Bank 5-8 stays in Closed Loop!

Very strange! when you say switched everything that can be switched - can you itemize what those are? There might be a part that was missed that can help diagnose.

Cheers

 

Not sure what "we switched everything that can be switched" covered. I am going to assume that means plugs, wires, coils.

Not coming out of closed loop means the computer thinks the car is not warmed up. What temp sensors go to that bank only?

There is also a discussion on here somewhere about rigging up a switch to get the computer to "blink" fault codes. That might be helpful.

Regards,
Jerry

 

Closed loop is where both banks should be when the is warmed. We start in open loop, with preset parameters...and as the engine warms up, we go into closed loop. Time to find a new tech, as the basics are clearly not being understood. The temp sensors are just one of several parameters that tell the ECU what to do.

 

from what I understand there is just 1 temp sensor at the bottom of the radiator right? Your ECU should just take into account MAF (which you said you switched) engine temperature (should feed both Motronic ECUS - which you said you switched as well) and O2 sensor (which you said you replaced)

How are you determining that the 5-8 bank is in closed loop on startup?

Cheers

 

First of all, you really mean that it is stuck in OPEN loop where the car ignores the input from the O2 sensor.

Secondly, it determines that the coolant is not hot enough by reading its coolant temp sensors. I would measure the coolant signals at the ECU to see if there is a broken wire or something similar.

 

Since there seems to be confusion of whether it's stuck in open or closed loop, if it's stuck in either it could be a bad coolant temp sensor (CTS) for the 1-5 bank making the ECU think it's either always warmed up or always cold.

You can measure the resistance of the resistance of the CTS. It should be around 1000 to 2000 ohms when cold; a few hundred when the engine is hot. If it measures very high resistance when cold, like 100,000 ohms or more, it most likely bad.

 

I believe there is just 1 temp sensor at the bottom of the radiator, but I could be wrong - the good thing is it's a cheap part I believe $25.

 

I believe that is either a water temp sending unit for the temp gage or the fan switch . CTS are located on the water manifold on the engine. Parts list calls out 2.

 

thanks John for correcting my ignorance...is this it?

Part #: 125769
125769 SENSOR/WATER TEMPERATURE $32...

If so the OP may want to try swapping this part? See if it's a bad sensor?
Image Unavailable, Please Login

 

That's it. Drawing shows one, parts list call for two. I assume one for each side like the 2.7 system no a 355No need to swap parts. Coolant will leak out making a mess. Better to check resistance with an Ohm meter. Also, the part can be had for about $15 is you look around for it.

 

There you go Rocco...John, thanks for helping out and educating me as well.

 

Just out of curiosity what is the visible symptom that bank is not working properly? Does the car stink? Does it lope along hobby horsing when moving from a start in first gear when it is cold? How does it drive when warmed up?

My 3.2 routinely lights up the check engine light because I set the K-Jet to run just a little bit rich. Interestingly it does not stink of rotten eggs. Which it did a little bit when I first got it. I believe that is because the cats were clogged up. I THINK the O2 sensors are in front of the cats and if so they could see a perfect mixture that the clogged cats would not process properly.

I wonder when "Italian Tune Ups" became obsolete?