Running On 5 Cylinders During Startup (occasionally)

[Birds]

Hey guys,

Car is a R33 GTS-T, reasonably standard. Just after some ideas/input where to look in regards to fixing this issue.

Most of the time I start her up and she starts on 6 cylinders, idling/running beautifully. Every 3 or 4 days though (this only started happening a few weeks ago), and usually after a really cold night, I'll start her up and she will be running on only 5 cylinders...very lumpy feeling. Give her 5 minutes of idling and the 6th cylinder will pickup / run completely normal after that. The amount of idling time has gradually been getting worse though (waited 15 minutes the other night) and I've procrastinated doing something about it (because it's so sporadic), but I had to drive to work on 5 cylinders today so it's time to start diagnosing and fixing.

Have just ordered some new spark plugs in case one of them is fouled. Coilpacks are Yellow Jackets, haven't had an issue with these, but obviously won't rule them out as a problem either. Now a little bit of fuel/liquid comes out of the exhaust pipe if I give it a rev while it is running on 5 cylinders, making me think that fuel supply is fine (unless injector is leaking/flooding the cylinder?) and ignition is not occurring. Maybe a loose coilpack not sitting right, or issue with the wiring loom. Maybe a bad earth? What do you guys think it could be?

Any input will be appreciated.

Cheers.

[ClutchBurndout-:(]

certainly sounds like a spark plug issue, when was the last time you did your plugs? to me its almost like one of the spark plugs has oil on them and the idleing time to wait before 6th kicks in is the oil burning away or dispersing thus allowing it to fire, have you checked the leak situation in the inside of the valley covers? first and easiest thing to do before jumping to conclusions is to change your plugs and make sure there isnt any oil leaking onto them! then report back

[Birds]

I changed them about 10,000-20,000km ago...I always use iridiums (I know they are supposed to last until 100,000km but that doesn't stop them from getting fouled). But the last batch I put in, I *suspect* might have been cheap copies (got them off eBay for pretty cheap). This is just an assumption though, and I have not yet seen the state of the plugs. Have decided to go with platinums this time round just for a change.

Your explanation certainly makes sense, I hope I don't have rocker cover leaks grrr. I too put it down to either something having to burn away (e.g. flooded cylinder bore, something covering spark plug tip) or something metal having to heat up and expand in order to be running properly.

Thanks!

[ClutchBurndout-:(]

I changed them about 10,000-20,000km ago...I always use iridiums (I know they are supposed to last until 100,000km but that doesn't stop them from getting fouled). But the last batch I put in, I *suspect* might have been cheap copies (got them off eBay for pretty cheap). This is just an assumption though, and I have not yet seen the state of the plugs. Have decided to go with platinums this time round just for a change.

Your explanation certainly makes sense, I hope I don't have rocker cover leaks grrr. I too put it down to either something having to burn away (e.g. flooded cylinder bore, something covering spark plug tip) or something metal having to heat up and expand in order to be running properly.

Thanks!

just out of curiosity, why special plugs? the best ones are the normal ones imo, but everyones different!

valley cover leak is easy to fix (if it is causing this issue) you just take the center cover out and tighten the screws up, done, but just for good measure check your valley gaskets are ok, i suspect if its leaking enough oil to foul a spark plug that the gasket could need replacing, but like i said, these are the first things to check before jumping to conclusions!

any time, dont forget to report back!

[Birds]

I don't know why to be honest, it's a bit of "only the best for my car" syndrome...which isn't always rational (read: most of the time, irrational lol). I've heard that regular copper plugs are just as good but I have put iridiums in a few cars before and had them run noticeable better than standard plugs (could also have been the freshness of new plugs going in). Also heard that some Toyotas don't respond well changing from platinum to iridium. For $100 every 20,000km it never bothered me forking out for supposedly "better" plugs. Trying platinum this time round and who knows, maybe copper next time just to see if it's all the same for less dollars.

[ClutchBurndout-:(]

I don't know why to be honest, it's a bit of "only the best for my car" syndrome...which isn't always rational (read: most of the time, irrational lol). I've heard that regular copper plugs are just as good but I have put iridiums in a few cars before and had them run noticeable better than standard plugs (could also have been the freshness of new plugs going in). Also heard that some Toyotas don't respond well changing from platinum to iridium. For $100 every 20,000km it never bothered me forking out for supposedly "better" plugs. Trying platinum this time round and who knows, maybe copper next time just to see if it's all the same for less dollars.

fair enough! everyones different

[siksII]

Hey mate,

Sounds like an ignition problem as others have said. I would start with working out which cylinder has the issue. Do this by pulling the coilpack leads one by one.

Once you have done this and found the bad cylinder (the one where when you remove the lead nothing changes) :

-Only swap the plug from the bad cylinder

-If that does not work then swap a coilpack from another cylinder over

-If the problem follows the coilpack then thats yous problem

-If it does not, then I would be suspect of the coilpack loom

-You can buy a new loom, they dont cost that much, check all the wiring and plugs going to the loom for damage

-If you dont want to buy a new loom then you can take apart the plugs and bend the pins so they have stronger contact

-I have not seen an issue like that which has not been solved by the above, so if you still have the problem then im out of ideas.

[Birds]

Good plan siks, I'll give that a go. Problem being that it's such a sporadic problem, so I'd have to wait for it to pop up again. I'll be changing spark plugs tonight regardless because I'm up to that service interval, but if it happens again I'll try the coil pack thing. Might leave my valley cover off so I have easy access when it does happen next.

[RANDY]

I get the same thing on very cold mornings... It'll come alive immediately if I give it a tiny bit of pedal.

Bit annoying sometimes... I can leave it for 20 seconds, and it will turn over on its own about once a second and eventually burst alive.

[SS8_Gohan]

Splitfires are the only way to go mate and NGK coppers, heat range 7 i believe, gap .8mm

[tridentt150v]

If you do what Siks says [and good write up], then you could have a lazy injector, Doesn't like the cold and only free's up when it warms up. Either buy new or get them cleaned and serviced.

[RANDY]

To further my last post..

I have splitfire coilpacks and NGK iridium (heatrange 6, 1.1mm gap, never falters under any rpm)

I do like the idea of the sticking pin in the injectors as a theory, and I was going to suggest this to the topic starter.... I will be getting mine overhauled in the next month or two.

[Birds]

Splitfires are the only way to go mate and NGK coppers, heat range 7 i believe, gap .8mm

How modified is your vehicle? Because NGK recommends heat range 5 which is the standard heat range for an R33 RB25DET. I've been using 6 and I reckon 7 would be too high unless your engine gets very hot, would take too long to heat up for daily use. Also the bigger the plug gap the better as far as I know...I've heard you should only gap down from 1.1 if you have misfire issues.

My ignition setup has been perfect until this one cylinder playing up issue! Could well be a lazy injector as mentioned, I hope not though, as I don't like the idea my piston has been earthing a spark all this time.

Cheers guys.

[ClutchBurndout-:(]

How modified is your vehicle? Because NGK recommends heat range 5 which is the standard heat range for an R33 RB25DET. I've been using 6 and I reckon 7 would be too high unless your engine gets very hot, would take too long to heat up for daily use. Also the bigger the plug gap the better as far as I know...I've heard you should only gap down from 1.1 if you have misfire issues.

My ignition setup has been perfect until this one cylinder playing up issue! Could well be a lazy injector as mentioned, I hope not though, as I don't like the idea my piston has been earthing a spark all this time.

Cheers guys.

6s would be optimal

1.0 or 1.1 is fine, to small a gap wont have a strong enough spark, but if its to big the spark can be blown out, thats why 1.1 is the most optimal i think

have you tried running an injector cleaner though?

[Birds]

Yeah, I used an injector cleaner once when I first got the vehicle but I've heard mixed things about them (leaving deposits etc.). I'm not a fan of bandaids, I'd sooner just get my injectors reco'd...or...replace them with bigger and go the turbo/ECU upgrade route

Could still be an ignition problem though...I haven't replaced my plugs/coilpacks yet as I am lazy

[siksII]

Could still be an ignition problem though...I haven't replaced my plugs/coilpacks yet as I am lazy

Too much talk too little action, you need to get off the forum and troubleshoot your car so you can report back to us all instead of procrastinating on the forum about it

[Birds]

Okay reporting back with *some* results. Replaced spark plugs, didn't solve the problem but the engine feels smoother (as it always does replacing spark plugs). I've come to the conclusion that the 100,000km claim to fame iridiums have is utter BS, given I had them in my vehicle for 15,000 and straight away I've noticed improvement by changing them...and switching to platinums.

I left my valley cover off when putting the intake piping back on so that I could access the coil pack loom next time she decided to play up and run on 5 cylinders. Today I wasn't in a rush and it started on 5 cylinders so I popped the bonnet, started pulling loom plugs off coil packs. Cylinder number 1 made no difference so there's our culprit. Now I think it'll either be a faulty coil pack or a lazy injector (or possibly the coil pack loom itself). Gonna switch the coilpacks between cylinders 1 and 2, that way when the problem happens next time I'll hopefully be able to pull the loom plug from cylinder 2 and it won't make a difference...evidencing a faulty coil pack. If it does make a difference then it's a fuel supply problem to cylinder, e.g. faulty injector. Comprende?

[Jezza-gtR]

6s would be optimal

1.0 or 1.1 is fine, to small a gap wont have a strong enough spark, but if its to big the spark can be blown out, thats why 1.1 is the most optimal i think

have you tried running an injector cleaner though?

1.0 - 1.1 is fine for N/A but not for turbo. 0.8 - 0.9 is for turbo. The smaller gap is for high RPM becuase they rev so quickly. If the gap is to big / spark to long it wont burn fast enough at high rpm.

Also for stanard / low modified turbo car just use Copper plugs, 6's with 0.9mm gap.

And Birds it does sound like there is some coil pack / injector related issue. Bring it to the shop!

[Humbla]

Splitfires are the only way to go mate and NGK coppers, heat range 7 i believe, gap .8mm

Yes perfect,good choice,been using this for 6 years no probs.

[siksII]

The smaller gap is for high RPM becuase they rev so quickly. If the gap is to big / spark to long it wont burn fast enough at high rpm.

Its got nothing to do with how fast the motor revs, if it does can you please elaborate?