Extremely Bad Missfire And Rough Idle

[Chris34]

Ok so firstly, the problem. Soon as I start the car, it idles fairly smoothly as per normal however you can feel these low-pitched subtle pops/thumps coming out of the exhaust which you can feel while sitting in the car. As I start driving it, the car starts jumping and that low-pitch popping sound becomes consistent with the revs and basically the car barely goes anywhere. I first had it looked at through a workshop and he said it was probably burnt out spark plugs, turns out yes my spark plugs were burnt out so brand new ones were put in.

I picked up the car and the car drove perfect! That was until boost comes in, as soon as boost came in, the same thing happened again (as above). Then for a short period of time on the way home, it was all clear and the car drove perfectly both on and off boost and was as it use to be. But then the problem came back where the missfire and popping/thumping would happen just above 1500rpm. I barely made it home.

Does ANYONE know what the problem is/what's causing it?

Not sure if it's relevant or not, however last week the car overheated due to the plastic spout on top of the stock radiator breaking. I had a new Koyo Aluminium Radiator installed and when I picked it up from that workshop that installed the radiator, that's when this problem occured. However they stated they touched nothing but take out the old radiator and drop in the new one.

[siddr20]

What are the new plugs installed? What are they gaped too?

[Chris34]

Mechanic said he just put standard copper plugs in. Gaped to 0.8 im pretty sure

[PIOTREK]

could be the coil pack, lead or crank angle sensor. also clean the air/flo sensore

[DanShirts]

could be the coil pack, lead or crank angle sensor. also clean the air/flo sensore

+1

Also, see if there is are codes, and check timing.

[lowbro]

If your plugs were that old, and it depends how many km's your OEM coil packs have done, I would suggest if you can afford it to replace all 6 x Coil Packs to compliment your new plugs with after market ones (Splitfire, Superspark etc) to save yourself any headaches in the long run. Superspark's are an excellent choice for the price range.

[lowbro]

In saying that I have a 2 x full sets of OEM coils for the R34 GTT that have only travelled 65000km's and are in perfect working order for purchase?

PM - If you are interested in talking more

[OMGGTR]

just a small suggestion... would this happen if the wrong plug was inserted into the wrong coil pack ???

[mad082]

if the coilpacks were plugged in correctly on the loom it would be a possibly cause, however the idle would be more affected as well.

i would be looking at new coils also

[Cefiro RB26]

Ok so firstly, the problem. Soon as I start the car, it idles fairly smoothly as per normal however you can feel these low-pitched subtle pops/thumps coming out of the exhaust which you can feel while sitting in the car. As I start driving it, the car starts jumping and that low-pitch popping sound becomes consistent with the revs and basically the car barely goes anywhere. I first had it looked at through a workshop and he said it was probably burnt out spark plugs, turns out yes my spark plugs were burnt out so brand new ones were put in.

I picked up the car and the car drove perfect! That was until boost comes in, as soon as boost came in, the same thing happened again (as above). Then for a short period of time on the way home, it was all clear and the car drove perfectly both on and off boost and was as it use to be. But then the problem came back where the missfire and popping/thumping would happen just above 1500rpm. I barely made it home.

Does ANYONE know what the problem is/what's causing it?

Not sure if it's relevant or not, however last week the car overheated due to the plastic spout on top of the stock radiator breaking. I had a new Koyo Aluminium Radiator installed and when I picked it up from that workshop that installed the radiator, that's when this problem occured. However they stated they touched nothing but take out the old radiator and drop in the new one.

Hay i had a very similar problem with my R34 after checking all the above mentioned problems new plugs new coils. i pulled the cas spun the shaft and there it was noisey bearings. pulled it apart marked it carefully pressed on new bearings put it back in bang full power again. no problems even put my old coils back in perfect.

It is actually the fastest check out of all the possible problems and $15 to fix.

[neofenrir34]

I maybe over doing it here but. You say it overheated? by how much and for how long? these things have alloy heads, i.e. to hot for to long and your head starts to warp (Very bad) Has it used any coolant at all?

might be something to look into

[Chris34]

Found out it was the wiring loom/harness for the coilpacks. 2 of the plug clips were cracked so they were basically half in half out sometimes.

In regards to the head being warped...is this something that could be potential in the near future? What's the easiest way to tell?

[mad082]

IF the head is warped the main damage is already done, but it can mean that the head gasket may let go some time in the future. really is a case of "how long is a piece of string" though.

[Altia_R34]

i think i may know what it is, i got the same problem turns out to be the crank shaft sensor, get it fixed or else it could fk up the timing and bend your valves