[Moph]

Hi gurus

I've been tidying up my Zook in preparation for next weekend's WA Auszookers trip, and have found that what I presumed was just a lead problem is something more. It hasn't been driven on-road for the last year, though I have started it every couple of months, and it's developed an extremely rough idle. When I checked the leads and plugs, no. 4 plug was sooted up and no. 2 lead had broken the connector at the dizzy end, so I thought that was the likely problem. It's a stock carbied G13BA, complete with crapped-out auto choke.

Replaced the leads (Bosch B35CSi, B58SI x2, B63SI x2) and plugs (Bosch Platinum Plus WR7DP) last night but the rough idle hasn't changed. Cylinders 1 & 2 aren't firing at all at idle - I can disconnect them and the idle doesn't change. I am getting spark to them as you can hear the 'tick tick tick' of sparks arcing across if I hold the lead end just off the spark plug, but they're obviously not firing.

The rotor and dizzy housing are relatively new (<10,000km) and don't look at all eroded, so there should be plenty of spark strength. Lead position is 1-3-4-2 per the marks on the dizzy housing, and I've quadruple checked the lead connections for correctness. Timing is set to 10* BTDC as it was when I last adjusted it (I run 98RON in it to avoid pinging).

What's next on the checklist in terms of possible problems?

Cheers
Moph

[alien]

is it maybe a fueling problem? (not getting enough)? Maybe try some "start ya bastard" down the carby and see what happens?

[atari4x4]

g16b swap is the only logical answer.

[Chop]

Its just letting you know you don't drive it enough!

[Moph]

Nah not a fueling problem - and the carby is nice and clean (visually) plus have already chucked a heap of carby cleaner through it (the spray-in kind).

Just put a new tank of 98 in and took it for a 15km run at 100kph ... it sits at that nicely with the AC running, so there's no noticeable loss of power at speed. Pulled up in the driveway with the engine nice and hot (ie choke ain't an issue) and still cylinders 1 & 2 aren't firing at idle. Checked timing and confirmed it is at 10* BTDC.

Might swap plugs 1 & 2 with plugs 3 & 4 to see if there's any change. I'm a bit stumped

[royce]

I'd check compression next, looking for a valve holding open or a head gasket

[sideways]

^

My LJ does the same thing on cyl 1. It's got low compression on just that cylinder.

I've got a compression tester you can borrow if you want. I wont be back in Perth until Tuesday though.

Checked valve clearances?

[Moph]

Have got a compression gauge here somewhere from when I did the rebuild a few years ago ... will hunt around and find it. No idea where my thickness shims have gone so will need to pick up another set tomorrow to check the valve clearances.

[Moph]

Bought myself a new Stanley compression gauge and measured 185-190-190-190 (1 -> 4) ... that's pretty much the same as the 180-180-180-190 I got on my old gauge after doing the rebuild 20,000km ago. So doesn't look like low compression is the cause

Those compression readings were with engine up to temp and dry cylinder (ie no oil squirted in), all four plugs out. It took a few piston strokes to get to those values. Think that's all normal but just saying anyway cause I'm a mechanical nub

It's still chugging at idle though and is due for an oil change, so I put 500mL of diesel in with the old oil and idled it gently for 5 minutes to flush the system through. Dumped that out and have chucked in 5L of cheapo 20W50 and a new oil filter to flush the diesel out of the system. Will run it through for a few hours tonight (just idling in the garage ... no windscreen atm) and change the oil and filter again tomorrow. No change in idle as a result of the flush though.

I also played around with the leads just to be sure, and had no issue running cylinders 3 & 4 with the leads that belong on cylinders 1 & 2. So not faulty leads.

As for the plugs ... something weird is going on there too. The old set of plugs are on the left (4-3-2-1) and the new set with <100km on them are on the right (4-3-2-1). Cylinder 4 is one of the two that is firing at idle, but it's carboned up already...

[JrZook]

Have you checked all your vacuum hoses and the PCV valve?

[losfer]

JrZook wrote:

Have you checked all your vacuum hoses and the PCV valve?

x2 was just about to post same thing

[Trebor]

Is it possible that it is the the distributor itself that is faulting??

[Moph]

JrZook wrote:

Have you checked all your vacuum hoses and the PCV valve?

This man was on the money. Still, I'm sure the Zook will enjoy the new plugs, leads, dizzy cap, rotor, coil, compression test and oil flush that I've done trying to solve the problem already

Can anyone tell me what the vac line spigot at the centre of the photo below is meant to connect to? I don't have a loose vac hose in the area

Also cleaned the PCV valve while I was at it - operates freely now. I noticed that the thread doesn't embed full depth into the manifold though when I screw it in, and there are perhaps 4-5 threads still visible when it reaches a very firm and distinct stop point. Is that normal?

[Moph]

Moph wrote:

JrZook wrote:

Have you checked all your vacuum hoses and the PCV valve?

This man was on the money ... front two cylinders were leaning out due to a vac leak at the front of the manifold, and that probably also explains why cylinder 4 was running rich and sooting up the plug. Still, I'm sure the Zook will enjoy the new plugs, leads, dizzy cap, rotor, coil, compression test and oil flush that I've done trying to solve the problem already

Can anyone tell me what the vac line spigot at the centre of the photo below is meant to connect to? I don't have a loose vac hose in the area

Also cleaned the PCV valve while I was at it - operates freely now. I noticed that the thread doesn't embed full depth into the manifold though when I screw it in, and there are perhaps 4-5 threads still visible when it reaches a very firm and distinct stop point. Is that normal?

[Marko_SJ]

Moph wrote:

Moph wrote:

JrZook wrote:

Have you checked all your vacuum hoses and the PCV valve?

This man was on the money ... front two cylinders were leaning out due to a vac leak at the front of the manifold, and that probably also explains why cylinder 4 was running rich and sooting up the plug. Still, I'm sure the Zook will enjoy the new plugs, leads, dizzy cap, rotor, coil, compression test and oil flush that I've done trying to solve the problem already

Can anyone tell me what the vac line spigot at the centre of the photo below is meant to connect to? I don't have a loose vac hose in the area

Also cleaned the PCV valve while I was at it - operates freely now. I noticed that the thread doesn't embed full depth into the manifold though when I screw it in, and there are perhaps 4-5 threads still visible when it reaches a very firm and distinct stop point. Is that normal?

If no one gets back to you by the time I've finished writing / end of the day I'll go and look for ya.

[Moph]

Think I found it ... there's a little sensor box/solenoid or similar fixed to the firewall near the VIN plate, and that had a loose hose dangling down behind the back of the alternator. The end of that hose was stretched so it's probably just worked it's way off. New hose fitted and idle is smoooooooth

[Marko_SJ]

Moph wrote:

Think I found it ... there's a little sensor box/solenoid or similar fixed to the firewall near the VIN plate, and that had a loose hose dangling down behind the back of the alternator. The end of that hose was stretched so it's probably just worked it's way off. New hose fitted and idle is smoooooooth

Yep thats what it is, I removed it from the front the other day as didn't wanna burn it.