Audi A4 1.9 TDI (1999) - power loss...limp mode?

[k3t4n]

Hi,

I have been suffering a really annoying problem ,which I still havent managed to solve.

It happens whilst driving over 60mph, especially noticeable going uphill , where the car doesnt seem to go any faster even with my foot to the floor. The revs stay constant and under 3k rpm, although a drop down to 4th gear doesnt increease speed, but just gives resistance. Used to be v noticeable until I swapped out the MAF, where it runs smoother but still feels as though the turbo isnt kicking in fully. Had only 1 code on a VAGCOM scan, showing something like 'signal too low' on the MAF, hence I swapped it out (costly at 80 quid).

I have taken to an independant specialist, who cleared the code and now even with no errors from the ECU, still runs poor. Checked hoses, pipes for cracks, but nothing from what I can tell. Also been advisd it could be variable vanes on the turbo. Ordered a 40 quid turbo cleaning kit from Innotec, so will see how that goes in the next few days.

Any ideas what else it could be, if it isnt the variable vanes? some ppl have mentioned the EGR, or N75, just wanted to know if anyone has had a similar experience and if there is a cure to this annoying problem. It used to go like a rocket, now I'm suffering being overtaken by micras. please help before I resort to getting rid.

thanks in advance

[Alan02]

Have you tried changing the fuel filter? Alot of people forget to check the basics ?

[k3t4n]

well I recently had a full service following a cylinder rebuild (cambelt snapped, so needed new valves, hydraulic lifters and cambelt kit). That was around 3k ago, so the fuel filter was apparently swapped out then. Is there a possibility that during wear in of the new engine components, that it could have clogged the new fuel filter? I dont want to rule out possibilities so long as I dont have to spend too much.

[producedapples]

I get the same issue, especially when going up hill, mines a 1999 (110) tdi, i have to switch off then on again to get it back working quickly....

I have replaced my turbo tho, as mine went bang, let me know how the vnt clean kit goes..... i have the orig EGR valve and N75 still on mine as it was going fine until turbo was replaced so doubt egr and n75

[Alan02]

Ok so fuel filter should be fine then. I would have thought if the VVT vanes were sticking, you should get a fault code. But once ignition turned off this code may be erased.
You mention hoses being checked, i take it they included Boost hoses and intercooler etc. Also, have a look at air filter for it being unserviceable, obstructed. If you rev up engine while observing boost hoses, do they baloon up, then settle down a bit while revs held at a high rpm ? This would show to some degree that the vanes are moving as you approach max. boost and settling back.

[k3t4n]

I will check the air filter and boost hoses tonight. the turbo cleaning kit should arrive today. Apparently I dont need to take off the turbo from the engine, but just disconnect from where it connects to the manifold. This may sound like a daft question, but does anyone know how to do this? Innotec say that I just need to spray into the manifold end (where it connects) into the turbo. The support guy on the phone said that should unfreeze sticky variable vanes and actuator lever.

would be v grateful for any photos so I can see which bolts to undo, etc. I have a reasonable degree of mechanical competance, but dont want to get myself in a situation where I make things worse. Any help appreciated!!!

Worst case, I could always take the cleaning kit to a mechanic, but feeling quote broke after spending so much already!! :(

[k3t4n]

still waiting for my turbo clean kit to arrive, but having put fuel system cleaner on my last fillup at the petrol station, the car seems to be running a lot smoother, and when going downhill, esp on the motorway, it seems to pull away fine and accelerates to around 90-ish before it struggles and then doesnt get much past this.

going UPHILL....massive difference...the car struggles even when downshifting to compensate the turbo lag, so im thinking that could that still be a variable vanes issue? surely if I am going fast downhill, and I can feel the turbo kick in, although not as potent as it used to be, then the uphill struggle must be down to something else?

also, any ideas how I can remove the turbo from the manifold end, just enough so I can spray in the turbo cleaner? any photos would be most appreciated or any advice on how to go about this.

thanks in advance

[barrycurran]

hi there, i have the same problem with my 1999 1.9tdi a4, have changed MAF and mechanic removed pipe from egr valve, improved slightly after meter was changed. have to change gear at 2000revs or power drops badly in next gear, needs switched off to reset
let me know if you solve your problem and how, i too have been overtaken by a micra but i had a full car at the time, still havent lived that one down lol

[k3t4n]

Ok I've now received the turbo cleaning kit. Having followed the instructions and tried to remove the 3 bolts on the exhaust manifold which connect the turbo, they are completely seized. Another issue is that I dont have much room to use a socket wrench, although I'm sure I will need to go to a garage now and get them to loosen the bolts, before I have another go.

[k3t4n]

ok had a garage perform the turbo cleaning, as I couldnt unseize the bolts, but now that they have had a go and advised a lot of gunk came out of the turbo, but no joy, as I STILL have limp mode. Not happy....thought this would have been the issue, and cant think what else it could be. Could someone PLEASE PLEASE give me some advice, as I dont want to blow more money trying to get it seen to. Audi have had a go but nothing came up on a scan, so they wanted 2-3 hours of time to investigate further ...not cheap at 110hr. Surely someone has had this problem before and been able to solve it easily?

[accy]

Had a similar problem to yours a while back, took it to a garage where the boost pressure sensor was changed, been perfect since

[obladeo]

Hi chap just looked at this thread and though one or two things.

You said you had a full service. One question is did you check to make sure that they had changed everything?

The reason i work on my own cars is that garages are there to make money. They say they have done something but they haven't. My uncle is an amazing machanic and he was telling me allot of the things they do (it's amazing trust me).

The reason a car will run crap is either air or fuel (sometimes the brian(ecu) but norm).

Check to make sure theses have been replaced in your service (they should look new)
Air filter (you can check this by hand as it only 4 clips)
Fuel filter just look at it should look new and shiney
May sound strange but check your oil filter is new and also your oil level is right as some cars monitor this and go limp.
best way to do this is to first
Clean the system out which everyone should do before and mot. Just sit and rev your engine untill all the crap has gone out the system
Next take your car on a quick run and then check the levels (let car cool for 5 mins).

Next is to check the sensors which is never good. Find all the sensors on your car and take them off and give the a good clean. Depending of the sensor user either wd40 or gt85 and a cloth to clean em.

The exhaust sensor cannot be checked if your car has one as it's inside a steal case. You will just need to replace it.

hope this helps if not just tell me to bugger off lol

[k3t4n]

thanks accy. Can you advise where the boost pressure sensor is located? Is this the MAP sensor you are referring to? I'm not too familiar with the location of these in the engine bay.

cheers

[k3t4n]

hey obladeo,

firstly many thanks for the long reply. I will definitely check out the things you mentioned. The car has been running better since I took it to the garage to get the turbo cleaned. I can get to 80mph and theres not much in the way of resistance. Assuming here that the garage did actually do the clean, as I supplied the Innotec turbo clean kit (£40) although I noted the bolts I couldnt get off the exhaust manifold where it joins to the turbo inlet are still v tight.

when driving in town or on the motorway though, it still feels flat through the gears, so guessing im still in limp mode, as the boost isnt all there, although I can feel some but not like how it was before. the chap before mentioned the boost pressure sensor. do you have any experience of cleaning/changing these? where are they located? Ive read on the forum that its sometimes the MAP sensor thats knackered, but I dont really want to spend until I know thats the problem.

appreciate your help so far

[mrp0ny]

Hi Guys

I have 2 x A6 1.9tdi's one with 413K on it on original engine, gearbox and turbo etc.

The Limp mode problem could be EGR, MAF sensor or especially the vacuum pipes (little thin pipes) on the left hand side as you open the bonnet. Basically the computer thinks there is too much fuel coming (incorrectly) and shuts it down to avoid damage. The other thing it could be is an incorrect ECU.

Just a few ideas....

David

[k3t4n]

Where is the EGR valve located? Is there any way I can clean it? Do I need to take it off to do so? Also, I have noticed a constant 'hissing' sound when accelerating...I dont recall this happening when I bought the car a few years back. Sounds like a boost leak but I could be wrong. Any ideas? p.s I bought a VAGCOM cable so I can connect to my laptop, but no error comes come up under the Engine tab.

[paddy006]

check all your hoses for leaks.
i had a simular problem that ended up being a tear in the rubber coupling that connects the pressure pipe to the egr manifold.

[yuley]

Hi, i'm having the same trouble on my 1.9tdi awx, it's really been ******* me off i've changed the maf sensor to no avail i've had it diagnosed on a new snap on diagnostic machine which brought up fault code 17965, basicly it's boost regulation pressure exceeded. The diagnostic machine gave me the reason for this which is a loose pipe or a tear in one, i've been told to check the main boost pipe which leads from the intercooler as this was the cause of someone elsses problem i've checked this and the fit isn't as snug as should be so i've ordered a new one from audi £45 i'm gonna fit this and hopefully it will do the trick, also gonna check vacuum pipes as mrp0ny say's above. Hope you get it sorted an post if you do cos i'm getting sick of it now, and never mind micras i got overtaken by 2 old dears in a fiat punto oh the shame..... a4 tdi 170bhp!!!!

[k3t4n]

ok just an update...

I am now able to get past 80 mph, but not as effortlessly as it used to be, saying that, I tried using electrical insulation tape on a couple of the thin vacuum pipes, as the braid is absolutely knackered on the ends, and the taping ensures that the pipes dont expand as much, so hopefully the pressure stays when driving or overtaking, ie, when more boost required.

I've noticed a slight difference, and the car feels slightly more responsive, but as these vacuum pipes are worn,and since the small difference has been felt since using the tape method, replacing these is prob the first thing ill do. I've been thinking it could be a MAP sensor, 02, etc. If that was the case, surely I'd have smoke blowing out my exhaust? havent seen any smoke now since the turbo clean, and its the same even if I floor it from 60-80 in 5th gear. I would like to get to the bottom of it, and hopefully restore the power, as the 'redeye' 110bhp model i have is certainly quick enough overtaking and the weight of the chassis combo with engine, plus the koni suspension ive added (done around a year ago-STR kit 35mm drop all round) makes this car very agile in its class.

Just one thing ive noticed, theres a plastic ball type thing located in the left hand side of the engine bay, a little way down into the engine bay, and the vac lines run into this and the braid is v frayed. Do I just pull the end off the ball to replace? Or does that require me to remove the ball thing as well? any help here would be most appreciated. thanks

[yuley]

Right i've now sorted my problem, it ended up being the boost sensor on the boost pipe at the rear of the engine i also replaced the n75 selaniod which didn't make any difference so i would try the sensor on the rear boost pipes if i was you, hope you sort it out... n75 selaniod £29 and boost sensor £49 from audi..

[k3t4n]

Having called Audi parts, they said the boost sensor is the MAP sensor. Does this normally come up under a VAGCOM scan? I havent got any codes coming up...worth changing the MAP sensor? yes it is £49...

[lordpleb]

Does it work then suddenly go from lots of power to none or just have none from the start? I have a 90hp A4 and that had a clogged cat + a leaky boost pipe so the cat wouldn't allow the exhaust to spin the turbo properley and because of the boost leak it meant it was very hard to diagnose. I fitted an aftermarket Frontmount Intercooler and new pipes as soon as i did that it wouldn't idle cos of lack of turbo. This car felt like it was in permenant limp mode from the word go.

[yuley]

If i was you then yes i'd try the map sensor it worked for me, you always have to eliminate the cheaper parts first before you start getting to the more exspensive bits, i replaced the n75 valve and it made no odds but the map sorted it out straight away and i wasn't getting any codes up that pointed straight to the map sensor either only 17965 which is boost pressure deviation which the map sensor is all about measuring the boost pressure. Hope it sorts out your problem, and if your car isn't kicking any nasty smoke out the back end then i would put money on a sensor problem rather than turbo..

[lordpleb]

If i was you then yes i'd try the map sensor it worked for me, you always have to eliminate the cheaper parts first before you start getting to the more exspensive bits, i replaced the n75 valve and it made no odds but the map sorted it out straight away and i wasn't getting any codes up that pointed straight to the map sensor either only 17965 which is boost pressure deviation which the map sensor is all about measuring the boost pressure. Hope it sorts out your problem, and if your car isn't kicking any nasty smoke out the back end then i would put money on a sensor problem rather than turbo..

Isnt the Map sensor built into the ECU? But when the cat was changed the car worked fine infact the best it has run.

[yuley]

Isnt the Map sensor built into the ECU? But when the cat was changed the car worked fine infact the best it has run.
Yes sorry your right, i'm talking about the boost sensor thats sat on top of the main pipe that runs at the rear of the engine, it's held in place with 2 screws.. The part number is 038906061C Sensor £49.48

[lordpleb]

Not sure, i'm talking about the boost sensor thats sat on top of the main pipe that runs at the rear of the engine, it held in place with 2 screws..

I think on the earlier models its built into the ECU.

[trickyfocus]

I'v got a4 1.9 tdi 110 ... I had same problem...... it was a hose split that goes to the turbo. it was split at the back so you could not see it till it came off.... the one with two jubilee clips and it's about 2 inch long and 2 inch thick.... orderd a new one 23 squid from audi. It's like driveing a diffrent car hope this helps.

[k3t4n]

Ok ordered a MAP sensor from Audi...will see how that goes once I pick it up in the next couple of days.

Can someone tell me what the plastic ball type thing located in the left hand side of the engine bay is? its a little way down into the engine bay, and the vac lines run into this and the braid is v frayed. Do I just pull the end off the ball to replace? Or does that require me to remove the ball thing as well? any help here would be most appreciated. thanks

[the_old_diver]

Can someone clarify things for me here; are we talking about the Mass Air Flow meter thing (MAF) just after the air filter or something else and if so what? Bit baffled by the acronyms. Thanks, OD

[k3t4n]

no not the MAF sensor (mass air flow), but the MAP (manifold absolute pressure) sensor which is at the rear of the engine bay.

I have now changed this and paid £49 and annoyed as I still have turbo lag. I feel theres got to be a leak somewhere along the pipe that goes from the vacuum reservoir to the egr. Can someone help me here? How do I remove the frayed/broked braided line from the vacuum reservoir (looks like a plastic black ball), without breaking it. I suspect you can just pull and it will eventually come off, just like the other vacuum lines I've now replaced. But want to know if I need to take out the vacuum reservoir first. any help appreciated, at my wits end :aargh4:

[jedichi]

I had this same problem on my 110. It was the small braided hoses from the left side of the engine to the back, they were all frayed, just replaced them and the car is fine now. (dont know what the hoses connected?!)

[k3t4n]

thanks jedichi!

do you know how to remove the thin braided line from the black plastic ball low in the engine bay? does it just come off if you pull? has a lot of resistance, so im not keen on breaking it and creating another problem. Just want to fix it, as I now have replacement braided hoses.

thanks

[jedichi]

Sorry mate I didn't need to replace that one. I would assume that it would just pull but don't quote me.

[k3t4n]

as I've replaced some of the braided rubber vacuum hoses (thin pipes) from the egr and n75, the limp mode prob has dramatically reduced itself. I can now accelerate to 60, not as well as before, but on motorway I can get to 80 reasonably well with some pushing. I want to swap out the knackered braided hose from the vacuum reservoir to the egr. Can anyone help? It doesnt seem to pull off the vacuum reservoir (black ball type thing in lower part of engine bay).

would be v grateful if someone could advise please.:beerchug:

[quattrogary]

Hi mate.Had same issue with 2000 b5 a4 115bhp.Took to several garages with no luck.Eventually stripped out several plastic covers to find small pipe underneath/right hand side of air filter housing had disconnected itself.Pipe was a bit short from new by the looks of it.Reconnected using dab of glue,what a difference.I expect this has been checked,but spend an hour with a real good torch.Still have this vehicle,gave to partner,coming up to 180k.

[howard.manton]

Here's one for the techies!!! Had my 1998 1.9tdi Quattro for 5 weeks now and it's given me nothing but problems!! On driving it home the day I bought it, it went into limp mode and has never really had any power since then. Turbo doesn't come in (Not limp mode) I've changed the Maf (twice) I've changed the N75 valve and cut the bad bits (frayed ends of the vacuum pipes) each time the car runs spot on for a couple of miles and then drops back to what it was before. It never regains any power unless I change something, take a pipe off, remove power from the valves and then put it back again.
The fault codes on the Vag com are the usual ones and when cleared they come back not straight away but after I've driven a couple of miles.
00553 - Mass Air Flow Sensor (G70) 28-00 - Short to B+
01117 - Generator Terminal DF Load Signal: Implausible Signal
00575 - Intake Manifold Pressure: Control Difference
Anyway, Ive just taken it through a car wash (no comments about being idle and doing it myself, cos a big fat bird did something monstrous on my screen on my way home from work. As I pulled out of the car wash the car went like s.o.a.s. (what that bird did to my screen off a spade). It drove perfect all the way home (5 miles) It's still going well (will be till morning I bet). Anyone any ideas??? I lifted the bonnet when I got in,,, no obvious changes, no water behind the plenum, no wet bits on the engine?????
I've ordered some silicone pipe and gonna re-pipe it later in the week, the boost actuator moves fine blah blah blah,,,, really at a loss now. Maybe time for VWA to have a look????:aargh4:

[jimicks]

Hi guys,

I had a valve sticking in the turbo some times, the turbo use to cut out and went onto limp mode, switch the engine off and on, it would go away. I found out if you put 2 stroke oil in the diesel this solved the problem, problem dissapeared

:biglaugh:

[jimquattro]

i changed the vacuum hoses on the plastic ball thingy just pull and twist they are on quite tight

[hibbsy21]

Hi guys,

I had a valve sticking in the turbo some times, the turbo use to cut out and went onto limp mode, switch the engine off and on, it would go away. I found out if you put 2 stroke oil in the diesel this solved the problem, problem dissapeared

:biglaugh:

How much two stroke? A cap? A Cup? A pint? (.....mmmm a pint.....) lol :biglaugh:

[James hbq]

as I've replaced some of the braided rubber vacuum hoses (thin pipes) from the egr and n75, the limp mode prob has dramatically reduced itself. I can now accelerate to 60, not as well as before, but on motorway I can get to 80 reasonably well with some pushing. I want to swap out the knackered braided hose from the vacuum reservoir to the egr. Can anyone help? It doesnt seem to pull off the vacuum reservoir (black ball type thing in lower part of engine bay).

would be v grateful if someone could advise please.:beerchug:
LIMP MODE (A4 1.9tdi 1996)
Originally limp car and 0575 code supressure in turbo
1)- I change all tube vacuum tube (even the shortest)( for the reservoir, black balloon, take care to pull off without swaying or cut it apart because the connector for tube is fragile and will break if pulled not vertically) i did break it

2)- Clean the turbo by taking it out completely, easier with the exhaust collector together/ cleaned the variable vanes/ Exhaust side/ with some white spirit (take care to mark how elements are assembled or draw them somewhere) and not to scratch the surface of elements which has a surface treatment.

3)- disassembled the intake collector (6 ALLEN SCREWS) , clean it thoroughly( lot of sticky sludges and soot ) by scratching the inside with white spirit or any degreasing liquid / washed clean with water / dry
i also clean the intake funnels BY THE SAME TIME

4)- bLANKED THE EGR

5) Checked the N75 to have around 24 OHMS beetween poles= meaning good

noW THE CAR IS AS NEW http://www.vwaudiforum.co.uk/forum/images/icons/icon10.gif

[trickyfocus]

Were do i buy the tube from .... there are two types, The braded tube and plastic..... and what sizes do i ask for .... and the clips to fit thanx in advance ......

[James hbq]

what tube are u referring to?

[Mantas Morkunas]

I have simular problem with 2001 b5 tdi 90 bhp. After remap i

[Mantas Morkunas]

I have simular problem with 2001 b5 1.9 tdi 90 bhp, after a remap it goes into limp mode ONLY when maintaining same speed for 10-15 mins, after it happens first time then its a matter of seconds till it goes into limp mode again after I restart engine, during a 60mile trip everyday it cuts out 10 or more times but not when accelerating or 3k rpm but when deaccelerating or maintaining speed, otherwise pulls really good in all gears and at any rpm and as soon as I deaccelerate turbo cuts out, (note most vacum pipes replaced even tho they were good, new n75 and no faults on VAG only underboost fault after it cuts out, turbo cleaned manifold cleaned, actuator moves freely.)

[Hjhutti]

hi all.

sorry to tag along but I have a 2008 Audi A4 (Diesel auto) - have replaced so many things - Turbo, N75, Map, Mas sensor, removed dpf, blanked EGR & remap. seems fine locally but struggles up hill on motorway & "glow plug" warning comes on - underboost. after switching off engine its ok. checked all pipes (by eye) as have replaced a few. on depressing accelerator large pipe (vacuum pipe) fills up (expands) which looks like doing what it should. any ideas please as I have hit a brick wall. thanks Harry

[VAG-Abound]

It's a pain isn't it :(?

Was it a new turbo, or did they recondition the existing one? Rough cost, as a guide to if they perhaps really did replace it and if so with what? Were the air side pipes checked as well?

[Hjhutti]

hi, reconditioned turbo. was an exchange so dropped one off & picked up the old one. not sure air side pipes - what are they?

[VAG-Abound]

I just meant the pipework from air filter to turbo, then through intercooler to engine intake. Making sure it is connected and reasonably leak free so that sensors don't get confused.