Running really rich

[Sasquatch]

Hi Guys,

Been noticing my 01 is running pretty rich and the mileage is really suffering lately.  I have not really had a chance to look her over yet, but below are the details that I have.

2001 Tiger 955i, 53,000 miles
Triumph off road tune, custom aftermarket exhaust
I did check all sensors are plugged in and making good connection
New plugs, clean air filter.

Runs awesome, just VERY rich.  Stinky exhaust rich.

Any ideas?

[Hassan]

I got same problem with my 1999 885i,

Pull of the return hose of the tank,if the fuel comes with a bit of pressure when you're pullin' the hose...

U got an inoperative fuel pump regulator...

[Hassan]

If you got an inoperative fuel pump regulator;

Fuel can't get back to the gastank and gets off the exhoust with a bad,bad smell...

[Bixxer Bob]

Hassan, we've been swapping PMs for a while, but it's only reading this did I fully understand what you are saying.  If the fuel rail pressure is too high the injectors are pushing in too much fuel and so it'll  be rich and also in your case would explain the very high tickover.

Sorry for the momentary highjack Sas, but I think he's onto something.  Sadly, I've no experience of the early girly fuel pressure sensor to comment on what's wrong or how to fix.

[Sasquatch]

Fuel pressure regulator, that is something to check.  I will get in the service manual and figure out the testing procedure.  Should be able to rig up a test fitting, I have a fuel pressure tester for fuel injected cars already.

[Bixxer Bob]

That'll be a step forward Sas as we seem to have a sudden spat of these and it's hard trying to workout what's wrong from a 1000 miles away.  

If you come up with one, a good DIY test would be a godsend  

[Sasquatch]

Question, with the Triumph off road tune, does it still use the O2 sensor?  (wondering if I have a faulty O2)

[Bixxer Bob]

Yes it does.  The O2 is narrow band so will only give three indications:

Around 0.1 volt = lean

0.45 volts = correct mix

Around 0.9 volts = rich

[Sasquatch]

Watching the O2 on the scanner it is bouncing between .1 and .86 volts.  But I checked my fuel pressure and it holds steady at between 44 and 46psi, so that is within specs.

I need to run a can of injector cleaner through it "just because" and see what that does.

I also ordered the cable so I can play with the tune edit software that is talked about so much here.  Hoping to get my mileage back up where it should be.

[Bixxer Bob]

Bouncing is normal, it's a dumb animal; it only knows rich or weak, it doesn't know by how much.


Regarding the cable you can use Tune ECU, but I don't think  Tunedit works with a standard cable, I'm pretty sure it only works with Tuneboy's own
(very expensive) cable.  I'd love to be wrong though!!!

If it does work, it'll allow you to read from the ECU, but won't allow you to write.  For that you'll need a software key.  Where Tunedit does score though is that it's much, much easier to use when modifying maps.

[Sasquatch]

I probably have the names of the programs mixed up.  It is the shareware one listed in the stickies.  Hopefully I can use it to lean out the mixture a bit without buying the expensive software and key.

[NKL]

Can an engine temp sensor give a low reading or do they just stop working, only ask because if ECU thinks the engine is colder than it is it will run rich

[Sasquatch]

It sure can.  That is why I really watched the temps on the scanner as my engine warmed up.  Both coolant and intake temps.

[Bixxer Bob]

Spot on!!  The baro sensor (built into the ECU and connected to the airbox via a pipe running down the right side of the subframe) is involved also.  The ECU takes  account of the engine temp to know whether to use the warm-up map or the normal running map.  It then uses the baro reading along with the air temp to work out how much oxygen is in the air and thus how much fuel is needed.  Simple eH???

[NKL]

I guess that's not what's wrong with yours then