[Titchthephot]

I have the new i30 (diesel manual) and I have noticed that at low speed (under  30) and usually in 3rd gear, the car wants to drive itself. It accelerates a bit (or more than likely..doesn't de-accelerate) and carries on driving at 30mph -even if I take my foot off the accelerator. If I change gear to second there is no high revving - so I can assume the cable isn't sticking. It is not a major problem (if I need to slow down the clever Hyundai people installed a thing called a 'brake'!!) but I just wondered if this was an electronic acceleration problem or is it just the way the gearing and drive of the i30 work? The car doesn't go out of control but I would have thought that if you take your foot of the pedal the car should slow to a stop. Any thoughts?

[Shambles]

It's a feature !!

[Doggie 1]

It's because it's a diesel and the speed isn't matched to the gear and is quite normal.
Just the torque of the diesel engine IMO.

[Dazzler]

I think you are describing the "anti-stall" function of the diesel.. The same thing that will let you pull away from a stop in 1st or 2nd without any throttle...

The revs are lower limited to about 1100RPM while driving. This corresponds to about 30KMH as you discovered in 3rd. Quite alarming until you work it out. There is still a wack of torque and I reckon it could be limited to idle speed instead but it's probably determined by emissions more than necessity.

[AlanHo]

I think you are describing the "anti-stall" function of the diesel.. The same thing that will let you pull away from a stop in 1st or 2nd without any throttle...

This is not the case with my 2012 car - the gearing is too high and it will stall.

However once on the move you can lift off the throttle and it will move along nicely at idling revs - no problem.

[Doggie 1]

 

Same on my GD too, as opposed to the FD.

Way back, many moons ago, this was discussed.  As Dazzler said, it is the antistall feature of the diesel.  The ECU says, "I'm going slow here and I need to increase speed slightly or I am going to stall".  I notice it most in 1st and 2nd when idling along in slow traffic or a car park.

Another interesting aspect is the extra boost applied when the aircon cuts in.  Unlike some petrol cars, where extra throtle is applied, the CRDi adds about 2psi of boost to compensate for the aircon compressor load.  I've seen this on the FD using a Scangauge, and can feel it when traveling at around 80-90km on flat road, when the power surge is quite noticeable.

[rustynutz]

Another interesting aspect is the extra boost applied when the aircon cuts in.  Unlike some petrol cars, where extra throtle is applied, the CRDi adds about 2psi of boost to compensate for the aircon compressor load.  I've seen this on the FD using a Scangauge, and can feel it when traveling at around 80-90km on flat road, when the power surge is quite noticeable.

I've noticed that myself....
I thought this can't be right, we're supposed to be losing power when we flick the aircon on, not gaining power.... 

[Titchthephot]

Thanks for all your replies. At least I know now and it's nothing to worry about.

[peon2t]

I have the new i30 (diesel manual) and I have noticed that at low speed (under  30) and usually in 3rd gear, the car wants to drive itself. It accelerates a bit (or more than likely..doesn't de-accelerate) and carries on driving at 30mph -even if I take my foot off the accelerator.

As already has been stated: This is perfectly normal. It's been like this in every diesel car I ever drove (which aren't that many, but still...)

This is not the case with my 2012 car - the gearing is too high and it will stall.

I'm surprised that you say this. I can drive away with zero throttle in first gear without any problems.

Probably also in second gear but I'm not sure if I ever tried it in the i30 (but I did in the Golf I drove before and there it was no problem when engaging the clutch slowly)

[HarTloT]

I also have similar problem. And drove a lot of different car brands with diesel engine. None of them had this problem. If it is a problem at Hyundai. Also noticed , when this happens, and I press accelerator pedal, engine starts to shake until it reach higher speed. Went to mechanics and connected it to test. Gave me P2212 error. Something with Throttle Actuator Control System. Don't know is that error connected to problem. I'll try to find out.

[Lakes]

I also have similar problem. And drove a lot of different car brands with diesel engine. None of them had this problem. If it is a problem at Hyundai. Also noticed , when this happens, and I press accelerator pedal, engine starts to shake until it reach higher speed. Went to mechanics and connected it to test. Gave me P2212 error. Something with Throttle Actuator Control System. Don't know is that error connected to problem. I'll try to find out.

That happened or was just a quirk of the first CRDi 1.6 5 speed, does not happen with the newer U2 1.6 CRDi 6 speed. i have had two FD Diesel's 1st one was 08 build it did what you describe sometimes. mostly in 3rd gear, the one i have now is 11 build u2 CRDi 6 speed can drive in any gear from low rev it won't do that, but other than that & a smoother delivery on Tq curve performs about the same.
still has the speed up on it's own feature but it's not as aggressive as the 08 speed up was.

[HarTloT]

I also have similar problem. And drove a lot of different car brands with diesel engine. None of them had this problem. If it is a problem at Hyundai. Also noticed , when this happens, and I press accelerator pedal, engine starts to shake until it reach higher speed. Went to mechanics and connected it to test. Gave me P2212 error. Something with Throttle Actuator Control System. Don't know is that error connected to problem. I'll try to find out.

That happened or was just a quirk of the first CRDi 1.6 5 speed, does not happen with the newer U2 1.6 CRDi 6 speed. i have had two FD Diesel's 1st one was 08 build it did what you describe sometimes. mostly in 3rd gear, the one i have now is 11 build u2 CRDi 6 speed can drive in any gear from low rev it won't do that, but other than that & a smoother delivery on Tq curve performs about the same.
still has the speed up on it's own feature but it's not as aggressive as the 08 speed up was.

Thanks for reply. Well I guess I'll just have to accept that. No big deal. It isn't related with error P2112. Problem was unplugged cable to TAC probably during regular service.