Horrible mpg on x35i

[sirajkas]

So this morning it was showing 8.9 mpg. Bmw service said they can't do anything about the poor mpg. They said "the engine is under powered for over 5k pounds truck and you have 21" wheels". why make those engines then?

Any advice on how I can get someone to look into this issue?

[opasha]

For those of you who cannot see his picture. I have flipped it:

[nyquistcondition]

First question - are you really getting 10Mpg or is it an instrumentation issue?

[hyde]

I don't think this is accurate.
I see you have half tank of gas left and the indicator is over 200miles.
This means you are getting at least 400 miles to the tank, which would mean approx 20mpg. Time to reset the on-board consumption stats and try again.

[sirajkas]

Last time few times I calculated, it was close to 12-13 but it's getting worst. Filled up the tank on Sunday and 90-100 miles later, it's down to half tank.

[chrisny]

That's the worst excuse I've ever heard. Find another service dept...

We get 16 and it is almost 100% local driving, 5 miles and under. I would imagine I would have to floor it non stop every time to get down to 10.

[opasha]

Originally Posted by chrisny

That's the worst excuse I've ever heard. Find another service dept...

We get 16 and it is almost 100% local driving, 5 miles and under. I would imagine I would have to floor it non stop every time to get down to 10.

Agreed. That's what I told Siraj as well. That service department is making excuses. It very well could be a damaged tank. He did nothing to it. His issue was actually posted a long time ago, BMW "corrected" it and gave it back to him, but he's still having issues. I feel like this dealer is not trying to take responsibility for something they may have screwed up. It could also be in the realm of a lemon if it is not something fixable and they won't own up to it. No 35 model should be that low. I have a 50i and I'm getting 14-17 mpg with my RaceChip.

[sirajkas]

Yes, few months ago I had fuel contamination issue. The gas station had a issue with the pump and it actually put diesel in the tank. The gas station's insurance adjuster back then felt there was no need to change the injectors even though bmw was recommending it.
I asked the service dept to check if the poor mpg is due to the fuel contamination issue from few months ago and they say it's not.

[42pilot]

You need to take your car to another BMW dealer. If I were you, I would also call customer care at BMW US headquarters in NJ (look for the number on line). I used this number to get my dealer's attention on a couple of issues. The headquarters listens to complaints on dealers and might be able to tell you who their best rated dealer is in your area.

Don't get too hung up on the dash indicator - it's more there for reference than accuracy.

When you take it to the dealer, tell them you are experiencing significantly lower than expected fuel consumption and ask them to scan, or re-flash the software. They will balk at re-flashing since this can take up to 4 hours. There are so many sensors on your (our) car, that, if any of them are off by even .25 volt (for example) back to the ECU, it could put your engine into a safe mode which would reduce performance and could increase consumption. You could also have a faulty injector that is flowing too much fuel, but not throwing a code. BMW software can electronically measure the flow rate of each injector, and looking at the exhaust gas temp sensor at the same time will confirm if they are working correctly. This is all part of the scanning software BMW dealers have. The equipment is expensive and they need to charge for it. Your job is to get them to do it under warranty. Also, poor mileage can also be traced back to a bad battery, believe it or not. The ECU requires a minimum amount of volt/amps work correctly. So you see, there is a lot that can influence the performance of your car.

The point is, there is a lot the dealer can do to diagnose your problem. Get the service manager and start a rational conversation, letting him/her know, there is a problem and you are willing to work with them to fix it.


Good luck.

[42pilot]

Originally Posted by sirajkas

Yes, few months ago I had fuel contamination issue. The gas station had a issue with the pump and it actually put diesel in the tank. The gas station's insurance adjuster back then felt there was no need to change the injectors even though bmw was recommending it.
I asked the service dept to check if the poor mpg is due to the fuel contamination issue from few months ago and they say it's not.

OMG...

This is where you need to start. Diesel is ok running through your gas car and shouldn't affect the injectors, but enough of it could damage your O2 sensors which could affect how the ECU manages your engine. The problem I would have is other contaminants in the fuel. I wouldn't think dirt, but more like other possible chemicals that could damage your injectors.

I would bet you lunch this is the root of the problem...

[sirajkas]

Originally Posted by 42pilot

OMG...

This is where you need to start. Diesel is ok running through your gas car and shouldn't affect the injectors, but enough of it could damage your O2 sensors which could affect how the ECU manages your engine. The problem I would have is other contaminants in the fuel. I wouldn't think dirt, but more like other possible chemicals that could damage your injectors.

I would bet you lunch this is the root of the problem...

I have a feeling that's causing it as well. I went to the service center twice to convince them to look into it and they say the injectors are fine. May be they are reluctant because they don't want to deal with the insurance.

[42pilot]

You need to be clear who will pay for their time. I would bet the shop time is between $95 - $125 per hour. They will do it as long as they know who is paying.

You need to get that fixed before other problems pop up - like burned pistons/valves, sensor replacement, etc...

[opasha]

Originally Posted by 42pilot

You need to be clear who will pay for their time. I would bet the shop time is between $95 - $125 per hour. They will do it as long as they know who is paying.

You need to get that fixed before other problems pop up - like burned pistons/valves, sensor replacement, etc...

That's exactly what I told him, which is why he posted in here for advice like yours - thanks for taking the time to guide him. No point in listening to his service department's advice. If gone ignored, he could face much greater problems esp after warranty. Also, safety is a huge concern if anything gets damaged.

[NPickles]

Originally Posted by sirajkas

Yes, few months ago I had fuel contamination issue. The gas station had a issue with the pump and it actually put diesel in the tank. The gas station's insurance adjuster back then felt there was no need to change the injectors even though bmw was recommending it.
I asked the service dept to check if the poor mpg is due to the fuel contamination issue from few months ago and they say it's not.

Again, I would think that this sounds like the root cause of your issues.

There are so many sensors in any modern engine that could be damaged if you end up with diesel in a petrol engine because it isn't supposed to be there and vice versa with petrol in a diesel engine.

What was your MPG like before the fuel contamination issue? Significantly better than 10-12?

It must be time to go back to the insurance adjuster and tell them what's happening, especially if BMW recommended changing the injectors and they declined to pay for it to be done.

I could see BMW not warranting it if it turned out to be sensor issues that may have been damaged by the diesel contamination, but then if it isn't that then it must be a warranty issue so either the insurance company will be paying or BMW will be paying for the work so they should just get on with it.

And has been said already, it may be time to get another dealer.

[NPickles]

When you run the car after it has warmed up does the exhaust smell really 'fuelly' like it is being overfuelled resulting in unburnt fuel in the exhaust?

[sirajkas]

Originally Posted by NPickles

When you run the car after it has warmed up does the exhaust smell really 'fuelly' like it is being overfuelled resulting in unburnt fuel in the exhaust?

Checked this morning and yes I think it does.

[sirajkas]

Originally Posted by NPickles

Again, I would think that this sounds like the root cause of your issues.

There are so many sensors in any modern engine that could be damaged if you end up with diesel in a petrol engine because it isn't supposed to be there and vice versa with petrol in a diesel engine.

What was your MPG like before the fuel contamination issue? Significantly better than 10-12?

It must be time to go back to the insurance adjuster and tell them what's happening, especially if BMW recommended changing the injectors and they declined to pay for it to be done.

I could see BMW not warranting it if it turned out to be sensor issues that may have been damaged by the diesel contamination, but then if it isn't that then it must be a warranty issue so either the insurance company will be paying or BMW will be paying for the work so they should just get on with it.

And has been said already, it may be time to get another dealer.

I never paid attention to mpg before the issue but I'm pretty sure it was normal. I wasn't making that much frequent trips to the gas station.

[sirajkas]

Originally Posted by opasha

That's exactly what I told him, which is why he posted in here for advice like yours - thanks for taking the time to guide him. No point in listening to his service department's advice. If gone ignored, he could face much greater problems esp after warranty. Also, safety is a huge concern if anything gets damaged.

Thanks Omar and 42pilot.. I'm planning to take it to another dealer on Monday.

[Ray knight]

Thats not right! My 50i got 14mpg avg, my F15 M5 which i drive HARD gets 13mpg and my x35d gets 28mpg avg. either the computer is reading wrong or you have a fueling issue. You are using premium fuel right?

[opasha]

Originally Posted by sirajkas

Thanks Omar and 42pilot.. I'm planning to take it to another dealer on Monday.

Good, keep us all posted, my friend .

[stewy604]

Sounds like the root of it could be from the diesel being run through. Hindsight is always 20/20, but if it was me, I wouldn't have even started the engine...towed it to the dealer and had the tank drained and flushed. As said above, there are many factors that will contribute to the proper function or dysfunction of your engine, sensors being key. 10 mpg is insanely low...I could get better mileage than that in my F-350 when towing 15,000 lbs.