Engine stuttering & engine warning light comes on over 4000rpm on mk2 2005 model

Hello - just wondering if anyone has had a similar problem…?
When I get to around 4000 rpm the engine usually stutters/power drops and the engine warning light comes on.
The car’s been to a Mazda garage and is about to go in again but they seem to be struggling to find out what’s wrong…
The cambelt sensor’s been changed and some connections to the cpu that were getting wet apparently. It’s done 70000m so I would hope it’s got life in it yet.
Apologies I’m not the most technically able owner!
Any thoughts welcome!

It’s not an especially unusual symptom* but there doesn’t seem to be one common cause. Over the years I’ve seen people fix this by changing a clogged fuel filter or by replacing a collapsed cat converter while others have blamed the coilpack or crank sensor.

It’s probably indicative of something that the engine light flashes. Presumably being a Mazda garage they can check for stored fault codes. Wet ECU connections are a concern but if the garage reckon they’ve dealt with that it may not be significant.

Something I’d try would be to see if the car will rev over 4000 when accelerating very gently as opposed to accelerating hard. If it will do that then the problem is more likely to be limited fuel supply (clogged filter maybe) whereas if it won’t then it’s more likely an ignition problem (coils won’t spark that often or tacho signal is too weak at that speed).

*Just try Googling “MX-5 won’t rev over 4k” or “Miata won’t rev over 4k” for examples.

Thanks Martin! Appreciate your reply - will follow your advice.

That car’s engine is, if it has been properly serviced, just getting into it’s stride.
What I’d keep in mind are the 2 Coil Packs which feed, of course, two leads apiece.
If a coil (one or both) is weakening it will activate the engine light…but fool a plug in test.
I do not suspect at this point the oil-pressure activated VT…around 4k is when it comes in, not that you’d really notice ( it’s not a Honda!)
Way down my suspect list are the plugs ( cracked ceramic) or a duff lead…but these over the years have chucked up easily fixed issues in my 104,ooo mile example.
If there is a coil pack issue, try Andrew @ Autolink in Dumfries for a used set, or Rhino666 on this forum.

thank you for that - I will pass ideas on to the garage who have it now!