running rough

[chimi500]

My ultra reliable tuscan that i keep telling everone about is starting to fall out with me.
I can only describe it as 'pulsing' one the motorway at 80ish and its running very uneven in traffic.
I have ccc cans that usually pop and bang a bit but thy are REALLY poping and banging now.
Its not using any oil or sounding different from the engine etc.
Any ideas, lucking at other posts i was thinking it might be the throttle boddies???

thanx carl

p.s I still love my tuscan ( just incase it reads this )

[lady topaz]

A dodgy lamda sensor on my previous Tuscan gave me very similar symptons. Being technically challenged thats all I can offer I am afraid.

Di

[yzf1070]

I would go along with Di on this one (sorry to see you leave us DI). However, I would not rule out the throttle body potentiometers......my limited knowledge on the subject of engine management is that the ECU fuel map runs in closed loop control at cruising and part open throttle conditions, during this mode the lamda sensors provide the closed loop control. At wide open throttle the ECU switches out the lamda sensors as they are not wide band, in this mode the ECU fueling is open loop control and derived solely from the programed fueling/RPM/timing map. If your car runs smoothly at wide open throttle or idle but rough at part throttle and cruising then it is more than likely Lamda sensor/s and/or throttle pot/s.

If you have an analog volt meter and you want to check the sensors out yourself.....There are 3 wires coming out of the sensors (+12V, signal +ve and signal -ve). Determine which is the 12v and the other 2 are the ones you want to connect the meter across. With the car idling the meter should fluctuate between approx 0.2 V and 0.8 V......if the sensor is no good then I would expect the meter to either show nothing like the above or very erratic feedback.

I have never tested the throttle pots, but if you again use the meter but select ohms and connect across the wires, operate the throttle full travel(engine NOT running) and observe that the resistance reading increases uniformally through out. Its important that the reading does not fall off part throttle travel or at the end of travel. Again erratic readings points towards a goosed pot.

I am by no means any expert on this and I can only offer what I have read up on the subject and tried my self with other cars, unfortunaltely I only had my Tusc for 6 months before it was sent away on holiday for serious engine repairs, but its these sort of tests I will do when I get it back to gain a base line for future such like diagnosis.

If your not comfortable with doing any of the above I would advise you to get the car checked out and repaired professionally.

Good luck and regards
G

[whitey]

pulsing at a constant speed sounds like the classic worn throttle bodies. Most of the decent independants now do uprated bodies to solve this.

Rough running in traffic and lack of popping etc sounds like it needs a decent tune etc

Would be straight to the dealers if it was my car!

cheers
Whitey

[mrmerlin]

Mine had a similar series of events recently and also has CCC's fitted. I'm afraid it was a few burnt out valves so I'd get it checked out quick if I were you.

[basil brush]

I've had similar problems resulting from a failed lambda sensor on 2 occasions. They do seem to be a weak point on Tuscans.

[rralston]

Yep - similar to above.

Could be Lamba sensors - one for each 3 cylinders front to rear, throttle pots, leads or plugs as an easy option.

Then onto throttle bodies, could be a cracked airbox actually - I had this on mine!

[custardkid]

is there not some software availible so you can plug a laptop in and check sensors, like on the Cerberas?