Intermittent random hesitation/dash warning lights on

[kiloran]

Wondering where to start looking for this issue. Car has been in use regularly over lockdown so these aren't due to it standing, not getting a long run, stale fuel, etc.

Issues are as follows:

Occasionally a slight hesitation/stumble that can be driven through. Usually when running on a steady throttle at 30/40mph. Fine under acceleration, fine at motorway/dual carriageway speeds.

A couple of times I've had the lambda sensor light flash briefly

On two occasions it's cut out/stalled completely running up to a quicker than expected stop (blooming wildlife!). Restarted easily both times

ABS light randomly flickers and lights but doesn't stay on (caveat, this car has had ABS issues in the past which have been resolved by pulling the fuse on top of the ABS relay). This ABS light issue is definitely more prevalent than usual though.

For most of my time with the car I have found the engine idle to be a bit temperamental. On short runs it will carry on running at high idle when stationary and traffic lights/roundabouts etc, even when fully warmed up. Switching it off and restarting always resolves that. Once it's at normal idle I do get some occasional brief periods of bouncing idle. There's a small coolant leak I need to track down, is coolant temperature used by the fuel injection ECU to set idle speed? Car's not overheating, temp gauge is rock solid where it should be.

It might be coincidence/chicken and egg but all this started when I accidentally "bounced" the engine. By which I mean I stopped, turned the ignition off, and too quickly turned the key back to the position where the full beam was still on at which point the engine "caught" and self-started (a bit like diesel run-on I guess). On the run home after that (around 10 miles on 30/40mph roads) it ran very lumpy, almost like it was in limp-home mode which I assume it doesn't have because it's a simple car unencumbered by expensive electronics. Down on power, stumbling, poor acceleration.

Parked up and left it, it was fine next morning but since then there have been these episodes of stumbling and random dash lights. The lambda light isn't permanently lit so I'd imagine there aren't any codes stored? I've got the slightly later diagnostics connectors in the engine bay but not checked for any codes yet.

Where should I start looking?

[Laird Scooby]

Originally Posted by kiloran

Wondering where to start looking for this issue. Car has been in use regularly over lockdown so these aren't due to it standing, not getting a long run, stale fuel, etc.

Issues are as follows:

Occasionally a slight hesitation/stumble that can be driven through. Usually when running on a steady throttle at 30/40mph. Fine under acceleration, fine at motorway/dual carriageway speeds.

A couple of times I've had the lambda sensor light flash briefly

On two occasions it's cut out/stalled completely running up to a quicker than expected stop (blooming wildlife!). Restarted easily both times

ABS light randomly flickers and lights but doesn't stay on (caveat, this car has had ABS issues in the past which have been resolved by pulling the fuse on top of the ABS relay). This ABS light issue is definitely more prevalent than usual though.

For most of my time with the car I have found the engine idle to be a bit temperamental. On short runs it will carry on running at high idle when stationary and traffic lights/roundabouts etc, even when fully warmed up. Switching it off and restarting always resolves that. Once it's at normal idle I do get some occasional brief periods of bouncing idle. There's a small coolant leak I need to track down, is coolant temperature used by the fuel injection ECU to set idle speed? Car's not overheating, temp gauge is rock solid where it should be.

It might be coincidence/chicken and egg but all this started when I accidentally "bounced" the engine. By which I mean I stopped, turned the ignition off, and too quickly turned the key back to the position where the full beam was still on at which point the engine "caught" and self-started (a bit like diesel run-on I guess). On the run home after that (around 10 miles on 30/40mph roads) it ran very lumpy, almost like it was in limp-home mode which I assume it doesn't have because it's a simple car unencumbered by expensive electronics. Down on power, stumbling, poor acceleration.

Parked up and left it, it was fine next morning but since then there have been these episodes of stumbling and random dash lights. The lambda light isn't permanently lit so I'd imagine there aren't any codes stored? I've got the slightly later diagnostics connectors in the engine bay but not checked for any codes yet.

Where should I start looking?

What engine and fuel system have you got? It sounds very much alternator related, when you first get in and turn the key to position 2 do all the warning lights come up as they should?

[kiloran]

B200F, 2l petrol, non-turbo, non-ac
Bosch ignition based on the cylindrical coil and cabling from the airbox to the throttle body. Twin diagnostics connectors in the engine bay.
All warning lights that should come on pre-ignition come on.

[Laird Scooby]

Originally Posted by kiloran

B200F, 2l petrol, non-turbo, non-ac
Bosch ignition based on the cylindrical coil and cabling from the airbox to the throttle body. Twin diagnostics connectors in the engine bay.
All warning lights that should come on pre-ignition come on.

What about the fuel system though? They all have Bosch ignition. It's Bosch LH2.4-Jetronic if it's a B200F anyway, when you say all warning lights i take it you mean the oil pressure, low washer fluid, ABS, no charge, EML, brake failure, handbrake and i think one other?

Does the no charge warning light come on during driving at all (this will bring on most of the others too), even if only briefly? Also does the no charge warning light ALWAYS come on at position 2 before you start? Have you checked the alternator output voltage at all?

[kiloran]

I've never seen the no charge light come on during driving. Will check the other things once I've found my multimeter, thanks.

[kiloran]

Brief update on this thread - after a couple of weeks this fault just went away never (fingers crossed) to be seen again. Wondering if it was fuel-related. With the cold nights we've been having it's been like winter in the mornings so it definitely isn't down to the weather improving/cold start issues