Stuttering/hesitation Often Under Load 1.9gti

[tompaltridge 0]

Hi all, I'm hoping someone can help me out here because this problem is doing my head in and I'm on the verge of giving up and selling up!!

Firstly, yes I've searched tons of other threads before posting and can't find definitive answers that relate to my exact problem...

 

Some detailed background - because that always helpfull when trying to diagnose probems! The car is a 1990 1.9, genuine 102k, completely stock engine/body etc. Bought it in Sept last year and was running perfectly until mid Jan. One day I decided to change the oil, so I did exactly that and nothing more (sump plug out, oil out, filter off, new one on and new oil in: you all know the drill). Following day I noticed some hesitation from the engine. I'd set off in first for example and with the usual amount of revs, and it would jerk back badly when the last of the clutch was engaged then pull again after I'd give it some more revs out of frustration! This felt like a massive power loss all of a sudden then it would go again. It now regularly does it every time I pull away, the only way I solve it is looking like a boy racer each time and using copious amounts of increasing revs and gradual clutch!!

 

It also happens in any other gear when accelerating mildly: I'll engage 2nd for example and gradually depress the accelerator and it will judder fairly violently and certainly not accelerate in relation the where my foot is! Only when I nail the throttle does the engine 'wake up' out of this state and pull strongly in all gears. Often I'll be on a motorway and cruising in 5th at about 60/70 and depress the throttle slightly to increase speed and there's such a power loss/delay it feels like I'm deccelerating!

 

It's worth mentioning here that when the block is cold the problem doesn't occur: on morning startup the car revs at 1500ish rpm, then for a minute or two down the road it's perfect, very smooth linear gradual power as I gradually open the throttle in any given gear. Only as the SAD starts to close and the engine starts to get some warmth do I begin to get the usual hesitation/jerking/power loss that I'm now used to...

 

So, I've researched it a bit and bought a second hand AFM which I fitted and for a couple of weeks everything was perfect again: it cured the problem completely. Now however it's gradually come back with a vengance, even after giving the AFM a good clean...!

 

The plugs, leads, dizzy cap and rotor arm are all about 2000/3000 miles old and seem to be in great condition still. I cannot find any leaks in ANY of the piping and have cleaned all of them out thoroughly. This only happens on half to two thirds throttle opening: anything 3/4 or beyond (especially wide open) is absolutely fine the engine pulls very well and strongly.

 

Does it have anything to do with me changing the oil that day or is that a massive coincidence?

Please stop me from selling the most fun car I've driven and buying another oil burner out of frustration!!

 

Cheers for any help,

Tom

[welshpug 1,657]

could be overfuelling, does it smell rich when warm?

[j_turnell 137 3 Cars]

You replaced the ecu temp sensor? could be running lean also, as when its cold the engine will be provided with more fuel, so possibly not as noticeable until the engine is warm. Dont loose heart sounds like an easy fix!

Edited March 1, 2007 by j_turnell

[DrSarty 90 1 Cars]

Dont lose heart sounds like an easy fix!

 

I regrettably cannot offer a technical solution, however I'm inclined to agree that it sounds like a relatively simple fuelling fix. Oil change was a coincidence I reckon too, and with a little logical fuel-side fault finding, perhaps component swapping, you'll get your Pug lovin' back pretty quickly.

 

As ^^^ above - don't lose heart - find it, fix it, love it

 

Rich The Dr

Edited March 1, 2007 by DrSarty

[tompaltridge 0]

Thanks for your replies

 

Firstly I don't think it's running rich, It doesn't smell like it is when warm like you say.. The running lean had occured to me before but why would it run well when I put my foot on the floor? Wouldn't the lean mix affect the whole rev range?

 

If it is do do with the fuel system, what can I do? I've not replaced the fuel filter and it looks fairly old, will this help? Could it be any of the injectors or fuel rail etc?

 

I've been thinking of doing something as a test (a bit of a science experiment really!) buying one of those bullsh*t "powerchip mod, add 20bhp" so called 'chips' that are prevalent on eBay for a quid or two. They are simply a 12p resistor that informs your ecu of more air entering the engine than really is yeah? So if I was to *temporarily * fit one, I'd find out if it's to do with weak mixture because it should run better at least or even, dare I say it, well!

 

Is this a wise idea at all just to find out about the mixture theory?

 

Cheers for all your help!

 

Tom

[inferno 1]

try changing for another decent AFM if that cured it last time it may have gone bang.

 

did u overfill with oil at all? are the breathers blocked at all? a new fuel filter can only be better than an old one.

 

ps i wouldnt buy the resister mod, but if you do... i have a nice anadised blue ECOTEK valve i could sell you too

 

maybe some1 local can swap parts over with you.

 

reading again, could be the coil breaking down possibly? or maybe theres a landa senser you dont know about and the dodgy petrol of the south is working evil:P

[travill 0]

you tried another throttle position sensor or ignition module?

[tompaltridge 0]

Yeah I'll also have a cheap and nasty set of Fox alloys and half of Halfrauds stick on tat while I'm at it

 

Again the ignition system is something I've been wondering about but dismissed again because it should affect the whole rev range in theory...

 

I must admit that yet another AFM seems the most likely solution because it fixed it last time and the symptoms could easily stem from the internal needle giving dodgy readings along it's contact.

 

I'm baffled as to why the replacement I got went wrong so quickly, but if I invest in a new one I shouldn't have that problem. Anyone know where I can get one for less than the £210 +vat that GSF charge?

I would be very interested in a recon AFM or a known good used one if there's one for sale from any members? Provided it really is a KNOWN good one that is...

 

Thanks

[inferno 1]

i have a good working afm from my gti, dont suppose you ever come over this way? theres no garentee it wouldnt get damaged in the post...

[Andrwn8304 0]

Sounds more like a air leak reasons being-

 

When its cold the cold start will be giving more fuel so when its warm and the cold start disengages it'll be running weak.

 

Check the plugs to see if there white or they're a nice tanned colour this is normally a good indication.

 

White = Weak mixture

Tan = Correct mixture

Black = Rich mixture

 

Hope this helps

[Guest Roland]

. . . One day I decided to change the oil, so I did exactly that and nothing more, sump plug out, oil out, filter off, new one on and new oil in: you all know the drill).

 

Following day I noticed some hesitation from the engine.. . .

 

It's worth mentioning here that when the block is cold the problem doesn't occur: . . . when the engine starts to get some warmth do I begin to get the usual hesitation/jerking/power loss that I'm now used to...

 

. . .Tom

 

 

 

Tom,

you might think I'm crazy but what grade oil did you put in the engine when you did the change?

 

There was a thread in Aussiefrogs which discussed oil viscosity and compression/consumption a while ago.

Redhotrod's comments are particularly relevant as he is a longtime mechanic and highly qualified.

http://www.aussiefrogs.com/forum/showthread.php?t=42362

 

I am assuming that the cam followers are hydraulic in which case they depend on the viscosity and pressure of the oil to work properly and open the valves at the right time and amount.

You comment that you don't have the problem when the engine is cold. That's when the oil is nice and thick = the viscosity of the oil is high.

 

I suggest that if you used a 10w-40 oil then change it to a 20w-50 and see if it makes a difference.

My next step would be to screw in an oil pressure guage somewhere and see what the pressures are when cold and hot.

Maybe your oil pump is not performing as well as it should.

 

I remember when I worked in Manchester - it was normal to replace oil pumps in older engines when we overhauled them.

 

So as I see it - all was OK before you changed the oil but not after.

 

Hope I have been of some help

Roland

[boombang 2]

Followers will be mechanical in an 8valve.

 

To check for an air leak is simple enough if you have a K&N or similar - take the filter off and put a hard plastic/metal plate over the hole when running - if it stalls there is no air leak.

Edited March 3, 2007 by boombang

[tompaltridge 0]

Rowland,

 

Thanks for that info, quite an interesting point that may have a lot of relevance because the oil I put in the car that day was Total 5w - 40 and was fully synthetic if I remember rightly. I know the Haynes recommends 10w - 40 or 15w - 40 but I thought at the time I'd treat the engine to some nice stuff!

 

Could this have been a bad idea?

 

Also the block takes exactly 5 litres of oil inc filter according to Haynes, so I put the whole tub in (5l) but considering there will be a few hundred millilitres clinging to all the gallery walls and other engine areas, it is probably overfilled slightly. Would this be significant?

 

Some additional info regarding the hot/cold viscocity of the oil in my engine:

The oil pressure guage needle is right the way to the top on cold startup. Even at tickover, because it's using the SAD and up at 1500 odd rpm, the oil pressure is at the top. When warm, the block's oil pressure drops to the half way mark on the pressure guage at tickover (about 900 rpm) and when revved/driving along it only goes as high as the 3/4 marker or fractionally higher.

To me this seemed fairly good, I'm not too familiar with these XU petrol engines but decent/high oil pressure is better than low pressure any day right? It's only ever at the very top of the scale when the block's cold so the oil's sludge-like anyway.

 

Should I change the oil to 15w - 40 and maybe part synthetic and only put 4 to 4.5 litres of the tub in to guarantee not overfilling it, then see how it runs?

 

Just a quick reply to boombang:

my intake system is stock but I should still be able to perform the same test so I'll give that a go and see what happens

 

Thanks so much for all the help, you really are saving me from selling this car, heh heh!!

 

Tom

[tompaltridge 0]

Good afternoon and sorry to bump this thread slightly but the problem persists, however has been slightly cured by a replacemnt AFM.

 

Reading back through other threads I thought I'd try the air leak theory again, and got my engine warm then put my hand cleanly over the first intake pipe coming from the radiator grille area. Next to nothing happened! There was a sucking noise from the air filter housing so this needs replacing I take it? The rpm stayed at about 900 and the engine was running fine overall. I then tried the AFM and put my hand over the entrance to it perfectly with no gaps and the engine STILL continued to run, although this time at about 500/600 rpm and not very well... So I have an airleak AFTER the AFM thats measuring the air (and so is directly responsible for smooth engine running I take it) which can't be good!!

 

Could this be the cause of the above stuttering and hesitation problems I've described? I'm planning to take off abosolutely every pipe and clean/inspect, including inlet manifold, TB and SAD. Is this a good idea to rectify the problem?

Cheers for any help guys,

Tom

[SPGTi 2]

I had a similar problem where at cold the engine ran fine but at 3-4000rpm on part throttle would hesitate and stutter, as I nailed the throttle it would go past 4000rpm and pull sweetly to the redline.

 

The problem was solved on a rolling road. It seemed that under part throttle the engine was under fuelling. The rolling road guy played about with the internals of the AFM and fuel pressure (PBVs are good sometimes) until it was running fine again. I have done 2 rallies since and (touching lots of wood) it has been fine since.

 

Steve

[Andrwn8304 0]

Good afternoon and sorry to bump this thread slightly but the problem persists, however has been slightly cured by a replacemnt AFM.

 

Reading back through other threads I thought I'd try the air leak theory again, and got my engine warm then put my hand cleanly over the first intake pipe coming from the radiator grille area. Next to nothing happened! There was a sucking noise from the air filter housing so this needs replacing I take it? The rpm stayed at about 900 and the engine was running fine overall. I then tried the AFM and put my hand over the entrance to it perfectly with no gaps and the engine STILL continued to run, although this time at about 500/600 rpm and not very well... So I have an airleak AFTER the AFM thats measuring the air (and so is directly responsible for smooth engine running I take it) which can't be good!!

 

Could this be the cause of the above stuttering and hesitation problems I've described? I'm planning to take off abosolutely every pipe and clean/inspect, including inlet manifold, TB and SAD. Is this a good idea to rectify the problem?

Cheers for any help guys,

Tom

 

 

When you blocked the AFM end it should have stalled so yes it sounds like a air leak between the AFM / Throttle Body Housing and Inlet Manifold.

[Guest georgerbrs]

Just thinking out loud here.......

 

Could it be that when the engine oil warms up it is somehow making its way into the combustion chambers and causing the problem, i had a similar experience to what you describe when my valve stem seals were on their way out.

[Andrwn8304 0]

When the valve stem oil seals goes it normally burns the oil so you see the plume of blue smoke from the exhaust, so i think its high improbable.

 

After thinking more of it I think it could 1 of 2 things

1 = Air Leak

2 = Electrical component failure

[Blish10 0]

I'm having the same sort of problem with my freshly rebuilt 1.6 but with SAAB throttle body housing, AFM and ECU, all new hoses etc (my dads mate used to work with pugs and now with saabs). I havent taken it past 3000 rpm yet but its juddering in 2nd, 3rd and 4th between 2-3000, regardless of temp. Obviously there are a few more variables, but with the symptoms sounding similar-could just overfuelling be my trouble??

Cheers

Simon

[tompaltridge 0]

Just to let anyone else know in the future if anyone reads this thread, I've got the problem half fixed now.

 

I took it to Peugeot and they replaced the distributor vaccum advance capsule (so try this if you've got simmilar problems) and it now pulls away in first fine with little revs like it should, which is great....

 

.....BUT, I still have slight hesitation at mid throttle. It's happening at almost exactly 2500rpm in all gears and only at part throttle (like before). It's still happening worse under load but below those revs it won't do it. I can be in 5th at around 2000rpm up an incline and it will pull fine then as soon as it hits about 2500 its judders. I'm probably going to go back to Peugeot because they charged me a load to get the problem fixed and it clearly isn't! The guy reccomended some injector cleaner which I'm currently getting through (I do low miles) but this can't totally be it. One of the previous posts sounds alot like my problem (posted by SPGTi on March 29th) and the car was taken to a rolling road and the fueling was sorted at mid throttle so that's an option I'm also considering.

 

I would greatly appreciate any info on a *reputable* rolling road firm near me (Bournemouth) or even better, a 205 GTI club down here that I could get some advice from? There's a pint or 3 in it for free for anyone that can have a look at my car with me!!

 

Cheers

[Rob_the_Sparky 9]

Forget injector cleaner, it is crap. If you think injectors are an issue get them cleaned mailorder - £12 each and next day service. I have had 2 sets done and felt improvements in top end power (but not much else). I have never felt any change from a dose of injector cleaner, despite trying it more than once.

 

As a wild aside a violent loss of power can be ignition related. I've just had this on my 309, first it just kangerooed a bit, got worse until I couldn't really drive it as it did it every time I used a bit of throttle. I fiddled/replaced all sorts and it appeared to go away. Next day it dumps me half way to work on the hard shoulder with a bust ignition amp, at least I now knew the problem or so I thought.

 

3-4 months later (quite recently) it started the same tricks again. I engaged brain and replaced the coil (a duff coil could put strain on the ignition amp) and hay presto it is running far smoother than it ever has done since I bought it.

 

The problem was initially intermittant and gets worse with a hot engine (sometimes taking several miles of travel to show up) as the ignition amp is overheating.

 

Rob