The values that I saw were using a handheld DC meter so it certainly may have been alternating between .1 and .8V. I do not have a scope. Also my OBD2 reader does not read live data. I guess I'll need to order another reader that connects to my laptop or PDA. What I was planning on doing in the meantime is verifying that the pins you listed above are all connected and not shorted. It would seem that a loose connection on pin 46 may result in a low voltage reading across all sensors.
BTW Tom, did you not Eric's comment that the blue taped connectors is for the pre-cat sensors? Have you corrected that?
After I pulled the wires and connectors back out on the driver's side, it turned out that the blue tape was on the pre-cat sensor wires on both sides. It was just hard to see with everything packed in under the metal plate. Tom
With the car not running, but the key on, I measure 0V on all but one of the sensor pins on the car side which is .4V relative to ground. With the car running, from cold, I measure 6V between the two heater pins and .4V between the two sensor pins on the car side. I ordered an OBD2 reader with live data support from eBay and am waiting for it to arrive.
These are very strange measurements. On my car, I have measured 1160 mV wrt to ground on the car side when the sensors are not connected, for the post-cat probes (pins 76 & 77). This polarisation by the Motronic allows it to check that the wires are not shorted somewhere during the sensors heating phase (very high impedance of the sensors during this phase). Live data monitoring is a must, it will show you an end-to-end status of your O2 sensors circuits (sensors clold then hot, wires, Motronic acquisition and processing) and a lot of other useful stuffs.
I ordered a bluetooth OBD2 reader ( http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&sspagename=ADME%3AB%3AEOIBSAA%3AUS%3A11&viewitem=&item=200232419165 ) and downloaded some free software (Digital Dash 5, OBD2Spy, OBD2Diag, and ScanTool) for my laptop. I'll send updates after the reader arrives.
Well, I received the OBDII Reader that I ordered off of EBay and it was cracked and didn't work. The seller isn't replying to my emails, so I guess I'll be spending more $$$ on a third OBDII reader. This time from Scantool.net.
I have received my third OBDII reader and it works. In defense of the EBay seller from China, he did contact me and offer to replace the defective unit. Anyway, I have collected data using the scantool software and OBD2007. The data is attached. The ScanTool readings were made with a little gas applied to make sure the readings were toggling. I have already replaced both pre-cat O2 sensors, but have not done anything with the post-cat sensors. I have also cleaned the MAF with MAF cleaner and the contacts with contact cleaner. I noticed that the check engine light should be on according to the readings, but it is not. The light does light up for a few seconds when I start the car, but then shuts off. Is there a connection somewhere that I should check? Any other feedback on the test results? Should I replace the post-cat sensors, or wait until the pending tests are completed? Is there a procedure to speed up the completion of the pending tests? I have already gone about 300 miles since the last reset. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Generally, to trip the "check engine" light, requires at least two drive cycles of 30 minutes or so in length, with the problem present. (at least that is what my local FNA dealer told me) This is to avoid false positives.
I am sure you will enjoy your reader. As the O2 sensors monitoring is not complete, the first screens are difficult to read and not very significant. Prefer the live data. You can leave your car idling when you look at the O2 sensors, they should toggle. A bit more revs may just increase the frequency of the toggling. It is surprisisng that in this condition your fuel system appears to be in "open loop" on the scantool. Something seems wrong in your set-up. Pre-cat sensors are new, so have a look to the MAF connections and the MAF itself for some durt or oil. Do you have a K&N filter or any other brand of filter which need to be oiled? Also, is your air pump running on cold start? I have discovered on my car that if the pump relay is not there, or cannot be checked by the Motronic, it will prevent the car to run in closed loop. Just some thoughts ... keep us informed!
The air pump was originally not working due to a blown fuse. I replaced the fuse several weeks ago, so it is now working. I can hear the whine when I start the car and for a few minutes afterwards. I will try to collect the live O2 data today. I am still learning the software. Also, I verified that the connection on the MAF end of the cabling is clean. I also sprayed MAF cleaner on the MAF sensor.
Just an FYI, connectors can go bad. The connector to my MAF was questionable, causing an uneven idle. Cleaning the connector would correct it for a month or two, but the problem would return. I messed with this for over a year, and recently had the connector replaced, and all is good. Idle is rock steady. Never had a CE light related to it, or any codes stored. These cars are getting old now. I have had friends have connector pins replaced on various Amp Junior Timer connectors on their 355's. The head service tech at Ferrari of Seattle says he sees it frequently on older Ferraris too. You have to pull the boots back to inspect them thoroughly, and even back probe them with a multi-tester to ensure a good connection.
Valuable tool, isn't it ?? Can you confirm that your car is able to run in closed loop when idling or under light load? The "Long Term Fuel Trim" parameters (LTFT) are also good indicators of the status of the fuel system. What are the values for Bank 1 and Bank2?
Here is the live info from the O2 sensors. Looks like they are flat line at 0V. The car is always open loop as far as I can tell. The LTFT is at 0%. They are also in the live data image. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Still strange. Some parameters are OK (rpm, air temp, water temp) but some other are not. In no way your car can idle with the MAF saying 0 g/s. It should be around 13 g/s except if it is disconnected somewhere. 0V flat line for the O2 sensors is not realistic. Do you read also 0V on the sensors when the engine is cold? It looks like some kind of dialog problem between the car and the OBD S/W or I/F. Check first that all the parameters are alive and significant because what you read now is doubtful : TPS when you press the pedal between 0% and 76%, O2 sensors when cold (I read 435 mV on my car), Ignition advance should change with light throtle, Short Term Fuel Trim (STFT) should toggle as the pre-cat sensors, ... etc
Yes, this is strange. One of my previous posts showed a load on the MAF via ScanTool. I am attaching another graph taking while driving. Still no O2 or MAF activity. I'll look into it some more. Image Unavailable, Please Login
I found some items that were not setup properly. Here is new data from a short drive. The O2 sensors have very minimal activity. Image Unavailable, Please Login Image Unavailable, Please Login
I was told today that the O2 sensor should have ground on one of the heater wires. I measured for continuity to ground and there is no connection between any of the four wires on the sensor end with battery ground. The car end has both heater wires and one signal wire shorted to ground though. Is this normal when the car is shut off? Or should heater wires not be shorted with the car off? With the car running, I measure 6V across the heater wires on the car end.
No! None of the heater wires are connected directly to the ground. The 4 heaters are connected together to the +12V after the fuel pump relay. The other side of the heaters are connected to the Motronic, pre-cat heaters being connected in parallel, as well as post-cat heaters (ie 2 pins on the Motronic). The Motronic can then check the presence and the resitance value of the heaters and possibly limit or regulate the current. I have never perform any measurement on these circuits. PM your mail address and I will send you the Moronic 5.2 diagnostic document which include the electrical diagram.
Yes, still something wrong with the O2 sensors and may be with the S/W parameters. How can it show you the STFT and LTFT for Bank 3 and Bank 4 ??? What are the values of O2 sensors and Fuel Trim when you use Scantool?
Here is a graph with the STFT and LTFT. ScanTool and OBD2007 return similar results. Image Unavailable, Please Login
Here's a plot from my Trans AM WS6 with the exact same software settings just to show that the tool is acquiring data. Image Unavailable, Please Login
Once connected to your F355 with OBD2007, in the terminal window, can you enter the 0100 command and report the result from your interface.
