Odd rev limiter

[MattWilde 10]

after bedding in the supercharger that has just been rebuilt i decided to see what the car could do (only got it 23/04/05). as i put my foot down the car accellerated ok but the rev limiter cut in at 5,500rpm, no where near the red line. Other odd things that are happening is the mpg always showing as 60-70mpg, the rev and mph needles twitching (seem to drop all of a sudden then return to normal with no change in the engine noise or feel) the car has just had a jabba stage 4 rebuild on the charger and i followed all the instructions for bedding in and to be honest i expected it to be quicker. very worried and confused, please help :?

[gradeAfailure 0]

Sounds like there's some electrical gremlins at work there... Was it ok before you had any of the work done?

[MattWilde 10]

never had it before the work was done so i don't know. and this is the first corrado i have ever owned so i have no benchmark to check it by

[potatonet 0]

check your relays, and fuses, I am guessing fuse is cracked, but it should have blown by now. buy a bentley manual =-)

[Supercharged 2]

VAC leak maybe as the MPG is always high, this may also affect the MAP sensor and the point at where it retards the timing.

[MattWilde 10]

any paticular fuse or relay that would affect the rev limiter? and the mpg thing, would that be a leak in a vacuum pipe or would the fuse/relay affect that too.

 

Thanks for the help

[potatonet 0]

never mind, forget what I said, get a new gear driven speed sensor for your tranny, yours is fried or is broken. and it did kick in at 6800 ure speed sensor was picking up the rpms to be 5500 when they were actually 6800. your MPG is up there because your car is over registering where it is going I think. part number is 02A 409 197 for the pinion and gor the guide its 02A 409 193. replace these 2 things you should be fine. rebuilding the charger is great and all but you really need a smaller pulley to feel the difference. drive it for 1000 miles and then put on a pulley. cheers. same thing happened on my buddies '93 RX7 changed it, it was fried.

[potatonet 0]

this is assuming you have a manual. its located on the back of the tranny. follow the speedometer cable.

[Henny 0]

Did Jabba do the charger only, or did they have the car in to sort it?

 

It sounds to me like there's a problem with either your vacuum pipework or an earth strap somewhere on the engine... Check them all out and make sure that the vacuum pipe from the back of the throttle to the ECU is EXACTLY 100cm long.

[MattWilde 10]

they had the car to do it (and it is a stage 4 with pulley and chip, which is why i thought it would be quicker) all the vacuum piping looks new so i will check the length of the ecu/throttle pipe. The digital rpm readout on the mfa shows what seems to be the correct rpm, and it is higher than the analouge reading on the dash but at idle it is only a few hundred over not the 1,300 over it would be when the limiter kicks in. The car also feels like it is driving into a head wind a points during the rise in revs, could this be the timing? sounds like all of the probs everyone is listing is there :( thanks again for all the suggestions, really really helpful

[Henny 0]

ah, the reason I asked if Jabba had had the whole car or just the charger is 'cos one of the good things they do while they have the car is to check the vacuum hose to the ECU and replace it (at your cost admittedly!) if it's even slightly dodgy...

 

Check the cable from your knock sensor too, and maybe even the lambda sensor...

[MattWilde 10]

sorry to sound maybe a little dumb, but i'm from a jap car background, so i don't know what all the cables and pipes are, been looking and working out what does what but i still need a little help. which one is the knock sensor cable?

[Henny 0]

The knock sensor is bolted to the front of the block with a 13mm headed bolt with a single (it's actually Co-axial) cable coming off it leading to a green plug over by the gearbox... 8)

[MattWilde 10]

cheers, that has been noted too. not liking this list that's building though

[beavis 0]

Rather sounds as if you have a weak fuel pump. The new found boost of the serviced charger may just be enough to lean the mixture off enough now that you get detonation and the knock sensor kicks in like a rev limiter would. Get your fuel pressure tested before you confirm a weak pump with a hole in one of your piston crowns.

It is unlikely to be your lambada probe whist on boost as it goes closed loop and does not read from it.

[MattWilde 10]

right, you were very close beavis. had a fuel leak which was causing most of the problems ranging from the mpg reading too high to the general poor performance, so that's all sorted........but the rev limiter still kicks in at 5500, strange this is, the garage had the mot testing machine thing on it and it read the same and the needle, only the digital mfa reading is still higher than the needle so i still think there is a problem, just don't know what. dodgy knock sensor? or am i gonna need to replace everything to do with the engine speed from the clocks to the sensor? soooo close

[MattWilde 10]

for got to add, the mechanic mentioned something about a sensor in the dizzy that 'could' be causing the rev limiter problem, does this sound reasonable? can't for the life of me remember the sensors name though, sorry

[Henny 0]

hall sensor? Yeah, they do break down over time and could cause this kind of fault... I'm not sure if the hall sensor is changable on a G60, I just changed the whole dizzy! :lol:

[MattWilde 10]

changing the whole dizzy doesn't bother me, and the sensor is internal on the g60 so i'm told so it isn't replaceable on it's own. seems to be the next step