Re-Map Rev Limit Changed :(

[J9HHY]

Had Car Re-Mapped (RS Tuner) and was brilliant. Car been sat on drive last couple of weeks, been fiddling with engine bay (battery disconnected). It idles around 950 still but revs out at 6800 again not 7500. Has me disconnecting the battery some how changed the rev limit? If so what do I do to get it back? Re-Map was done by a friend who had his RS Tuner reformatted (or what ever they do).

 

[mattg]

I had the exact same thing mate. The map has a safety mechanism whereby you can't get to the higher limit until the oil has come up to temperature - makes sense really as it wouldn't do any good revving that high on cold starting!

 

[Bluebeard]

I think that disconnecting the battery for a certain period of time rests the ECU. I'm 99% sure I read that on here somewhere....

*edit, i'm assuming the car is upto temperature??

 

[J9HHY]

should be, had been driving it over 10 mins (5miles), wouldn't take her to the limiter unless she was hot!

 

[Bluebeard]

Try driving for 30 minutes. I don't think 5 miles will be enough tbh mate. My valver takes a good half hour to get up to the indicated 90 degrees.

 

[mattg]

Agreed, will probably take longer than 10 mins. Takes my 182 around 20/25 mins I reckon.

 

[DannyR]

Yea, usually takes around 20 mins for mine to come into life!

 

[J9HHY]

damn was out for a hour but only tried a few times! Will do next time, thanks

 

[Chris n nic]

Yeah don't go off the temp guage on the dash fella..its the oil temp that will make the limiter kick in

Cheers

Chris

 

[Matteh]

oil temp has nothing to do with the rev limit

coolant maybe, but im sure its 7500rpm either way

 

[Chris n nic]

wasn't sure tbh...all I know is that the limiter is lower until the engine is warm...but the dash temp can be up to temp and the limiter will still be lower, Would it not make sense for the engine to not allow you to rev it too high until the oil is up to temp?

Chris

 

[Matteh]

it would, yeh

but that's just not how it works

 

[172Ben]

It is, its limits the amount of revs if the oil isnt up to temp.

 

[caister]

wasn't sure tbh...all I know is that the limiter is lower until the engine is warm...but the dash temp can be up to temp and the limiter will still be lower, Would it not make sense for the engine to not allow you to rev it too high until the oil is up to temp?

Chris

It would make sense BUT its French and therefore works off of the coolant temperature IIRC!!!

 

[ForceIndia]

Why do people want a higher rev limit? I was under the impression that power drops away after 6500rpm?

 

[J9HHY]

it has helped me out on different tracks, certain places I needed to change up 50 yards before corner, now I can hold power all the way too the bend. Also when I went to a rolling road day people were getting max bhp at like 6800-7000 revs so I guess it still pulls that high up!

 

[Brett]

Why do people want a higher rev limit? I was under the impression that power drops away after 6500rpm?

Good point. After say 6900rpm you can realy feel the power drop off. Not so much in 2nd because its a lower gear but in 3rd I can defrinately feel it.

A lot of standard 172's that have been on the rollers make their max power at around 6800rpm iirc.

Edit: As the post above says it can be useful on track, hadn't thought of that.

 

[MarkCup]

Aye, that's the only time I use the extra rpm I have available.

Completely pointless at any/all other times...much quicker progress made by shifting into the next gear.

 

[J9HHY]

yeh but u coming up to a 3 gear corner, u doing 6500revs with 50-100 yards to go, you don't shift up and then shift back down again for the corner. Balance everything goes. Being able to hold them revs that lil longer does make a difference!

 

[f0xy]

oil temp has nothing to do with the rev limit

indeed. considering the ECU has no pin in for oil temperature....so it would have no idea how warm or cold the oil actually is!

 

[J9HHY]

so foxy it is the coolant temp yeh? Isn't that what's on the dash?

 

[f0xy]

Coolant temprature is whats shown on the dash, yeah.

As to weather it controls the limiter, or if there is a 'timer' that counts how long the cars been running that controls it, im unsure......but the pin diagram for a 172 ph1 shows no pins at all for anything oil temperature related

 

[Matteh]

yup

having wired a 172 engine in to a mk1, i can confirm that the oil temperature (and level) circuit does not go near the ecu

mine rev limits at 7500rpm no problems


on my old 'crap' megane f4r map, the limiter was controlled by temperature. but if the car was warm and you stalled it and restarted it straight away, it would revert back to the lower limiter for a couple of minutes. not sure if the stock 172 map does the same