New Engine Features for Croft

I am sure most of you that I had the pleasure of chatting with at Croft heard about my engine woes. Thought I would post up a comprehensive description to get some ideas and also record the symptoms since I know I am not the first and won’t be the last.

Car is standard 177bhp car with no real engine mods aparts from airbox and SS exhaust. Has not missed a beat until I hit junction 1 of the M1 on my way to Croft

Popping on Overrun
This was the first thing I noticed. Always had a bit of this but usually after a bit of enthusistic driving. Now even when coming off of a light throttle there is lots of popping - sounds like a bleedin’ TVR

Refusal to idle
First thing I noticed that when coming to a halt and depressing the clutch that there was more hunting than I remembered. By the time I made the first stop on the M1 it would not idle at all and disengaging the clutch resulted in a stall. Engine will maintain a smooth (well as smooth as it ever was ) idle with a tiny bit of throttle but without that it just stops. I particularly enjoyed this feature sitting on the M25/M4 last night - good heal 'n toe practise I suppose. Worth noting that when engine is in its warmup cylce it idles (at the normal 1500’ish rpm) completely normally.

5500 rpm Rev-Limit
This was the most useful new feature for a visit to Croft After warming up, the engine will rev normally in first and second but will not break 5500rpm in third. Once the limit has been hit in third, engine will not rev higher than 5500rpm in any gear until it has been stopped and started again.

SteveE kindly assisted (well I offered words of encouragement and he got his hands dirty) in checking the ECU wheel speed sensor and numerous ECU rests (five thottle depressions etc) were tried but to no avail.

Any advice greatly appreciated. Being a self-confessed mechanical numpty I guess it may need some professional TLC. Any ideas who might do a reaonsable job, is this a service Dave Andrews would/could provide?


I didn’t know your car was poorly at Croft

Anyway, these symptoms are consistant with a real misfire - can you check ALL plugs are sparking properly ?

My logic as follows: the pops would be unburnt fuel from the misfiring cylinder(s). the poor idle also related to not firing on all 4. the 5500 rpm limit is deffo a misfire symptom and well documented on here.

remove each plug and check for ‘sooting’ but also earth each one against the block (make sure you do this properly) and check to see it sparks when you turn the engine over - you need a lovely assistant for this

you should also remov the plug cover and see if any of the leads are tracking (look for this in the dark).

Let us know how you get on


The other thing is the reason people unplugged the wheel sensor was to get pops and bangs on the overun … so … maybe the wiring or sensor is knackered.

You had the recall ECU map ?

I maybe complete wrong but with that new map the idle rises when cold when you move, so it senses the wheel movement - does yours do that ? Did it ever do that ?

Bad idle can also be that damn IVAC or whatever its called - is that stuck and can that cause a genuine misfire ??

But hey, I agree its a good excuse for a Honda …

Sorry to know that your camera was playing up as well - I can understand your frustration even more now

I had exactly the same problem at croft and im pretty sure its connected to the speed sensor on the o/s rear wheel.
Mine is currently at the local lotus dealer so i will let you know the outcome.


didnae even know you were there… would have liked to have met, shame… just not enough time really. sorry to hear you also had some bothers… hope it gets sorted.

Too busy tinkering to socialise but still a really good day. I got a good few laps in before i was black flagged lets organise another track day soon

I would look at: wheel speed sensor, plugs, coil, ecu, IACV

why’dya get black flagged ?? i never saw anyone with the roof off

Ben, it’s also probably the TPS… Get to a rover breakers and get the TPS for �10 and try a new one of them… I think you can reset the TPS with the ig. on and pressing the throttle to full 5 times in a row…

This would explain why for all those things, if the ECU thinks you have the throttle open even when it’s closed then you’ll get popping on the over run (it shouldn’t be as bad as you say with just the WSS gone), it’ll choke up on richness when you come to a halt and so will stall and could also cause a proper misfire as it’s too rich to ignite…

For my money I’d do that then go for the wheel speed sensor…

If you can get to a dealer of someone with the plug in tool then go for a spin with it plugged in it’ll have the TPS on display and also ECU wheel speed so you’ll be able to tell.


Thanks for all the advice guys. The TPS seems to add up the most since 1000-5500 rpm it pulls as smoothly as it ever did. Car sitting forlornly on the drive at the moment since I have not had a chance to do anything about it yet.

Evosal any news from the dealer yet? I’ll keep you updated…

Had a call today, apparently a loose connection !!! i presume on the wheel sensor they had replaced the day before croft.
I cant collect it until thursday but i will be sure to speak to the mechanic to find out exactly what it was.

Had a call today, apparently a loose connection !!! i presume on the wheel sensor they had replaced the day before croft.
I cant collect it until thursday but i will be sure to speak to the mechanic to find out exactly what it was.

Cheers Evosal I am popping into B&C on Thursday morning so that can plug in the diagnostic but will make sure that they focus on the wheel sensor. Will let you know…

Running perfect now !!! I asked what the problem was and they say it was the female part of the connector to the rear wheel speed sensor worn and not getting good connection

Cheers Evosal, did they replace the sensor? I have just ordered a new one after B&C checked it and said, yep its the wheel-speed sensor.

The wheel sensor was replaced by them the day before croft

Ah yes, should have read the whole thread again Mine should be fixed soon too! Cheers