Engine over-revving when dropping out of hybrid battery use

[Tim79]

Hi all, interesting engine behaviour during a long drive to Cornwall yesterday. Car is a ‘22 plate plug-in ultimate, brand new in may this year, now done about 4,500 miles. I set off from Hampshire yesterday afternoon with a full battery but obviously after about 35 miles that had drained itself so I was left with a combination of the small hybrid battery and petrol! About 30 mins east of Exeter, having been driving about an hour and a half, the hybrid battery and engine behaving “normally” up to this point, switching between battery and petrol almost imperceptibly, I noticed that as the hybrid battery drained itself after about half a mile of driving, the moment the petrol engine kicked in it started revving hugely and the car seemed like it was stuck in gear. As soon as a downhill bit of road appeared then as you would expect the engine stopped and the hybrid drive kicked back in, until it exhausted itself and then the engine came back on with massive revs. And repeat every couple of minutes until we got to Exeter and stopped for a comfort break. Engine off, car locked etc for 20 mins and then off we went again. Car behaving absolutely normal again, as though the pause at Exeter had reset something until about another hour had passed. Now by Bodmin moor, when the same started happening again, dropping out of hybrid battery drive into massive revving engine and refusal to change gear. For some reason I had the presence of mind at that point to try to force the car to change gear and the paddles did allow that, for about a mile when the car then automatically reverted to “D” and then began revving like mad again and sticking in a gear. I should have said, thru all of this no warning lights or messages, no odd smells or smoke, nothing visual at all to suggest anything wrong, apart from what I could hear going on under the bonnet. I called the AA out this morning who plugged into the Ecu only to find no warning codes or faults stored. So really weird - anyone else heard of this type of issue? Thanks, Tim .

[Deleted User 487]

Where you driving up inclines/hills? As the HEV does tend to hold onto the current gear before (eventually) changing up. The result is that it reaches around 3000rpm, and begins to sound quite harsh!

[Tim79]

No, flat gradient, perhaps v slight incline at most and light throttle. I reckon revs well north of 3k too, must have been 5 at least, though obviously hard to tell without any sort of rev counter in that model. Loud and high enough to make me come off the throttle though for fear of rods through the bonnet!

[Tim79]

Maybe some sort of particulate filter regen? Just can’t work out why, as thought they only did that when clogged up with town driving when we’d been at 60-70 on the motorway for hours!

[roadster]

No, flat gradient, perhaps v slight incline at most and light throttle. I reckon revs well north of 3k too, must have been 5 at least, though obviously hard to tell without any sort of rev counter in that model. Loud and high enough to make me come off the throttle though for fear of rods through the bonnet!

Their is a rev counter available. I mostly use the cube style panel display so that I can see when the engine starts up. I also select the engine temperature display in the information central portion because I try not to over stress the engine when its cold. The engine is occasionally loud a rattly when it first cuts in under load and this has been noted by myself and others in previous posts. The engine does warm up quickly and tends to stay at a reasonable operating temperature thereafter.

[Chris003]

Hi all, interesting engine behaviour during a long drive to Cornwall yesterday. Car is a ‘22 plate plug-in ultimate, brand new in may this year, now done about 4,500 miles. I set off from Hampshire yesterday afternoon with a full battery but obviously after about 35 miles that had drained itself so I was left with a combination of the small hybrid battery and petrol! About 30 mins east of Exeter, having been driving about an hour and a half, the hybrid battery and engine behaving “normally” up to this point, switching between battery and petrol almost imperceptibly, I noticed that as the hybrid battery drained itself after about half a mile of driving, the moment the petrol engine kicked in it started revving hugely and the car seemed like it was stuck in gear. As soon as a downhill bit of road appeared then as you would expect the engine stopped and the hybrid drive kicked back in, until it exhausted itself and then the engine came back on with massive revs. And repeat every couple of minutes until we got to Exeter and stopped for a comfort break. Engine off, car locked etc for 20 mins and then off we went again. Car behaving absolutely normal again, as though the pause at Exeter had reset something until about another hour had passed. Now by Bodmin moor, when the same started happening again, dropping out of hybrid battery drive into massive revving engine and refusal to change gear. For some reason I had the presence of mind at that point to try to force the car to change gear and the paddles did allow that, for about a mile when the car then automatically reverted to “D” and then began revving like mad again and sticking in a gear. I should have said, thru all of this no warning lights or messages, no odd smells or smoke, nothing visual at all to suggest anything wrong, apart from what I could hear going on under the bonnet. I called the AA out this morning who plugged into the Ecu only to find no warning codes or faults stored. So really weird - anyone else heard of this type of issue? Thanks, Tim .

Hello,

Just had the exact same experience on a longish journey.
Dropping out of EV mode automatically, the revs go direct to 3000, and as I accelerate it does not change gear when expected, so I have to use the paddle.
If I lift the accelerator it goes to EV again, then with just a touch of accelerator again, it jumps exactly to 3000 revs again.
No extended battery at this time, so just running in HEV mode.

Did anyone solve the problem? Or have you not encountered it since?

Ultimate plug-in.

Regards
Chris

[roadster]

The engine is surprisingly noisy when it does this but its not exactly over-reving at 3000. Using the central display in its cube layout and also monitoring engine temperature from the information option it should be possible to see if the noise is worse when the engine is cold and exactly what rpm is reached. This may give you evidence to pursue with the dealer if you are concerned. My car, in ECO mode, does this very rarely and I try to avoid big throttle openings until it is warmed up..

[tuscon-ie]

Noticed this high rev issue also on 2023 PHEV 4,400 km ,. Seems to happen when battery is depleted and running in petrol mode. Any incline from low speed (1st, 2nd gears) it seems to delay going into next gear and screams high rev. Taking foot off accelerator and back on sometimes shifts the gear but not always. Its very noticeable and does not feel right. Anyone get more info from dealer or get resolution to their issue?

[ntaylo]

I wanted to add my own recent, similar experience - Hyundai Tucson PHEV Premium, 21 plate with 20,000 miles on clock.

This issue has occurred twice now, in both cases while making long-ish journeys in Hybrid (HEV) engine mode. First time the EV battery was nearly fully charged; second time the EV battery had around 7 miles of charge remaining. As with other posters, the ICE suddenly started to exhibit gross over-revving due to operating in a lower than normal gear: typical revs were 4,000rpm at 55mph or 4,500rpm at 60mph. Flicking the paddle control allowed the gear to change up (from third apparently) and revs to drop temporarily but then the vehicle dropped gear again and the revs surged. The hybrid system continued to revert to EV mode when the accelerator was eased but the over-revving condition recurred as soon as the ICE kicked back in.

On both occasions, this situation continued until I pulled over, stopped the engine, left it for a couple of minutes before restarting and then continuing on my way with engine behaviour reverting back to normal.

No warning lights appeared on the dash during these episodes. Happening once I may have overlooked it as a peculiarity but now it has happened again I'm concerned and have booked the car into the main dealer for diagnostic checks. Not sure what they will find, if anything, and unfortunately the earliest it could be scheduled was over a month away.

[PhilHornby]

the ICE suddenly started to exhibit gross over-revving due to operating in a lower than normal gear

Gross over-revving is not possible in this vehicle - it has a computer-controlled automatic gearbox!
If you think you can do better than Hyundai's Automotive & Software Engineers, put the car in "Sport" and use the paddles. It still won't let you grossly over (or under) rev the engine though...

Before overtaking, I often put the car in "Sport" and pull the paddle for a downshift. If such a downshift would be inappropriate, it ignores me. During the overtake - despite being in 'manual' - the car will still upshift as and when peak power/the rev limiter is reached. If you try to come to a stop with the car in 6th, you'll see it shuffling down the box, as you decelerate.

In normal ECO mode driving, the fact that the software uses more revs than you would, just illustrates what you've been doing wrong all these years