Help with slight misfire !

[TVRSJW]

Ok car ran great (new plugs and lead etc last year and done about 6-7K ) no shunting and very smooth for last 6-7K miles , then last night went for a run out and on very light throttle in any gear it “flutters / hesitates but it’s very very slight , needle on rev counter does not even move !! as soon as you accelerate it’s fine and pulls well , but.....it pops and bangs a lot more now On decel but is fully decatted) But more than normal

So today done following

Plugged into rover gauge no fault codes and all looked ok (to me anyway don’t know how to read the the trims etc )

Cleaned stepper motor
New plugs BPR6ES checked gap
New leads
New quality Doctor distributor Rotor arm (old one the brass arm was loose )
Cap

And general check on everything pipes etc

Test drive after each alteration end result is it feels a bit better but still not as smooth as it was !?!

(Always fill same garage with super unleaded so no change there either )

Any ideas / help ? (Pic of Rover gauge screen when it was at operating temp if it helps ?)

[TVRSJW]

No I use a tanks worth most weeks so very fresh !

No extenders were junked last year when I changed the plugs back then and it ran very smooth till now !

[TVRSJW]

Get thanks

Yes I test drive after each component fitted so I would know what was at fault , all parts are from known sources like the NGK plugs from motor factor with direct account with NGK etc I’m careful to buy parts that are known supply , the rotor was from Distributor doctor also known for good quality etc

I have a new coil (always had new spare) and I have an IGN Amp (Quality used from my old Chim and some dialetic grease) again known to work so will fit them And see ???

It’s had new injectors in the last five years ,only thing then would be Fuel filter ? Or some kind of vac or intake leak but can’t see anything obvious and not touch anything to induce an issue

After that I’m stumped ?

[TVRSJW]

No not using the Beru extenders , and the rotor I fitted was a quality part from Distributor Doctor , the one I took out was with the rivet Type and was loose but new bonded rotor arm never made any difference (the one I took out was worse condition)

Will put in new coil and amp and temp ECU sender and if don’t cure then off the specialist I think !

[TVRSJW]

Yes starting to think it’s the throttle pot (as above and all new parts fitted bow to include ECU temp sender) still not cured

I had an ACT TPS fitted about 10K ago (16 months ago) and car has ran great till now called my TVR specialist but he is stacked out with work so can’t get in at present

I’m also told a test meter can pass a faulty TPS and really needs an oscilloscope to test ?

[TVRSJW]

So if I look at throttle position % on rover gauge screen “bar goes green” look to that was smoothness ? Will also test with multimeter

If you rev it (stationary) between 1600-2200rpm “ish” at a constant to hold revs you can hear it just very slightly missing like little hiccup buts it random

[TVRSJW]

Ok so far....

No faults code checked twice
ECU reset - didn’t cure
New plugs - didn’t cure
New leads - didn’t cure
New cap and bonded quality rotor arm - did t cure
New ECU temp sender - didn’t cure
Stepper cleaned and checked - didn’t cure
Fitted coil/amp - helped a lot smooth things out but not 100% as it was before the issue , it’s still not happy and....it’s decatted so pops and bangs but the pops and bangs are on overtime now !

Took it out yesterday and today and noticed that when I boot it it accelerates and with foot at constant accelerating it all of sudden feels like a “turbo” has kicked in and pulls harder much harder but I’ve not moved my foot and throttle did it 3 times today ????

[TVRSJW]

Thanks yes pops and bangs only when off the throttle , not when on throttle

Agreed it needs the timings checked etc was hoping to get it into my nearest specialist to do all the needed checks but called last week and there too busy at present and would call me if they get a slot !

I can only use RG to basics like fault codes not a clue to to read fuel trims etc and now at the stage of thinking of finding a good local garage to check things it’s just I don’t know any that could do it ? As they wouldn’t have RG or even know how to use mine ? Yes they can check timing but need somewhere that can solve it with all the needed equipment as can’t wait for months for my specialist to book me in !

There is a garage in my town (Tamworth) that is a Land Rover specialist and must know the RV8 ? I just don’t want to be messed about billed only for issues to remain!

I can change most parts but ain’t no tech and have a 1/4 socket set and some hammers !!!! So resistance checks (not got a multimeter or used one ! ) and timing strobes is not something I could do , it’s just finding a garage I trust that can that’s local to be able to take there and go back and collect etc

Tbh bit disappointed couldn’t get it in to nearest TVR specialist but understand if there stacked out there stacked out !

I’m just trying to resolve what I can within my ability’s (which are limited lol...) and keep the old gal going ! But I’m becoming the butt of all the TVR jokes with my petrolhead mates !

[TVRSJW]

Progress update - it was Throttle pot adjustment !

After changing most of the ignition system in an attempt to fix including AFM , an expert has fixed it and it needed TPS adjustment , and that’s with an ACT TPS fitted last year !

Just glad it has been sorted thanks to all that offered advice !!