spark plug gaps

[Stott69]

So Ive pulled the plugs out of the Aristo (2jzgte single @ 10psi). They're a little oilly but main thing is the gaps look huge, like up to 3mm. I take it this is huge?

[matt dunn]

So Ive pulled the plugs out of the Aristo (2jzgte single @ 10psi). They're a little oilly but main thing is the gaps look huge, like up to 3mm. I take it this is huge?

looks can be decieving, best to measure if you can,

but 3mm is huge yes.

My suggestion would be 0.8 to 1.0 mm

[strx7]

this the same car that sometimes has starting issues????

[Stott69]

Yip. Fault code that I pulled was 25, which could be ignition, hence checking plugs.

[Dell'Orto]

Haha shit, replace them STAT. If they are huge gaps they'll kill your coils. Denso plugs are cheap as $&#$%

[Lloyd]

So often the basics get overlooked. Checking the plugs should be one of the first things to do.

As Matt said, measure them. They should be 0.8mm or 1.1mm for standard ones. I'm surprised your coils have lasted this long if they're up to 3mm as the JZs are notoriously hard on coils in the first place. Most Japanese stuff will run plus in the 0.8-1.3mm range.

[Crucible]

Yip. Fault code that I pulled was 25, which could be ignition, hence checking plugs.

Was this not a system lean code? All good..just curious what made you check the plugs.

This have a missfire prob aswell?

[Stott69]

Was a slightly unsettled idle, think Ive found that, spring in the bottom of coil 2 is missing. Checking the cheap things first, will check fuel pressure once I score a gauge.

[Stott69]

Oh and eyeomiter is out, plugs look to be about 1.5 against a rule. Will regap once I get feeler gauges.

[matt dunn]

Oh and eyeomiter is out, plugs look to be about 1.5 against a rule. Will regap once I get feeler gauges.

If they are at 1.5 they are worn and need replacing not re-gaping.

[Mr Ree]

Oh and eyeomiter is out, plugs look to be about 1.5 against a rule. Will regap once I get feeler gauges.

Dont waste your time, mate.

Just order a new set through Mark, which come pre gapped, and you are golden.

[JZCrazy]

Error 25. Air fuel ratio rich/lean malfunction.

Oxygen sensor related. Check the wiring to o2 sensor and the sensor.


I have a couple of spare sets of 1j-2jz coils if you need any.

[Dell'Orto]

Or if it's misfiring from dodgy plugs/coils...

[Crucible]

Error 25. Air fuel ratio rich/lean malfunction.

Oxygen sensor related. Check the wiring to o2 sensor and the sensor.

Or force it rich and see if O2 responds by going to 1v on signal wire.

[touge_ae101]

Really don't want anything bigger than .7mm for turbo. up to 1.1 for a na engine

[Lloyd]

Big gaps are fine, but you need the ignition system to cope with it. 0.7mm is a damn small gap. Plenty of manufacturers will specify 1.1mm for turbo applications still, though they tend to have decent ignition system to deal with it. Small gaps do mean it's easier to fire the spark, but it doesn't make it any easier to ignite the mixture.

[Stott69]

Lots of wisdom coming in will through a new set of plugs in and fix coil 2 and see what difference I get. Might just fix the easy stuff then send it in to the shop for the hot start issue if its still there.

[Stott69]

Called Mark and ordered new plugs. Theres two different factory gap sizes for S1 &S2 Aristos, mine being .8, post '93 being 1.1.

[Mr Ree]

Is that because of the jump to the higher output vvti coils?

[steroidcontaskie]

Not 100% sure, but I thought vvti didnt come in till 1997, so it wouldnt seem to be that.