Help with slight misfire !

[QBee]

Pops and bangs are a product of a lean mixture.
So we are looking for what is causing the mixture to be too lean.

[Penelope Stopit]

Have you checked the ignition coil and amplifier supply voltage?

If answer is no

Do you know the correct method of checking it while under ignition coil load?

[blitzracing]

QBee said:

Pops and bangs are a product of a lean mixture.
So we are looking for what is causing the mixture to be too lean.

Pops and bangs on the over run are lean mixture- if you get them under load you are either very lean, or the ignition timing is erratic- as in separate to a misfire. The problem you have is your odd acceleration could simply be the fault coming and going, like dropping a cylinder that then decides to fire. So far the diagnosis is has been by mostly swapping parts and not an effective way of doing things really. You need to do basic strobe checks for ignition timing / advance and possible timing scatter. You need to get a passenger to look at the short term trim in RoverGauge as you go up through the RPM to see what the mixture is doing and see if its moving to either 100% adding or removing fuel and sticking there when the fault is present.

[Steve_D]

I've just had a quick scan back through this and can't see mention of the timing being checked/tested.
Pops and bangs could be lean mix but could also be timing.
What is the timing set to and does it change with both revs and vacuum?
Have seen 2 dizzy here where the bob weights have broken up (old age).

Steve

[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 !

[blitzracing]

If your call LandRover dealer is able to deal with the Range RoverClassic, then you should be OK as its all pretty basic. TBH if they cant find this fault with or without RoverGauge they should not be a garage! A big shiny dealing selling just new stuff may not have the skills as they just expect to plug in an OBD reader and get an answer.

[Bavarian]

Do you have the new dizzy cap from Distributor Doctor as well? I bought there arm and cap. Arm was fine, but cap did not fit as my original one. it was more loose. Distributor Doctor told me, that is normal ... But combination of old cap and new arm is now much better ;-)

[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 !!

[blitzracing]

Odd that- its fine at idle in the screenshot of RoverGauge, so would not need adjusting unless the resistance sweep is odd or its going open circuit at some point in its travel, in which case it should throw an AFM / TP mismatch error. Any more accurate details of what was actually wrong with the TP?