running rich bmw 320i e30 1989

[kumar]

Hi Guys, Help !!!!!!
I have BMW 320i e30 m20 1989 with only 51,ooo miles , I have refurbished the fuel tank, new fuel pump, all injectors cleaned and overhauled and I have just fitted fuel pressure regulator the problem is running rich about 8/9 percent co mixture. The mixture adjustment on AFM doesn't bring the co down. It doesn't have a Lamda Sensor.
Thermo Time switch and coolant sensors have been replaced.
Throttle position switch is setup correctly.
starts up fine and idle doesn't surge

[fixedwheelnut]

Hi Guys, Help !!!!!!
I have BMW 320i e30 m20 1989 with only 51,ooo miles , I have refurbished the fuel tank, new fuel pump, all injectors cleaned and overhauled and I have just fitted fuel pressure regulator the problem is running rich about 8/9 percent co mixture. The mixture adjustment on AFM doesn't bring the co down. It doesn't have a Lamda Sensor.
Thermo Time switch and coolant sensors have been replaced.
Throttle position switch is setup correctly.
starts up fine and idle doesn't surge

Check the temperature sensor readings at the ECU as the round plug under the inlet manifold of M20's is a common cause of problems, some info in the Wiki here;
https://www.e30zone.net/e30wiki/index.p ... emp_Sensor

round plug diagram:
https://www.e30zone.net/e30wiki/index.php?title=C191

[kumar]

Many thanks, I will carry out all the checks and update

[kumar]

Hi Guys,
I know it been a quite a while but from my last post, I have done all the recommended the car runs well but checking emissions its running at 4-5 % CO. The AFM adjustment doesn't bring the Co down. There is no vacuum leaks, I have new plug, injectors have been refurbished new fuel pump and fuel tank refurbished. New coolant sensor,TPS adjusted correctly. The AFM is the only area I can think of, Is there any suggestions what to do in AFM (air flow meter

[Tzantushka]

Long shot, but you have the correct FPR?

As the 320i has a different fuel pressure regulator to a 325i. I had to send a few back as I was being sent the wrong parts.
A pressure check on the fuel rail is also good to know what’s happening so you can rule that out.

Plus good to confirm you have the right DME.

[kumar]

Hi
Many thanks for that,
- I will check if the FPR is the correct one
- Check the fuel pressure at the fuel rail
the car starts and runs and as far as I know the DME is original

[kumar]

What is the fuel rail pressure on BMW 320i e30 M20B20 ?

[fixedwheelnut]

What is the fuel rail pressure on BMW 320i e30 M20B20 ?

Courtesy of @Brianmoore reply to a previous thread;
"Fuel pressure on a M20B25, measured by connecting a 'tee' into the supply hose near the fuel rail, should be 3 bar (approx. 45 PSI) above the pressure in the inlet manifold plenum. With the engine idling, and the throttle nearly closed, the pressure in the plenum will be half a bar or so less than air pressure outside of the engine, so your gauge should read around 40 PSI or a bit lower, as you say. If you snap the throttle wide open at low engine revs, the plenum pressure will increase for a short while to approximately outside pressure, so the gauge should blip up to 45 PSI, falling back as the engine revs rise and manifold pressure decreases again.
If you are seeing only 2.2 bar, then the first thing to do is to start clamping off the fuel return hose from the pressure regulator, and see if you can bring the pressure up to 3 bar. If you can, the pressure regulator is faulty, but if you can't, then it is a pump problem or a blockage in the supply line. Moving the pressure gauge to the outlet of the pump at the tank will determine which."

viewtopic.php?t=277368

[Tzantushka]

I think 320i fuel pressure is 2.0 bar (M20B20)
(can't validate quickly...)

test procedure is the same.

[kumar]

Many thanks for the precious note, I have a fuel pressure of 6 bar on idle. I had the fuel tank refurbished with a new fuel pump. Just for test purpose I put the return fuel in separate container then I have 3 bar and the engine runs perfectly normal. It just seem to me there is resistance causing pressure rise. I would have thought the return fuel to flow back easily into the tank.