Skoda Fabia mk2 1.9TDI High Revs

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Hi.

Car: Skoda Fabia Mk2 (5J)
Engine Code: BSW

I am currently having some problems with high revs on start up and hope that someone might be able to help.
Previously the engine would start at 2000rpm and go very unsteady when cold – tapping the throttle once would stable the revs around 900rpm. I replaced the coolant temperature sensor and haven’t seen this exact issue since.

Now when I start the engine the revs sometimes go to 1000-1400rpm and sometimes is starts in “normal” condition around 900rpm. The high revs seem to be random i.e. it doesn’t depend on the ambient temperature or engine temperature. It doesn’t help to turn off the engine and turn it on again.

I’m not sure if this could be related to the previously “cold start (2000rpm) problem”. Also I’m almost certain that the “random rpm problem” have been present all along, but have gone unnoticed because of the “cold start problem”.

I have been scouting the internet for a solution and among other possible solutions I read that the fuel shut-off solenoid on the injection pump could cause something like this. Not sure if this could be related to the issue.

Any help is appreciated.
 
Last edited:

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
He's referring to DTC's(digital trouble codes). Does your CEL(check engine light) turn on when this occurs? Any unusual oil consumption?
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
He's referring to DTC's(digital trouble codes). Does your CEL(check engine light) turn on when this occurs? Any unusual oil consumption?
Ooh, my bad :).

I haven't done a diagnostic read out yet -- I ordered a OBD2 but haven't received it yet.

No engine or indication light's.
I did check on the oil level in December and no unusual consumption.
I will check again to verify.
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Update (just in case anyone is experiencing something similar).

Did a DTC readout and got a "P2100 – Throttle actuator control (TAC) motor – open circuit" code.

Going to remove the EGR valve and intake manifold for a cleaning.
Also, I think the high and uneven rpm at startup during freezing temperatures is due to a faulty glow plug. So I will be replacing those.
 

Carlos_TJ

Veteran Member
Joined
Aug 3, 2014
Location
Tijuana Mexico
TDI
2009 Bora (BXE PD)
Sounds like your accelerator pedal is erratic at best and the ECU doing what is supposed to do when there is no accel pedal signal: increase rpms so you can get home (albeit slowly)
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
If you clean your intake when you take it OFF the car, make sure you also get all the excess oil out of the intercooler. Trust me on this one.
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
As Carlos mentioned, it's almost certainly your accel pedal (and what a coincidence, that's a part that the DTC is complaining about!).

Clogged intake and EGR aren't likely going to cause high revs. I'm guessing this is a PD engine, in which case such clogging is even less likely (compared to VE engines).
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Sorry for not responding sooner. Apparently the email notification's from tdiclub went somewhere else than my inbox.

Thank you for your replies. I will look into the APPS.
The reason why i did not check this before were due to the P2100 symptoms list from "www.yourmechanic.com", which were different from what I was experiencing.

I did remove the EGR valve, Throttle valve, and Intake manifold for a cleaning. But everything were almost clean, so i just used a bit of EGR cleaner and mounted everything back into place. Also did a 750ml turbo + DPF clean-out -- lots of smoke.
The engine ran more silent and smoother after the clean-out, but the idle revs were the same.

I have been checking a lot of different stuff trying to solve this problem, but may not be relevant if it turns out to be the APPS.

Any advice regarding the APPS replacement is greatly appreciated.
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Try the ross-tech wiki site for DTC interpretations. You will see that this listing has more to do with our TDI's.
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Try the ross-tech wiki site for DTC interpretations. You will see that this listing has more to do with our TDI's.
Thank you for the link. I did already look at ross-tech, but I can't find any information on the P2100/Throttle fault.
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
UPDATE:

I removed the gas pedal and took it apart.
Everything looked new and working. I used a bit of contact cleaner on the resistor PCB and the connectors. I also had a look at the spring and gave it some grease.

When I took it apart I noticed that the plastic housing around the throttle arm can be adjusted a bit. Adjusting the plastic housing from the inner position to the outer position will adjust the idle revs from approx 850rpm to 1500rpm.
I wonder if over time the screws and plastic have loosened and resulted in higher revs after some driving.

I tightened the plastic housing in the 850rpm idle position and put the gas pedal back in place. It's now 3 days ago and I haven't seen the idle revs going to 1100-1200rmp since.

However, when i cleaned the connectors from the throttle arm to the resistor pcb, some of the very very very small connector-arms got rotated :). I tried to but them back into place, but for me it was impossible. The gas response feel a bit weird, slow and lacking power. When i log the throttle position from OBD2 with Torque i get max 80%.

I'm not going to use more time fixing the old gas pedal, so I ordered a new(used) one.
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Thank you for the update. I would leave the glow plugs alone since there is no related fault codes.
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Thank you for the update. I would leave the glow plugs alone since there is no related fault codes.
Alright. I haven't replaced the glow plugs yet. The very high and uneven idle revs stopped after the increase in outside temperature, so i guess it will be forgotten until next winter :).

Yesterday I went for a drive to check the throttle position. I compared full gas pedal throttle to increasing the cruise control in 5th gear and using the cruise control gave the highest acceleration/torque.

So I definitely think that adjusting the throttle arm reduced the max throttle position. But since the adjustment I haven't seen the high idle problem, so I'm positive that the throttle position sensor is the problem.

Initially I thought the error code were pointing to the throttle body, which was why i started out by cleaning that, the EGR and the intake.
 

lthomsen

Member
Joined
Jan 30, 2018
Location
Denmark
TDI
Skoda Fabia Mk1(6Y5) 1.9TDI & Skoda Fabia Mk2(5J) 1.9TDI
Update:

I installed the new gas pedal yesterday -- https://imgur.com/a/ikOgK (left pedal).

Everything feels improved. More acceleration/torque. Torque reads 100% acceleration now. No high idle issues so far. So definitely something went wrong when i thought it was a good idea to have a look inside :).
After installing the new pedal, I also realized that the old one was close to non-responsive between 0-60% throttle.

As you can see on the pictures, the new gas pedal came with a plastic adjusting tool. The plastic tool can adjust the plastic housing for the throttle arm, thus adjusting the rpm offset between 0-100% throttle.
 
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