Hi all-- So I took my 348 ('92) to a mechanic who listened to the catalytic converters with a stethoscope... they sounded just fine, he said. However, the car still wants to stall when I come to a stop. And the "Check Engine 5-8" came on for the first time today--previously, it was just the "Check Engine 1-4." What is causing this stalling issue? Is it necessarily the CATS? I have a few ideas, but what do you guys think?
Does the engine put out the same amount of power? Maybe an 02 sensor? Maybe a throttle butterfly out of adjustment, or stuck extra air valve? I hate fuel injection. I think your problem might be a super rich condition which could be cause by a alternate air valve that is stuck closed therefore making your car run rich (I know the 308's had them I'm not sure about the 348) or your throttle butterfly could be out of adustment making that car want to stall at idle, or both. If the car warms up how does it run, or does it just run strangley and want to stall out all the time? If your cats are plugged, the car will run extremely sluggish all the time.
I have not experienced any loss of power whatsoever. The stalling issue comes up when the car is warm and when the style of driving is frequent stopping and going.
So when you come to a fast stop the idle drops and stalls? (this is of course with the clutch depressed fully?) It could be an extra air valve which isn't opening when warm so your car is running a little choked. Does your car run abnormally cool? Does it smell like it's running rich?
Can you describe your symptom(s) more per Jim's request? Are you saying that it seems to be running well -- i.e., pulls normally, can run to high RPM, idles well (when it doesn't stall), etc., and it's only when coming to a stop (with the throttle fully closed) that the RPM drops below the normal idle RPM? If you use the throttle pedal during the stopping process to limit the rate of RPM drop to be slower does it do better? Is your '92 a motronic 2.7? Your comment that it doesn't mis-behave when "cold" is a good clue -- when "cold" (i.e., no useable O2 sensor output) these injection systems run much more like an unintelligent open-loop K-Jet system (so it's a good sign that the major components are generally working OK). There should be some sort of sensor/switch/potentiometer on the throttle shaft to "tell" the injection ECU when you are under "fully-closed throttle + RPM dropping + warm" conditions so it doesn't overly cut the fuel supply trying to keep the A/F mixture at the closed-loop (warm-running only) target -- just a thought...
Thanks for your help guys... here are some more clues... Yes, when I come to a fast stop the idle drops below the normal idle and stalls, or wants to stall (the car is in neutral and the gas pedal is not pressed at all) I don't know how to judge if the car is running abnormally cool or rich... The car runs well--pulls normally, revs to high RPM, etc. There is never a loss of power. The engine idles well when I am not experiencing this problem generally (the problem occurs about 50% of the times I drive it--I drive frequently) Yes, the car has the Motronic 2.7 ECU...
This can mimic the classic reset the ECU's LBM. Did you try 1 disconnect battery. 10 seconds 2 reconnect battery 3 start car with no accessories running 4 let idle for 10 minutes 5 o.k. try to stall it now.
Sounds like a thermocouple problem.It's sensing an cat or fuel mixture problem on the bank of cylinders(1-4 or 5-8) and shutting the offending bank of cylinders.Need a Ferrari shop with T5 tester to verify.
one more thing. This is just a shot in the dark, but; Does the car stall exactly the same when you come to idle, ONLY when you're running the air conditioner? There is a setting for correction of the required amount of additional fuel to run the ac. Try driving without the ac on, and see if you get the same problem.
I actually rarely use the air conditoning. The problem has occurred while the air conditioning was been off.
Just for kicks, load test your alternator and battery too....my 348 was stalling out allot too . it happened that the alternator was only putting out 8.5 volts .If thats it let me know, I can recommend a good place to have the starter built up with military diodes. If its the ¼ 5/8 bank it likely is a clogged catalytic converter. Having gone through this myself, I can offer you some advice and parts help too. Hope this helps, [email protected]
OK, so I'm experiencing the very same thing re. idle/stall when hot. Any idea where this ended up? I was going to do the ECU reset via battery disconnect knob later today. Couldn't hurt. Edit: I am reviewing everything on NoDoubt's 348 pages: http://www.club348.com/technical/Tech/348.html#EngineStallsOverheats. A great source for us Mondial t people!
The ECU reset is particularly important if you have had the battery disconnected/replaced/run down in the recent past. It's a good starting point to correct your idle problem. You know the procedure to follow? Are you getting any "check engine" warning lights? Have you checked for stored fault codes? Edit: come to think of it, if you have been using your battery disconnect knob and NOT re-initializing the ECU's, that could be your problem right there. Remember, DON'T touch the gas pedal after you restart, or the ECU's will get the wrong information!
try this, it works Adjust the air bypass screw #4 shown below. All you have to do is use a 14mm box end wrench to loosen the lock nut #3, Then use a straight blade screwdriver to turn the screw #4 out one complete turn. Now re-tighten the lock nut #3 while simultaneously holding the screw #4 in place with the screwdriver. Do this to both throttle bodies Found here.... http://www.club348.com/technical/Tech/348.html#EngineStallsOverheats
Quick Q on ECU reset: Should I do it with the motor hot or cold? Edit: Whoops! Missed the "reset it COLD" blurb in the www.club348.com pages.
For any check engine light, I would recommend that you read the code to see what the ECU is complaining about. I once had a series of stalls with no check-engine light. In that case resetting the ECU cleared the problem. Also check the electrical connections to the MAFs. The strain relief on much of the wiring is not as good as it could be. Watch for any wires that are pulling on their connections (overall good practice, though not necessarily directly related to your problem). Lou
Never mind the O2 sensor and the throttle plates and...... 1. The freakin' air bypass valves were closed. Shut. 2. The freakin' Slow Down 1-4 bulb wiggled loose from the socket. 5 mins worth of adjustment solved the whole thing. It's hell when 2 things go wrong at the same time.
