4AGE 16V engine overheat when at high speed

[jondee86]

(07-04-2020 04:59 PM)chenfon Wrote:  Did u guys know how many ohms that this 2 water sensor will send out?

The green sensor is the water temperature signal for the ECU. A reading
of 1.4 kOhms is about right for 25degC. The brown sensor is the cold start
injector time switch. Pin to pin resistance should be 20-40 Ohms below
40degC water temp and 40-60 Ohms above 40degC.

You can check if the cold start injector is working by pulling the injector
out of the intake manifold and putting the end into a bottle. Crank the
engine. If gasoline squirts into the bottle then the injector time switch is
working. If it is not working then the engine will need to be cranked several
times to get it started, or use starting fluid.

From memory, the "rule of thumb" for ignition leads is a resistance of
around 1 kOhms for each inch of length

Cheers... jondee86

[chenfon]

Dear all

Juz to update my findings after few days work.
My engine suddent dead is really ignition issue, and not the high voltage cable, not sparkplug, not distributer sensor, not ignition coil and also not ECU issue.

Base on the repair manual check parts by parts. Finally is only 01 signal cable from distributer send back to ECU broken, from the cable condition is mainly due to high temperature surrounding and the cable rubber become plastic and fragile. (Refer photo as the BLACK cavle broken and other 2 coming soon)



After reconnect the cable (all 3). Test the Ohm signal send back to ECU and all within specification. Test start..... "she" alive...

For this case. I also have replace and recheck lot of related item and gained more knowledge on this 4AGE... thanks...

Anyway. I plan to replace the distribute signal cable with new, but have no idea what cable size i need for it. Any suggestion.

Thank you

[Dave W]

You can pry off the back side of the yellow plug. Trim the current wire ends, and re-attached the wires to the spades. Carefully remove the old ends of the wires from the spades. Then, re-bend the prongs, on to the newly cut ends, and then add a new solder to each of the connections. Finally seal the connector plug with RTV inside the plug, before pushing the back of the connector back into place.
[good for another 25 yrs.]
Dave W

[Bean]

If I remember correctly it's a 16 gauge wire.
You might want to consider a heat shield or wrap the header to lower the temperature in that area

[jondee86]

The length of wiring outside the conduit is too short to provide sufficient
flexibility to prevent the wires failing from fatigue. After that heavy plug has
jiggled around a few million times it can fail where it joins to the plug. If the
cover on the wire is stripped back for a soldered join that creates a weak
spot due to lack of support for the copper wire.

There should have been a larger loop of cable there to spread the flexing.
Even with the soft braided sheath used on the factory wiring failures can
occur at the point where the wires enter the distributor. That is where the
wires are subject to maximum bending as the cable flexes with the movement
of the car. Rare, but it does happen.

Cheers... jondee86

[chenfon]

Thanks guys. this weekend will try to replace the said cable with new. hope every thing go smooth. thanks.

another issue come out after she come alive, during idle the engine seem minor shake and sound like 1 sparkplug not work. but all OK when i check 1 by 1 plug by direct pull out during idle. Possible TBody dirty? or the "Idle thermostat" below TBody dirty? due during cold start, the RPM beautiful at 850rpm (with minor shake) but after drive few minute and stop at idle, the RPM will at 1100rpm with non stop up and down (100rpm). wonder what will cause this other then TB? please do advise. tq

on the engine overheat during high speed, i had tighten all the coolent hose with hose clip. After test for few days, it still have minor high temp (high speed) where gauge display 2/3. still work on it. tq

[chenfon]

another issue come out after she come alive, during idle the engine seem minor shake and sound like 1 sparkplug not work. but all OK when i check 1 by 1 plug by direct pull out during idle. Possible TBody dirty? or the "Idle thermostat" below TBody dirty? due during cold start, the RPM beautiful at 850rpm (with minor shake) but after drive few minute and stop at idle, the RPM will at 1100rpm with non stop up and down (100rpm). wonder what will cause this other then TB? please do advise. tq

Above issue done. after check vacuum on the system found the hose from manifold to fuel pressure regulator minor crack (leakage).

and also found that 1 of my "fuel injector plug" plastic aging crack and connection not good. any of yours replace before on it? pricing wise? tqvm

[Rascal21]

Common for the fuel injector connectors to crack with age, you can get new with cable stumps (so you can splice the ones from engine harness onto them) on ebay for practically nothing, here's a quick example of available replacement items https://www.ebay.com/itm/Engine-Fuel-inj...SwcGhefbS7
They're the usual square Bosch type as found on most old Audi's/VW's

While you're at it, change all vacuum hoses too, get a few meters of clear silicone vacuum hoses, that way, down the line when you have other issues, you'll be able to see if your engine is suffering from vapor issues in the vacuum system, I had that happen once when I had too much oil in the engine (stupid mistake) which made it suffer from one of the most excessive blowby's I've ever seen (because my 4A-GE is an early 3-rib that has never been opened, should have had an overhaul 10 years ago), clogging up the entire vacuum system and the engine died within 1 minute of first startup after fresh oil change, the clear silicone hoses tipped me off about the issue in 30 seconds of visual inspection in engine bay, checked oil level, there was the issue, instead of spending weeks disassembling the whole thing while asking on forums/facebook as has usually been the norm, as veterans here can readily confirm.

While you're at it, replace coil, ignition leads, rotor and distributor cap, even if you did it 2 or 3 or 7 years ago these cheap replacement parts just aren't the same quality as OEM replacement parts which can last for over 30 years.

Be ready for igniter to die also, with the abuse it has suffered from those broken wires shortening each other out you just never know, mine has a knack for killing igniters if I leave ignition key on for too long without running engine (no idea why yet) and for yours to last through this kind of abuse is, to me, incredible.

[Dave W]

If you are concerned about the wiring outside the distributor being to short, not allowing flexibility, which could lead to a fatigue failure. You can add a support/heat shield. I used one of the distributor hold down bolts to attach a small heat shield , then add padding and tie-wrapped the plugs to the shield. That way the short wires are not carrying all the harass wt.
Dave W

[chenfon]

Dear all

just to update on the my engine overheat issue. Finally have sufficient free time to dismantle the radiator and DIY overhaul service, found that the inside serious blocked and it might due to i recently had done the "scale" wash in engine cooling system with chemical, all the dirt clog at radiator.

after 1 by 1 slot clear, reinstall with new thermostat and radiator hose. Test run and found no more overheat issue, now the temperature always at 1/3 of the gauge although i at high speed.




so as conclusion that all above issue is due to radiator clog. thanks allot on the ideal and suggestion from the member. love u guys. tqvm