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Starting a new thread since there is no results for just running rich and running rich at idle. Most post are about running rich at WOT.

So new 440 injectors with all new seals installed. Stock EJ20 Z4 ECU installed and JECS MAF with an EJ20 motor. So this should be normal operation at this point. Upon start up the car runs at idle and seems to be firing on 4 cylinders but is running very rich so could be fouling out some plugs causing missfires. ECU does not indicate this though it is showing code 21, 31, and 45.

So if I have fouled plugs and not getting complete combustion than the ECU should be trying to adjust fuel but if the plugs are bad enough I would imagine it might not help. If the 02 sensor was bad I would get a code and perhaps that could cause a rich condition. The car starts first try each time and I am verifying rich condition with AEM wideband. AFR at idle is at 10 or lower.

During the install I didn't mess with the coolant temp sensor and I have added coolant and burped the system. Now I haven't done the resistance check on it yet since I can't reach it. I am having trouble understanding if it is bad how this may attribute to my running rich.
Also while testing and running the car the gauge climbs to about 3/4 and then I shut it off. I am trying to get the fans to kick on so I know the thermostat is opening and the temps should drop. This hasn't happened yet.

During the install I didn't mess with the TPS but I have tested it and even adjusted to no effect to clearing the code or helping with the rich condition. the car idles at around 750 and doesn't jump around so I don't think I have an issue there.

During the install I didn't mess with the Pressure Sensor and/or PES. I haven't tested it yet as I haven't wanted to remove all that crap until I could do some reading and see if I could find a reason or relation first. Doing some reading on NASTYSOCKS seems like this could be an issue but I don't have any misfire codes as they did.

So back to running rich at idle. I somewhat know that a bad coolant temp sensor will/can make the car run bad, but full rich?
Also should I keep running the engine? I keep reading about excess fuel can wash out the cylinders and leak into the oil. CJ already mentioned to change the oil but don't want to do this until this is sorted.

According to the ECU code list:

21 Water temperature sensor
31 Throttle sensor
45 Atmospheric pressure sensor


I'd be replacing the CTS - #21 - reset the ECU and see what comes back. When the engine is in 'limp mode' or the ECU is seeing other issues (due to codes) it will run Rich, which is safer than Lean.

If your temp gauge is seeing 3/4, then your cooling system has an issue too. NEVER should go over 1/2 in normal operation (or even when driven hard, in my experience). ..it needs burped.

Remember - the temp gauge is NOT the CTS, but the single wire connector right next to the CTS on the water pipe under the IM.

GL,
Td

Did you ever fix the speedo issue? That would def cause the car to run like shit.

mike-tracy wrote:Did you ever fix the speedo issue? That would def cause the car to run like shit.

I installed the cable I got from CJ, but I haven't driven it. It has only moved from the garage to the driveway.

And it wasn't running this bad when I did have it installed

Alright so I ended up asking Rob and we got it sorted out. he asked if I followed his write up and I said yes. He then asked if I de-pinned and merge the wire. I said yes but I would double check. Well I had in facted depinned and merged the wire but in doing so I moved the pin21 to spot from 20, Repositioned and codes gone.
However, now I have code 23 wrong MAF. So I searched and searched. All the write say it's plug and play but I had remembered reading something about splicing the blue wire to ground, so I found the thread and did just that. Didn't clear the code though. So I went ahead and took the car for a drive hoping it would learn but it is still pig rich. Idle is fine, temp is fine but doesn't want to make power since it is so rich. Going to swap plugs and see if that changes anuthing.

Swapped plugs with no luck yesterday. Going to try and get another JECs MAF and see what that does.

Can you elaborate on the pin relocation you were talking about? Do the fans now come on?

Code 23 is an issue with the MAF, not "incorrect MAF". A bad MAF could explain you running rich if it's incorrectly reading the air coming into the engine. Have you checked the wiring from the MAF to the ECU?

So yes I ended up checking as per the FSM and viola!

I had cut the black/ground wire that goes to the MAF, right at the ECU. Problem solved and she's running great.

Lesson learned: If it worked before the swap it probably still works. Double check your work and if that doesn't work. Look at the FSM and be 100% sure before you start wasting money parts that you don't need.

Glad she's running great, and good advice for others