E36 328is Crazy high fuel consumption

[OptiManc]

seismic22 said:

The "laboured" like performance you describe is exactly like what im experiencing in my latest 323i. Ive just changed the CAT for another second hand item but that didnt work and shes showing no codes, has had a new crank sensor and the cam sensor is definitely ok. I managed to pick up a cheap CCV valve so im going to try that over the weekend and have a thorough look for air leaks.

Sorry you're having similar issues @seismic22, are you suffering with high fuel consumption too?

I havent consider the CCV valve, could you report back over the weekend with results?

[OptiManc]

seismic22 said:

I will report back, I have Friday off work so will be tackling it then!

Yes Fuel consumption is very poor, I dont think as bad as you though, I cant get 300 miles out of a full tank but can get fairly close.

Cool thanks. I can get near 300, say around 245-265 on the motorway with no stops and smooth driving. But around town its shocking!

Looking forward to your results with bated breath!

[OptiManc]

seismic22 said:

Im sorry to say that its made no difference.

I changed the CCV valve and cleaned the breather pipe and the ccv to dipstick pipe out.

My next thing to look at is the brake booster non return valve coming out the manifold. I was driving rather fast late at night on the motorway the other day and after a prolonged period like this performance suddenly picked up briefly and with it the brake pedal became firmer. It soon went again though so for the sake of a second hand one down the scrappy I'm going to give it a go. Also going to change the gearbox oil and fuel filter but I cant imagine its either one of these

Oh..also i'm currently seeing 23mpg average (worked out from brim to brim test), I know this could be worse but it could also be alot better!

Edited by seismic22 on Saturday 15th December 10:15

Thanks for the update seismic22, sorry it didnt work for you. Thats an interesting suggestion with the breaks; i'm sure my breaks have been checked and OK'd. But I've had the same experience as you, suddenly performance improves for a moment, its prompt, sharp and effortless then goes back to laboured and thirsty.

I've been seriously considering changing the Transmission ECU; I have one from my old '92 E36 320i, if the part numbers are the same i'll swap them out else find another. I have been advised here to have the ECU checked but I cant anyone who is willing to do it or think its worth doing.

Please keep us posted on your results!

[OptiManc]

ian_touring said:

Hope you manage to fix this, OP. When my 323 touring thermostat failed in the open position, I was getting 17mpg around town. Depressing, paying the price of, say, M3 performance, without any of the benefits.

Thanks! Tell me about it!

[OptiManc]

Hi
Unfortunately no, its still the same - sorry you're experiencing the same problems.

I haven't checked the fuel pressure no, its going in for a service at some point I'll remember to get them to check it. In the hot weather mine seems to get worse and it has been overheating, I think the wax coupling is worn, so perhaps that's a cause of my poor fuel consumption. Worth checking on yours?

[OptiManc]

...and here it is. Yep, already changed it, in fact I think it was one of the first things I changed myself after the multiple workshop visits.

[OptiManc]

Rollcage said:

As I posted about a year ago, it need proper diagnostic evaluation. With all the will in the world, randomly changing components because some chaps off the internet said so won't do you any favours. Performed by a competent operator, it's worthwhile doing, and will save you money.

I have had it diagnosed 3 times from two places, one being BM Tech in Manchester and another a mobile diagnostic guy. At the first scan it was the MAF, changed that but no change improvement in drive/consumption. After that no reported errors, even risked a ROM flash. I am always told though such and such..."don't always show up on the scanner"

[OptiManc]

Rollcage said:

Fault code readers will be next to useless in this situation.

IMHO it needs a lappy and someone in the passenger seat while you drive, while monitoring parameters like lambda readings, MAF readings, fuel pressure, throttle opening etc.

There is plenty of software that will chuck out the data, but interpreting it correctly is another matter.

Thanks, I guess once I have the data I can ask the interweb to give me lowdown. Will seriously look into getting the cables and software, and a ye olde laptop with serial connection too.

[OptiManc]

Thanks for that, I am going to look for software and cables this weekend, I think there's a link in the thread for cables.

Yes oil level and oil are fine - almost new after >5000 miles.

[OptiManc]

Sorry for not updating, I didn't get the cables in the end but took it to a recommended garage near by who took the car in for three days and were able to diagnose and test a whole host of areas, it was a while back so cant remember the exact details now. Cost me a packet though! In the end they change a part on the fuel line which has a slight crack but didn't show signs of leakage but couldn't be sure as it may have evaporated under the conditions - it didn't make a difference.

I sold the in November a couple days before my birthday, it was sent to Poland for parts.

[OptiManc]

The Nur said:

I would't blame him if he decided to save some money and poured a couple of gallons over the car

That or sell it, which I did but I couldn't sell it to someone else to drive - its my car! So when a buyer for parts came a long I let it go.