1.6 NA Revs it self when holding the accelerator

Hi wondering if anyone can help, have a 93 1.6 mk1, that’s been stood for 4/5 years.

Engine starts but idols a little high tends to settle until you move the wheel, but my issue is when holding the accelerator the engine responds althou its being revved.

I’ve plugged a light into the diagnostics port, but only get the solid light, no flashes. I’ve changed spark plugs, leads, fuel filter.

I’m about to drain the fuel and see if that helps. I’ve also disconnected the tps but it didn’t make a difference. When I removed the maf the engine will cut out if you touch the accelerator.

Just after advice to get the bottom of this issue as I almost have my summer project road worthy my first project car so learning as I go with it really.

Will upload a video to YouTube


Maybe put some Silkolene Proboost through it. I swear by that stuff.

What happens if you disconnect the idle air control valve (under the throttle body)?

Dropping the fuel either tonight or tomorrow been struggling to find somewhere to dispose of it.
Will check the icv as well

Thanks for the help so far, going to check all the lines as well to make sure there’s no air leaks.


Just watched the video. It reminds me of odd behaviour I found while tuning an aftermarket ECU: the settings made it over-eager to keep the revs up when trying to settle into idling, so it would rev up to about 2000 rpm, realise that was too fast for idle and cut the fuel momentarily. And repeat, and repeat.

Obviously yours is the stock ECU but I wonder if a similar effect is in play here. Maybe the throttle position sensor is poorly adjusted so that small throttle opening isn’t opening the “throttle closed” switch. So it revs up until it decides “that’s too fast for idling with the throttle closed, guess I’m on the overrun, cut the fuel”.

I haven’t the experience with 1.6s to know if that can happen but it might be something to explore.

Okay, update I got the dash working, blown fuse.
Completely rebuilt the engine from header and block and still have the same issue.
ECU looks in good order.
I can lean into revs upto 3k when cold, but around 2.1k when warmed up.

Removed the sensor below the throttle body made no difference (not sure if it should have done anything)

I can’t quite understand exactly what effect you’re describing but if you mean it’s still doing a version of what it was before then it suggests something is cutting out at a particular rpm then recovering and repeatedly cycling. Maybe the ignition is breaking down or the CAS signal is disappearing. I’d see if the Diagnostics have any stored fault codes. What happens if you very slowly build the revs?

Yeah after my tear down I still have the same issue. We plugged an led in and didn’t get any lights only the first solid one.
Same happens if I slowly lean into it as well.


What exactly does “same happens” mean, though?

Does it instantly start that cycling behaviour as soon as you even touch the throttle or does it let you creep the revs up gradually to some threshold before it begins the cycling?

Sorry so will try cover as much as I can.
Start the car fine, will idol all day can even drive it back and forth under 2k rpm.
On a cold start I can increase the accelerator upto 3k, when its warm only to around 2.1k before it starts cutting out/revving itself like it does.
ECU looks in good nick,
Replaced fuel, fuel filter, plugs, leads, water pump, thermostat, radiator, all belts, pulleys seals, oil and filter.

If I:
Remove the maf, engine starts but dies as soon as I touch the accelerator.
Remove what I believe to be the TPS plug, on the side of the throttle body makes no difference.
Remove the Idol control valve plug thats on the bottom of the throttle body, didn’t make any difference.

Thinking of ordering newish ignition coil and the above sensors, and the one half way down the inlet manifold to see if it makes a difference.

After that thou I’m really out of idea’s.
If anyone’s local in the Burnley area who knows there stuff and could just have a quick look, could be something silly being my first project car would treat you a beer and a burger.

Is there anything I’d have to do via the diagnostics port, cars literally been stood 5 years, until I connected it up to a battery and started working my way through issues.

Thanks Again

It has exactly the same symptoms as a governor cutting in.
Burnley…you have CBS on your doorstep, Carl’s your man.

My Mk2 1.8i gave similar symptoms when the throttle position sensor failed. A new one cured it instantly. Thankfully an inexpensive item, which is very easy to replace. I bought one from MX5 parts.

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Only gone and fixed it, well happy tried MAF and TPS to no joy. Then were recommended to try ECU.
Boom she’s happy again, thanks everyone

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