4Y 2.2 Backfiring / missing

[barnicle]

Hi All
I wonder if anyone can help me with the following problem.
My Hilux 2.2 4Y motor started miss firing, back firing and running on 3 cylinders after being used continuously at low speeds ( less than 30km ) not always in low or 4x4 ratio.Especially when cold.
I checked the timing ( 9 deg BTDC ) serviced the carb and replace all the necessary parts, with no effect.
Check the spark and found that the number 2 cylinder and sometimes number 3 cylinder made very little difference when spark plug lead was removed, although they both had a spark. The plugs were black and obviously not working well.
I replaced all the leads and the plugs went well for 1-2 days, then back to backfiring and missing when cold and plugs black.
I have now redone the head with new valves, guides and seals. Still Backfires immediately. Vehicle NOT smoking or using oil so don,t suspect oil rings. Each time new plugs used vehicle runs well but backfires, untill stands for a day then miss fires and runs on 3 cylinders. Help please!!

[Ou Legend]

Klink vir my na jou coilpack wat foutief is.

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[barnicle]

Dankie Ek kyk daarna

[pietpetoors]

Did u check distributer cap and roter?

[barnicle]

Yes have replace distributer cap, but not the roter as it looked ok.

[LouisZ]

1st off,

Is the Firing order ok? Should be 1342.

Is it the old dizzy with points? Set points

Timing could be high, go down to about 7.

Rotors you have to check at the tip, if it is burned you get a weak spark. Look for it, right at the tip you wil see unevenness, this cause it to act as an insulator.

[Mud Dog]

Something that you mention in that the problem remains specific to the same one or two cylinders despite having replaced plugs, leads and dizzy cap. If it were the coil it's more likely that it misfires intermittently across all the cylinders. This leads me to think that there is a problem with the cylinder itself. I know you said you did head and valves (were the valves ground into the seats?), but have you done a compression test across all 4 cylinders? If the compression is weak on that cylinder (could be a broken piston ring) then it will be the one to start misfiring first. The black plug indicates that it's burning rich or not at all (especially if it's wet when removing it straight after running the motor). Poor compression could also cause poor combustion, so even if it's not misfiring all the time, the plug would still be black. Do the compression test, not difficult, and it will at least eliminate or confirm a mechanical fault rather than an electrical one.

[Hoppy]

Do a dry and wet compression test or a cylinder leak test first, if it checks out ok, check the following;

1. The choke might be set to rich, this will kill the plugs and cause the black fouling.

2. The oil pump pressure valve is stuck, to high oil pressure will "pump the lifters up" so that the valves doesn't seal, as soon as the engine oil gets hot and the pressure drops and they seal again, replace it with a genuine Toyota pump.

[barnicle]

Firing order correct.
Rotor not burned and clean.
Points replaced with electronic system.
Timing reset to 7deg, improved but still missing when idling and backfires now and then. Has effected power or my imagination.
Choke checked - seems to be working ok.
Checked cylinders for scoring when head was off so hopefully no broken rings.
Valves and seats were ground in by reputable engineering firm.
Not sure how to check oil pump pressure valve??? possibly just replace.
Agree that compression needs to be checked before moving on. What is the best gauge to buy??
Thanks to all for the input and ideas will post report on compression as soon as I have obtained a gauge.

[Muz]

hi Donald

I could have a look with you sometime, not that far from Sandton. had a similar issue with a 88'carolla engine last week or two. recon'd the head, going like a rocket now. If you need help buzz me 082 857 2208

[barnicle]

Thanks for the kind offer Murray

The vehicle is however in Hoedspruit. Hence the slow action, as I only get there once a month. I may call if not successful once I've tried all the options at the end of the month.

[willem2013]

Hi I have a problem on a 2.2gwm with the 4y in and it was backfiring and it was like surging and now there is no spark what can be the the problem not geting spark please help