Strange Popping, Popcorn Roasting Sound At Around 7000 Rpm

[Dose Pipe Sutututu]

Hi all,

I've just noticed this sound from my car when I decided to drive it without the stereo on for change, probably the first time in a year and when I go to give it some stick I observed a popping sound from the motor, as if it was like a popcorn roasting sound that your popcorn maker would make around 7000rpm.

Could this be detonation?

I am running 14PSI which I think is reasonably safe, as the ECU has been remapped by the previous owner who removed the rev limiter (moron, well the tuner, which I think was Autosport Engineering, which btw charged 8k for a RB20 transplant into a 180sx, not to mention dodgey wiring which I had to redo, ECU & A/C wiring was a mess, skipped relays & pressure sensors, not to mention the fuel pump constantly on!)

Around 3 months ago, I removed all the injectors, and brought it to an autoparts store for them to be cleaned and tested, which turned out that most of them were nearly clogged. So I cannot imagine the car leaning out and causing that popping sound.

Please could someone shed some light into this.

Cheers,

Johnny

[ludi_konj]

misfiring... check spark plugs

[jnr32r]

sounds like it may be pinging... may be running lean if not re mapped properly

[predator]

misfire is generally a much more pronounced skip..

But could be either pinging or over rich as well.

[Dose Pipe Sutututu]

Well I noticed it is mainly around 6000 - 7000 rpm ... Well I can not imagine the car running lean, as I just got the injectors clean which would probably cause the car to run slightly more richer.

I think best bet is to throw it on a dyno & get a re-map.

[TTT]

new plugs = $4 each at most.

electrical tape to tape up coils cost $5

alot cheaper than a dyno run and re-re-chip.

AND, if you are going to get it re-done on the dyno, you'd want brand new plugs in there anyway, adn to make sure your coil packs aren't arcing (taped up)

it's cheap but it works.

the last r32 I bought would missfire (make popcorn or what ever you want to call it) high in the revs.

I taped up the coil packs.

Start at the bottom (right at the tip of the rubber bit).

I did tight layers, each bit of tape going half over the previous.

I went up the coil pack, down and back up.

so 3 layers.

right up to the top of the actual pack.

put them back in, went for a drive..

much better..

only slight missfire right up in the rev range.

got new plugs

gapped to 0.8mm

put them in.

missfire completely gone..

hit rev limit instead

For $30 and 1 hour of your time, it's well worth trying before going to a workshop for dyno and re-chip.

[mad082]

i agree with GTST on this. try new plugs first. even if it isn't the problem, it won't hurt to put new plugs in and tape up the coils. and at about $30 for the lot, it's a cheap place to start.

[ludi_konj]

also when a car pings i believe it doesn't make a popping sound it makes more of a high pitched sound. at times its hard to hear as well.

[tridentt150v]

It sounds like a rattle when its at its worst.

[Dose Pipe Sutututu]

Well I know what pinging sounds like, pinging would sound like my roundabout camry with 300 000km+ on the clock.. made a metalic sound tappin sound like someone left all their cutlery under the bonet...

It's more of a popping sound, like eating pop rocks....

I'll definately tape up or epoxy my coil packs, and buy some standard NGK plugs and see how they go... I got Iridiums atm, but they are from the previous owner.

Edited June 1, 2007 by johnnilicte