Huge stutter under load...Help!

[M0R81U5]

I know there are a couple of other threads about similar topics, but I couldn't find anything with symptoms matching mine, if I've missed something though, please feel free to point me in the right direction.

Currently I have a problem where if I accelerate hard at around 5-6K in any gear the car will violently jerk and stutter. Like almost headbutt the windscreen violent. if I keep my foot down it will stutter 3 or 4 times then pick up again. It has very very occasionally done something like this over about 18 mths of the 2 yrs I've owned it, but since I fitted my new intercooler kit about a month back it will do it everytime I accelerate. I also feels to my 'seatofthepants-o-meter' to be not producing as much power as previously, but I can't substantiate this. If I accelerate to about 4K-ish and let off the throttle it gets a little jerky then too.

Its a manual prefacelift with the only real mods being a HDCB clutch, coilovers and not the I/C with silicon piping. I threw a boost gauge on there and it is making boost and doesn't appear to be spiking (the highest reading i've seen under full load was 10psi). All intercooler piping is firm and doesn't seem to have moved since I fitted it.

A few other things (dunno if they could be the culprit or not):

• Lifters are poo. They have needed doing for about the last 12mths. I have these and am just waiting for some time to fit them. I've been using MBL8 in the meantime which only seems to be effective for about 2000k's
• Alternator. I had some doubts about the condition of this. I've got a new one of these to fit aswell
• Plugs. I did these about 20K ago. I did notice a very small amount of oil around a few of the plugs when i changed these, so I'll be changing the seals when I do the lifters and also cleaning up the coil packs
• Oil is changed every 5K religiously, tranny oil was done about 15K ago, clutch was replaced about the same time

I don't know what else to say excpet help! It's driving me bananas...big jerky, stuttery bananas. Any suggestions or questions before I have to bite the bullet and take it to a workshop would be very much appreciated.
Cheers

 

[bradc]

Most likely incorrect plugs that have worn down or coil pack break down.

 

[M0R81U5]

Cheers Brad, plugs are defintely the correct ones, they are the same iridiums that a bunch of people on here are running.

Is there any way to test for a dud coil pack other than swapping them out?

 

[snickells]

Yup, was going to say plugs too. Easy fix.

 

[M0R81U5]

Iridiums are supposed to last 100K though right? What could have killed em after barely 20K?

I'll pull them out and check them...

 

[Guest]

I pulled some out at similar mileage and the back ones were already beginning to look a bit worse from the heat. Assuming there were no other problems I personally wouldn't trust them past 40,000kms.

 

[fieldy107]

Clean your coil packs, I had what sounds like the same problem and was thinking plugs/leads. A coil pack clean completely cured my problem though and it cost almost nothing if you do it yourself.

 

[snickells]

Check your not getting oil coming in from the oil seals on your turbo's, as this can lead to some nasty spoiling which will kill your plugs.

Check by removing the air intake from the rear turbo (which you'll do when you check your plugs anyway) and look down into it with a torch. You'll see oil coating the walls which will give you an indicator of what's going on.

 

[VOLK]

+1 coil packs. Let me guess, it doesn't stutter at those revs with lighter load right? The issue has most likely been helped along with your new IC providing cooler, denser air capable of holding more fuel ultimately making the mix harder to ignite. When it stutters, does it sound like it's missing badly? If you're ever heard the vast majority of R32/R33 skylines with upped boost and old coilpacks you'll know the noise I mean.

 

[timmae2006]

My mates R33 gtr did the same thing and one of his coil packs was gone big crack in it.....could be your problem too

 

[fieldy107]

Is there any way to test for a dud coil pack other than swapping them out?

Just give them a clean and then drive it. When we cleaned mine they didn't look dirty at all, so was not really expecting a quick spray of contact cleaner to help anything. It definitely did the trick though, my car was stuttering hard at like 10 psi, now I run 15 with no stuttering.

 

[M0R81U5]

Check your not getting oil coming in from the oil seals on your turbo's, as this can lead to some nasty spoiling which will kill your plugs.

Check by removing the air intake from the rear turbo (which you'll do when you check your plugs anyway) and look down into it with a torch. You'll see oil coating the walls which will give you an indicator of what's going on.

Funny you mention that. When i was changing all the piping over i noticed a little more oil than I was comfortable with in the piping and original IC. i've only ever changed one cooler before on my old 180 and it was virtually spotless, so I have nothing to compare this to. I took a couple of pics and was going to ask for opinions.

A couple of those pics its hard to see, but there was a bit of oil in there. The two rags were just wiped once inside the pipe and came out like that.
Thoughts?

 

[M0R81U5]

Oh and thanks Chris, Tim & Joey, I've been planning on cleaning the coil packs just as a matter of course after I read the guide posted up on here a few weeks back. I've been driving around with a can of contact cleaner in the boot for about 2 weeks now

Fingers crossed thats all it is.

 

[M0R81U5]

Quick update on my problem, I whipped out the coilpacks and cleaned the crap out of them and at the same time pulled the plugs out of the front bank. They are pretty black but not excessively considering how rich these things run. There was no oil or residue in the spark plug tubes whatsoever.

Anyway, it felt a little better at first, but now it's just as bad as it was. I'll be doing the litters in a couple of weeks, so I might throw a new set of plugs in there at the same time, any other ideas out there?

 

[VOLK]

Methinks your coil packs or leads are porked. Perhaps even the rear plugs as it's the hotter head of the two.

Still getting the same symptoms? Light throttle revs smooth but boost breaks down?

 

[M0R81U5]

Yeah exactly the same symptoms. Light throttle is OK, but give it a bit of stick and you will almost certainly headbutt the windscreen.
The leads were replaced about 20K ago when I did the plugs last. I'll pull the rear plugs when I do the lifters and report back in.

 

[M0R81U5]

I really didn't want to have to dredge up this old thread, but I still have this damn problem. From about 4-4500 rpm on WOT the car just burps, farts and jerks about. It sounds as though it is losing all spark.
Today I replaced the coilpacks, which I thought was definitely the cause and fitted some new NGK leads. I also replaced the plugs again about a thousand K's ago.

Does anyone have any suggestions for me, I'm all out of ideas?

 

[reeve]

hey man, sounds stupid but unmount your crank angle sensor and just temporarily hook it around the top of your washer bottle, i had a similar issue for months, i changed plugs, leads, coils, ignition module, fuel pump, fuel filter, boost solenoid, air flow meter, ecu, and the list goes on. turned out the leads were arcing and fucking with the crank angle sensor making it think the car was doing 150000 revs therefore it was cutting the spark. hope this helps mate, i know the pain, after months of shit i was close to burning it out!!!!!!

 

[naughtika]

hey man, sounds stupid but unmount your crank angle sensor and just temporarily hook it around the top of your washer bottle, i had a similar issue for months, i changed plugs, leads, coils, ignition module, fuel pump, fuel filter, boost solenoid, air flow meter, ecu, and the list goes on. turned out the leads were arcing and fucking with the crank angle sensor making it think the car was doing 150000 revs therefore it was cutting the spark. hope this helps mate, i know the pain, after months of shit i was close to burning it out!!!!!!

did you have plastic insulation on it to avoid it touching each other? just curious to know...

 

[M0R81U5]

hey man, sounds stupid but unmount your crank angle sensor and just temporarily hook it around the top of your washer bottle, i had a similar issue for months, i changed plugs, leads, coils, ignition module, fuel pump, fuel filter, boost solenoid, air flow meter, ecu, and the list goes on. turned out the leads were arcing and fucking with the crank angle sensor making it think the car was doing 150000 revs therefore it was cutting the spark. hope this helps mate, i know the pain, after months of shit i was close to burning it out!!!!!!

Thanks Andrew, I'll give it a try. Man, over the weekend I was all ready to get rid of the car, it's doing my head in. If your leads were causing the problem, wouldn't it have been sorted after you replaced them?

N00b question time....where exactly do I find the crank angle sensor?