Hi all I have a 1991 Ferrari 348 TS European Spec. Recently the car has developed a judder when accelerating at low speed in a high gear. So for example, if rpm is around 2500rpm in third gear and I squeeze the accelerator pedal, the car judders rapidly until the revs climb past 4000rpm and then it clears up and then revs happily to the redline. Car is running fine apart from this. . The car has covered around 30,000 miles, the CATs have been replaced with straight through pipes. The problem started after the car was left without starting for some months during which the battery went dead. I had the battery recharged and it starts fine. I performed the reset by disconnecting the battery for 10 minutes and then letting it idle for 20 minutes. However no change. Does this sound like an electrical (ignition) problem or a fueling one? All help greatly appreciated. Thanks
No not to me, it sounds mechanical, gearbox remotely but likely some other drive line issue loose axle, loose brake rotor etc but as sjd mentions check the cv boots and see if any are torn vibrations are a common symptom with cv joins at eol. Good luck!
OK will check CV joints, loose axle and brake rotors. However if it is the CV joint, wouldn't it do it all the time? Why only under load in a high gear? Thanks for the advice.
depends on load and rpm, same with warped rotors only notice it at certain rpm's for example. Not saying it is cv mind you just saying judders is often mechanical unless judder is not the right word and you mean hesitate or something of course.
Skipping under load (especially lower RPM) is most likely secondary ignition. Usually problem gets worse when its damp out. I would check coils, plus and wires, and spray the with a light water mist and see if it gets worse.
So I checked the axles with the car on a 2 post lift. The axle boots were in place and there wasn't any circular play. I understand to check them thoroughly it would require removal. The engine mounts seem very flat and could well be totally finished, could this really be the problem? I checked the resistance across the MAF as directed in my348.com and both had a resistance of 382ohm (my 348.com states factory value is 383ohms). Then I checked the spark plugs, they are relatively new and clean. If the problem is a misfire, then this is only happening under load so that is why the spark plugs are not fluffed. I cleaned all the connectors to the TPS, MAF, etc... None of this had any affect. Does anyone know how to get the error codes from the CPU's without a specific scanner? Thanks
A somewhat weak spark would cause misfire at lower revs and while trying to accelerate but will be fine at higher revs. If during the judder you also feel that the engine runs with lower power, then the ignition is probably the suspect. I would next try with a new ignition coil, one side then the other. The coils are Bosch 0 221 503 407, used on many other cars, so they are cheap (plenty on Ebay, $50-60).
Good point, will replace the fuel and see what happens. If not this then will try cleaning the injectors.
Tried pulling up the handbrake and then releasing the clutch with between 1500-2500 rpm. I was hoping to mimic the load conditions are see if there is any misfire. However under these conditions there was no vibration/judder! Does this mean it is more likely to something to do with the axles?
When I hear judder I think mechanical... clutch, gearbox, axles, cv, warped rotors etc to distinguish from a mis-fire or timing/fuel/spark issue which affects inline acceleration or causes lurching. Perhaps clarify if you mean judder or lurching. Describing it inaccurately is akin to describing chest pain as stabbing when you bend when it is actually your knee that hurts when you bend. lurching - make an abrupt, unsteady, uncontrolled movement or series of movements; stagger judder - especially of something mechanical) shake and vibrate rapidly and with force
It is easy to determine whether it is engine or transmission: if the judder appears within about the same rpm range in 3rd, 4th and 5th gear, then it is the engine; otherwise it is the transmission (if the judder appears only within certain speed range).
Anybody have the part number for the CV joint? Tried searching for it on the internet but didn't have any luck. Maybe it's called something different??? Any a precaution I took the axles of just to check them and there was a little play in one of the CV joints. Thought I'd fix this anyway.
Also, I retro fitted the 'check engine' bulbs to the dashboard to see if I get any CELs that would turn the warning lights on. However this does not happen. I know they are working because if I disconnect the TPS, they light up immediately.
Tried swapping the axles left to right now This is going to be a little hard to differentiate? The feeling is akin to driving over metal grating, one can feel it even in the steering wheel! It is less pronounced in the lower gears and more in the higher gears. Once that section of the RPM is over the car then is perfect upto the redline. The engine note when this is happening does not seem right, although again due to the aftermarket exhaust it is a little tricky to say definitively. Using a gas analyser one bank is running slightly leaner than the other. However the resistance value of the MAF are both identical with the engine off. Also the TPS values seem to be correct. Could a bad O2 sensor cause this problem? Any way to check an O2 sensor? Thanks
So, it is engine (rpm) related, not transmission. Misfiring on a couple of cylinders will cause the kind of judder you described (running over metal grating). The potentiometers on the MAF-s (the CO screws) are set both at 383 Ohm only as a starting point. Then, they are used to fine tune the two banks, i.e. make them equal which will probably result in the two potentiometers having somewhat different values. Since you have a gas analyser, make both banks equal. The CO screws (potentiometers) on the MAF-s are actually not connected to the MAF's circuitry in any way; they are connected only to the ECU-s and are used to trim the mixture. Why are they inside the MAF-s? - just for convenience.
OK Great advice. Will do as you describe. Two things I was able to work out yesterday. One was that one of the ignition leads had twice the resistance of the others (12kOhms vs 6kOhms for the rest). Also I have a leak in the tappet cover gasket at the front of the engine. This has resulted in oil working its way down and the crank sensor was quite dirty. Will clean this and change the lead, then balance the two banks.
Eurospares has all the diagrams so you can find the part number that way; but if your ordering new OEM I usually order from maranello (ferrariparts) as they are much quicker but there website is not as good for 348s. They are very helpful on the phone as well.
