Lumpy running

[billh]

I've got a 1.8 140 roadsport SV (02 year on 10k miles) that's a bit of a mare in traffic, at about walking pace it's really hard to drive it smoothly. I've put up with it so far because I try and avoid traffic, but next year I'm going to be commuting in it a lot more.

 

I wondered if it was driver induced, but no matter how hard I try to be smooth and gentle, if I press the accelerator when crawling it's really jerky. Otherwise it runs brilliantly.

 

As I understand it I need to get the ECU mapped properly, and this may require fitting vernier pulleys.

 

Is this correct and will it stop the popping I get occasionally on overrun? (Cos it makes me smile every time)

 

And the next question is, where's the nearest place to Bristol to get it done and roughly how much should it cost?

[Sheds Moderator]

My car had a monumental flat spot when on/off throttle. Traced to a crushed air hose connected to the ECU pressure sensor. Yours may be something else but a session of wire wiggling with the motor running can often point up results.

[Peter Carmichael]

A Roadsport is not *mappable*, so any running issues are probably down to a sensor that has gone bad (or dodgy wiring). Definitely get it checked out. Rover garages will charge you 70 quid to plug in Testbook and tell you that everything is OK. Go to a good independent who has the test gear and if possible watch him do his work...

[billh]

Damn, there goes my excuse for an upgrade 😬

 

Thanks chaps

[old captain slow]

My 1.6 K SS does exactly the same thing. I have tested and prodded everything obvious and found nothing wrong. It has a complete dead spot between tick over and 2k rpm I'm taking it to Dave Andrews next month to get Verniers fitted. I'll see if he works any other magic on it and report back.

 

C7 CDW

[Tony C]

My 1.8, 140bhp SV did the same as yours.

 

I started by fitting vernier cam sprockets, but that interfered further with the slow-running idle because, I understand, the IACV can't handle the pulses in the plenum that arise because of the optimised cam timing.

 

So decided to fit Direct to Head Throttle Bodies (DTHTB's).

 

These require a mappable ECU, so I bought an Emerald ECU and had it mapped on Dave Walker's RR.

 

I now have a much improved idle and slow running. If you want to, you can release the clutch without touching the accelerator and the car will just trickle along. It will also respond nicely if the accelerator is depressed 😬

 

General throttle response is MUCH improved and the low rev torque is higher and the torque curve is flatter.

 

If that doesn't give you enough reasons to upgrade ...............

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

[Tony Whitley]

It might be simply the Throttle Position Sensor - £50+ from Rover or M1 7 SMW 1.4-now-1.8K Mem.No. 10376 Picture here 😬