R33 Rough Idle Feels Like Fouled Plugs..

[Guest Rotary20B]

G'day,

Started car this morning to find it idled like it was running on 4 or 5 cyls. Took it for a short drive, felt like fouled plugs. Will not rev cleanly, feels like it isn't running on all cyls, very rough, no smoke what I can see.

Bought a new set of plugs, changed them over tonight, started it up.. same thing.

Very rough on idle, smooths out while not under load at around 4500-5000rpm.

Took air cleaner off and started it up, same symptons.. any ideas?

Car is a basically stock RB25DET, running 9psi, 3" exhaust, stock intercooler. Bought new splitfires about 12 months ago. Was running fine up until this morning, driving it last night noticed it hesitated a little when first taking off. Thought then that it felt like plugs were starting to foul.

Edited February 13, 2009 by Rotary20B

[eeiko321]

G'day,

Started car this morning to find it idled like it was running on 4 or 5 cyls. Took it for a short drive, felt like fouled plugs. Will not rev cleanly, feels like it isn't running on all cyls, very rough, no smoke what I can see.

Bought a new set of plugs, changed them over tonight, started it up.. same thing.

Very rough on idle, smooths out while not under load at around 4500-5000rpm.

Took air cleaner off and started it up, same symptons.. any ideas?

Car is a basically stock RB25DET, running 9psi, 3" exhaust, stock intercooler. Bought new splitfires about 12 months ago. Was running fine up until this morning, driving it last night noticed it hesitated a little when first taking off. Thought then that it felt like plugs were starting to foul.

sometimes it could be the igniton coil failing. but this idle fault can be caused by a no# of things...like the ECU, Injectors etc

it could be your ignition leads also

firstly, did you wash your engine bay by any chance? i reacall doing this and caused a shortage on the ignition system.

if not..what i would do first..

get an ohm meter or a multi meter - test all the ignition leads one by one..... dont pull them all out cause you may be confused where they go.

the longer ones, the resistance should be within 20 - 30 Ohms....

the shorter ones should be between 10 - 15 Ohms....

let us know how you go

Edited February 13, 2009 by eeiko321

[Guest Rotary20B]

sometimes it could be the igniton coil failing. but this idle fault can be caused by a no# of things...like the ECU, Injectors etc

it could be your ignition leads also

firstly, did you wash your engine bay by any chance? i reacall doing this and caused a shortage on the ignition system.

if not..what i would do first..

get an ohm meter or a multi meter - test all the ignition leads one by one..... dont pull them all out cause you may be confused where they go.

the longer ones, the resistance should be within 20 - 30 Ohms....

the shorter ones should be between 10 - 15 Ohms....

let us know how you go

Don't think it is coils.. coils are less than 12 months old, brand new splitfires.

Ignition leads? the coils sit straight on top of the plugs. The boots are all in perfect condition still.

No, haven't washed engine bay lately.

Any other ideas?

[Get EPIC]

G'day,

Started car this morning to find it idled like it was running on 4 or 5 cyls. Took it for a short drive, felt like fouled plugs. Will not rev cleanly, feels like it isn't running on all cyls, very rough, no smoke what I can see.

Bought a new set of plugs, changed them over tonight, started it up.. same thing.

Very rough on idle, smooths out while not under load at around 4500-5000rpm.

Took air cleaner off and started it up, same symptons.. any ideas?

Car is a basically stock RB25DET, running 9psi, 3" exhaust, stock intercooler. Bought new splitfires about 12 months ago. Was running fine up until this morning, driving it last night noticed it hesitated a little when first taking off. Thought then that it felt like plugs were starting to foul.

May as well check your air flow meter.Mine felt a little rough before i had my aac valve cleaned.

[eeiko321]

Don't think it is coils.. coils are less than 12 months old, brand new splitfires.

Ignition leads? the coils sit straight on top of the plugs. The boots are all in perfect condition still.

No, haven't washed engine bay lately.

Any other ideas?

yes the ACC valves and throttle position sensor etc can also have build up which can cause rough idle and sometimes stalling as well....

imi not sure where they are located on the RB25 but if you look aaround the intake to the throttle body, im sure you could figure it out.

it may need to be dismantled and cleaned out with Carby cleaner

[syfon]

G'day,

Started car this morning to find it idled like it was running on 4 or 5 cyls. Took it for a short drive, felt like fouled plugs. Will not rev cleanly, feels like it isn't running on all cyls, very rough, no smoke what I can see.

Bought a new set of plugs, changed them over tonight, started it up.. same thing.

Very rough on idle, smooths out while not under load at around 4500-5000rpm.

Took air cleaner off and started it up, same symptons.. any ideas?

Car is a basically stock RB25DET, running 9psi, 3" exhaust, stock intercooler. Bought new splitfires about 12 months ago. Was running fine up until this morning, driving it last night noticed it hesitated a little when first taking off. Thought then that it felt like plugs were starting to foul.

Could be the oxygen sensor? My brother had a very similar problem with his sr20. Replaced the oxygen sensor and all fixed....

[blind_elk]

Bought a new set of plugs, changed them over tonight, started it up.. same thing.

Did you actually inspect the plugs you removed? Did they look fouled?

I had a similar problem. I replaced the coils anyway (they were original, I thought they were the culprit). While I had access to the plugs, I pulled them to check condition, and noticed one plug was wet with what I thought at the time was oil, but I think now was only petrol. Gave it a clean, haven't had a problem since.

[GTR-N1]

Bad Fuel?

If it clears itself on a run and it idles normally after that run, it can be bad fuel!

But if it idles rough after the run, one has to wonder about ignition module > coil packs > leads etc

[Guest Rotary20B]

Thanks guys.

Yes plugs were not fouled, I replaced them with new plugs too as thats what I thought the problem would be originally.

Car won't clear itself while driving, only seems to clear a bit if revved to around 4500rpm in neutral and held there.

Anyone else had similar problems/symptoms with a faulty O2 sensor?

[eeiko321]

Thanks guys.

Yes plugs were not fouled, I replaced them with new plugs too as thats what I thought the problem would be originally.

Car won't clear itself while driving, only seems to clear a bit if revved to around 4500rpm in neutral and held there.

Anyone else had similar problems/symptoms with a faulty O2 sensor?

so im guessing they are firing properly?

as in did you test while the car is running ..earthing out the lead before the spark plug or testing with multi meter?

coz if worse comes to worse.......

what i would do....and when im out of ideas.....id take it to a Mechanical workshop........get them to inspect it...

and QUOTE on what the problem is......

and when they do find it.......then you will know whether you will be able to do a DIY.....

and perhaps watever the problem is...ask if anyone here has carried out the DIY procedure...coz im sure there would be mechanics in the Diagnostics section in this forum floating around.

see how you go

[Guest Rotary20B]

Anyone know of a good workshop around Aspley/Geebung area in Brisbane?

[SKYNET]

i had a similar problem with my S1 stagea[RB25det]

fixed it by changing the plugs

my mech also told me to to check/clean the tips of the coilpacks[where they connect to sparkplugs]

[this is for for factory coilpacks-im not sure if splitfires r different?]

unplug them-remove blk rubber covers/boots & check

also id suggest cleaning out the AAC valve-like the other guy said-with carby cleaner

mine ran a bit smoother afterwards & its easy to do

theres a tut with pics in the stagea DIY section

[eeiko321]

i had a similar problem with my S1 stagea[RB25det]

fixed it by changing the plugs

my mech also told me to to check/clean the tips of the coilpacks[where they connect to sparkplugs]

[this is for for factory coilpacks-im not sure if splitfires r different?]

unplug them-remove blk rubber covers/boots & check

also id suggest cleaning out the AAC valve-like the other guy said-with carby cleaner

mine ran a bit smoother afterwards & its easy to do

theres a tut with pics in the stagea DIY section

i think hes mentioned he already bought a new set of plugs.

although, i do recall my First motorcycle.... the Carby CBR250RR

it was running too rich...and fould plugs all the time

and each time when it did....the plugs just didnt seem like the same afterwards...

.