Toyota Liteace 5K Engine Misfire

[Izzie]

Greetings!

As per subject matter, I have isolated the misfire to Cylinder No.3 after a “spark” plug test. I’m getting a No Spark for that particular cylinder.

Steps taken:
1.Swapped the HT wires = no improvement.
2.Replaced the affected spark plug = no improvement.
3.Replaced contact point and condenser = no improvement.
4.Replaced ignition coil = no improvement.
5.Inspected and cleaned the distributor cap and rotor = no improvement.

The distributor is fairly new (8mos old). It was replaced, as suggested by the mechanic, because the van won’t start then.

I went to two auto shops. The first concluded that it needs a top overhaul. In the second auto shop, I request for a (dry) compression test and the results for all cylinders are okay. (No wet compression test was made.) But the second shop also concluded a top overhaul is needed.

I got confused so I did some research and the reasons for misfiring:
1.Loss of Spark
2.Improper Air/Fuel ratio.
3.Loss of Compression.

If we apply the “process of elimination”, I’m still at number one. There is no spark. So why a top overhaul is needed?
I’m at loss here so can anybody provide me some advice? I live in santolan, pasig. Can any fellow tsikoteers refer me to mechanic that’s within the area?

Thanks!

[jick.cejoco]

Check your points gap at four lobes of the distributor cam. Number three lobe might be worn out

[RIPmyBrother]

Hi !

My comment:
"To overhaul the Topend helps only to reduce the misfire problem in the wallet from the mechanic but not your engine".
;-)


Your steps from the trouble shooting where good and logical :shake:
After changing the parts (points, spark plugs, coil), swapping the HT wires and checking the compresion (all cylinder are good) it is logical that the problem is the distributor cap and finger.
Change the finger only because it is better to change it together with the cap (my experience).
You inspected and cleaned it but sometimes you cant see micro cracks in the plastik and this very thin cracks can cause the the spark spark went somewhere (to negative ground).
Please report if that was the problem, thank you.

Regards
Ruediger

[Izzie]

*jick.cejoco

Hmm...you have a point there.

I removed the distributor cap and rotor. Inspected the four lobes and I don't think the number 3 lobe is worn. I cranked the engine (w/o the cap and rotor), and looking closely at the contact point....i don't see much play. Maybe the "air gap" of the contact point needs adjustment? Timing?

*Ruediger

Thanks for the comment. The internet helps a lot and that's where I get the information I need in trying to solve this problem. Especially here in this forum.

As for your suggestion, I will try to look for that "short" by spraying a mist of water on the distributor/HT wires while the engine is running.

Although the distributor assembly is fairly new, I'm thinking of replacing this with another one but this time it will be an OEM. If I can find one though.

I have to double check the timing first before I replace it.

Cheers!

[dr. d]

you used a substitute distributor cap!!??
well, if i were me, i would replace the distributor cap. ...i don't have much faith in substitutes for vital parts.. experience.. but check my comment below first.

inspect the no. 3 tower again. check with an ohmmeter, between the tower outside, and the point inside, to see if it is "open".
also, did you actually see the spark, or lack thereof? if not, maybe you should do it. remove the #3 HT from the sparking plug, expose the metal electrode by pulling it out of the rubber insulating cover (don't pull it out of the cover; push it thru the cover!), and position the exposed metal electrode very close" to the engine (metal). crank the engine. a spark should be seen at the end. if none or very weak, there's something wrong with your spark delivery system proximal to the HT cable's end. this may be the distributor cap or the HT cable.
if you have a timing light or gun, clamp the sensor around the #3 HT cable and see if the timing gun's light fires. if it does not, then your #3 HT is "open".
good luck.

...good old troubleshooting... haven't had this much fun in a long time..

[Chinoi]

Try this cheap screwdriver voltage tester. Touch tip of screwdriver any portion of HTW. Neon bulb will glow from induced high voltage from HTW.

It's simple , accurate, cheap and SAFE.

[dr. d]

Try this cheap screwdriver voltage tester. Touch tip of screwdriver any portion of HTW. Neon bulb will glow from induced high voltage from HTW.

It's simple , accurate, cheap and SAFE.

oo nga, 'no!
now why didn't i think of that?..
alamkuna... walang ganyan pang-kotse noon.. meron ganyan, nguni't pambahay (220V) lang ginagamit noon..

[Izzie]

* dr.d

Oh yes, I forgot to mention that on my first post. I did substitute the distributor cap 3 times. Swapping with the old OEM cap and to a new cap, that I bought BEFORE replacing the OEM distributor assembly. Still no improvement.

Definitely no spark in #3. But will do it again following your suggestion.

Thanks Chinoi for the tip! Unfortunately, the CD-King store here is close. Will look somewhere else.

[Chinoi]

*Izzie

Meron niyan sa Ace Hardware, Electrical Supplies. Maraming mekaniko nagugulat sa tester na naisip ko na iyan.


Actually meron ako mga neon bulb naka dikit sa htw para malaman ko kung may pumapalya.

[Chinoi]

*Izzie

Sorry, hindi ko alam kung carburator type ang engine mo.

Na try mo ba silipin mga kulay ng spark plug gap mo. It migh help isolate your misfiring problem.