Cutting Out Except When Accelerating!

[lagonda 42]

Had this problem on & off for over a year now. I clean, swap, replace various parts....& it runs fine. 2 weeks later .... it's doing it again. & so on...getting really annoying....wondered if anyone else has had same trouble, & sorted it PERMANENTLY!

It doesn't seem to be temperature related, it can happen soon after starting. That said it can be guaranteed to happen when it's really hot, say after waiting interminably for French traffic lights to change on a hot day in town. It doesn't happen all the time, often it'll run fine after a period of cutting out.

Has to be significant that it never happens when accelerating, just when cruising, & it's certainly more pronounced when backing off.

Have fitted new leads, new distributor signal wire, new engine management temp. sender, changed plugs, swapped coil, ignition amplifier, tachymetric relay & rotor arm. Cleaned throttle body, cleaned AFM tracks & checked resistances OK, flap operates smoothly, cleaned air filter. Cleaned/lubricated SAD with WD40 & checked shutter operates OK. Air hoses all appear to be OK, no obvious holes/leaks.

Any ideas, anyone?!

[welshpug 1,666]

check operation of TPS

[jimbean 0]

Had this problem on & off for over a year now. I clean, swap, replace various parts....& it runs fine. 2 weeks later .... it's doing it again. & so on...getting really annoying....wondered if anyone else has had same trouble, & sorted it PERMANENTLY!

It doesn't seem to be temperature related, it can happen soon after starting. That said it can be guaranteed to happen when it's really hot, say after waiting interminably for French traffic lights to change on a hot day in town. It doesn't happen all the time, often it'll run fine after a period of cutting out.

Has to be significant that it never happens when accelerating, just when cruising, & it's certainly more pronounced when backing off.

Have fitted new leads, new distributor signal wire, new engine management temp. sender, changed plugs, swapped coil, ignition amplifier, tachymetric relay & rotor arm. Cleaned throttle body, cleaned AFM tracks & checked resistances OK, flap operates smoothly, cleaned air filter. Cleaned/lubricated SAD with WD40 & checked shutter operates OK. Air hoses all appear to be OK, no obvious holes/leaks.

Any ideas, anyone?!

 

 

Check the wiring loom at the bulkhead if the loom not clipped in it can rub against the exhaust manafold

 

Check the earths on the gearbox

 

Also .... TPS?... only sees idle and full throttle on a gti.... if fault occurs at cruise/mid throttle this will not be at fault

Edited July 11, 2009 by jimbean

[boombang 2]

Any air leaks?

 

Checked the oil filler neck/breather bolt into the side of the inlet manifold?

[lagonda 42]

Hi,

 

As stated, don't think it will be throttle switch, however no harm in checking it out.

 

Gearbox earth already checked, cleaned, OK. Pretty certain wiring well away from exhaust, but will check.

 

Air leaks from the hoses that matter would probably show up as oil leaks...& they're clean. Bolt holding oil filler to manifold is pretty tight...but will check...obviously can't be REALLY tight as plastic will shatter. What French idiot ran that drilling all the way through?! Couldn't they have put a stud in there? Doh! Unreal that people have been building cars for more than 100 years, yet idiocies such as this are still committed.

[boombang 2]

Air leaks from the hoses that matter would probably show up as oil leaks...& they're clean.

 

That doesn't make any sense!

 

Take off all pipework before the AFM, block the hole up with something sturdy (I use Haynes manual), and if it doesn't stall you got an air leak.

[lagonda 42]

Hi Boombang,

 

Other than the AFM to throttle body hose, & possibly those to the SAD, the hoses that could leak AND have a bearing are part of the crankcase breather circuit...so any air leak would also leak oil. Even those above might show oil weepage as certainly the AFM-throttle body hose is oily inside.

 

Anyway...good idea....tried it....engine stalls almost instantly....& there is a LOT of suction there...so it's not an air leak....but thanks for the tip....& also means one other possible culprit to tick off the list. Incidentally I tried doing it with dipstick slightly withdrawn....& it did run on for a few seconds before stalling.

 

Also checked wiring....no wiring runs remotely near the exhaust, so it's not that. Will check TPS but really doubt that has antyhing to do with my problem...but you never know.

 

If it helps, it misfires particularly once everything is REALLY hot, either when I've been stationary in traffic, or when I've left the car parked once hot & then driven off fairly soon after. It's most pronounced between 40mph & 70mph in top gear....it would be, wouldn't it! Incidentally, idle is fine, around 1000rpm.

[Rob_the_Sparky 10]

Ideas:

 

Unlikely to be ignition as this system is under more stress under hard acceleration, hence you tend to get mis-fires under load rather than on the cruise.

 

Long shots:

 

On the cruise the intake manifold pressure drops and FPR is meant to manage this by altering the fuel pressure accordingly. Never seen an FPR fault though so not sure what the symptoms would be.

Not convinced that the engine would continue to run in the presance of a small air leak with the AFM inlet blocked.

Injectors? Maybe a fault that shows up with shorter opening times??

 

Try thinking about what areas you were working in when it starts working. You have clearly disturbed something critical if you make it work fine for a while, just not realised what that was (or it is just an intermittant fault that comes and goes anyway).

 

It is certainly an unusual problem...

 

Rob

 

P.S. I know I said not ignition but the ignition amp can suffer in a hot engine bay, both if it is lacking heat transfer paste and if it is about buggered...

[lagonda 42]

Hi Rob,

Yes that's what I thought re ignition. I have substituted a spare ignition amp, & it seems to make no difference.

 

Now here's the odd thing. Drove the car yesterday for the first time since blocking off the AFM inlet as suggested by Boombang. And guess what?! The car ran fine, 140 mile round trip....had a brief stint of misfiring around 60mph on the return journey, predictably after we'd stopped for a short period (heat soak seems to be part of the problem).

 

So....could it be by doing that I've sucked free some s*ite from the throttle body or elsewhere? The suction was pretty strong.

[boombang 2]

What make is the ignition amp and does it have thermal paste between it and the heat sink?

 

Sounds pretty unlikely that something has been sucked through, yesterday here was a lot cooler which might well have something to do with it.

 

 

Never ever seen a post about the air temp sensor in the AFM - I assume it alters output signal on air temp? - but perhaps this could be playing up. When you tested the readings it could well have been cold and fine. It gets hot and signals out go a bit mental. Very unsure about that, but if ruled out everything else, might be worth an AFM swap.

[lagonda 42]

Pretty certain it's Bosch...that said, spare is certainly Ducellier, & swapping makes no difference. Yes, has thermal paste.

 

Am in France so weather not necessarily the same. Gets pretty hot.

 

Needless to say, after that brief respite, the obtuse b*stard is playing up again. Temperature cetainly affects it, but that said, pretty cool today, yet it was misfiring just 1/2 mile from cold start. That said, certainly worst when restarting whilst still very hot.

 

Have now noticed idle speed is often up to 1300 from its normal 1000...so air leak a possibility. But, of course, with my car, a leak that is only significant under certain temperature/load conditions. Any ideas?

 

Could it be the SAD playing up?

 

AFM air temp sensor...possibly...anyone know how to test it?

[jimbean 0]

Pretty certain it's Bosch...that said, spare is certainly Ducellier, & swapping makes no difference. Yes, has thermal paste.

 

Am in France so weather not necessarily the same. Gets pretty hot.

 

Needless to say, after that brief respite, the obtuse b*stard is playing up again. Temperature cetainly affects it, but that said, pretty cool today, yet it was misfiring just 1/2 mile from cold start. That said, certainly worst when restarting whilst still very hot.

 

Have now noticed idle speed is often up to 1300 from its normal 1000...so air leak a possibility. But, of course, with my car, a leak that is only significant under certain temperature/load conditions. Any ideas?

 

Could it be the SAD playing up?

 

AFM air temp sensor...possibly...anyone know how to test it?

 

 

Easy way to find a air leak...

 

Break cleaning fluid.... squirt it over all inlet parts at idle

 

if the revs pick up ... you found yor leak.....

[lagonda 42]

Finally think I might have sorted this, fingers crossed as obligatory 2 weeks (see initial post) haven't passed yet!

 

I pulled the radiator fan temp sensor plug to clean terminals, to (successfully) get that going. After that, thought I might as well do the same with the two yellow earthing plugs nearby, and also the plugs going into the little black fuse box above.

 

Next time I drove the car....NO MISFIRING! NO CUTTING OUT! Even yesterday, when it was really hot.

 

Can't say I'm actually enjoying driving the car, I don't trust it enough for that....but at least some of the hate is dissipating.....slowly...give it time....

 

What's it got in store next?!

[jackherer 543]

The engine management doesn't use the earths you cleaned up but it does get power from the black fuse box (shunt box).

[lagonda 42]

Thanks for that....nice to narrow the field down! If (I mean "when" of course) it happens again, I'll know straight where to go.

 

Only ever owned Fiats & Lancias before this.....& Italian cars have a (completely undeserved in my extensive experience) reputation for dodgy electrics. Don't understand that at all, this Peugeot has had more electrical issues than all the other cars I've ever owned, put together!

[jackherer 543]

I don't think there is anything wrong with Peugeot electrics as such but IMO the 205 engine bay is a very harsh environment, I have removed many looms from BX 16vs that still looked new after 15+ years that then age badly in a matter of months in a 205.

[lagonda 42]

Yes, it's very strange...brown multi-plug a case in point...seems to be in perfect location....if it ever got damp, it would dry out quickly. Yet the terminals on mine had actually partly corroded away! I suspect the miserly thin gauge wiring is a strong culprit.