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M40 Flatspot

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So been for a few spirited drives now, and have a flatspot in 2nd and occasionally third gear where it feels like the car wants to surge but it can't like it wants to back fire. I was thinking maybe the airflow meter or a loss of vacume somewhere? Anyone with any pointers would be appreciated.

m40 1.6

Custom Airbox and Pod Filter.

Cheers, Nathan

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m40 1.6

Maybe there's your problem... lol someone had to say it

Joax, we all know the 1.6s are absolute beasts :P

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^ I was waiting for someone to say it. Just wait till I skool you on the track.

Does anyone have any serious pointers to what It could be?

Have had the AFM cleaned, oil change, new spark plugs.

What about intake boot leaking? Mine is cracked but not split

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get a new intake boot as a matter of precidence dude. Are you getting any sudden losses of power or you just think it is delayed.

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Yeah i was kinda thinking i shudn't say it, in case you completely own me on the track....

I'm guessing it didnt have this problem before you started "racifying" it?

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Nah it has always had it, I only really noticed it on the track before I modded it, its like its stuttering/hesitating and not getting enough air/fuel mix right or something. I am sure its something to do with the AFM/Intake area.

Cheers Moonbeams, I will get onto that

Its like I put my foot down to rev it out, and it either stutters completely (like dies) or it just has a sudden loss of power and feels like its only making 50hp let alone 100 and then it clicks back to normal, (always at full throttle in the higher rev range i.e 4k plus for a 1600 motor, red line is 6,5

Any advice or pointers is appreciated.

Has had new plugs, oil change etc

Edited by Brams

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Bump, I know its a motor nobody has but can anyone help me out here?? Going to clean the throttle body with carb cleaner too//could be seizing a little?

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check for cracks/leaks in exhaust manifold, inlet manifold. Check spark plugs, spark leads, clean contacts.

Have you triple checked the flux capacitor?

Edited by bmw3

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Could be the TPS (throttle position sensor) oiled up and not telling the ECU when you're at WOT (wide open throttle), may cause that problem. Stops the ecu changing the fueling map.

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Cheers Andy

Anything else anyone?

Cheers David also, is that a matter of just cleaning the TPS?

Edited by Brams

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You'll need to get it checked to see if it switches at both ends.

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re-reading your thread, have had same problem before in my 320i, a new coil remedied the problem. But also reading up E30 book it suggests it could be the TPS or air flow meter as well. Suggest you clean the airflow meter out and check that its not sticking. Use a bit of carb cleaner and a tooth brush.

Edited by bmw3

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Cheers Andy

Anything else anyone?

Cheers David also, is that a matter of just cleaning the TPS?

Your problem seems similar to one i had on my M40 1.8 race car. Basically it wouldn't rev out and hesitated and sort of died around 4500-5000 rpm. Problem - a worn camshaft. Fitted a new cam and it was sweet as a nut.

There are plenty of people on this forum with spare camshafts as we have fitted modified ones in our race cars - the Fox has four from memory!!!!

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Cheers Bruce, anyone got one for cheap??????

Thanks Nathan

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Cheers Bruce, anyone got one for cheap??????

Thanks Nathan

I've got one somewhere Nath... Might have to get some money for that one though...

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Haha cheers Paul...how much we talking? Maybe not this week after shelling out for these tyres, dad wants a wof before I order them, so looks like I can give u the word on Friday. But wheels should be at the Depot tmoro which is mean..going OT.

Anyone else got any ideas?

Am going to:

Clean Plug Leads

Clean AFM

Check Intake for vacume leaks

Check exhaust manifold for leaks and seal when exhaust gets refitted again

Driving it yesterday..it didn't do it, was weird, but I didnt have it revving out to redline or there abouts on the speedo this time.

Strange.

Anyway any input is helpful.

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Haha cheers Paul...how much we talking? Maybe not this week after shelling out for these tyres, dad wants a wof before I order them, so looks like I can give u the word on Friday. But wheels should be at the Depot tmoro which is mean..going OT.

Anyone else got any ideas?

Am going to:

Clean Plug Leads

Clean AFM

Check Intake for vacume leaks

Check exhaust manifold for leaks and seal when exhaust gets refitted again

Driving it yesterday..it didn't do it, was weird, but I didnt have it revving out to redline or there abouts on the speedo this time.

Strange.

Anyway any input is helpful.

Hey Nath, How did you get on? Is it still hesitating?

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^ Hey,

Have got a new camshaft to swap over, just have no idea how to do it/where to find info on doing it. Links are appreciated.

Have also got hold of a ohmeter to test resistance on the TPS.

Have also replaced the split intake boot but I wasn't expecting any difference with that, just peace of mind.

And have got another ECU which may help the fuel mapping troubles.

Hopefully will have some progress in the coming days.

Edited by Forrest

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Pretty sure the haynes book covers camshafts? You've got one aye?

If not i do, and its available to rent :P

Or borrow :lol:

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^ I have had a look, and I can't seem to find anything about it. You more than welcome to help me Paul :D

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There are instructions there, but only for removing the entire head, valves etc... :o

Dunno about just the shaft, might be able to lend a hand sometime though... kinda busy getting my sisters car soted/the racecar ready/my other car sorted lol

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