Motor intermittent jerks

[gunner93]

My motor suddenly developed intermittent jerks on acceleration and becoming worse by the day. :rant: This usually happens after cold starts. However, after 5 mins of up to operating temp, the motor is ok. Could anyone help me to understand whats going on? Is it plugs or coil packs or something else?

 

[kieran]

start with plugs buddy the cheapest fix but coil packs can do the same i had this a few times on my s15 always was plug when they got to the end of their life

 

[gunner93]

start with plugs buddy the cheapest fix but coil packs can do the same i had this a few times on my s15 always was plug when they got to the end of their life

I had the plugs out last night for inspection. They were Denso Iridiums IK20 at 40,000km. Funny that Denso claimed in their website they can last up to 100,000km. The plugs and coil packs visually looks ok to me. Anyway, I'll get a set of fresh plugs probably a notch colder and will share with you again. Thanks for your reply Kieran.

 

[sillbeers15]

I had similar encounter sometime back.

My ride would have intermitent jerk right after cold start but would be OK after some 15 mins of driving.

I started by replacing plugs, swap my HKS R45 plugs to 45I plugs...and all worked for the next few cold starts and same problem appeared again.

This time I ordered a new Z32 AFM to replace the old one eventhought I put very little miles on my ride. Problem still existed.

Finally, the problem was resolved after I've ordered new coils to replace!

After my encounter, I've heard another S15 complained similar problem and it turned out to be the crank position sensor that played up!

Hope the above info. helps.

 

[gunner93]

Thanks Sillbeers15 for sharing. Coils are nasty arent they?

 

[Nicely]

I agree. Sparks first, then check the coilpacks. Check for loose connectors first. Then just buy one coilpack initially, as its likely to only be one if its them. Its a process of elimination. Replace each coilpack in turn until you find the dodgy one.

 

[gunner93]

Its a process of elimination. Replace each coilpack in turn until you find the dodgy one.

Hmmm did not think of that. Thanks for that Nicely.

 

[ichi-go]

Usually if it's running 3 cylinders, the idling will be very rough and sounds like rex. What I do is disconnect each coilpack, if the idling/sound gets worse, replug it back. If it didn't do anything, that's your faulty coilpack.

If you are experiencing faulty coilpacks, i suggest you upgrade to splitfires. ALOT of people in ns.com experienced what they call as domino effect. Let's say u replaced coilpack cylinder 1 today, few days/weeks/months later, coilpack cylinder 4 dies. Then the rest will follow shortly. Even I'm having this problem at the moment. Splitfires are the only way to go

 

[sillbeers15]

I replaced all 4 coils at one shot...these are wear and tear parts, I don see the logic to replace one tyre at a time either...when you finally reach the last, you need to replace the first again?

I don believe in Spilt fire coils either....the stock stuff is good. If I want more juice at high rev, I would go for the HKS DLI stuff. But I don't get mis-firing at high rev at all. So I'm staying put.

It is the same logic with ECU, I'm very tempted to convert my religion to HKS V-Pro from PowerFC. Then again, I cannot fault my powerFC....so again I'm staying put for the moment till the day it iches really bad!

 

[gunner93]

Update: New plugs in and the missfire somewhat reduced but its still there this morning.

Just as I'd suspected earlier, say it together now... the COILS!

This is the inscription : HANSHIN MCP-3350 22448 91F00.

Is it common that even its not cracked it can still cause miss fire?

 

[gunner93]

This is good info on spark plugs reading...

http://www.max-boost.co.uk/max-boost/internet_articles/maxracesoftware/Spark%20Plug%20Reading.htm

 

[ichi-go]

I replaced all 4 coils at one shot...these are wear and tear parts, I don see the logic to replace one tyre at a time either...when you finally reach the last, you need to replace the first again?

I'm not sure how much you get your stock coils for but for me, splitfires are the way to go.

Why buy something that you know that will fail sooner or later when you know something known and proven can replace it?

I went to Nissan for a quote for the coils.

A$190 per coil. $760 for whole set of original coils

Splitfires $420 delivered

Go figure

 

[gunner93]

Different strokes for different folks. Over here the stock coils goes for GBP235 (RM1,600 for 4 pcs). Grrrrrr.....

 

[ichi-go]

LOL good luck.

 

[gunner93]

This thread is a repeat. Pls see here...

http://forum.s15oc.com/showthread.php?t=2208

Thanks