Loss of power - Limp Mode?

S

sbchilton

Member
Hello Folks
About 6 weeks ago I lost power on my 1.4TDi on the way home which left me struggling to get to 60mph on the motorway, I pulled over and re-started the engine and everything was fine. Thought it might of been a one off as I was a little past my 90k service (which I have now done).
Anyway it happened again this morning on my way to work and the same re-start procedure fixed it. Does anyone know any obvious places to look before I need to take it in.


Cheers - Scott
 
The first thing to do is check around the back and sides of the engine for split or loose rubber pipes around the turbo area - this is a major cause of limp mode.

Another thing to do would be to get a diagnostic done, if there#s someone in your area with the necessary tools.

Cheers,

Mike
 
Hi Mike
Is the amount of time between the occurrences typical of any particular problem? Also I have been hearing a very faint hiss when the radio is off and I'm accelerating, it sounds like it's coming from the footwell but it's hard to tell.
I normally use a local friend/mechanic for most of the work but he doesn't have VAG-COM any suggestions of anyone with diagnostics in the Derby/Nottingham area?

Cheers - Scott
 
I daresay there are VCDS equipped members in your area, but the trouble is, people don't put themselves on the Membership map.

The hissing is likely to be one of the many vacuum pipes that run along the bulkhead in that area and aren't really diagnostic of a fault.

If you've access to axel stands then get under the car and take a look at the piping and also from above too - this is the first step to take.

Cheers,

Mike
 
My tuppenceworth - did you notice the hissing sound before you experienced the problem? If so I'd say that sounds exactly like an air leak - positive pressure air generated by the turbo just escaping. Air leaks are becoming fairly common on the TDis now - a factor of age as the rubber components start to perish/lose flexibility.

Getting a diagnositc done to pull fault codes is also important.
 
Thanks for your comments guys
My mates garage has a lift so we'll have a good scout under the car and around the engine for hose leaks, I think the fuel filter also needs changing so i'll do that at the same time.
The hissing sound is constant as I accelerate regardless of limp mode, it sounds like water moving though pipes but I had never really noticed before as I normally have the iPod plugged in :)
 
Mine was hissing and it was a split inter-cooler. I hope it is just a vacuum pip or pipe clip. Would be a lot easier. Good luck.
 
A constant hissing sound when you get on the gas is definitely inidicative of an air leak in my book.
 
Turn your A/C off and see if the sound stops.

When was the air filter last changed?

Diagnostic will prob throw up an N75 fault and / or charge pressure control limit fault.
 
Last edited:
Hi

The car doesn't have A/C however I think it's been a while since the air filter has been changed, I think that might be a good first job :)

Cheers - Scott
 
Ok, had Suzy (a 90bhp diesel) 3-weeks now and it's an amazingly good car (our second). Purchased the car solely for 30-mile M6 journeys to the hospital, but can see more uses every day. No problems with the car and the motor just pulls and pulls and returns 53mpg at 80mph runs...

Last night, drops back onto the M6 at Junction 15 heading south and half way up that long drag (at 80mph) the power just drops away; meander home at 70mph plus but zero pull.

A few late night A2OC checks and see the switch-it-off and switch-it-back-on remedies; tried it this morning around the block and sorted.

Followed with a VCDS check and sure enough a 17965 - Charge Pressure Control P1557 fault found, so cancelled that...

The theory from a friendly expert who analyzed the car last weekend is that Suzy is going into limp mode possibly because of over boost. And I was being a tad zealous with the right-hand pedal. Visiting again this evening and will be a little more sympathetic and see what happens.
 
As you have a 90, the most likely cause of limp-home is sticking vanes on the variable nozzle turbo.
However, the other common cause that also needs to be examined is whether the intercooler has sprung a leak - they tend to split at the bottom and spew all that lovely compressed air out! A quick visual inspection of the bottom of the intercooler for signs of black oil spray/residue will give you an indication.
 
That is interesting dan-b. There was certainly evidence, lots of, black oil spray/residue at the front of the car immediately before purchase. Safford Audi, for the previous owner, steam cleaned the front end and 300-miles on no reappearance of engine oil. I'll have a good look under at the weekend. I've also been told it can be an 'overboost' issue and having seen the 'map' on this engine it does 'overboost' by some 5%; and I was at the time giving it 'lots' of overboost. However, last nights run up and down the M6 at 85 to 90mph but less than 4000rpm was without problem. Fingers crossed... What a superb car is the A2; filling up last night along side a friends 2014 Audi RS4 I told him genuinely I wouldn't swap the RS4 for the A2, so much more useable; but then I've an RS3 and a ragtop TT in the garage... Just love this A2!
 
My wife's A2 (also a 90) is the only Audi that we have ever had breakdown in any way (said he touching wood). That too showed an overboost error.

Strangely enough, after being told that it was almost certainly the turbo, it turns out that it was contaminated fuel, thick black gloop oozed out of the filter when it was removed.

I guess the theory about the "overboost" error is that too much boost and not enough fuel is the problem. In our case the boost was fine, but the flow of fuel was not sufficient (and contaminated too) so it threw the "overboost" error.

If it happens again, try replacing the fuel filter, firstly to see if the fuel is clean and not contaminated (ours was due to a refill at a well known supermarket containing "gloop") but secondly to ensure that it is not blocking and reducing the fuel flow.

Steve B
 
It was sticking vanes, dan_b, as reported elsewhere with photos, and since done the car runs perfectly and doing more miles than our RS3 and TT together... What a GREAT motor car
 
I've got the same on my 1.9 tdi Galaxy currently trying bardall turbo cleaner for a tank full of fuel
But it looks liked a strip down is needed over Christmas break.
 
Not sure if you've sorted your problem but I wanted to express my extreme thanks to this forum for it's invaluable help in solving the same issue I had and share some of the steps that got me there. Bit of background: I bought what looked like a nice spec 2001 Silver 1.4TDI (75BHP) from a guy that turned out to have pulled the wool over my eyes about a couple of issues the cropped up as soon as 30 mins after I picked up the car. Of course he pleads innocence and will hear nothing of a return for a refund or contribution to repairs (so far). Long story, I was saddled with (amongst many, many others) the limp mode problem when putting my foot down in 4th or 5th on the motorway, usually around 3000 - 3500 rpm when accelerating to join the traffic flow (just the point where you least need a drop in power, eh?). I spent hours (days?) and much money on solving this, so I'll share the areas that this forum has kindly pointed out to check and then indicate what my specific problem was:

1. Get a code reading (this is important - don't waste your time and money until you at least have an idea of where the fault might lie. I spend more money than I should at my garage so they were obliging to read the error codes on my car for free. I had one related to the cam shaft and boost pressure. Replaced cam shaft sensor (easy job on the 1.4TDI) but problem persisted)
2. Vacuum hoses from N75 relay at front right top of engine bay - checked for splits/leaks. Replaced some of the obviously worn pipes, but found no specific splits. Problem persisted)
3. MAF sensor - Didn't check this, didn't see it called out as a common related issue. I think it will be accompanied by an engine warning light on the dash, which I didn't have)
4. MAP sensor - Replaced this with a Bosch original that I managed to find for £30 at a friendly local parts store that ordered it in same day for me. Beat eBay, local VW and local parts store change both in time and at 50% of the price or less! But didn't solve the problem
5. Intercooler - this is at front left of radiator. Checked this for splits or oil leaks, but looked 100%
6. Checked large turbo air pipes to head and from intercooler and to and from exhaust manifold for leaks, found nothing obvious
7. Fuel filter - was recently replaced
8. Took out the heat shield above the CV joint to get a better view of the turbo. Saw more oil on and around turbo than I expected and pipe leading from intercooler into turbo looked a little loose. Checked where the vacuum pipes run into (out?) of the turbo and found (more by feeling than by sight) that one of them had completely popped out (there are two) and the rubber hose at the attachment point had stretch so it was no longer a tight fit. Also removed the air intake pipe mentioned above and found the o-ring had perished (cross section was square not round any more and rubber was hard). Replaced this and re-fitted pipe. Test drive - SUCCESS!
9. If none of the above are the problem, it might be the Turbo. If you have a variable vane turbo (not on the 75BHP 1.4 AFAIK), check that mechanism for movement.

I think that is about it, hope it helps someone!
 
professer1975 said:
Not sure if you've sorted your problem but I wanted to express my extreme thanks to this forum for it's invaluable help in solving the same issue I had and share some of the steps that got me there. Bit of background: I bought what looked like a nice spec 2001 Silver 1.4TDI (75BHP) from a guy that turned out to have pulled the wool over my eyes about a couple of issues the cropped up as soon as 30 mins after I picked up the car. Of course he pleads innocence and will hear nothing of a return for a refund or contribution to repairs (so far). Long story, I was saddled with (amongst many, many others) the limp mode problem when putting my foot down in 4th or 5th on the motorway, usually around 3000 - 3500 rpm when accelerating to join the traffic flow (just the point where you least need a drop in power, eh?). I spent hours (days?) and much money on solving this, so I'll share the areas that this forum has kindly pointed out to check and then indicate what my specific problem was:

1. Get a code reading (this is important - don't waste your time and money until you at least have an idea of where the fault might lie. I spend more money than I should at my garage so they were obliging to read the error codes on my car for free. I had one related to the cam shaft and boost pressure. Replaced cam shaft sensor (easy job on the 1.4TDI) but problem persisted)
2. Vacuum hoses from N75 relay at front right top of engine bay - checked for splits/leaks. Replaced some of the obviously worn pipes, but found no specific splits. Problem persisted)
3. MAF sensor - Didn't check this, didn't see it called out as a common related issue. I think it will be accompanied by an engine warning light on the dash, which I didn't have)
4. MAP sensor - Replaced this with a Bosch original that I managed to find for £30 at a friendly local parts store that ordered it in same day for me. Beat eBay, local VW and local parts store change both in time and at 50% of the price or less! But didn't solve the problem
5. Intercooler - this is at front left of radiator. Checked this for splits or oil leaks, but looked 100%
6. Checked large turbo air pipes to head and from intercooler and to and from exhaust manifold for leaks, found nothing obvious
7. Fuel filter - was recently replaced
8. Took out the heat shield above the CV joint to get a better view of the turbo. Saw more oil on and around turbo than I expected and pipe leading from intercooler into turbo looked a little loose. Checked where the vacuum pipes run into (out?) of the turbo and found (more by feeling than by sight) that one of them had completely popped out (there are two) and the rubber hose at the attachment point had stretch so it was no longer a tight fit. Also removed the air intake pipe mentioned above and found the o-ring had perished (cross section was square not round any more and rubber was hard). Replaced this and re-fitted pipe. Test drive - SUCCESS!
9. If none of the above are the problem, it might be the Turbo. If you have a variable vane turbo (not on the 75BHP 1.4 AFAIK), check that mechanism for movement.

I think that is about it, hope it helps someone!
Click to expand...

So here is my check list that I shall have a look at when I get home later :)
 
professer1975 said:
Not sure if you've sorted your problem but I wanted to express my extreme thanks to this forum for it's invaluable help in solving the same issue I had and share some of the steps that got me there. Bit of background: I bought what looked like a nice spec 2001 Silver 1.4TDI (75BHP) from a guy that turned out to have pulled the wool over my eyes about a couple of issues the cropped up as soon as 30 mins after I picked up the car. Of course he pleads innocence and will hear nothing of a return for a refund or contribution to repairs (so far). Long story, I was saddled with (amongst many, many others) the limp mode problem when putting my foot down in 4th or 5th on the motorway, usually around 3000 - 3500 rpm when accelerating to join the traffic flow (just the point where you least need a drop in power, eh?). I spent hours (days?) and much money on solving this, so I'll share the areas that this forum has kindly pointed out to check and then indicate what my specific problem was:

1. Get a code reading (this is important - don't waste your time and money until you at least have an idea of where the fault might lie. I spend more money than I should at my garage so they were obliging to read the error codes on my car for free. I had one related to the cam shaft and boost pressure. Replaced cam shaft sensor (easy job on the 1.4TDI) but problem persisted)
2. Vacuum hoses from N75 relay at front right top of engine bay - checked for splits/leaks. Replaced some of the obviously worn pipes, but found no specific splits. Problem persisted)
3. MAF sensor - Didn't check this, didn't see it called out as a common related issue. I think it will be accompanied by an engine warning light on the dash, which I didn't have)
4. MAP sensor - Replaced this with a Bosch original that I managed to find for £30 at a friendly local parts store that ordered it in same day for me. Beat eBay, local VW and local parts store change both in time and at 50% of the price or less! But didn't solve the problem
5. Intercooler - this is at front left of radiator. Checked this for splits or oil leaks, but looked 100%
6. Checked large turbo air pipes to head and from intercooler and to and from exhaust manifold for leaks, found nothing obvious
7. Fuel filter - was recently replaced
8. Took out the heat shield above the CV joint to get a better view of the turbo. Saw more oil on and around turbo than I expected and pipe leading from intercooler into turbo looked a little loose. Checked where the vacuum pipes run into (out?) of the turbo and found (more by feeling than by sight) that one of them had completely popped out (there are two) and the rubber hose at the attachment point had stretch so it was no longer a tight fit. Also removed the air intake pipe mentioned above and found the o-ring had perished (cross section was square not round any more and rubber was hard). Replaced this and re-fitted pipe. Test drive - SUCCESS!
9. If none of the above are the problem, it might be the Turbo. If you have a variable vane turbo (not on the 75BHP 1.4 AFAIK), check that mechanism for movement.

I think that is about it, hope it helps someone!
Click to expand...

Hi there, Im having this issue at the moment. Did you remove the driveshaft or take the heat shield off with the driveshaft in place?
 
You must log in or register to reply here.
Back
Top