Engine Running Rich, Where to begin... Options

[D1A3]

I've been told my 2.0L engine is running rich. Can anyone give me some tips on where to start to verify this and get it resolved? I am runnign the stock D-Jet FI.

Thanks,
Jason

[Dave_Darling]

Where to start? Fuel pressure (should be 29 PSI), check for unplugged hoses, cracked or leaking hoses, mis-routed hoses, wires that are not plugged in or are plugged in but not securely... Is the intake temperature sensor (two-wire sensor on top of the manifold) plugged in at all?

Maybe the MPS is toast. Pull a vacuum on it with a vacuum pump (e.g., Mity Vac) of about 15" and see if it holds for more than a few seconds.

Lots of things could be causing it. Once, a chewed-up valve was causing it. It was an intake valve and the mixture was getting pushed back into the manifold, raising the pressure. The FI saw that "extra" air (which already had some fuel in it!) and dumped even more fuel in...

Or you could have an ignition problem that is acting like a rich mixture. How's the timing??

--DD

[D1A3]

Hi Dave,

Here is what I can tell you... Engine was rebuilt about 1000 miles ago. I trust the engine was rebuilt correctly and that the valves are in good shape (again, just an assumption). All vaccum hoses are new and I'm confident they are attached correctly. Timing is set correctly. Engine overall runs GREAT! I just had a few guys the other nigte say the engine smelled like it was runnign a little rich...

I will check the MPS. Is this the Pressure sensor called out on Page 17, #11 or #7 on page 40 of the Haynes Manual?

Is the intake temperature sensor the same as #9 on page 17 in that same Haynes diagram?

Other than timing, what could I check with the ignition?

Would the adjustment on the brianbox affect this at all?

Thanks,
Jason

[D1A3]

OK, I checked the pressur esensor and it holds a vaccum just fine. i checked the wiring to the temperature ( i think) and the connections seem to be OK.

Need some more help here...

[lapuwali]

I think you just need to stop listening to your friends...

If there's no evidence that it's "running rich" other than some uncalibrated noses, then it's probably fine. Try pulling a spark plug and see if it's black (rich), tan (good), or white-ish (lean).

[r_towle]

CHT (cylinder head temp sensor)
Timing not set right
fuel pressure to high
MPS not the right one (please state year, and serial number of both the MPS and the FI computer)
Check your plugs before you go to far...if they are golden brown, you are set up correctly.

these engines tend to run a bit rich, and that is OK....compared to a modern car, or a water cooled car, these cars like to be a little on the rich side.

You have a new motor...how many times have you changed the oil, and when?
Initial break in, the gas will leak by the rings on the pistons until they have had time and proper break in to seat correctly...

After the break in period, you need to change the oil and filter, cause there may be gas in the oil, along with any small metal shavings from assembly.

the throttle position sender may not be set correctly, giving you to much fuel for a given rpm...
the haynes manual tells you how to set it, along with pbanders web site.
pbanders has a site on the rennlist that has loads of Djet troubleshooting information and test.

Rich

[nbscooters]

Hey Jason, I have the same problem but I know my engine is running a little rich because I am getting about 23 MPG. Hopefully its a simple fix.

[jk76.914]

Mine was fuel pressure. You need a pressure gauge. Check my other posts for my suggestion on building a bulletproof, but inexpensive gauge. Good luck.