1.6 FSI Map Controlled Engine Cooling Thermostat Woes

A

Andrew

A2OC Donor
England
Thought I would post if nothing else than to just to build up the body of forum knowledge.

'Nothing Special' I think is showing contempt for the new name I gave my A2 last week after 8 years of ownership.

Symptoms

1. For the last nine months from cold the dash temperature seems to have been taking an age to reach 90 degrees, longer than I think it should. It started in the very cold weather we had last winter, 'Beast From The East' and all that, but being very cold I was not unduly concerned. As the weather got warmer the temperature reached 90 degrees faster but again slower than I would have thought it should. Thermostat everyone cries but as the car drove very well with no loss of mpg I ignored it.

I have my own VCDS kit and the car has been scanned several times this year and never showed any faults but matters came to a head this week.

2. For the last 18 months since the manifold flap refurb the fuel consumption on the dash has been showing a rock solid 40mpg. Imagine my horror this week when I glanced down and saw 35mpg!, came out of the blue. Something is very wrong.

3. Following advice about an Italian tune up, once a week coming back from the Sainsbury's shop on a quiet slip road I always let it rip, letting it reach 6000rpm, exhilarating. This week by the end of the slip road I could only make a little under 5000rpm. No excessive head winds or load that could explain it.

4. I know at 70mph I should have 3200rpm, this stuck in my mind as I contributed this statistic to a summer FSI thread. To reach 70mph this week I had to run at 4000rpm, oh dear.

Ran a scan today and all the above begins to make sense.

Address 01: Engine Labels: Redir Fail!
Part No: 036 906 013 F
Component: MED7.5.11 5130
Coding: 00051
Shop #: WSC 02138
VCID: 122BEA385E4E8BD14F-5140
WAUZZZ8Z65N000662 AUZ7Z0D2613505

1 Fault Found:
17700 - Map Controlled Engine Cooling Thermostat (F265)
P1292 - 35-10 - Open Circuit - Intermittent
Readiness: 0000 0000

Lots of reading for me today on here, occurred a few times over the years with useful links, and elsewhere.

Turns out....

1. A map controlled thermostat is not a dumb mechanical thermostat I learn but is controlled electrically by the ECU depending on engine load. The idea is high load = more heat = ECU opens thermostat flow to radiator; low throttle = less heat = ECU adjusts thermostat to reduce coolant flow. Apparently this increases mpg and reduces emissions, all clever stuff. Trust the FSI to be different, or maybe now it is now common in modern engines.

2. It's a pig of job to change, being behind the top of the engine with the intake manifold partly in the way.

Now my questions.

1. At one stage I thought I would have to buy the whole thermostat housing (~£200) with an integral thermostat but it appears the thermostat can be replaced separately. Am I correct?

2. A separate thermostat, part number 032121121N, varies drastically in cost from £30 to over £100 with lots of manufacturers. Can anyone offer a recommendation?

https://www.autodoc.co.uk/car-parts/oem/032121121n

Thanks - Andy
 
Last edited:
Andrew said:
4. I know at 70mph I should have 3200rpm, this stuck in my mind as I contributed this statistic to a summer FSI thread. To reach 70mph this week I had to run at 4000rpm, oh dear.
Click to expand...

Andy,

Can you confirm if this is in the same gear? If it is then you have more to worry about than the thermostat.....

I assume as you are down on power then 70mph needed 4th rather than 5th gear?

Does VCDS provide any options for a thermostat output test? If so, you may be able to remove it, run the test and see the results, this may help with the diagnosis as it could be a faulty sensor rather than the thermostat.

Steve
 
the thermostat sits in that exact position in the equivalent structure in diagram 121-121075 for the AUA / BBY engine (previous page to this one). Moreover, if you look at the aftermarket parts references for the BAD engine part 8 linked to above by Spike - go across to the right hand column and click the left / right arrow button, the parts links all come up as thermostats from various suppliers, so that would suggest it is, even though the mounting is slightly different.
 
Catnip64 said:
Andy,

Can you confirm if this is in the same gear? If it is then you have more to worry about than the thermostat.....

I assume as you are down on power then 70mph needed 4th rather than 5th gear?

Does VCDS provide any options for a thermostat output test? If so, you may be able to remove it, run the test and see the results, this may help with the diagnosis as it could be a faulty sensor rather than the thermostat.

Steve
Click to expand...
Thanks for the reply you have a very good point. I just assumed I was in 5th as I would be normally at that speed in 5th but I was very much dwelling on the slip road 'failure' I might not have changed up to 5th. I will check tomorrow.

I am very much a novice with VCDS hopefully somebody more experienced can reply about your VCDS suggestion.

Andy
 
spike said:
Some background info on electronically controlled stats in this post - https://www.a2oc.net/community/inde...-which-thermostat-opens-fsi.19338/post-146597

And the Audi parts diagm - https://audi.7zap.com/en/rdw/audi+a2/a2/2004-248/1/121-121076/

Item 8 looks like the 'Autodoc' part but a thorough read of the background info should help decide if it is actually a thermostat or a heating element per the parts list description

Cheers Spike
Click to expand...
Thanks, I think I came across those earlier and scanned them but I need to digest them properly. Not now after a couple beers I will get a headache! That 7zap diagram was the source of my partnumber. I am playing safe and have asked CreweAudi for a price before I commit.

Andy
 
Robin_Cox said:
the thermostat sits in that exact position in the equivalent structure in diagram 121-121075 for the AUA / BBY engine (previous page to this one). Moreover, if you look at the aftermarket parts references for the BAD engine part 8 linked to above by Spike - go across to the right hand column and click the left / right arrow button, the parts links all come up as thermostats from various suppliers, so that would suggest it is, even though the mounting is slightly different.
Click to expand...
Thank you I will follow up the aftermarket link tomorrow. Using the desktop now might disturb my sleeping wife which is why I am using my iPad at the moment. The iPad thinks the diagram number is a telephone number and wants to call it!, and the Aftermarket button struggles to work.

Andy
 
Catnip64 said:
Andy,

Can you confirm if this is in the same gear? If it is then you have more to worry about than the thermostat.....

I assume as you are down on power then 70mph needed 4th rather than 5th gear?

Does VCDS provide any options for a thermostat output test? If so, you may be able to remove it, run the test and see the results, this may help with the diagnosis as it could be a faulty sensor rather than the thermostat.

Steve
Click to expand...
You were quite correct to query this. Checked today and I must have been in 4th as today 3200rpm in 5th. One less symptom to worry about.

Thanks - Andy
 
Feeling guilty I have not updated this thread. Nothing worse to research a problem and find a relevant thread that peters out after a few posts with no resolution.

Parts

Absorbed the price options on the Autodoc list linked in post #1. Beats me how the same part can vary from £30 to £135. CrewAudi replied very promptly to my enquiry (thank you) with a figure of £78 and compared well with the glut in the list around this figure. I think I will go with CrewAudi unless anyone can recommend one of the manufactures or know who supplied the original thermostat. Will report back if it possible to identify the manufacturer of the part on removal to build up forum knowledge.

The Work

Thought I would stick my head under the bonnet and see what is entailed for the removal of the thermostat and replacement. It 'plugs into' the thermostat housing at the rear right of the block under the inlet manifold. A sod to get at but he good news I can actually see it, WITH a mirror, secured by three bolts, but lots in the way. Printed out the workshop guide that starts with drain coolant, and a sequence of work to create a 'hole' to get at it. Main culprit is the top hose from the coolant bottle so detach pipes and move aside and take out coolant bottle to give some elbow room. Followed by detaching and moving aside the large wiring loom and gear selector cable and you have the access hole for thermostat replacement.

Performance

I cleared the fault code and went for a run round the block and rescanned. The fault did not come back but thinking about it after, from cold on the short run the coolant temperature would have got nowhere near were the ecu would activate the fancy heating element in the thermostat so would never have flagged a fault. Right waste of time that was.

Waited a few days until chance for a proper run out for weekly Sainsbury's trip. Still seems to be taking too long for the temperature gauge to reach 90, but mpg coming back up and high revs on slip road back to normal. Scanned and no fault stored.

Now in a quandary over thermostat replacement, decided to do nothing yet and scan weekly.

Now a request for fellow FSI owners. We are in early November with typical temperatures and these do vary a little over the country as well as driving routes, but if possible can you note and post how many miles it takes your FSI to reach 90 degrees on the dash. Thanks.

Andy
 
the thermostat housing makes sense to change at teh same time. It is prone to hairline cracks as are all other plastic coolant pipes due to the high running temp of the engine.

- Bret
 
Vorsprung durch Technik said:
Takes 1.4 miles of early morning busy school run for ours to reach 90 degrees, a bit less when it's warm outside.Journey duration is 10 mins.
Click to expand...
Thanks. As I suspect mine takes too long. On a 4 mile run, first mile slow 20/30 mph but free flowing with remainder at free flowing 50/60 mph, I do NOT reach 90 degrees. I will go for a run tomorrow to tie down my figure.

Andy
 
bretti_kivi said:
the thermostat housing makes sense to change at teh same time. It is prone to hairline cracks as are all other plastic coolant pipes due to the high running temp of the engine.

- Bret
Click to expand...
Thanks for the undoubtly good advice but I think the Audi thermostat housing is well over £100 and I am a pensioner!
The thermostat housing reminds me of a delimbed octopus ready for cooking!

Andy
 
Got some figures now for dash temperature to reach 90 degrees. The ambient temperature was 15C, it took 8 minutes over a distance of 4.9 miles. The test route consisted of 0.9 miles getting out of my village, a few T-junctions and a roundabout generally slow but free flowing at a probable avarerage speed of 20mph, the remaining 4 miles free flowing main A road at 55/60 mph at 2600 rpm. Still thinking it is too long for a petrol FSI.

Scanned afterwards and the thermostat error of post #1 has NOT reoccurred.

Andy
 
I too had noticed that my FSI was taking a long time to warm up now the weather has turned colder. I do a short commute of about 6 miles, most of which is across country and I am doing 50-60mph, and the whole trip takes about 12 minutes. This morning I decided to check my figures to compare with Andrew's above and got a similar result. The DIS was showing 12C outside and for the first 7 minutes the temperature gauge did not move off the cold end of the scale, then it moved up to 90C over the next couple of minutes. This is my first winter of owning the car (I bought it last spring) and I wondered if something was wrong, but when the weather is warmer it heats up much more quickly. Having read this thread I now think it is a characteristic of the electronically controlled thermostat.
Clive
 
Cliverb said:
I too had noticed that my FSI was taking a long time to warm up now the weather has turned colder. I do a short commute of about 6 miles, most of which is across country and I am doing 50-60mph, and the whole trip takes about 12 minutes. This morning I decided to check my figures to compare with Andrew's above and got a similar result. The DIS was showing 12C outside and for the first 7 minutes the temperature gauge did not move off the cold end of the scale, then it moved up to 90C over the next couple of minutes. This is my first winter of owning the car (I bought it last spring) and I wondered if something was wrong, but when the weather is warmer it heats up much more quickly. Having read this thread I now think it is a characteristic of the electronically controlled thermostat.
Clive
Click to expand...
OR you have a duff thermostat as well! I have owned my FSI for 8 years and only in the last year have I noticed the slow warm up, before that I do not remember anything untoward but I was not focused on the warm up time.

Has your car been scanned since you bought in the spring? I am not too far away if you would like a scan and do not have VCDS, pop across.

IDEALLY IT WOULD BE GOOOD TO HAVE 2 OR 3 MORE TESTIMONIES FROM OTHER FSI OWNERS.

Thank you for taking your data and posting.

Andy
.
 
Hi Andy, no I haven't scanned my car since I bought it - I have bought a cheap scanner off ebay but haven't used it yet, I will do soon.
 
Time I did something about my diminishing mpg problem:(.

I have scanned with VCDS every week since post #1 and the thermostat fault has NOT reappeared (or any other engine fault) BUT the mpg continues to fall. I am now down to the dash showing 31mpg, as opposed to the normal 40mpg (or more on long runs). If it continues at this rate by Easter I will have to tow and be connected to a petrol tender tanker:rolleyes:!

I have barely scratched the surface of VCDS so made a decision, as the kit is expensive, its time I learned how to use it and a good exercise would be to see what is going on regarding the coolant temperature. Head stuck in manual all week, basically provides an outline, it’s not much use, far too general with statements like ‘refer to Manufacturer’s Workshop Guide; every car is different depending on model/age/variant/…’, ‘this may or not be present/work depending on ….. refer to …..’.

Made some progress and thought I would post it as a record for me and anyone in the future. Spent some time using basic measuring blocks and this screen, it is good that this is safe and you can’t do any damage! :).

Reduced VCDS Snapshot.jpg


Some questions along the way.

Q1. The blue ’REDIR FAIL!’ does not look good. Anybody care to explain? (I have just noticed it looks like a link; will try it next time.)

Q2. Is there a reference list anywhere for our A2 engines of exactly what information is in all 256 groups?, e.g. found a group with a field value for my A2 of 108654km, what is it?, it is not my total mileage. The manual just says step through them all, what all 256?, or refer to ‘Manufac..…’! Taking a punt the second temperature field in group 001 is actually coolant temperature.

The Log button looks useful. Learned it dumps the data in a file in Excel (or similar) format. Clicked the ‘Log’ button and then the ‘Start’ button (which replaces the ‘Add to Log’ after clicking ‘Log’) and went off for a test drive. More or less an extended version of the route I described in post#14.

Three points came out of this.

  1. It very much underlined the dash coolant gauge is very much a driver’s comfort instrument, and the 90°C should only be viewed as a broad indicator the coolant temperature is within operating range and little to do with reality. It blatantly lies, I could see the temperature on VCDS it was 108°C and the dash showed its resolute 90°C! The dash gauge did broadly match VCDS as it climbed from 60°C but trailed by about 5°C until it got to its unwavering false 90°C.
  2. Note to self.
    (a)Set the laptop preferences so it continues working with the top down. With the top open sat on the front passenger seat, it’s mesmerising, irresistible and highly dangerous when driving!
    (b)Remember to click ‘Stop’ to end the logging or VCDS will not load next time and trying to do anything with the logging file comes up ‘file in use’. A cold boot fixed it.
No point in taking the log if I can’t utilise it so last Tuesday evening was relearning Excel, or at least the very basics (probably about 0.1% of what it can do!). Only used Excel before for small simple tasks but it never struck me before I opened it up, that these log files at a sampling rate of about 3.5/sec, produce an Excel file that is over 5000 lines long for my half hour test drive, which threw me for a while, eek@.

Sorted it in the end and produced this.

1545176216025.png


First, I have to point out the ambient temperature was not 38°C here in Eynsham last week:). I had popped out on a very short trip in the morning, probably half a mile but I was surprised to see how much heat was retained by the engine/coolant three hours later (just right for a shower:rolleyes:). For the record the ambient temperature was 12°C.

Enough of me rambling, some car stuff.

Q3. The local max and min just after 5 minutes. As an explanation am I right in thinking this is the point when the cabin climate decided to start seriously using the coolant heat, at just under 80°C? This corresponds to the point of hitting the loacal A road and reaching 50/60 mph.The two further graphs below also have a blip at this temperature point, but only marginal and nowhere near as pronounced, strange but maybe normal/expected.

The thermostat appears to open at the correct temperature (or just short) and halt the temperature climb. (Nearly all the thermostats for sale on the Autodoc link in post #1 have an opening spec of 109°C so this has to be the spec for the FSI).

Q4. It is taking 15 minutes for the coolant to reach working temperature; virtually all my car use now is for trips under 15 minutes. I am thinking this is too long and the cause of my lost mpg. Am I right?

The last 10 minutes of the graph and the high plateau corresponds to constant 60mph on dual carriage.

Q5. I am not seeing much evidence of the fancy electronic function of the thermostat when it heats the wax to open the thermostat under low load, unless this is the saw tooth nature of the high plateau. Comment anyone?


Thought it might be useful to redo the test run from overnight cold to see the true length of time for the coolant to reach working temperature.

1545244138819.png


Q6. Strange the time to reach working temperature was slightly shorter starting from a lower ambient temperature!, but the same general graph.

Another test, more or less same route.

1545176808435.png


Broadly the same graph outcome.

Q7. Any idea on the strange blips around 5 minutes? It might correspond to sitting at traffic lights waiting to join the A road, but I would have thought the temperature would go up. When the log is active is active there is a ‘Marker’ function available, clicking ‘Marker’ puts an entry in the log. I can see now this would be very useful to pinpoint changes in driving pattern/key points e.g. sat at traffic lights, but is far too dangerous to use when driving alone!

Q8. Does anybody have any links to reference material for the FSI thermostat so I can compare these graphs.

Any help/comment appreciated. Thanks.



Andy
 
You must log in or register to reply here.
Back
Top