fluttering idle? possible misfire?? HELP

[plugy]

Hi all

My 306 cab 1.8 16v has 51k miles on it - 2001 and in the last 12 month or more has only covered less than 1k miles.

I've noticed recently (especially when warm!) that when you park up with the engine running the idle is slightly eratic - fluttering from 800ish rpm to approx 1000rpm momenterally then, dropping back down again.. with occasional blip up to 900rpm in between.

it appears to pull well and such, when cold it is slightly eratic, but not too fussed as it's still on the choke and would expect a little bit of eratic idle until its warm.

I've been on the 306cab.com forum and was pointed to an ICV ( Idle control valve) reset procedure of:

Ignition on
Throttle down for 10 seconds
Off the throttle for 5 seconds
startup and wait 1 minute.
did this twice and nothing's changed...

I come from a classic car background with points, dizzy caps etc.. I'm thinking it could be a single plug that is becoming weak or oxidization on a contact at the igntion coil? or possibly a partially blocked fuel filter?

It Doesn't stall when approaching traffic lights etc (like many appear to have problems with stalling) mine's fine, but the idle isn't as smooth as I would have imagined it to be..

any recomendations?

I would remove the plugs and replace, but knowing this is the 1.8 with the sagem ECU which when removing the coil etc, which can spike the ecu I'm understandably concerned.

Rob

[Popeye_6]

ive got the same thing going on with my gti 6. ive hooked it up to a code reader and it comes up with no codes (snap on modus)

before it came up with lambda malfunction so i replaced that, ive changed the spark plugs but no joy and ive tried replacing each coil pack with a known good one, still no joy.

[plugy]

ive got the same thing going on with my gti 6. ive hooked it up to a code reader and it comes up with no codes (snap on modus)

before it came up with lambda malfunction so i replaced that, ive changed the spark plugs but no joy and ive tried replacing each coil pack with a known good one, still no joy.

Right... thats now the second person who has the same fault and replaced very similar items (lambda sensors) so it must be a common problem with no clear solution. I've seen the question asked so many times and yet no defining answer....

so... lambda sensor code, replaced which showed no code, so.. it's likely it isn't sensor related.

coming from owning classic cars, this kinda thing was pretty normal and was "p*ss to sort out"

usually its either a duff/weak plug
weak or failing contact on a HT lead or an amplifier module
fuel starvation through a damaged diaphragm in the fuel pump or partially blocked fuel filter.

if the problem persisted after checking the above (not replacing parts willy nilly) I'd then I'd start investigating inlet manifold gaskets for air or fuel leaks, as either one will disrupt the balance of fuel and air mixture.

the only other things I could think is... oxidized contacts on the ecu and connections.
Possibly "possibly?" throttle position sensor "IF" the 306 has one...
or... brake servo (if it feels it needs to top up the pressure and raises engine speed to create enough pressure?) finally... power steering at fault somewhere.... as that too can raise the engine Rpm

I've searched for a fair few hours all over peugeot and french car related forums surrounding this very problem and have found NO answer. when it comes to people explaining the same issues the posts appear to go quiet and no further posts etc (many where it sounds like the OP has given up!)

surely they can't run like this normally? surely they are supposed to be a nice smooth even steady tick over speed?

just had a thought....
take a look at that induction pipe that connects to the air scoop at the front grill.. (that furry pipe) where it connects on to the scoop at the front grill, if it isn't a tight fit, it is possible that air could be faulting the readings causing more air to enter than required and pulling more fuel through, richening the mixture, causing the revs to for a second.. flutter up and fall again.

aside from the cleaning the ICV out and resetting it, MAF sensor? possibly, known a few MAF sensors not to come back as faulty when they were. ( I don't take all diagnostic readings as gospel anymore).



Thanks

rob

[Toms306]

Replace the ICV mate, resetting it or cleaning it really doesnt work in my experience! Don't buy a cheap one though, make sure its a bosch/marelli (whatever yours is originally) cos the cheap ones seem to be crap as well.

[Joe]

give the inlet a good spray with brake cleaner mate its a FREE thing to tick off the list!

[samass]

Could possibly be tps, not maf, only the hdis have a maf.
If you think it might be connections, get in there and clean em up, but id have thought thatd give a constant fault, instead of an erratic idle...
Best bet would be to find some one with peugeot planet to have a look, replacing sensors gets very expensive...

[Niall]

My 1.8 did it and iirc grants did too. I tried replacing everything but in the end, a new ECU temp sensor and a bloody good service almost got rid. I say almost because it was still there but no where near as bad as when I first got the car. I think it could be a problem with the shocking management on the 1.8

[Jake]

The 1.8t Audi im driving at the moment does this... Just gay petrols for you!

[Niall]

Yeah your right. Audi petrols are gay.

[Grant]

My meridian did this, but my XS was fine. Then i changed the gearbox, and idle is not a word known to the car. It revs, by itself, to what it feels like lol

[plugy]

well.. after having a look at the ICV and re initializing it again... checking the plugs and such...

I've come to the conclusion that is down to the power steering!

when warm, do this experiment:

Park up on the handbrake on level ground, out of gear, foot off the clutch - foot off the accelerator.
with the steering wheel in the "dead ahead" position, apply a small amount of turn to the wheel (enough so you can "just!" hear the power steering pump. The revs will alter to approx 1000rpm, now let go of the steering wheel. you shouldn't hear the power steering pump anymore. the revs should also drop back down, and they will no doubt rise again.

do the above a few times, steering wheel in the dead ahead position (making sure the steering wheel and power steering pump are in a "relaxed" position, i.e lightly holding the wheel, should give you no feedback. take the steering wheel from the "relaxed" position, just a light turn "just" enough to make the power steering pump audible, the revs will rise while you hold the steering wheel there. then, allow the steering wheel to come back into the "relaxed" position and the power steering pump will no longer be audible.

leave it a few seconds between each attempt, and the revs will climb when apply a small turn (very small) and when you relax the steering wheel and the pump is no longer audible, the revs will momenterily drop to approx 800rpm, and will rise again (as the problem was previously).

now... go from "lock to lock" as if you are bleeding a new steering rack, it doesn't need to be done quickly just at a steady rate. do this 4 times at least, lock to lock and come back to the dead ahead position. ensuring the steering wheel and power steering pump are both relaxed (no force pushing through the wheel and the pump is no longer audible).... see how long it takes for the revs to go from 800rpm to 1k.. I did this earlier with mine and i waited over 5 minutes and it still didn't flutter from 800rpm.. where previous to "lock to lock" treatment it would do it every 5-10 seconds.

I strongly believe (in my case) it is power steering related, possibly needing a fluid change, due to the hydraulic fluid breaking down, requiring engine speed to increase to make up for the fluid breakdown..
OR
power steering pressure switch, giving false readings

try the above, and let me know what yours does!

Rob

found this.. and some cutting out symptoms are related to this..

http://www.ebay.co.uk/itm/POWER-STEERING...0893955046

[Ruan]

I'd put money on it being an engine control issue... The ecu is always fighting to keep the engine rpm steady at idle, any external forces in the feedback loop will cause the engine rpm to adjust, the ecu should then compensate and adjust the icv, injection trim and spark accordingly, it simply sounds like an icv issue, until you've replaced the icv, I'd highly doubt its to do with the power steering, I've owned and worked on quite a few 306s now, and have never come across a pas pump causing anything similar, or at least, nothing that could possibly affect the idle so that it couldn't hold it remotely steady.

Hope this helps.

[cwspellowe]

Under the inlet manifold there's a blue plug on the PAS pipe. Disconnect it. If its PAS related it'll stop after that. It's been known on the gti6 forum to cause all kinda of issues.

Is probably not that but worth a try.

[lewisdmz]

Under the inlet manifold there's a blue plug on the PAS pipe. Disconnect it. If its PAS related it'll stop after that. It's been known on the gti6 forum to cause all kinda of issues.

Is probably not that but worth a try.

What this man said.