Rb20det Hot Missfire

[inissane]

well during this hot weather an intermittent missfire has shown its head. Its not just an on boost thing, when its missing its idle and on throttle and all except it sounds normal only on deceleration. power is down offcourse when its on sounds like a wrx well and truly

thing is car will be fine after start then driving well with full power, then get stuck in traffic for 5-10 mins and its gone into complete missing mode - so basically it is on off and seems to be when very hot

now i know most common to look for this kinda thing is spark plugs and coils, i replaced spark plugs a few days ago (bcpr6es) i think 1mm gap but b4 it was doing it with the stock plugs which seemed like a bigger gap like 1.1 or 1.2

any ideas guys?? can the coils or any other item fail when really hot??

[Josh]

Maybe your water temp sensor - the one that controls the flow of coolant to the injectors(I think thats what it does) - maybe that is playing havoc... pretty sure its the one on the left(If your looking from the front of the car), of the two sensors on the water tube running from the top of the radiator.

[RB30-POWER]

coil or ignitor more then likely.

one guy was saying the other day, if you want to narrow it down if you think its the ignitor, get a heat gun onto it and see if you can replicate the problem..

as for the coils, remove the cover, at night when its dark and see if you can see the spark jumping out of the coils. (also inspect for hairline cracks)

[TokyoTaxi]

Interested to hear some results as I sometimes get this too. Usually after a really good heat soak it misfires a bit ( only at idle ).

Also, after shutting down for 5 mins or so and then re-starting it hunts till I start driving again then it settles.

BTW I'm running 0.8mm gapped PFR6A11's and have Splitfire Coilpacks and I'm "guessing" they're not the problem.

[blind_elk]

The ignitors become susceptible to heat and start to cause misfires.

[TokyoTaxi]

Meaning Ignition Control Module ( x 1 ) bolted on the back of the valley / coil cover or the ignition coils ( x 6 ) themselves ?

[blind_elk]

Ignition Control Module ( x 1 ) bolted on the back of the valley / coil cover

<{POST_SNAPBACK}>

Yes

[T04GTR]

all of the above.

[Bozz]

RB20DET plugs that plug into the coil packs are getting very brittle at this age, another possiblilty is simply unplugging and replugging in all the connectors on all 6 coils. It's free to try and i've had a few doing this very symptom.

[sl33py]

If your getting misfiring at idle and also under partial load (non boost) when the engine has warmed up (or even before), try replacing your throttle position sensor. I had the problem your describing. If you stay in second and slowly let it wind out to 5rpm, u could feel it misfire every now and then. It made it a b*tch to drive in stop start traffic, since ur keeping it very near the clutch catch point a lot.. it would every now and then just misfire and kill the engine cos it suddenly lost enough power to keep the engine running (we're talking really crawling traffic here though). Anyway, cost me 110 delivered from justjap and now I only have the misfire on boost at very high revs (Splitfire time!)

[inissane]

ok cheers for input peoples,

while it was missing like crazy on idle i unplugged each coil one at a time and no.3 made bugger all difference so hereth the problem i guess

so that means its either the no3 coil or the coil plug itself hey??

considering that it starts doing it only when hot after about 15mins of driving and i think once i went over a harsh bump and the miss kicked in

[RB30-POWER]

What you should do is swap number 3 coil with say number 2 coil.

If the misfire is now on number 2. Its the Coil.

If the misfire is still on 3, you know its the ignitor pack.

[inissane]

yup cheers rb30-power good idea, and its the coil cause it then missed on 2, gonna get a second hand one i think though splitfires would be nice

[TokyoTaxi]

Update time. Replaced Ignition Control Module, no joy. Replaced TPS ( complete Throttle Body w/TPS fitted ) and it's slightly better but not fixed. Going to try cleaning AFM next and if that doesn't work I'll check the coils ( 3-4 year old Splitfire's ).

[grandmasterb]

How'd you go with this in the end, did u figure out what the problem was???

Cheers B

[TokyoTaxi]

Hey B,

Here's where I'm at now. On a hot day ( around 30 + degrees ) at idle I'm still getting a faint and intermittent popping at the exhaust and idle fluctuation of around 50rpm ( misfire ). Other than that it's fine.

So far I've replaced Spark Plugs ( with new BCPR6ES ), Crank Angle sensor ( 2nd hand ), AAC Valve ( 2nd hand ) Ignition Control Module ( 2nd hand ), Throttle Body with TPS ( 2nd hand ) and checked Splitfire Coil Packs ( coils seem fine ).

So..... I'm going to install a brand new OEM O2 sensor ( picking up today ) and see how that goes and if no joy, I'm thinking it might be an issue with the ECU tune ( chipped stock ECU ) and will pop it on the dyno see what shows.

I will say one thing though..... Now that I've replaced all those parts with cleaned and really good condition 2nd hand parts ( lot of hunting around !! ), the car goes like a rocket

[TokyoTaxi]

I'm assuming there are some member's who are not sure what an O2 Sensor looks like so here's a couple of pics

[TokyoTaxi]

Sensor went in a little while ago and the engine idles quite a bit better but still has some faint signs of popping out the exhaust which I'm convinced can be tuned out ( car's overdue for some TLC on the dyno ).

I pulled the old O2 sensor out ( about 4 years old ) only to find it had the following stamped on it: FORD Can't even remember what place fitted it but the meat pie part is out and the sushi part is now in

[Grant]

I get the same thing happening to me if I'm stuck idleing for more then a few minutes on a very hot day. (35+)

Normally goes away after moving for a minute or so though, once some air starts to circulate through the engine bay.

I've recently raised the rear of my bonnet to try and reduce the engine bay temperatures, but haven't had a hot day since doing it, so can't give you any findings.

Can definately see some 'heat haze' coming out near my windscreen now, so obviously some of the heat is escaping.

[brendan S13RB]

G'day,

I'm only new to this forum and it may sound like a stupid idea, but has anyone cosidered the possibility of vapour lock....Ie as all components underneath the bonnet get heat soaked the fuel lines have the same issue and the fuel is begining to vapourise prior to entering the into the cylinder. This generally causes the engine to miss under the conditions that people have described, as i have had similar symptoms in my car (s13 with RB20).

I would be interested to hear peoples opinions on this theory and what the issue was if you have fixed it ?

Cheers