Rev-limiter at 4000?

[s6boy]

Well that's what it feels like anyway. Hoping for a bit of advice really.
What happens is this, oil up to temp, hard acceleration in 3rd(all fine), into 4th @ about 4-4500 foot down and what feels like a harsh rev-limiter as power is cut, foot straight off and then gently back on and no problem smooth as you like although getting near the red line does bring a little hesitancy but this could be my imagination. I haven't tried this in lower gears as I presume the power off would be even more violent and might damage something. This has coincided with the idle when hot rising to 1200. Also when not upto temp and turned off ie for a petrol stop it will not re-start until properly cooled down resulting in embarasement and missed meetings.
Had the plugs changed throttle pots balanced and all the above is still happening any ideas? Thanks John.


Should have mentioned it's a 3.6 Tuscan

Edited by s6boy on Tuesday 24th April 11:35

[David Godfrey]

fuel filter?

[VARLEYHYD]

Iv'e had this in the sagaris, what felt like revlimiter, but if you ease off and dont floor it, then ok upto max rpm ok. It was the Coil that had broken down. it felt more like fuel starvation than harsh rev limiter Good luck

Edited by VARLEYHYD on Sunday 6th May 09:08

[T66ORA]

Had the same on the Tamora, but higher up the rev range, new coil pack and leads for good measure and all was

[s6boy]

Thanks for the replies, coil pack and leads make sense and will be first to be changed, but I can't see this affecting the idle when hot or starting probs when part warm

[Johan G]

I friend in the Swedish TVRCC had a problem which was not 100% identical to yours, but a bit similar. He did not have idle or hot start problems if I remember right, but the engine would not rev more than 5 - 6k. After hooking up his Cerbera Speed Six ECU to a computer he finally found out that the signal from the crank position sensor was disturbed at those revs and after looking around he found that the cable from the sensor was routed in among the ignition cables. Not good. He then rerouted the sensor cable, and voila, the engine would rev up past 6k revs with no problem.

It may not be so likely that this is the problem you have since yours seems more dependant on temperature, but maybe worth a quick check before buying other new parts?

\ Johan G

[s6boy]

Thanks Johan will have this checked out at the same time as the coil.
Is there an upgraded coil and lead pack or just the standard factory ones, and where can they be sourced?

[scotty1]

s6boy said:

Thanks Johan will have this checked out at the same time as the coil.
Is there an upgraded coil and lead pack or just the standard factory ones, and where can they be sourced?

It's an old SAAB part on the T350, probably the same, whip it off and take it down to any car spares shop they should be able to match it.

[Peppe]

Hi !

Had the same problem on my S6 Cerbera. It was the HT leads that where placed to close to the crank sensor wire.

See previous tread:

www.pistonheads.co.uk/gassing/topic.asp?h=0&f=6&t=313122


// Peppe

[s6boy]

Thanks Peppe, I think that's what Johan was referring to and I've been searching for the thread this afternoon. I will be getting it looked into when the leads and coil are changed, but can I ask, did you also have starting problems and increased revs when hot?
Cheers
John

Ps. Your boat sounds interesting

[Peppe]

Hi !

No, i didn´t have problems starting the car when warm, but it was a little lumpy on low revs 1000-2000 rpm. Between 2000 and 5000 rpm it felt OK.

I have i friend att our MOT station so i went there to check the emisions, and it wouldn´t have passed a test at that time. The Swedish MOT station test at idle and at 2500 rpm:s, neither of the values was ok.
After i solved the problem it the car came through MOT without any problems.

My boat isn´t as nice as this that belongs to a friend of mine:

www.tvrcc.org/images/dalarally2005/dalarally2005_27.jpg

Put the speakers on and listen :

www.tvrcc.org/images/dalarally2005/dalarally2005_28.avi

It is a Wellcraft Scarab 32 with 2 times 8.2 liter chevy V8:s, 550 hp each. top speed 80 miles/h with the engines screaming at 5500 rpm behind you, that is really something.

The picture and the movie is from the Swedish TVRCC meeting in september 2005.

// Peppe

[s6boy]

Update...couldn't replicate the problem with engineer in the car - bloody typical! However went ahead and changed the coil pack and leads anyway. No problems engine wise on the way home and does seem to be pulling cleaner from low revs in a higher gears, only time will tell about the original problem though.
Strange side effect that I can't explain, with the mis-fire/hesitation first cooling fan was coming on at 94 which apparently is correct, however for as long as I've had the car it would come on at 89/90. Now with just the coil and leads replaced it has gone back to 89/90? Go figure.
Thanks to those who offered suggestions and Peppe, had the crank sensor cable inspected and it was clear of all HT leads Cheers John