Help with fault please !

[TVRSJW]

Hey all worth asking ! Car (standard 4.0 1996) on cruising on light throttle car will intermittently lose power and feels like engine braking for a few seconds then all of a sudden start going again (doesn’t feel like a misfire not spluttering just no power as if engine braking ) car never cuts out and will start and idle fine and will accelerate fine can give it some and it feels fine then cruising again and it will repeat so I’ve so far

Changed plugs
Changed leads
Ran with and without plug extenders
Checked battery connections
Checked relays in footwell
Changed coil checked connections
Changed ign amp
Nothing so far has cured , wondered if anyone knows about this quite specific problem (I understand the shunting and misfire issues but never felt anything like this before ? ) feels
Like your stabbing the break pedal and throttle has no effect for that 1 or 2 seconds then kicks back in ! Cracking weekend now this 🤷🏻‍♂️😢😢

[blitzracing]

What does the tacho' do when it dies?

[TVRSJW]

Hey Blitz that’s the weird bit the tachometer seems steady was expecting to see the revs drop et but it does not seem to do this , remember old cars with pull out choke it’s like pulling choke out and it engine breaks (not engine die in ) push back in and engine pulls again

Car never cuts out dip clutch while moving and it will drop to tick over fine revs fine and pulls strong

Drove back 30 miles today and it started to engine break off and on a few times till it went from 50mph to 10mph dipped clutch and went to second gear and it just started to pull again

But funny you ask this as I was expecting to see Tacho drop and match a misfire type situation but it’s doesnt !

[ianwayne]

Perhaps the fuel pump is intermittently dropping pressure or you have a restriction in the fuel lines?

[Sardonicus]

A typical failing of the throttle pot symptom , get Rovergauge on it and have a look , but my suggested is a possibility

[thicksliced]

The air ducting to the afm started to fail on my Griffith and the inner delaminated and was flapping around and acting like a choke giving very similar symptoms.I was 100% convinced it was ignition related but was wrong again. Worth checking.

[TVRSJW]

Update : last min managed to get car over to Dom at Powers (scary drive on M6 wagons everywhere praying it was not gonna bog down on me !!!!)

Placed on his machine and came up as TPS (throttle pot) checked voltage etc and not working !

So left with them to source one and fit etc at least I know what it is now !

[Classic Chim]

Sardonicus said:

A typical failing of the throttle pot symptom , get Rovergauge on it and have a look , but my suggested is a possibility

Boom

Glad you’ve had a diagnosis O/P

Not nice motorway driving not knowing what the engine will do

Edited by Classic Chim on Tuesday 7th May 15:54

[bobfather]

I'll give you £10 for your broken TPS!!

[Sardonicus]

Classic Chim said:

Sardonicus said:

A typical failing of the throttle pot symptom , get Rovergauge on it and have a look , but my suggested is a possibility

Boom

Same symptom as mine in 2006 before Rover-gauge was widely available and another owners car since and the price when I replaced mine about £60 all in from the local LR main agent shame they not that now with Megasquirt if no ref voltage reaches the ECU (broken TPS etc) it wont start period easier to diagnosis this way however but a bh if your stuck on the side of the road with no laptop good old Lucas

Edited by Sardonicus on Tuesday 7th May 16:02

[TVRSJW]

Car back from Powers and new throttle pot fitted !

Once again thanks for all your help and suggestions , owning a Chim can be scary and frustrating sometimes when you have limited knowledge on the spanner’s !

[swisstoni]

If you are a bit rubbish at spannering (like me) Powers and Dom are one of the reasons that make TVR ownership a halfway sensible proposition.

TVR have a few excellent specialists.