Background The car is 1991 TS Euro model i.e. Motronic 2.5 (yes, only one TPS on 5-8 bank) and no CEL or ECU lights included. Plugs and wires done a year and 5000 km ago. 5-8 bank MAF changed to a no-name, China Inc. version same time as plugs and wires as the original one failed. Also new exhaust was installed during winter for this driving season, at time cats and O2 sensors, including wiring looked good per visual inspection. Symptoms Car run well last driving season (~ 4000km) and also started this season well (~ 1000km) but past couple of days there I have been smelling some gas fumes which I don't recall to have had earlier. Nothing overwhelming but clearly a scent of Eau de Benzina in the air. We have had abnormally warm May here in Frozen Tundra, day temperatures in +27C° / 80F° range and classified this new odor as side effect of warm ambient temperature. Gas scent is around only when engine runs. Yesterday after dropping Mrs. to local ladies wine tasting event at city center and driving back in a stop-and-go traffic suddenly engine sounds changed to more mellow note, idle dropped a 100 rpm or so and about 200 - 250 horses escaped from engine bay. No problems to driving home, though. Everything felt smooth while driving and idle at the stop lights was steady but lower. No CEL because there is not a bulb in the holder. And I didn't see slow down light either. It was just a 50 - 100 hp version of 348. My assumption I assume that engine went to limp mode and dropped a bank due to excessive heat on one of the cats. And this overheating is due to excessive rich AFR. So a real issue instead of Cat Temp ECU ghost. And primary reason for too rich AFR would likely be China Inc. MAF reaching the of its life span i.e. 12 months or so. Or it could be one of the n+1 other issues which could be found in a 33 year old Italian car... Question What kind of troubleshooting procedure would be most appropriate to verify the root cause? - Driving to a local indy shop with exhaust gas analyser to verify if the AFR really is too rich? - Do Euro cars have any carbon cans etc. systems which might cause gas door while engine is running? - Any idea is appreciated!
Are the fumes coming from the tailpipes or from the engine bay. Perhaps check the evaporative system plumbing between the charcoal canister and the intake manifolds (if Euro cars have this plumbing). Image Unavailable, Please Login It might cause some of the symptoms, but I don't know if/how it would affect the idle (?).
I had a similar issue and I had to adjust the CO on the MAF. Does the Chinese MAF have an adjustment? I attempted to put one in but aborted mission when I couldn't get a good OHM reading from the Chinese MAF. Ended up putting a Saab MAF in.
You can check the injector pulse width with oscilloscope, compare the non-running side with the running side. If the car wants to push huge amount of fuel because of MAF, it should be visible here. If the engine is running rich eg. because of broken FPR, it will not show here. You can also check with strobo that the spark is going to the plugs, just remember that 2 of the leads will give ugly or no signal due to the system. You can also check the fuel pressure with pressure gauge and AF mixture with a lambda sond. For some reason I have a fuel pressure gauge with compatible connectors, a lambda sond and AFR meter and an extra low-pressure FPR if you want help to search for the fault. Others I can loan, the FPR I can also sell if the fault is there. I live near enough to have a 348-blast at next weekend if you want me to sparr with the research. Oh, and to check the FPR's you'll need to either run the car or use a jump-wire instead of relay at the passenger footwell. The car will not run fuel pumps by just turning the ignition on - at least my won't.
My car developed a rich condition and the shut down warning light. After MUCH ignition diagnostic work it was the FPR on one bank - it failed. If cylinder 1 or 5 are fouling, there you go. Replace your FPRs or better still upgrade to adjustables. Later I had to replace the O2 sensors since they were jacked up from the rich condition. Thankfully the cats seem fine.
Thank you for guidance! I hope FPRs are fine as both of them were changed to new Volvo/Bosch units only a year ago. But better to check also these.
I believe Euro cars with cats have the same charcoal canister system. Good point. Must check. Idle impact was highly likely a limp mode / bank shut down which could be the caused by too rich AFR. And evaporative system leak could cause too rich AFR.
I suspect MAF much more than FPR but first thing would be to verify if AF ratio is really, really rich.
I thought that the ECU only shuts down a bank under either a catastrophic event - like throwing a piston through one side of the block - or in response to the TCU reporting unsafe heat levels in the cat. In the latter case, that's a fuel, O2 sensor or cat problem, it seems to me. The TC is pretty unsophisticated and it only deals with measuring heat levels and flashing dash lights in response. I believe it does 1) nothing 2) lights up as a warning for the appropriate bank 3) shuts down the appropriate bank until a safe operating temp is restored. All in response to heat measured by the thermocouple in the cat. In my case, I could make a hard right and get the 5-8 bank light to go on even though the 1-4 bank was the culprit and was the one that typically lit up.
According to Kari, his 348 is Motronic 2.5 which, as far as I know, does not have bank shutdown function. When the EGT goes above the "dangerous" level, the Cat Temp ECU will only flash the SDL. This is if it is a CAT version. The 2.5 NON-CAT versions did not even have any Cat Temp ECU-s nor any Thermocouples. The problem Kari is experiencing is probably for other reasons and I would first test with another MAF in place of the China made one. After all they are just $20 at AliExpress (see at: https://www.aliexpress.com/item/1005006239858520.html?src=google&aff_fcid=c3cc6d682a4d40ccbd54990b01cb1b4c-1717387827443-07130-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=c3cc6d682a4d40ccbd54990b01cb1b4c-1717387827443-07130-UneMJZVf&terminal_id=427d56601cb94cf7879fc8499000b4e6&afSmartRedirect=y) so one could buy a few for diagnostics purposes and, perhaps, short time running. Otherwise, I heard from a parts supplier here in Kuala Lumpur, who once tried to sell China MAF-s (same generation as the 348's but for other cars), that, if they function at all, will usually last for 2-3 months.
I can confirm what Miro said above that the 2.5 does not do a shut down if the cat ECU throws a solid light. I had a bad one on my car early in my ownership and it would throw a solid light sometime at cold start up as well as later when well warmed up. I had a very respected Ferrari independent mechanic look at me strangely when I drove in and told him not to worry about the light being on and the car would operate fine. What surprised me was the fact even being a Euro car it still had a 2.5. Always thought it was an '89 only use.
Yes, it is strange that Kari's 348 is, as he informed, 1991 model but Motronic 2.5. My 1991 348TB, UK spec, was Motronic 2.7. I also found info, posted on this forum in 2005, that the change from 2.5 to 2.7 took place some time during 1990, at serial number 86406 (my car was 88xxx). Kari, are you sure your car is 1991 model?
Hmm.. That is interesting information. The symptoms were clearly pointing to bank shut down. But I hadn't chance to follow-up the situation as I had to leave to a business trip. Anyway. 1991 car but still 2.5 as there is only TPS. Once I get back from Barcelona I will take another China Inc. MAF from the shelf. When I got the China Inc. MAF I bought 3 pcs at the same token, just in case. Then again I could buy a pair of BOSCH from Miroljub shouldn't they be soooooooo expensive... Perhaps, it is time for a stand alone ECU project and say bye-bye to MAFs all together.
Have a look at your Cat Temp ECU-s. If the connector to the car harness (not the one for the Thermocouple) has 4 pins, it does not have bank shut-down. In the case of 2.7 (with shut-down function), the equivalent connector on the Cat Temp ECU has 6 pins. I noticed that the two Bosch MAF-s on Ebay have "or best offer" so they are open for some negotiation.
If the MAF is causing a rich condition shouldn't the O2 sensor tell the ECU to reduce the injector open time to lean it out? Ultimately, if it can not reduce the injector timing sufficiently to lean it out it would through a code for Lambda control.
Theme 1991 reoccurs in different plaques and stickers. Also on the original papers first registration is officially on 1991 in Monaco. But VIN is 85xxx... So, you are right car is likely 1990 production model, but was sold as 1991 model by Charles Pozzi S.A. Anyway, now to eat one more tapas dinner with customers and then early birdie flight back to home and I can do more fact checking.
Another easy check you can do is see the Bosch number on one of your engine ECU-s. Motronic 2.5 are Bosch 0 261 200 190 whereas Motronic 2.7 are Bosch 0 261 200 457, 0 261 200 489 or 0 261 203 327.
As it seems my Motronic 2.5 car doesn't have "bank shut down" -functionality then coil / power module could be an explanation for the symptoms I experienced. And it was exceptionally hot while driving in bumper to bumper traffic. I'll continue troubleshooting during weekend when I am in the same zip code with the car.
Coils and power modules are cheap. Both are standard Bosch parts. Ignition coil Bosch 0221503407 Also 99-2004 Land Rover Discovery --------------- Ignition Power Module Bosch 0227 100 200 Porsche part 99360270601 (94-95 911)
And a few more... Ignition Coil: PROTON WAJA PW811201 (WIRA, GEN2) Range Rover & Discovery (1999–2004) ALFA ROMEO 134386, 60558152, 60586072, 60809606, 7648797, 76487970 AUDI 489 051 051 CITROEN 5970.53, 134386, 60558152 FIAT 60586072, 76487970 HONDA 30520-PDF-E00, 30520-PDF-E01, 60558152 KIA 95-97 0K011-18-100 LANCIA 60586072, 76487970 PEUGEOT 5970.53 SEAT 489 051 051, ZS 234 LAMBORGHINI 489 051 051 MASERATI 134386, 76487970 VW 048 905 105 1 BOSCH 0 221 503 407 HELLA 5DA 749 475-041 BERU 0040100233, 0040100234, ZS234 BREMI 11883 FEBI BILSTEIN 36618, GN10 211 DELPHI GN10211-12B1 FACET 9.6068, EPS 1.970.168, KW 470 168 HUCO ERR 6045, 138793 METZGER 0880074, ERR6566 NGK U2006, 48025 BOUGICORD 155076 INTERMOTOR 12623 ERA 880131 MEAT & DORIA 85.30097, 10311 HOFFER 8010311 TESLA CL302, CL544 VALEO 24 51 66 FAE 80279 MAPCO 80001 MARELLI 060810175010 BI0022MM BAE680AG Ignition Module: Alfa Romeo, Fiat 9607361280, 60809477, 60558153 BMW 12141461441 Citroen 96073612, 9607361280 Opel 1208074, 90444650, 90449574 Porsche 99360270600, 99360270601 Peugeot 594554, 96073612 Bosch 0 227 100 200 MARELLI 940138514, 940038514010 VALEO 245525 BERU ZM026 HÜCO 138401, 138402 STANDARD LX-932 HELLA 5DA 006 623-601 Interchangeable BOSCH: 0 227 100 201 0 227 100 202 0 227 100 204 0 227 100 213 0 227 100 215
Thank you, John and Miroljub! Now I'll go to garage to check up things. Dead line to get everything sorted out by next weekend. Ferrari Nordics gathering and Concourse d'elegance. https://www.facebook.com/shellasemat/videos/ferrarit-shell-liedossa/464379942745311/ https://concours.fi/in-english/ Both events in area and it would be disappointing to get there with Tesla...
Now when car has been in garage 6 days it starts and drives normally. A quick around the blocks test drive that is, we are back in standard summer weather, +16C and sunny at 09:30 and heavy down pour at 09:42... On 5-8 bank side the there is one screw which attach coil to heat sink missing. I'll get that fixed at least.
