shuddering at low speeds
Discussion
I've just achieved a dream and purchased a 4.2 Cerbera. It's fantastic!! When I bought the beast from a dealer they fitted a sports exhaust for me....I now wake the neighbours up at 7am every weekend...soon start to get complaints! What I find though when running slow at say 30 mph the car is quite shuddery and you need to ride the clutch or rev up to make it relatively smooth. Is this anything to do with the sports exhaust? It's great when you put the foot down and there's no problem with shuddering at high speeds. Any views?
I seem to remember the 4.2's are most happy when driven at higher revs (as compared to the 4.5s). But then, even my brand new (well, 6 months) 4.5 exhibits a tiny bit of judder at very low revs (barely noticeable, but I feel it's there). My previous 4.5 (98 one) did it up to some 2000 revs, a tune-up would cure it and it would come back over a couple of months. Maybe your dealer can tweak it a little?
Oh well, you just have to keep the revs up then. "Honestly officer, it just doesn't drive right if I go slow...."
Oh well, you just have to keep the revs up then. "Honestly officer, it just doesn't drive right if I go slow...."
Sorry if I'm repeating myself in these emails as I'm new to all this. Must say though it's impressive with all the support and enthusiasm out there. As for the shuddering, I'm probably discribing it wrong, given that it's a Sport exhaust that's fitted, it's more like the car stuters in tune with the popping of the exhaust. I've only had the car a week so perhaps it's me having to get use to having to keep the revs up a low speeds!
quote:
I'm probably discribing it wrong, given that it's a Sport exhaust that's fitted, it's more like the car stuters in tune with the popping of the exhaust. I've only had the car a week so perhaps it's me having to get use to having to keep the revs up a low speeds!
Are you saying that the exhaust pops whilst its accelerating/revving, or just on the overun?
quote:
When you are holding it at about 30 mph it feels as though it is spluttering in tune with the sport exhaust. This is the best way I can describe it. Its not a big problem
This isnt gospel, but ive always been under the assumption that an exhaust should only pop and bang on the overun. If it does it whilst the throttle is open doesnt it means that the car isnt running properly. I had a car that did this on a power run at a RR, the operator said it was ignition breakdown.
Could be that your fuel maps need to be reloaded. Take it to a TVR dealer and ask him to reset the ECU. See if that cures the problem. They will probably do it for free. It takes about 10 minutes, 7 of which are spent getting to the ECU behind the panel at the front of the passenger footwell and removing the four allen screws to get to the innards.
Then they hook up the laptop, switch the ignition on, and after clearing all the faults (which might also give you a clue as to what the problem is), they just click on the Reset ECU button. If this fixes it, and the problem returns later, you need to contact the factory and ask for an updated fuel map chip.
Regards,
Faisal.
Then they hook up the laptop, switch the ignition on, and after clearing all the faults (which might also give you a clue as to what the problem is), they just click on the Reset ECU button. If this fixes it, and the problem returns later, you need to contact the factory and ask for an updated fuel map chip.
Regards,
Faisal.
Sounds like the fuelmapping to me. Your ECU will be mapped to the old exhaust characteristics. It's probably not expecting the exhaust gas to be so free flowing at low revs, so is holding back the fuel. Result... you run lean and get a small stuttering misfire.
All it needs is the chip remapped.
Just my guess.
Domster
All it needs is the chip remapped.
Just my guess.
Domster
Gassing Station | Cerbera | Top of Page | What's New | My Stuff