J

jhepb1

New Member

• Mar 26, 2011

• #1

Hi, I have a Series ii with a Rover V8 EFI engine. The engine code on the block says it's a TVR350i unit (!) with 9.75 cr. The problem is that it starts fine but once hot, the idle cycles up and down, like someone was tapping the accelerator pedal rapidly. On the road, it backfires and surges, sometimes cutting out. I changed the AFM and this solved the problem, then it came back after a couple of days. I refitted the old AFM and the same thing happened - no more problems for a couple of days then they returned. Refitting the new AFM had the same effect. I suspect the ECU but does anyone recognise this issue before I spend more money?

Please help!

Jim

 

G-man

BBQ king

• Mar 26, 2011

• #2

check for airleaks

 

discool

Well-Known Member

• Mar 26, 2011

• #3

When i had my TVR many years ago I had to replace the ecu's coolent temp sensor the car ok when cold but was undrivable when hot with the spluttering & reving engine in traffic.
I've never had the problem with my RRC or now the disco.

 

J

jhepb1

New Member

• Mar 26, 2011

• #4

Ok, thanks. I'll try these.

 

vougese39

Well-Known Member

• Mar 31, 2011

• #5

Get the ecu fault read just swapping parts will not clear the faults.
As it is surging could be poor connections at Afm or temp sensor or base idle not set.
Have you got the road speed transducer fitted?

 

J

jhepb1

New Member

• Apr 1, 2011

• #6

Don't know about the transducer but I've had the LR since last summer and this problem only started in December - just as the weather got really cold here in Devon. I've ordered a new temp sensor and thermostat (it also runs hot - forgot to mention that earlier) because apparently the sensor can affect idling and mixture (and the hot running can't be helping, I suppose).
Once they're on, I give you an update. In the meantime, thanks for your posting.
Jim

 

J

jhepb1

New Member

• Apr 18, 2011

• #7

Ok, I've now replaced the water temperature sensor and the thermostat. The engine has been running hot (needle just below red on the gauge) so I replaced the 82 degree stat with a 74 degree one. I also retarded the timing a bit and reset the mixture screw on the AFM (now 2 and a half turns back from fully in). All now seems well. No more surging and the idle's much smoother.
Not sure what the root of the problem was. Maybe the hot running made the sensor send readings to the ecu which caused the idle to hunt. Any ideas?

 

J

jhepb1

New Member

• Apr 24, 2011

• #8

The problem returned after a couple of days so I accepted defeat and bought another ECU. The problem went away again so I refitted the old ECU. The problem came back. So, it was the ECU after all. No surprise, I suppose.
Thanks to all who offered their ideas and advice.