Sudden rough running

[Alex10391]

Hi all, had an odd issue out of the blue last night.

Drove car to get some fuel (3 miles or so), running fine, went to fire back up and it spluttered into life (just) after a long crank, cut out and then when restarted, it could barely idle, requiring a constant light throttle to keep it going.

Got it back home by which point it would hold idle but the idle now seems lumpier than usual, hovering around 800-900rpm whereas normally it holds steady at 900rpm. It also smells rich and felt sluggish on the way back.

Prior to this, last weekend I did over 150 miles with no issue and it was driving perfectly.

A few weeks back I did have new leads (with ceramic ends), distributor cap and rotor arm at Sportmotive among other works, after which it was driving better than ever.

So can’t think what’s triggered this sudden issue - welcome any thoughts?

Thanks

[nawarne]

Hi Alex - firstly, it's very hard to diagnose the issue you're asking about without seeing and listening to the car.

Personally, I'd go through the HT system to the plugs. You say several components were changed recently? I'd make sure all the items you listed were still well 'seated'. Maybe in a dark garage, look for arcing around the dissy cap, plug leads?
Next, I'd be looking at security of connections to the coolant temp' sensor/other inputs to the ECU.

Best of all is to find someone local (are you a TVRCC member?) with Rovergauge and hook it up to your car. The readout from this diagnostic will give you a much more focused area of where to look. Without this guide, you'll struggle to pinpoint where the fault lies.

Nick

[DVR V8]

A lot of problems like this have been due to Chinese patterned rotor arms. Have you kept the original lucas one.

[Andy70]

when my cars have ever had symptoms like that it generally means its down a cylinder, so i just pull off lead at a time and replace it and move to the next while its ticking over to see if it drops more, if you get to one and it runs the same, that would be the dodgy one, just an idea?

[Mutley00]

DVR V8 said:

A lot of problems like this have been due to Chinese patterned rotor arms. Have you kept the original lucas one.

I wouldn't go anywhere else than this for mine https://distributordoctor.com/

[DVR V8]

Mutley00 said:

DVR V8 said:

A lot of problems like this have been due to Chinese patterned rotor arms. Have you kept the original lucas one.

I wouldn't go anywhere else than this for mine https://distributordoctor.com/

Absolutely agree if you find a excellent replacement. Suggested this as i had the same issue some 15 years ago. An independent fitted and aftermarket one. Ran OK for a week then went very sluggish. Second week failed to start. Put the lucas one back in and ran sweet. Didn't mention leads or plugs as mine runs fine on 7 cylinders. There is a reason why some are £4.99 and the original ones were £20 to £25.

[Alex10391]

Great tips thank you guys. Just found the sudden switch from driving and running fine to not, following a restart baffling. Will try the rotor arm first since it’s a relatively easy first place to start.

Edited by Alex10391 on Monday 14th April 06:57

[Fez887]

Try removing the extenders if you have then, and fitting socks…

[Alex10391]

Update: ordered a new rotor arm from distributor doctor, as advised. Fitted it last night, fired up this evening and it runs and drives perfectly again. Result!

[Belle427]

Dont overlook the cap either, im not sure what the distributor doctors are like but thats probably where i would head as most of the aftermarket junk is poor fitment wise.