| Author | Message | ||
| JM Zarka (Crazy_horse)
New member Username: Crazy_horse Post Number: 33 Registered: 2-2002 |
one more thing I do not use the car a lot and I do turn off the battery switch when not using it. | ||
| JM Zarka (Crazy_horse)
New member Username: Crazy_horse Post Number: 32 Registered: 2-2002 |
I have exactly the same problem on my 88 Mondial. The funny thing is that it started right after major service (7500 miles) where they put new timing belts, new distributor caps , new plugs and new fluids. Other than that the car runs great.Strange indeed. | ||
| William Heung (William_heung)
New member Username: William_heung Post Number: 4 Registered: 7-2002 |
Thanks Rob for the Detail. I check the car again last nite and found out I actually did not disconnect the battery from my Sunday drive. Just to see if it has solved itself, I started the car with on problem. Its start with a health roar and idle at 950 rpm. I let it idle 3-4 mins, turn on the air-con, it's okay. So I thought. Beep the throttle and it die again. Start it again with couple of crank and trottle. Let it idle till the fans kick in. Playing with the trottle after create no ploblem at all. The unstable idling only happen 5 mins on startup. Strange?? | ||
| Rob Schermerhorn (Rexrcr)
Junior Member Username: Rexrcr Post Number: 96 Registered: 11-2002 |
Make certain you don't move the throttle while the ecu's are relearning their base parameters when first re-connecting the battery and starting the engine. Our proceedure was from cold start, re-connect battery, start the engine, no throttle changes, idle until cooling fans opperate. By that point you're good to go. I think if you contact Bosch they may tell you in takes less time, but I've found that the phisical sound reminder works better than monitoring time with a watch. This goes for all Motronic cars. | ||
| William Heung (William_heung)
New member Username: William_heung Post Number: 3 Registered: 7-2002 |
Thanks to all who reply. Sorry I could not reply earlier as I was away on the weekend. I think I know now, why this happened occasionally and not all the time. As I don't drive the car often, (like once a month on a 20km trip) I disconnect the battery when not in use and reconnect again before I start from the factory Twist-Turn connector) Could this contribute to the problem? Over the weekend I readjusted the idle speed and set both side equally with a vacum gauge. Drove it for a day and no problem, Unfortunately I did not read these replies and the battery is turn off now. Boy, life is not that simple in the electronic world. BTW, Jens, Sorry to hear about your transmission problem, I hope you have solution to it. The Chassis number of my car is 85993. I don't know which month it was built. Any idea? This is a Euro model with no cats. | ||
| Jeff Edison (Euro308guy)
Junior Member Username: Euro308guy Post Number: 147 Registered: 7-2002 |
Good post Rob. | ||
| JRV (Jrvall)
Member Username: Jrvall Post Number: 550 Registered: 11-2002 |
Rob, Thanks, that makes a lot of sense. Regards, JRV | ||
| Rob Schermerhorn (Rexrcr)
Junior Member Username: Rexrcr Post Number: 93 Registered: 11-2002 |
JRV, A bit too sensitive. The density of the mercury "slows" or dampens the reaction to the air pressure pulses. Also, at least on 348 with only two throttle bodies, one is only interested in balance, as opposed to absolute pressure values, which is why we only used a U-tube manometer. I am sure one can utilize a mercury manometer set up for a 355, F40, multiple throttle, and just go for even values of two columns. An extreme example is balancing flow for a twin or triple motorcycle engine, absolutely cannot be done with a bourdon tube type gauge, the pulses are much too strong. | ||
| JRV (Jrvall)
Member Username: Jrvall Post Number: 544 Registered: 11-2002 |
>>(don't bother with vacuum gauges, doesn't work nearly as well). << Rob, I haven't tried them for this application, but why don't/won't they work ok? TIA | ||
| Rob Schermerhorn (Rexrcr)
Junior Member Username: Rexrcr Post Number: 88 Registered: 11-2002 |
Dear William, First, is this a sudden situation or the vehicle has deteriorated over time? Any recent service? If I had no history on the car, this is my approach: Connect a large U-tube mercury manometer to the intake plenum, one port on the 1-4 bank, one on the 5-8 (don't bother with vacuum gauges, doesn't work nearly as well). Disconnect the idle air speed motors electrical connector and block their ports into each plenum. Balance the airflow relative to each bank by adjusting the brass colored screw on each throttle body. Do not touch the butterfly stop screws, the throttle bodies are factory set. Monitor idle speed, should adjust to about 1000 rpm, adjust with airflow bleed, not butterfly. Ensure that the exhaust is not blocked by a bad catalyst. Measure exhaust gas content for additional clues. Reset ECU's per JRV's procedure and allow them to "relearn". Last car I could not flow balance at idle was a Challenge race car and turned out to require valve reseating. So, you could also try a leak down test to see what's up if the above does not work. | ||
| Steve (Steve)
Member Username: Steve Post Number: 273 Registered: 2-2001 |
Being a carb. guy with the 308 but have don many Jag/Chev TPI conversions this seems to be a typical FI question.I assume the 348 has a similar principle here so I would look 1st for a vaccum leak than at the IAC (idle air control) valve and next at the throttle plate setting. Normally when you start a FI car with a cold engine the CPU runs in an OPEN LOOP condition which set the various sensors allowing the car to run in a rich mode. After X seconds the CPU goes into close loop (must see water temp reach X )then it checks the O2 sensor and starts to adjust the A/F mixture.Barring the vacuum leak , I would disconnect the IAC and start it up. Engine should idle at 500-700 rpm.If it stalls then adjust the throttle screw until you get 500-700 rpm.If you get this then shut down and reconnect the IAC. Start it up and the CPU should find the correct idle speed that the CPU is programmed for. my 2 cents | ||
| billy bob (Fatbillybob)
Junior Member Username: Fatbillybob Post Number: 139 Registered: 8-2002 |
two plugs on both air meters and two plugs on the throttle position switchs. Remove clean and reconnect. Try that. Try shaking one of the plugs as the engine idles. note a change. Look for vacum leak in the bellows between the throttle and mass air flow sensor | ||
| JRV (Jrvall)
Member Username: Jrvall Post Number: 537 Registered: 11-2002 |
Have you reset the computers? Anytime a batterey is changed or goes dead, the computers need to relearn idle parameters. The computers have 'adaptive logic' chips. The procedure is: disconnect battery ground cable (not kill switch) for 1 minute, reconnect, start engine and do nothing, just let engine run, for 10 minutes. This allows computers to build new parameters. DO NOT play with throttle or A/C during this procedure. Try this first. | ||
| Jens Haller (Jh280774)
Junior Member Username: Jh280774 Post Number: 166 Registered: 9-2001 |
Hello William, Sorry that I can�t help you with this but surely someone can! If you don�t find the answer in this chat nobody knows it  I am driving a 348tb 1990 as well and encountered exactly the same problems with the ac and the window switches. Ideling is ok though. Which VIN number do you have by the way? My car was produced January 1990 and has VIN 84181. It was checked at the factory in Maranello from a certain Mr. Riccardo! Hope you will have lots of fun with your car in the future. I am having deep trouble with the transmission at the moment. Whole unit seems to be done. Really sad (and expensive!) Best wishes from Germany! Con saluti cordialissimi, Jens Haller | ||
| William Heung (William_heung)
New member Username: William_heung Post Number: 2 Registered: 7-2002 |
Dear Gang, I owned a 90-348Tb which has been good to me beside the Climate control Unit and window switches which was fixed. One of the long term on going problem that I cannot solve was idleing. The engine jumps to a healthy roar each time I crank the key and it immediately idle smoothly at 1100 rpm. Good for about 5 mins(Temp gauge almost mid way) and the engine RPM drops and the engine struggle to stay alive and eventually died. With the help of the trottle the engine start again with no problem by this time will have to nurse with the trottle to stay alive. It will go away after a while and stay good through out. It will repeat it self again with the same problem on the next cold start. Climate in Malaysia is 80-100 Deg F all year round so cold starting is not a problem. What can be wrong? Kind Regards.... William |