Fluctuating Idle Issue - S54 swap

[328ijunkie]

^Notice the factory doesnt use solder anywhere

they crimp everything.

[E30Strube]

As a follow up to this...I figured out the problem. I spliced in a new connector for my O2 sensors and soldered the connections. Apparently that was the issue with the car going into limp mode. I cut out the soldered joints and used BMW butt connectors with heat shrink insulators. After changing them out, the O2 sensors activated and the car went into closed loop like it should. For the idle issue, I changed the TPS and adjusted the TBs. Once that was done, no more codes and the car runs like a champ.

I'm still amazed that a few simple solder connections could cause these issues.

[nando]

Do you have PAsoft 1.4? You should be able to dump software from DME, then send it to me, I will see if there is something wrong with the tune.

PAsoft can't do anything with MSS54 other than read/reset codes.

[E30Strube]

As a follow up to this, I seem to have solved the idle issue (P1122, P1222, P0122, P0223, P0506) by replacing the TPS and adjusting the TBs. The car still goes into "safe" mode (won't go past 4000rpm). After connecting the car to a BMW scanner, the O2 sensors are not active. To the ECU, they are basically not there. I'm not sure why they wouldn't be reading.

[DesertBMW]

These are the last codes:

P1122
P1222
P0506
P0030
P0050
P0036
P0223
P0122
P0056

Do you have PAsoft 1.4? You should be able to dump software from DME, then send it to me, I will see if there is something wrong with the tune.

[gobuffs]

Im having a similar issue. Appears I have a noisy TPS signal causing the computer to think I am pumping the pedal ad idle. Hopefully I can fix it tonight for Ofest.

[E30Strube]

These are the last codes:

P1122
P1222
P0506
P0030
P0050
P0036
P0223
P0122
P0056

[E30Strube]

For the moment, wrap a wire around and run it to ground? It's half assed, but it's a quick solution for testing.

Thats what I did ;) And it works. I will fix it properly whenever I decide to flush the system sometime. That time is not now lol.

[nrubenstein]

For the moment, wrap a wire around and run it to ground? It's half assed, but it's a quick solution for testing.

[E30Strube]

I'm using this



Because the E30 sensor doesn't have a wire ground, and the pipe piece is insulated on both sides via the rubber o-rings, the sensor doesn't get grounded. For anyone that uses this, they should weld on a small stud to attach a ground wire.

[Andrew325is]

It sounds like you're on the right track. For the coolant temp sensor on mine I just tapped the top of the thermostat housing. Use a 1/2 inch drill bit to make the hole then tap it with a 14x1.5mm tap (Snap-on has them). It's not thick metal so just be careful.

[E30Strube]

The e30 coolant sensor is the only one that has only a single wire going to it for grounding I believe. Will get the code definitions...

[nrubenstein]

It does seem like the issue is when it switches to closed loop or tries to at least.

The O2 sensors are located at the end of the header. The tune will not work with a MAF as per the tuner. I've also tried the ECU in a stock E46 M3 and the car did not experience the idle issues I have. The car runs the same whether the O2s are plugged in or not. I've changed the O2 sensors to new ones, verified they are going to the correct pins and are in fact the pre-cat sensors. I'm getting codes for O2 sensor heater circuit. I thought it may be a grounding issue, so I even put the grounds for the sensors directly to chassis ground and that did nothing.

So, it starts doing the idle hunt, even when it has NO O2 sensors hooked up at all? If that is the case, perhaps try disconnecting the DME coolant temp sensor? (Or anything else you can think of to force it to stay in open loop mode.) I'm also wondering if the E30 coolant temp sensor is the only one that is having issues due to paint?

Finally, what are you reading the codes with? Are you using a GT1, or other real diagnostic tool, or something more generic like an OBD scanner and/or Peake Tool? The Peake is better than an OBD scanner, but it is nothing like what you will get when you hook up a real diagnostic tool.

[E30Strube]

It does seem like the issue is when it switches to closed loop or tries to at least.

The O2 sensors are located at the end of the header. The tune will not work with a MAF as per the tuner. I've also tried the ECU in a stock E46 M3 and the car did not experience the idle issues I have. The car runs the same whether the O2s are plugged in or not. I've changed the O2 sensors to new ones, verified they are going to the correct pins and are in fact the pre-cat sensors. I'm getting codes for O2 sensor heater circuit. I thought it may be a grounding issue, so I even put the grounds for the sensors directly to chassis ground and that did nothing.

[nrubenstein]

Where are your o2 sensors? Any exhaust leaks? The symptoms indicate that it is running poorly WHEN it switches to closed loop. Have you spoken to whomever tuned it? Have you tried running it with a MAF? (I know this means you have to swap manifolds, which is a bit of a pain, but would indicate whether or not you have an issue with the AN tune.)

Edit: have you tried running it with the O2s disconnected?