Hit 2nd instead of 4th at 80+ have I damaged something?

[J14RK D]

On the motorway and got a call for a little fun off an evo, unfortunately when dropping to 4th for full chat I managed to get second instead and as you can imagine I got a shed load of engine breaking and god knows what revs. I quickly dipped the clutch but since then I seem to hit a limit at 6500 rpm. I'm not 100% sure but I could swear it used to rev right up to 7k+. could I have damaged something or is it normal?

 

[lacroupade]

you should have hit the rev limiter anyway so I would have thought the only thing hurt is your pride LOL I thought 6500 is correct depending on what engine you have....

 

[smokedog]

you should have hit the rev limiter

There is no limiter when you down shift, no expert so don't know what damage it may of cause. But if your car is running fine, I would just forget about it.

I think if you downshift at too high a speed, it will over rev the engine causing the valves to float and destroying the engine.

 

[ksher]

I think the ECU will automatically limit the engine speed. Your engine should be okay. You're better worried about the gearbox and the clutch.

 

[Z4coupebeaver]

I'm afraid the ECU will not prevent the engine over-reving when it is due to a downshift.

I don't know about BMW but Porsche logs any such over-revs and throw out engine warrantly claims if this is recorded in the ECU.

You have 2 choices - forget about it and hope for the best or strip the engine down to check for damage. I would do the former.

I've not done the calculation but I would guess that at 80 you may have hit 7-8K revs, probably less. Modern quality engines can cope with short term exposure to these revs without any problem. I wouldn't worry.

 

[Newbers]

If it runs you are fine. If you broke anything it would be really obvious ie you could have thrown a rod or bent one or more valves. This would be very obvious. Bear in mind that BMW are obliged to build huge tolerances in to their cars to make them resistant to real world incidents. I don't know where a race prepared engine would redline but it would be a lot higher than a standard road car.

I have to say that I am pretty sceptical about it being recorded in the ECU. If you are concerned Google (unlikely to be helpful) or take it to your local back street garage. For £30 they will connect it to their computer and tell you every code and then delete them for you. Unless you are worried about your warranty I definitely wouldn't bother tho.

 

[TO//M]

There ain't no pill for stupid. If things still seem well then you have an affirmation that BMW that you own a well engineered and well built automobile. Try to treat it kinder.

 

[lacroupade]

Hydraulic tappets?

 

[aquazi]

Having come from previous high revving low torque cars (celica and 2sk) this was fairly common among other members... the most common damage would be the piston con rods and blown bearings.... But if damaged then this would be pretty obvious.

 

[J14RK D]

Cheers for the feedback guys, it doesn't seem to make any difference to the rest of the rev range tbh. I did however go from 99 Ron vpower to 97 Ron bp if that could have made any difference.

I think I'm just going to try and forget about it. :roll:

 

[decio]

Don't bother yourself with this! It is a ZF gear box practically indestructible. You can damage it only if you bleed out the oil. In your case when you hit the second gear there was some lets say significant torsional strain on your crank shaft but that part of the engine is constructed for thous occasional stresses.

 

[Animal]

I think it would be harder to do that in the M on full chat scary thought though.

 

[ga41]

I think it would be harder to do that in the M on full chat scary thought though.

I did. At full chat. Scared myself to death. Car was fine though.

 

[J14RK D]

It's definitely not right. Is there any way that the ecu would or could limit the power without giving an engine warning light. Just raced my friend in my old 330ci and although I got him off the lights the gap stayed the same up to about 110mph where I had to slow down. I have to change early and it's although the vanos for the high revs is not kicking in and so it is running lean or something, I'm obviously limited with my knowledge of this engine but the change in power at 5k that used to be there has gone.

 

[paddy wright]

It's definitely not right. Is there any way that the ecu would or could limit the power without giving an engine warning light. Just raced my friend in my old 330ci and although I got him off the lights the gap stayed the same up to about 110mph where I had to slow down. I have to change early and it's although the vanos for the high revs is not kicking in and so it is running lean or something, I'm obviously limited with my knowledge of this engine but the change in power at 5k that used to be there has gone.

Can I suggest u dont post speeds on forum as police can and will track these posts if needed and ban u!

 

[Blue]

Time to plug it into a computer-ma-bob I think and see what it says, I would imagine that a Vanos fault would be logged there.

If the Vanos is stuffed then time to drop Mr Vanos a line I would imagine, he gets good write ups!

 

[J14RK D]

It's definitely not right. Is there any way that the ecu would or could limit the power without giving an engine warning light. Just raced my friend in my old 330ci and although I got him off the lights the gap stayed the same up to about 110mph where I had to slow down. I have to change early and it's although the vanos for the high revs is not kicking in and so it is running lean or something, I'm obviously limited with my knowledge of this engine but the change in power at 5k that used to be there has gone.

Can I suggest u dont post speeds on forum as police can and will track these posts if needed and ban u!

Ohh that was a typo, I meant to say 70

 

[billygilly]

they can't ban or charge you for a claim they must have evidence..

p.s i shot someone last week

 

[ZED_NOT_ZEE]

A money shift sometimes takes a good 10,000km or so before the engine shows obvious issues. Usually the short-term issues make themselves known by loss of torque at high revs, or a slight knocking sound at idle. (similar to a vanos rattle actually.)

If it was *really* bad you'd have some bent valves and a good ol' check engine light.

The other thing that could happen is you mess up your 2nd gear synchros on your transmission, or if your clutch is fairly worn, it could kill it off mighty quick. (you'd be experiencing a slipping clutch).

I don't think it was a good idea to race your buddy after this mis-shift... especialy without performing an oil change. Just in case the over-rev caused any stripping and loose metal particles to be floating in your oil.

The loss of torque you are describing could be a VANOS issue, DISA valve issue, clogged Catalytic converter, etc. Good idea to have the ECU read to see if there are any issues... otherwise just wait and see if anything happens.

Also take it to a good local indy mechanic and have them do a compression test, just for good measure. If there's an issue, it's a lot cheaper to fix it now than later where one small engine issue quickly turns into a complete rebuild.

For the record, as some other members have mentioned--the ECU does not and can not compensate for blown shifts. It will rev-limit if you are accelerating. But if you down shift to 2nd instead of 4th, the engine will immediately spin at the ratio of the tranny and prop shaft as soon as the clutch is re-engaged. The ECU can't, at this point, stop the engine from spinning so quickly, because there's nothing to ECU can do. Even if it were to shut off the engine (starve it of fuel)... as long as the car is travelling at the same speed in 2nd gear, the engine will be spinning faster than it is designed to. The only thing to do at this point is quickly open the clutch again and let the engine slow down to a proper speed.

The only Z4's that will prevent a blown shift are the SMG manual equipped which will not allow a downshift that will over-rev the engine.

Hope this helps, good luck.

 

[Newbers]

Slightly off topic but I hired a (non-descript French car) the other day. Just out of the airport, on to the autoroute and I was doing a speed considerably in excess of what I should have been. I selected 6th but before letting the clutch had a quick look on the gear knob to check that there actually were 6 gears. This turned out to be a good move as somehow, very easily I'd selected reverse. I shudder to think what might have happened had I let the clutch out.......