Advise needed, please..

[hmk]

I have searched most of the site and no wiser. so asking for help and advice.

I have a lupo which is an automatic 1.4 16 v  year 04. bought some years ago with only 25k one owner.

Had a good few years problem free drining. now on 54k. did regular service and looked after it.

last year suddenly the idle went crazy and car was in limp mode. turned out TB failed. got a second hand one which was cleaned and worked care free until a year later. RAC came out and said TB was done. not suprised as it was a used unit.

So I got a new pierburg unit installed and programmed in using vag software. a month later same problem again. Again RAC to the rescue. They checked the car over and stated the EGR was failing. they cleaned it on site where i had broken down and got the car going. within an hour,broke down again.

So I replaced the EGR with a new pierburg EGR. car was also again reprogrammed and worked fine.

Today the car broke down again. luckily i was at a friends garage.

As it was cold I started the car and let it idle to warm up, got caught in a conversation and left the care idling. The car was idling for about 30 to 40 mins, when the revs suddenly went up, the car reved high for about 3 mins and then started to idle up and down erratically.

now when i start the car it seems top be in limp mode any pressure on the accelerator drops the idle so the car is not really driveable?

any advise would be appreciated?

thank you in advance.

Hoping to get in touch with guys who programmed it tomorrow.

again thank you.

 

[mk2]

From the description, could be anything! Even the gearbox. Any diagnostic codes? Why has it been reprogrammed? That's kinda wierd. (Or do you mean the fault codes were cleared?)

Surprised about the throttle bodies. They get gunged, but don't usually fail. And a long run on the motorway once a month sorts out the EGR. Leaving the car idling from cold for a while kills engines. Any engine. Drive it straightaway once starting from cold.

Edited December 6, 2023 by mk2

[hmk]

Thanks for the reply. 

The tb was was reset using vcd. Not reprogrammed if that makes sense. Because it was replaced.

Now been advised by garage to put old tb back in. I am cleaning it now although it's that dirty inside.  The new one is a pierburg and the old one is vw ag.

gearbox is ok recently serviced.

will have to get codes again and will put them up. The egr as stated already is also new.

[hmk]

Old one is the first photo. 

[hmk]

These are the codes now original tb back in.

[hmk]

Ok, thanks for reply.

I put car back together. Cleared codes. Using a snap on apollo d8 scanner if that means anything. The codes being returned are:

17989 tb basic setting not performed.

17950 angle sensor throttle motor - g187 not a plausible signal p1542.

Again thank you for any help.

[mk2]

Hmm. That does sound like the throttle body- well actually the TPS sensor inside it.

Ok, so what I'd do to prove it is try and look at the throttle readings (engine on, but not running). Not familiar with the D8, so you'll have to explore till you find it- in there should be an option to watch the live throttle data measurements. It'll either tell you readings in volts, typically between 0.4-4.6 ish, or in % 0-100. And if you have a graphing function, you could display the data on there: As you slowly press the throttle pedal from off to full to the floor, you should see a smooth increase in readings. If you get that, the the TPS is fine. Chances are it's the motor linkage to the throttle flap.

Actually you can check the movement of the throttle flap by trying to push it open with your fingers. There should be resistance, but not crazy stiff. Sticky throttles can give those codes- the ECU tries to open it by applying a specific voltage, which should (a split second later) go to the position demanded. If it takes too long, or doesn't reach the point the ECU expects, it'll flag a fault. All your codes could be from that.

But, a new throttle body should work perfectly out of the box. So I'm thinking that there might be a wiring issue, or perhaps not enough voltage to make the throttle flap motor work at full power. Could be a power relay, a loose fuse or a loose connectir somewhere. Or even a broken(intermittant) loom wire. The EGR fault codes hint at a wiring fault as well- like a plug not connected or a broken wire.

You could try spraying some penetrating lube at the throttle flap spindle bearings to see if that loosens it up a bit, if it was a bit slow/stiff. When operating, they open and close really fast, like zip-zip. Half a second from closed to open back to closed again.

 

[hmk]

I was thinking the same.

The new tb when installed did not change the engines idle, it was still erratic until VCD was used to set the basic settings..

The car then ran fine until a 3 days after. going to it put on a laptop with vcd tomorrow. then leave it with the electrician to see if the problem occurs again, so he can work out the problem as it happens.

The actuator tests did run without any problems, the throttle flap moved through a range of angles, so did not think there is an issue with the tps/linkage inside the tb. unless the actuator tests run a higher voltage to run the tests?

cheers

 

 

Edited December 6, 2023 by hmk

[Rich]

Those codes look like a circuit is down which will be like a failing unit.

 

My mate is having this problem with a GTi, he actually won't let me look at it.

Edited December 8, 2023 by Rich

[hmk]

Hello,

Thanks for reply.

Are we saying the TB is failing?

I have put the original unit back in as i was getting the same idling issue with the new TB.

its currentlky idling at 1000 rpm . when the accelerator is applied it starts to become erratic .

when i change gear from park to drive, the car feels like its been hit from behind like a rear end collision.

I have not looked at car agin since yesterday...its too cold and i work nights.

Got tired for velectrician to turn up, so ordered vcds.

waiting on that now.

again, thans for reply.

hmk.

 

[hmk]

excuse the my spelling, just woke up..

[mk2]

Not sure on the details of your exact unit, but typically, there are 6 pins. Two go directly to the motor. The other 4 (maybe 6) are a +ve feed and and earth, the other two are the returns, one increases as the throttle opens and the other decreases as the throttle opens. Basically a failsafe system. There are two potentiometers connected in parrallel (internally), but in reverse if you see what I mean. I wonder if maybe the earth line is high resistance, or maybe the positive feed is being dragged down by some other sensor elsewhere. EGR circuit?

I don't think the problem has anything to do with the throttle body.

[hmk]

cool, will look at it again. my shift finishes sunday morning. so will get back on it monday.

i have a multi meter somewhere.

hmk

cheers.

[hmk]

Hello, FOlks.

Hope all is good.

I left car as was last 3 days. Started it this morning. Same problem. Ran for a few seconds then died. Restarted and it started was.running for about 29 mins with a rough idle 1000rpm. Press 4he accelerator and the idle drops. Restarted a third time now after running rough for 20mins and it's running fine. Like nothing was wrong. EPC light is in and so is the engine check light. Am going run the scanner now see what comes up.

[hmk]

Ran diag while engine running. Pedal flat to the floor diag showing tb at 95.2 % dash showing roughly 5000 rpm car surging.

removed video (saving space), as problem cured.

 

Edited December 13, 2023 by hmk
removing video

[mk2]

You'll break the engine doing that... 

i wrote:  >>>engine on, but not running<<< Not familiar with the D8, so you'll have to explore till you find it- in there should be an option to watch the live throttle data measurements. It'll either tell you readings in volts, typically between 0.4-4.6 ish, or in % 0-100. And if you have a graphing function, you could display the data on there: As you slowly press the throttle pedal from off to full to the floor, you should see a smooth increase in readings.

[hmk]

Problem seems to be fixed.

Passed Car to Electrical/Diagnostic Engineer in Dewsbury that came highly recomended.

He rang me this morning to collect car as it was cured.

There was corrosion in the wiring loom on the connectors which was causing signal issues from ecu and auto gearbox.

have driven car around and it seems fine.

no doubt will know over the next few days.

hopefully its all sorted.

thank you for your input and help.

hmk,

again thank you.

[Rich]

I'd like to state that I already said that. 

Happy it is fixed.