Lumpy 450 - is it TADTS ?
Discussion
Fellow 450's - is the 450 naturally a lumpy drive.
Mine is much better since I bought it a year ago having changed plugs, dizzy cap, rotor, leads, coil and removed vacuum advance but I wouldn't call it smooth at low speeds - no problem when wanting performance :)
Having driven a friends 400 it was soooo much smoother
Can I get my 450 to be the same - its only done 16k miles - any suggestions on other components to check ?
thanks
Chris
Mine is much better since I bought it a year ago having changed plugs, dizzy cap, rotor, leads, coil and removed vacuum advance but I wouldn't call it smooth at low speeds - no problem when wanting performance :)
Having driven a friends 400 it was soooo much smoother
Can I get my 450 to be the same - its only done 16k miles - any suggestions on other components to check ?
thanks
Chris
I'd be interested to hear other views on this: my 450 is the same (it had 16,000 miles on it in April when I bought it, now has 19,000 miles on it). It was slightly better after a major service but is now pretty much the same.
At full chat it is fine. Curiously on Shell Optimax it runs much worse, whilst on normal 95 RON fuels it seems no different except the tickover can drop so low it sometimes stalls, but there is no pinking, even at hard acceleration from low revs in high gears.
At full chat it is fine. Curiously on Shell Optimax it runs much worse, whilst on normal 95 RON fuels it seems no different except the tickover can drop so low it sometimes stalls, but there is no pinking, even at hard acceleration from low revs in high gears.
Mine was very lumpy at low speeds, put on some magnacore leads and spark plug extension thingies (the technical name) and saw an improvement then it has got a lot better since I replaced the rotor arm and dizzy cap.
I'll see what it's like after it has it's service next week, with all it's new shiney plugs. I think a new bosch coil is on the shopping list to finish things off
Mine seems to need the igition system in top condition...
Rich
I'll see what it's like after it has it's service next week, with all it's new shiney plugs. I think a new bosch coil is on the shopping list to finish things off
Mine seems to need the igition system in top condition...
Rich
I have just received a new distributor cap and rotor arm and the Magnecor KV85 (red plug leads) and plug extenders should be here by the weekend. Apart from the plug leads I'm working on the basis that even if the cheap parts I'm replacing are not the problem, at least I then have a spare.
Stepper motor is as clean as a whistle, as is its seat in the plenum, but how would you know it was not working, other than the ECU showing error 48? Run the engine with it visible and the hole sealed?
Someone at the regional meeting suggested the airflow meter might be faulty but, at £200 I'd rather replace the cheap stuff first!
Stepper motor is as clean as a whistle, as is its seat in the plenum, but how would you know it was not working, other than the ECU showing error 48? Run the engine with it visible and the hole sealed?
Someone at the regional meeting suggested the airflow meter might be faulty but, at £200 I'd rather replace the cheap stuff first!
Thanks for the feedback - I should have mentioned that the stepper motor is as clean as a whistle and I also have new plug extenders as well as leads (standard rover v8)
If some cars are nice and smooth I at least know its possible to reach the desired result.
When I bought the car after the test drive the garage said they had found an "air leak" which was making the car jerky - which they fixed. Other than vacuum connection where else could air leak occur ?
Car is due a service shortly so will ensure timing is checked
I have also heard that Mark Adams does a chip which helps with the drivability at low revs
cheers
Chris
If some cars are nice and smooth I at least know its possible to reach the desired result.
When I bought the car after the test drive the garage said they had found an "air leak" which was making the car jerky - which they fixed. Other than vacuum connection where else could air leak occur ?
Car is due a service shortly so will ensure timing is checked
I have also heard that Mark Adams does a chip which helps with the drivability at low revs
cheers
Chris
The 450 is renowned as being the smoothest of all the tvr v8's due to the fact it is bassically a standard 4.6 range rover engine with a cam in it, you could disconnect the vacum advance pipe that will make it run much smoother low down, these engines do eat cams quite quickly so a cam check up may be worth doing.
v8 racing said:
these engines do eat cams quite quickly so a cam check up may be worth doing.
That's interesting, Rob, I mentioned the cam at service: they said it sounded ok, but I think it sounds awful. There's a very definite rattle when it's hot. There's also a faint top-end rattle (from both rocker shafts, but more noticeable on the off-side), which I put down to being related to the camshaft.
It's gonna have to come out....
My 450 was running lumpy at about 2k rpm with light throttle. It's been serviced recently and is now running better (still not as smooth as a baby's backside tho). Incidentally, the stepper was cleaned (as well as new plugs of course) so this might have helped matters. It still goes like a rocket tho', so not that fussed.
Glad you posted this thread - puts my mind at rest that some others are doing similar things.
Maybe a set of leads would help - not sure when they were last changed.
Rich
edited for too many entries of the lazy word 'tho'
>> Edited by r.mojo on Thursday 25th August 21:12
Glad you posted this thread - puts my mind at rest that some others are doing similar things.
Maybe a set of leads would help - not sure when they were last changed.
Rich
edited for too many entries of the lazy word 'tho'
>> Edited by r.mojo on Thursday 25th August 21:12
Apologies to Chris 'TVR+Bubblecar' first (for butting in on your thread), but hopefully some of it will benefit you. 
I've replaced the original (six year old) plug leads & extenders, distributor cap and rotor arm. It's pleasing to report that there is a difference, albeit minor. At least I know I now have some good working spares of each.
The stepper motor works too: I took it out and started the engine for a couple of seconds. The plenum, as expected, sucked in a huge amount of air through the stepper motor housing and the motor tried to close the gap!
I've blasted the vacuum advance tube on the compressor. Whilst it was obviously not blocked, by design it is a fairly thin, restricted thing. It would certainly still do its job, but maybe a little slowly? There's been a few threads suggesting removing it altogether to make the engine run smoother at tickover, but I can't see what the benefit is. In fact, I can only imagine it being a detriment to running the engine at speed.
The next cheapest thing is to either replace the throttle pot. (or buy an oscilloscope to test it), or stick it on the rolling road to see if anything looks marginal. After that we're into air mass meter territory.
I've replaced the original (six year old) plug leads & extenders, distributor cap and rotor arm. It's pleasing to report that there is a difference, albeit minor. At least I know I now have some good working spares of each. The stepper motor works too: I took it out and started the engine for a couple of seconds. The plenum, as expected, sucked in a huge amount of air through the stepper motor housing and the motor tried to close the gap!
I've blasted the vacuum advance tube on the compressor. Whilst it was obviously not blocked, by design it is a fairly thin, restricted thing. It would certainly still do its job, but maybe a little slowly? There's been a few threads suggesting removing it altogether to make the engine run smoother at tickover, but I can't see what the benefit is. In fact, I can only imagine it being a detriment to running the engine at speed.
The next cheapest thing is to either replace the throttle pot. (or buy an oscilloscope to test it), or stick it on the rolling road to see if anything looks marginal. After that we're into air mass meter territory.
Hi dave the main reason you disconnect the vacum advance is basicaly to reduce a given rpm against the throttle angle, you then increase the throttle angle to get back to the same rpm but by doing this you have much higher air speed through the ports hence better mixing and much smoother running, an omex 150 system would cure nearly all the low rpm rough running on the rover v8 tivs. Rob
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