My 355 has just failed its MOT on emissions. Details as follows: Fast Idle 1st attempt: CO = 0.83 % (max allowed = 0.3) HC = 147 ppm (max allowed = 200) This is a pass but still quite high! Lambda = 1.017 (this is ok) Fast idle 2nd attempt: CO = 0.88 % (max allowed = 0.3) HC = 172 ppm (max allowed = 200ppm) This is still a pass but quite high! Lambda = 1.017 (this is ok) Note: car was hotter (very hot, with fans on) on 2nd attempt and readings were poorer than the 1st try. Natural idle: Co level = 0.78 % (max allowed = 0.5) It has failed on CO, whilst lambda and HC were fine (although the HC looks quite high within the allowable range!). Any emissions readings that can be provided from other 355's would be much appreciated together with experiences others have had with passing emissions tests. What are typical CO and HC readings? The car has 25K miles on it and to my knowledge is on the original CATS. I'm suspecting these may be at least partly to blame - any comments from others who have changed broken cats for new ones and have pre and post test emissions readings would be much appreciated. With HC and (particularly) CO readings so high, is it likely to be more than just CATS? Maybe lambda sensors getting a little tired as well, although lambda readings appear to be reasonable to me. I understand these cars are normally towards the upper end of the emission range window but any info as to typical readings observed on these cars would be much appreciated.
When mine failed, it turned out to be the O2 sensors. See http://www.ferrarichat.com/forum/showthread.php?t=201140 It passed the 25MPH test but failed the 15MPH test. The only issues were with the computer and the NO (PPM) readings. The NO for 15MPH was 667 (Max Allowed 424, Avg of All Vehicles 57). The NO for 25 MPH was 444 (Max 711, Avg 50) After replacing all four O2 sensors, my readings were: 15 MPH RPM 1821, %CO2 14.6, %O2 0.1, HC(PPM) 10, CO% 0.2, NO(PPM) 36 25 MPH RPM 2285, %CO2 14.7, %O2 0.1, HC(PPM) 9, CO% 0.1, NO(PPM) 39
The lambda is a little high. The cheapest option is to replace the O2 sensors and recheck... Does your exhaust smell "fuelly" at idle? Your 355's O2 sensors are standard bosch ones. Pull them out, read the number, go to a good parts store and order them on the bosch number telling them they are for a Saab. Get the generic replacements and you can wire them in 20 minutes per side using the connection kit that comes with universals. If they are over 10 years old and have never been changed, this will save you other fueling problems later... - should not cost you more than $50-60 per side. Secondly, your cats should catch any small increased richness, and result in numbers close to 0 both in CO and HC. The fact you have the increased amounts, suggests the cats are not doing too well either. But you need to know the mixture going in is right first. Pulling them out is a 30 minute job on each side without lifting the car up. You can do a visual to check the matrix has not collapsed or clogged up. If you need to relpace cats, you can go and buy some universal metallic core 200 CEL at Magnaflow for USD 100 per side (match the width to your pipes, I believe 2" to 2.25") and take them to a good exhaust welder who can do the conversion for about $200. They will outperform the OEM ones and cost you a fraction (but may not be legal in California). Marco
Marco / Tom - Thanks for your advice. Much appreciated. Marco - I'm in the UK so don't need to worry too much about California! Will take your advice and replace the lambda sensors. Do you suggest just to replace the 2 front ones (its a 5.2 car)? I believe the rear ones are not instrumental in actually controlling fuelling. The car always smells quite rich when cold (I believe they all do), but I haven't really noticed too much at operating temp. I guess from your comments that you'd expect the car to be running pretty much bang on stoichiometric (lambda = 1) at the UK MOT fast idle speed (about 2600 rpm)?
I'm not sure what year your 355 is, but be careful when you order the new O2 sensors. Read my thread referenced above, especially pages 4 and 5. Bosch specifies incorrect part numbers for the O2 sensors and this has propagated down to all of the auto parts providers. I believe you need 15738 in the post-cat location and 15730 in the pre-cat location.
If the pre-cat 02 sensors have not been replaced then it would be recommended. The post-cat sensors are there to measure catalyst efficiency. Just because the radiator fans were on and the car was hot does not mean that the catalysts were up to temperature. It needs to be taken for a hard drive and then pulled in and immediately tested. Try the latter first.
Should be hovering around stoichiometry (output 645mV on the connectors) as an average. Our O2 sensors are narrow band so aren't really that precise, and the ECU averages by going a few duty cycles slightly rich, and a few cycles slightly lean across stoichiometry. There is an engine cycle of lag between an adjustment of the injector duty cycle and the combustion gasses making their way to the O2 sensors... Your reading is somewhat close enough to Lambda 1 so I am wondering if the O2 sensors have aged a bit and are telling the ECU that they are at Lambda 1 when in fact the real mixture is at a little more - but you're pretty damn close that it is within the measuring instrument's error range. The front ones are used for mixture control, the rear ones kick off OBD warnings if the post cat mixture is too rich. Hence why I am on the fence abut this. Have you checked that the Check engine lights work? I'd first fix the O2 sensors as they are cheap and besides having a set of new high quality BOSCH ones (don't skimp on quality) will do you NO harm. If that fails then the cat performance is borderline, but strange that is is not triggering a CEL... M
It is normal for fuel smell on a cold engine as it goes through the enrichment at startup (are you air bypass valves working?) and of course the obvious, the CATs NEED to be at working temperature (a good indicator is the oil temperature being at working temp, not the water), otherwise they will not be working optimally... Marco
Once again, thanks for your comments and advice guys. I'm going to order a pair of replacement bosch front lambda sensors, as advised, and then go down the CAT route if necessary. My personal view is that I'm thinking the lambda isn't far out enough for it to be a mixture problem (although maybe its contributing slightly). Both my CO and HC are high and I guess CATS that aren't working very well would give this effect. Nothing to be lost by trying new sensors first as they could probably do with renewing anyway. Any advice on best replacement CATS? I know hyperflow are well regarded, but they aren't cheap. Has anyone experience of alternative metallic sports CATS?
You can do a whole exhaust job for a king's ransom, and get a subjective few HP's more put of it. Or you can save a bunch of money and still do better than the OEM... http://www.ferrarichat.com/forum/showthread.php?t=212160&page=2 - I did fry them once when my MAF shorted out. I was pouring black smoke out the exhaust and the cats were glowing bright red. I then killed it on another occasion while driving in another rain squall (I pride myself in driving in any condition and fixing the car afterwards) when the MAF actually blew the circuit board. (I learned how to hook up both ECU's to the good MAF which carried me through 4 months of motoring until I found a new replacement). See the molten cat here http://www.ferrarichat.com/forum/showthread.php?t=227951 I have replaced it (Magnaflow just sent me a new one for free once I mailed them the pictures) with another one and is flawless. Incidentally, when it failed, it did not blow up or catch fire or anything nasty like that. Magnaflow makes a great product with a great service.
First off, make sure your "check engine" light self test works....it should come on when you start the car, and turn off shortly after it starts. If you never see it, then you need to replace the bulb in the dash. If it remains on all the time, then you need to scan for codes with a code reader. For O2 sensors, I would just get the Bosch ones with the correct connector already attached, rather than Bosch "universal" ones and have to do the splicing (which you might mess up creating more headaches). Part number for the pre-cat is 0258003819 or "3819". Don't bother with the post cat, unless you have a "low catalyst efficiency" code and CE light.
With all due respect, I totally disagree. As far as I can tell, most Bosch stuff is now made in China crap. I bought Walker's very well made universal O2 sensors. They come with high quality butt splices that have a little hole for solder after you crimp. They also give you four little pieces of shrink tubing and very clear instructions on how to wire them. I crimped, soldered, and shrunk the tubing along with a big piece I put on to cover the whole thing and I am very happy with my now noticeably smoother running engine.
Without O2 and CO2 readings it is difficult to determine weather the Catalytic converters are working. These readings look correct if they were taken pre cat, I would expect O2 of .2-.5 measured precat and 1.2-2.0 post cat. I suspect you have catalytic converters that are not operating but do not have sufficient information to confirm.
+1 -- although I'd be more suspicious that they don't have anything inside Have you previously passed this test (with the same hardware)? You might want to just remove an O2 sensor (or an inspection plug, if so equipped) and visually confirm if the catalyst structure is still present inside, or not, before buying parts -- JMO.
I am giving general advice to someone of unknown capabilities. While your experience with the Walker brand O2 sensor worked out, as did your splicing, I have found it is safer to recommend the oem part with the oem connector already attached to simplify matters, and minimize variables. I personally have used a Bosch "universal" pre cat O2 sensor on my 355 which required the splicing of the original connector. It worked out fine, but I don't believe this is always a good option for others.
My employers car just failed recently as well (99 355 F1 Spider). No CEL light. When we scanned it I expected to see an O2 sensor code but instead pulled up P0410 (from memory), Secondary air injection pump failure or something like that. Replaced a solenoid valve and a tube (not sure exactly would have to ask tech), drove it for a day and blew clean when re tested. I did not keep the fail so I can't help you with exact reading at the moment but the after was. 1999 355 F1 Spider 12,500KM (7,700 Miles) Curb Idle HC ppm 150 allowed - reading 4 co% 0.7 allowed - reading 0 NO ppm N/A 40 km/h HC ppm 52 allowed - reading 4 CO% 0.29 allowed - reading 0 NO ppm 385 allowed - reading 0 The exhaust when we ran it the first time did not smell "rich" but seemed WAY too hot. The rubber boots on the exhaust tips were smoking at the end of the run. That was drastically reduced on the second run when the AIP was working properly again. The last time I ran my own car the readings were 1999 355 F1 Spider 32,500KM (20,100 Miles) Curb Idle HC ppm 150 allowed - reading 15 CO% 0.7 allowed - reading 0.02 NO ppm N/A 40 km/h HC ppm 52 allowed - reading 12 CO% 0.29 allowed - reading 0.09 NO ppm 385 allowed - reading 50
Thanks to all for the helpful comments and advice. The CE light is working and ISN'T coming on. In response to Edwards discussion concerning the air injection system: I understood that the air injection pump is only supposed to function for the first minute or two when the car is started from cold. Hence I'm struggling to figure out why this could affect the emissions when the engine is at normal working temperature based on the above example. Any more info on this please and why it may affect emissions when the engine is hot? I must admit I'm not sure whether mine is working or not. Thank you for the continued help.
