and discovered a new (to me) way to overheat an engine! (lgnition timing was corrected each time l moved the exhaust cam)

[Power_uP]

If everything else looks fine then it won't hurt to check the timing anyway. If you've never done it before then remember to bridge the terminals in the diagnostic socket. I haven't done it in years, but I did watch this video and its exactly like I remember: 4AGE timing procedure

If you can get some Forte coolant flush (or whichever brand you prefer) then its probably worth it too given the age of the car.

Perhaps check if the radiator is blocked, but if it just has a few bent fins then it won't make a noticeable difference, hell here's the radiator from my old 86 and that car wasn't overheating.

[chenfon]

thanks guys on the suggestion and knowledge, will work into it once my car able to start back.

this 4age 16V RWD suddently "die" during my daily use. after i parked and for parts purchase, get back car and start to ideal running. suddently it die off. try to start, it able to start for 30S with very rougth run and have backfire from exhaust.

due i at outside and without any tools onhand. so get a mechanic to check and he mention spark OK, fuel OK, air OK, battery OK and suspect my ECU gone.

now the car towed back to my house and my self yet check any thing on it. any suggestion guys? tq

[totta Crolla]

Maybe try a diagnostic check before condemning the ecu? It is actually quite rare for 16v ecu's to give any problems. It sounds very much like a fuel supply problem and the 30 second start may mean that the engine is running on the fuel supplied only by the cold start injector.
Diagnostic details here: http://www.aeu86.org/forum/Thread-Diagno...ic%2Bcheck

[Bean]

As he said and check the timing belt, it may have jumped

Also make sure you have a good ground to the injectors. On a stock car the injectors grab ground from the intake manifold.

It'll start off the cold air injector and die again

[Ivan141]

I have seen a dead 16v ECU once... that car wouldnt run anymore though..

[jondee86]

(06-20-2020 10:18 PM)Bean Wrote:  ... check the timing belt, it may have jumped

Working with the fact that you had overheating and we have discovered
that retarded cam timing can cause overheating, plus a sudden drastic
change in engine operation, I'd say that a loose cambelt has jumped a few
teeth.

It is not unheard of for the cambelt to jump teeth during an engine stop/
start cycle. Not sure why but the belt has to be loose (or severely worn)
for it to happen.

The cold start injector only supplies fuel when the engine is cranking. The
engine will only continue to run for a second or two after you release the
key if the main injectors are not working.

Cheers... jondee86

[chenfon]

(06-21-2020 02:01 AM)jondee86 Wrote:  

(06-20-2020 10:18 PM)Bean Wrote:  ... check the timing belt, it may have jumped

Working with the fact that you had overheating and we have discovered
that retarded cam timing can cause overheating, plus a sudden drastic
change in engine operation, I'd say that a loose cambelt has jumped a few
teeth.

It is not unheard of for the cambelt to jump teeth during an engine stop/
start cycle. Not sure why but the belt has to be loose (or severely worn)
for it to happen.

The cold start injector only supplies fuel when the engine is cranking. The
engine will only continue to run for a second or two after you release the
key if the main injectors are not working.

Cheers... jondee86

Dear jondee86.
Today check again on the 4age 16v RWD. for the timing belt is still at the place that it. No jump teeth found (refer attachment photo)

But i found that ignition cable 1 and 4 with totally no ohms on it (sound funny due 2 cable in same time?)and had replace all the ignition cable to new. Test start result remain. Totally cant start at all.

[chenfon]

Did u guys know how many ohms that this 2 water sensor will send out? Location of sensor as below photo.

Current check 1 is 1.4k ohms and 1 is 55 ohm. Suspect the 55 ohm sensor might not as per specification due found it housing was broken.

Plz do advise if this sensor malfunction, will the engine also cant start? Tqvm