Honda S2000 Misfire

[Qube]

Hi,

Drove in to work this morn... hit the Vtec to overtake on the straight and there was a slight stutter and misfire.. pressed the throttle a few times and i heard a few pops from the intake system..

Oil pressure if fine. Fitted new plugs a few months ago.. only thing lately i can think of i had to put Morrison's fuel in a few days ago..

Could one of the tips of the spark plugs broken or a coil connector come slighlty loose ?

Thinking of calling in nearby Shell garage to top up with V-power ?

Sludge in the Vtec solenoid ?

Any ideas ?

[havoc]

Describe the 'pops', and are you sure it was intake not exhaust? Is it doing it persistently, or just a one-off?

Possibilities? Lots, sadly.

1) Do you have a diagnostic tool. This will tell you what the engine has recorded (assuming your CEL (Check Engine Light) has come on).
2) Describe how it's behaving differently, and is it sound or performance?
3) How has it been serviced? And on-time?
4) How is it used - lots of short journeys, lots of long M-way journeys?
5) Age/mileage

As for fixes:-
- How old are the plugs? And are they OE (Honda), Denso or NGK?
- A round of injector cleaner is a very good and cheap first step.
- Avoiding supermarket fuel entirely when dealing with a 119bhp/litre engine is widely considered to be a safe move.

...beyond this, you can look at valve clearances, MAP sensor, O2 sensor, clogged injectors, burnt valves, etc. etc. etc.

If you want more info, or to do a search, www.s2ki.co.uk has a lot of good people, and lots of threads about 'random misfires' - although in a lot of cases it seems to be an over-sensitive / over-paranoid ECU rather than an actual physical problem.

[Qube]

havoc said:

Describe the 'pops', and are you sure it was intake not exhaust? Is it doing it persistently, or just a one-off?

Possibilities? Lots, sadly.

1) Do you have a diagnostic tool. This will tell you what the engine has recorded (assuming your CEL (Check Engine Light) has come on).
2) Describe how it's behaving differently, and is it sound or performance?
3) How has it been serviced? And on-time?
4) How is it used - lots of short journeys, lots of long M-way journeys?
5) Age/mileage

As for fixes:-
- How old are the plugs? And are they OE (Honda), Denso or NGK?
- A round of injector cleaner is a very good and cheap first step.
- Avoiding supermarket fuel entirely when dealing with a 119bhp/litre engine is widely considered to be a safe move.

...beyond this, you can look at valve clearances, MAP sensor, O2 sensor, clogged injectors, burnt valves, etc. etc. etc.

If you want more info, or to do a search, www.s2ki.co.uk has a lot of good people, and lots of threads about 'random misfires' - although in a lot of cases it seems to be an over-sensitive / over-paranoid ECU rather than an actual physical problem.

Thanks for the reply...


The car has been running nice and crisp lately..

As for the questions....

1) I don't have a tool
2) Ticks over perfect at idle and to 5300 revs, after 5300 the car becomes persistantly hesitant, feels like the car isn't getting fuel or the plugs are being blown out... Performance to 5300 fine, problem becomes apparent after 5300 rpm.

3)Serviced at Honda dealer @ 2500, 11000, 19000, 27000 service due at 36k, clock showing 34.5K. The car doesnt' use oil at all between services and stays clear like honey.

4)Mostly rural roads and towns.... on occassion motorway trips. normal daily run 16 miles @ 60mph zone and 4 miles crawling in traffic.

5)04', 34.5k

Engine light has not come on.. Filled up with V-power earlier (no differance).. Adjusted the valve clearances when i changed the plugs... Denso Iridium plugs set to 42 thou.....


I'll get some injector clean today...

will check the plugs & map sensor tomorrow. Clean the vtec solenoid and reset the ecu...

[P.J.]

I would first blame the petrol, have had this problem before from supermarket fuel, however i had the problem at low revs under 1/2 load. A press of throttle cleared its throat so to speak. Redline injector cleaner SI2( i think ) is good, recommended by BMW. The tool for diagnostics when engine warning lightcomes on can be made by opening up a paperclip and insurting open ends into port, this will cause the warning light to flash in a certain sequence and you can de code what is wrong. What is your densos gapped to in mm?

[havoc]

Qube said:

Denso Iridium plugs set to 42 thou.....

How old? A few years back, Denso had a problem with part of the ceramic breaking up in some cars, with potentially damaging effects. Current ones, AIUI, are NOT a problem though.

I'm surprised that it's at high revs though - if it was fuel I'd expect it to be lumpy and rough throughout the range...

5,300 is too short to be the VTEC cut-over (6k), but it MAY be where the fuelling map starts to change...I'm not tecchy enough here...which would lend itself to an injector issue...but then I'd also think that fouled injectors would be more obvious at low revs than wide-open.

This is confusing...definitely post up on s2ki, and do let us know how you get on!

[Qube]

filled up with v-power and squirted half a load of redex in the tank with no differance...

reset the ecu... just the same

DEnso plugs replaced about 3 months ago from JDM

the problem has become apperant at idle now too and under load @ 3 going up hills.. more gas more misfires

looks like the spanners will be out..... may revert to old plugs and check valve clearances tomorrow

I need an exorcist. keep you informed...

Edited by Qube on Friday 24th October 23:05

[NORTS]

Could this be the FIRST VTEC failure? Shock horror..........

Could be a faulty fuel bump, blockage in the line.... many things. Best taking to Honda for them to diagnose.

[Qube]

Rain to bad to investigate further yesterday.. First job was to check the plugs.. on removing the cover plate and coils I could smell unburnt fuel and noticed brown stains on coil 3 and 4.. Here we go maybe both plugs had possibly come loose.. but no, to my startlement after removing plug 3 the colour on the plug was nice and grey. On removing the plug from the plug socket the Iridium plug ceramic body could be turned within it's metal body.. the plug was firing but under compression the gas in the cylinder was being forced back through the body of the plug.. plug 1 and 2 where fine on removal but plug 4 had a slight crack through the ceramic body where the tip of the coil came into contact....

Next step was to replace the old NGK R's which I kept in case. Here goes pressed the big red button and walla no missfire. A quick trip around the block on the vtec proved the missfire had now gone..

Gotta to say although the Denso Iridium plugs had packed in, the car sounded and drove smoother than with the NGK's..

Fixed at last...

Looks like a need to order a new set plugs from Honda...

[gothmog]

Plenty of tales of woe of people using iridiums on the DC2 integra forums, best to stick with the stock NGK platinums.

Don't go to Honda though they'll literally charge you double!

I got a set from ebay for my 'teg from this store http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

I believe the S2000 uses the same plug (PFR7G-11S), but do your own research obviously

[havoc]

gothmog said:

I believe the S2000 uses the same plug (PFR7G-11S), but do your own research obviously

I'm 99% certain it does, as I ordered two sets last year and did them both together.

...so either that was an old set of Denso's, or they STILL haven't sorted their build quality out!!! I take it you've checked there was no crap down in the cylinders themselves?!?

Glad she's OK,

M.

[Qube]

havoc said:

gothmog said:

I believe the S2000 uses the same plug (PFR7G-11S), but do your own research obviously

I'm 99% certain it does, as I ordered two sets last year and did them both together.

...so either that was an old set of Denso's, or they STILL haven't sorted their build quality out!!! I take it you've checked there was no crap down in the cylinders themselves?!?

Glad she's OK,

M.

The plugs on removal where intact, it's the first time I've seen a fully turnable ceramic shaft from top to bottom.. The plug was still firing God who knows what would of happened if the coils where not holding the plugs in place.. A hole in the bonnet maybe..

Thanks for the help

[havoc]

Qube said:

A hole in the bonnet maybe..

Thanks for the help

You're very welcome - glad it's turned out to be pretty minor!

As for 'a hole in the bonnet' - I remember a pic on s2ki of a car which had a noticeable "inverted dent" in the centre of the bonnet...presumably from something similar!

[Qube]

gothmog said:

Plenty of tales of woe of people using iridiums on the DC2 integra forums, best to stick with the stock NGK platinums.

Don't go to Honda though they'll literally charge you double!

I got a set from ebay for my 'teg from this store http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

I believe the S2000 uses the same plug (PFR7G-11S), but do your own research obviously

Thanks, the plug type is the same as the teg...

Fitted a new set of NGK IX Iridium BKR7EIX-11 plugs today. Car feels much crisper and revs very smoothly through the gears.. Whether it's me but the car feels less harsh and pulls harder with Iridium plugs at high rpm's.......

[MB 1]

Good old Denso's.... Hmmmm.