400 HC HAVE HICCUPS AT LOW REVS

[Christian3000s]

Hi Guys, just replaced the 3000s by a 1994 400 HC. Stunning car, but it have some hiccups at low revs (warm engine or not), for example at cruising speed when under 2000 rpm, like if the car would be runned with 5th gear engaged when you should drive it with 3th. Any set up needed, or is normal with this kind of engine?

[zed4]

Search for shunting. It is common with these engines. You can try certain things to replace it, I think a common mod is to fit a smoothbore induction hose kit, make sure the stepper motor is nice and clean and working correctly, make sure the idle control screw is set correctly, maybe reset the ECU too.

[DastardlyDick]

Hi - I have a 400HC and it drives very smoothly at low revs. It's absolutely standard and, surprisingly, still on the original camshaft after 85,000 miles! I would suggest that you keep your plugs/extenders/rotor arm/dizzie cap/leads etc in top condition though - and the stepper motor nice and clean of course!

[swisstoni]

I had a 400HC from new. There should be no shunting at any revs. Mine did eventually develop some shunting at the revs you describe but I never cured the problem before I sold the car. It appeared shortly after an expensive TVR Main Dealer service as I remember!

The problem seemed electrical to me. Very frustrating - I hope you get to the bottom of it soon.