Rough running and poor start-up?

[griff59]

Recently my Griff has become very difficult to start, the rev counter is all over the place and the engine dies if I put my foot on the throttle ad it won't run long enough to warm up.
I've checked electrical connections in the engine bay, sensors, relays, HT leads, plugs, all seem fine and secure.
I'm going to have a look at the battery compartment today as it's a bit of a mess in there, something may have been disturbed. This is really strange, I drove it home from the garage and all was fine, it's intermittent, but even on a good day it doesn't sound right, like it's slightly miss-firing.
The car is off to the garage to get this sorted, but not for a couple of weeks, so any ideas about this would be much appreciated.

Edited by griff59 on Tuesday 30th April 08:56

Edited by griff59 on Tuesday 30th April 08:59

[Ducati0]

Stepper motor leads come adrift ? Or may need cleaning ? This will affect the cold start / running, but think there are a few on here with better knowledge than me. But might be a good place to start.

[griff59]

Ducati0 said:

Stepper motor leads come adrift ? Or may need cleaning ? This will affect the cold start / running, but think there are a few on here with better knowledge than me. But might be a good place to start.

Thanks for this.
The car took a long time to warm up yesterday, but I managed it, after that it actually drove very well, it's an intermittent thing, unfortunately.
I just thought of something important, when I picked up the car the fuel guage was on 0, I never let it go down to below a quarter of a tank, I filled it up with £10 of regular not super just to get me home. Yesterday, after I filled it up with super it seemed to improve, I'm wondering if there is some gunge in the bottom of the tank that's polluted the fuel system?

Edited by griff59 on Wednesday 1st May 09:53

Edited by griff59 on Wednesday 1st May 09:54

[Ducati0]

griff59 said:

Thanks for this.
The car took a long time to warm up yesterday, but I managed it, after that it actually drove very well, it's an intermittent thing, unfortunately.
I just thought of something important, when I picked up the car the fuel guage was on 0, I never let it go down to below a quarter of a tank, I filled it up with £10 of regular not super just to get me home. Yesterday, after I filled it up with super it seemed to improve, I'm wondering if there is some gunge in the bottom of the tank that's polluted the fuel system?

Edited by griff59 on Wednesday 1st May 09:53

Edited by griff59 on Wednesday 1st May 09:54

My 4.3 pre-cat Griff does not run great on 95 Ron and will really hold back when accelerating. So where possible I only use super unleaded. They are quite sensitive to different fuels.

[Penelope Stopit]

If the rev counter is rapidly moving from one position to another rather than going up and down matching engine revs there is a very good chance that an electrical fault is causing this

[neutral 3]

Sounds like the fuel filter needs changing.
My late 500, ran noticeably better, with a new filter fitted. And whilst the filter is being changed, check the fuel hoses for cracks and their jubilee clips for corrosion and also the connectors to the pump for corrosion.

[Classic Chim]

Penelope Stopit said:

If the rev counter is rapidly moving from one position to another rather than going up and down matching engine revs there is a very good chance that an electrical fault is causing this

Can you confirm if this is what’s happening,, if so ^^^^^^^^ this.
Probably a temperamental stepper that’s now working fine.
Water temp sensor is also known to fail and cause poor running,, you mention it took awhile to warm up?
Saying that your gauge reading is not from that sensor so hard to diagnose without some Rovergauge readings.

[neutral 3]

Classic Chim said:

Can you confirm if this is what’s happening,, if so ^^^^^^^^ this.
Probably a temperamental stepper that’s now working fine.
Water temp sensor is also known to fail and cause poor running,, you mention it took awhile to warm up?
Saying that your gauge reading is not from that sensor so hard to diagnose without some Rovergauge readings.

Do you mean the temp gauge sender unit can fail and cause poor running ?
What are the symtoms ?

[griff59]

Classic Chim said:

Can you confirm if this is what’s happening,, if so ^^^^^^^^ this.
Probably a temperamental stepper that’s now working fine.
Water temp sensor is also known to fail and cause poor running,, you mention it took awhile to warm up?
Saying that your gauge reading is not from that sensor so hard to diagnose without some Rovergauge readings.

OK, it's different every time I start it, last time it ticked over on the key, and went to about 900 revs, then sounded like it was going to stall, then the revs shot back up to 900 this happened about three times, even after the engine warmed up. The gauges are all reading correctly, and the rev counter matches the engine speed.
Two relays in the battery compartment were replaced at the last service, I had the old ones and changed them over, these are cans about an inch square, the new ones were brown plastic,I don't know what these are, but after a couple of starts things did seem to improve after I put the old ones back???

[griff59]

Problem cured, it was the wires from the injector fuel sensor to the ECU, three wires had to be replaced and a new loom made up. All running fine, keep a look-out folks if you have similar symptoms to mine.

[Ducati0]

What had actually happened to the wires ?

[Ducati0]

Ducati0 said:

What had actually happened to the wires, also how was that diagnosed ?

[griff59]

Ducati0 said:

What had actually happened to the wires ?

My local TVR specialist did the work, I didn't go into detail about the actual condition of the wires, he did mention heat damage, maybe insulation breakdown, and shorting.
It was intermittent, maybe due to the wiring moving about, and heat, as it seemed to get worse the longer I drove the car, eventually it would just stall. However, after rebuilding this part of the loom all seems fine.