I have a 2007 FEH with just over 90,000 miles. Up until recently I have had no issues with the vehicle and average about 33-34 MPG. Recently, I have encountered an issue with the gas to electric/hybrid transition. After driving for about 30-40 min, it will not go into the hybrid mode. The gas engine continues to run. Has happened while sitting in stop and go traffic on the freeway and while sitting at stop lights/drive throughs. All times have been in fairly mild to cool temperature ranges with no a/c or defrost on.

Anybody have an suggestions?

Thanks,
Jeff

 

By cool what temperatures at night exactly? NiMh batteries have some limits near and below freezing. They may also take up to a hour to warm up depending on initial cold starting temperature and your specific driving schedule. The engine and trans will warm up much faster.

So just near and below freezing (32F) your hybrid will behave remarkably different. It is still a hybrid. The battery is still providing power and Re-Gen braking is still charging it. Just at much lower and limited power levels. Once the NiMh warms up to 70 to 80F it is ready for full power operation. Battery temperatures below 50F will force the hybrid system into prolonged engine running modes.

Just because the IC engine won't shut off yet does not take away hybrid operation.

So how cold and how long parked in that cold? These batteries are also slow to cool. They may take 18 hours parked to reach outside air temp.

 

Temps have been well above freezing. In fact the hybrid mode actually works initially and then after driving it for the 30-40 minutes, this has been both 30-40 min of freeway driving and 30-40 min of normal city driving, the vehicle will not transition from the IC engine to the electric engine. Battery charge looks full on the dash display.

Thanks,
Jeff

 

If it is making it into electric (hybrid) mode initially and then later it won't, then it comes back, there must be something else. Some other system that will not turn on a light but stops the electric mode.

Can you get it scanned for codes?

 

Sounds like the ME coolant pump is not working and things are getting to hot for EV after awhile.

GaryG

 

Sounds like to me the identical problem I had at 33K miles on my 07 last summer. It gave no other warnings to me, other than it did what you are describing. On the first start of the day, the engine would run until it was warmed up as normal (a couple of minutes), and then it would go into electric mode as normal (for the next 15 minutes of driving, or so, which was during the summer, so probably why yours lasts longer), again as normal. However, after a little more driving, it would NOT go into electric only mode, EVER, until the engine was shut down manually and the car cooled (several hours). It seemed to me that it was a battery cooling issue. There were no driver malfunction messages displayed. There was a much louder sound of air in the back when the vehicle wouldn’t go into electric mode, which had never been that loud before.

Had to take it to the dealer. The first thing they made sure was that the battery filter was clean, which it was. They hooked it up to their computer and it was a problem with the $7K battery pack that the dealer had to replace, fortunately for me, for free. The dealer writeup was that it was a short in the battery. It was making a bunch of extra noise (fan noise) back there, so maybe you could listen to yours for that clue. You should still be within warranty as well, which could be a great blessing to get a new battery at 90K. Don't hesitate to take it in.

 

wow.......

 

I would be curious to know what you find out on this problem as I'm experiencing a similar problem intermittently with my '05 just recently. I don't know if it's a coincidence or not but I just recently replaced the thermostat because the original seemed to be not allowing the engine to get above 170 degrees. The new thermostat definitely operates at a higher range of 175-190. Almost immediately after replacing the thermostat I started having this intermittent problem with hybrid mode. It isn't happening every day, but something is up. If it is a battery issue, I'll be looking for a salvaged used battery. They seem to be available for under $1000 via salvage yards. I would definitely want to know if that is actually the problem before pulling the trigger on that fix though.

2005 FEH with 115,550 mi. Averaging 29 - 31 mixed driving MPG

 

What piece of hardware are you using to report on the engine temperature of 175-190-Scanguage II?

 

Yes - I should have mentioned that. I have a Scangauge II hooked up all the time mounted just above my rear view mirror.