1.2Tdi low power in higher gears

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iwcham1979

Member
Hi guys, I have some problems with my 1.2Tdi 3L. The car loses all power past the second gear, but there is no limp mode. It loses speed uphill, doesn't get past 120kmh, but there is no limp mode or codes. There is NO smoke whatsoever, even if the car has been remapped from 60 to 80hp so I guess there is not enough fuel or air getting into the engine. Since there is no limp mode, should I rule out the sticky turbo vanes as the culprit? I have plugged out the maf sensor and it hasn't changed a thing.
ASV is not working, is stuck in the open position, and i disconnected the wiring to it in case it may be acting up... EGR was completely non functional, clogged so i just removed the hose and plugged the hole.... Intake is not very clean but not clogged up. I tried disconnecting the air hose to have it suck clean air, didnt get any improvement....
Today I tried swapping several MAF sensors and situation is the same. I ordered another air filter and will try changing it tomorrow, or running without it. I doubt it will cure anything, since it has been replaced recently, but I have to start somewhere. Maf values are from 370mg to 500mg idle with different mafs read from a Delphi diagnostics software. When I rev the car in neutral all the way to red line and keep my foot down it barely gets to 600mg air.... What should the values for this engine be in neutral and full throttle? (Is it more than 800mg or so like on a 1.9Tdi) What should the turbo boost be? Do I measure it by flooring it all the way in neutral? Suggestions appreciated. There are NO codes, apart from the ASV and glow plug code, which is irrelevant. The car doesn't smoke at all, and it doesn't use more fuel. It idles and sounds fine... It goes like sting up to the forth gear then loses power completely and 2500rpm in fifth gear is the limit.... Thanks guys... The ECU map is good. Another 3L hits 81hp in fifth gear with it.... The car hasnt' been in use for almost six months, so I wonder if turbo vanes could be stuck or not operating correctly without it throwing a code or going in limp mode.... I can move the actuator with my hand without problems though...
 
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It was changed 3000km ago... However the car has not been in use for almost 6 months. Maybe something clogging due to a long period of not running?!

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Which model of Polo with a PD engine and VNT turbo did you take your ECU map from? I didn't know there was one.

RAB
 
Honestly dont know the engone code exactly but it is a 9n. I guess the map from A2 1.4tdi 90hp can be used as well... :)
We checked today using vcds. The turbo makes boost but is losing it. Vacum hoses are fine.. Any ideas. The actuator on the turbo, it doesnt move when i switch the ignition on. Should it move?

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As far as I know, no 9N Polo had a VNT turbo, so your map is presumably for a wastegate turbo. The VNT actuator requires vacuum, not sure about a wastegate. The actuator won't move when you switch on ignition anyway, only when you rev up. Can you move it manually?

RAB
 
Well, they use the map from a Polo 9N since Lupo 3L has a Vnt turbo, not a wg turbo as Lupo 1.4tdi... My map is Ok. I used a tested map my acquaintance uses on his 3L manual that produces 81bhp. So map is fine 1000% Below is his dyno... The problem is mechanical or electrical. Today we did some tests with vcds... IT shows that the turbo boosts fine but doesnt hold the boost, but looses it. Thats why it goes like crazy in 2nd and 3rd gear but looses breath in 4th and 5th.... The guy who is a mechanic told me the turbo actuator I guess should move somewhat when I turn on the ignition. Maybe he thought it was a wg turbo... Why would a turbo make perfect boost in second gear and produce more than 80hp and lose it in higher gears completely?
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Guys I think i figured it out, not 100% sure though. It suddenly dawned on me. Some facts: The car drove well before the manual conversion. The car lost power immediately after the conversion. Maf is fine, no error codes, no boost leaks. The car can't hold boost even with the map from a manual 3L that makes 81hp. Why does it not perform with that map? Because that other Lupo had the actuator rod adjusted, unlike mine.

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Guys we managed to pinpoint the problem, but not the solution. It is the transmission speed sensor and ABS related. It has nothing to do with the engine itself. We tried unplugging the speed sensor and all the power is restored 100% The car goes like crazy. But I have no speedo readings... The sensor is directly connected to the tacho wiring harness. It works but causes severe power loss. Any idea how to fix this? Is there a relay that needs to be disconnected? Some people leave the transmission ecu plugged in but in my case it causes the car to shut down immediately... Any ideas appreciated!

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iwcham1979 said:
Guys we managed to pinpoint the problem, but not the solution. It is the transmission speed sensor and ABS related. It has nothing to do with the engine itself. We tried unplugging the speed sensor and all the power is restored 100% The car goes like crazy. But I have no speedo readings... The sensor is directly connected to the tacho wiring harness. It works but causes severe power loss. Any idea how to fix this? Is there a relay that needs to be disconnected? Some people leave the transmission ecu plugged in but in my case it causes the car to shut down immediately... Any ideas appreciated!

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Click to expand...

So without the G68 everything runs fine, just out of curiosity, replace the G68 with the one from your friend's car, does that change anything?
You've got such a strange problem that it's really hard to say what's what and especially with a custom remap.

I'm really interested in having a look at the ECU file if you are willing to share it. Never seen one adopted from a 9N. Will of course share mine.
 
I tried removin the cluster all together and leaving the sensor plugged in. The car runs fine with the cluster removed! Either way, the car runs fine as long as there is no sensor to tacho connection...

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Guys, the issue solved. I found a good mechanic who obviously knew very well what he was doing. He stripped the rubber insulation from the Ecu plug, didnt even unplug the ecu, clipped the single tiny wire from the whole bunch of wires and that was it... He plugged in the speed sensor, all fine.... But he pointed to one more issue that needs to be addressed immediately, and of which I was aware but didnt know mattered much. ... Namely, he said my ABS didn't work any more and the braking bias is seriously out of whack and can be dangerous because the fluid is first pushed to the rear brakes or so and front incorrectly.... He tried what not to make it work on another Lupo he was working on, but without success.... The suggested course of action is to ditch the Abs module and put the master brake cyllinder from a car that didnt come with ABS... What do you think? Is there really no way to make it work, reestablish the canbus connection? Strangely, the car does NOT throw any ABS related errors. When I unplug.the ABS module, the dash throws the abs and handbrake lights and beeps. When I plug it back in all the lights go out. Everything appears to work when it does not. I tested it in the snow and it definitely doesnt work. I also had a situation when I had to brake sharply at 120km/h. It was very dangerous. The car didnt brake in straight line and i barely kept it on the road...

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May this power reduction connected to a slip clutch detection (explaining full power without G68) ?
Can the engine "remap it-self" to avoid slip ?

My search bring me here, my A2 1.2 have no power (but speed is still, slowly, over 140kmh) with no reason for that.
The only explanation I have is a weak clutch that did slip after rebuilding the gearbox, but does not slip any-more... as I have much less power.

If this can be a reason, how to double-check in VCDS ?

I have no error on the car what so ever, consumption is 0.2L more, turbo & EGR have been cleaned.
Full power is way below eco mode before, 208.000 kms, have this issue since a year.
 
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1200TDI said:
May this power reduction connected to a slip clutch detection (explaining full power without G68) ?
Can the engine "remap it-self" to avoid slip ?

My search bring me here, my A2 1.2 have no power (but speed is still, slowly, over 140kmh) with no reason for that.
The only explanation I have is a weak clutch that did slip after rebuilding the gearbox, but does not slip any-more... as I have much less power.

If this can be a reason, how to double-check in VCDS ?

I have no error on the car what so ever, consumption is 0.2L more, turbo & EGR have been cleaned.
Full power is way below eco mode before, 208.000 kms, have this issue since a year.
Click to expand...

VNT mechanism gummed up? Can you manually move the actuator arm? Is the actuator diaphragm intact?

RAB
 
Hello Rab,
I had indeed the classic error 17965 (too much city use), this is why last year removed EGR, turbo, intake manifold for a deep cleaning.
The turbo was check by a pro as I wanted it renew but that was not required, just cleaned.
You could move the rod very easily with finger after. I have no error since.
Of course it was a little better after, but just and nothing compare the Lupo 3L I own too (or that car 2 years ago), it still lack power.

A bad setting or defective item (injector ? Air leak ?) is hidden somewhere without to generate error.
So I was wonder what can I check with VCDS.
It's so bad that I'm ready to exchange the engine, but that would be silly if it's an "easy fix".
Also cannot find low mileage one on the market

Last, engine noise is normal, goes to 4.500 trm or more, but eventually smoke gray if the sun is behind to underline it.
 
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Is the diaphragm of the VNT actuator OK? Connect a length of tubing to it and suck! Does the linkage move and is there any resistance?
Are you sure that nothing is disconnected - check all the small bore tubing connections.
Fuel filter? Tandem pump? Air filter? These items won't show up on VCDS.

RAB
 
Air & Fuel filter are 10K, tandem pump I don't know (no power difference between full tank and empty)
I don't drive it often, as it's my wife car. When I drive it it's obvious to me, not to her... (well now she agree) so can't say how it happen.

If you say there is no "auto-tune" to degrade de power in case of a weak clutch (now does not slip), I will go to the mechanics to take compression, and test air leaks.

thank you
 
For the tandem pump, full or near empty tank won't make any difference. Small tubes all checked? VNT actuator checked?

RAB
 
Hello !
3 years after getting worst and worst, the car now accelerate like a FIAT 500L from 1972. Way too much small distance in town, very few highway, I think the catalytic converter is clog, from this video it seems the guilty one is the second, always cooler than first..
Does someone have an advise to clean these without to remove the frame to extract them ?
No highway will help as bad it is, 4 years in progress... Is removing one of the two catalytic converter acceptable ?
Am I alone with a 20 PS Audi 1.2 ?
Thank you for your time & advise
 
1200TDI said:
Hello !
3 years after getting worst and worst, the car now accelerate like a FIAT 500L from 1972. Way too much small distance in town, very few highway, I think the catalytic converter is clog, from this video it seems the guilty one is the second, always cooler than first..
Does someone have an advise to clean these without to remove the frame to extract them ?
No highway will help as bad it is, 4 years in progress... Is removing one of the two catalytic converter acceptable ?
Am I alone with a 20 PS Audi 1.2 ?
Thank you for your time & advise
Click to expand...
Have you scanned the car with VCDS?

Can you push down the VNT actuator (engine not running)? It should spring back up. Is your turbo working? If you take off the turbo inlet, you should be able check if the turbo rotates by hand. If you cannot rotate it, the oil from the turbo will run into the exhaust when the engine runs.

Take the inlet manifold off the engine and clean it. It will be full of gunk.

RAB
 
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