1987 3.2 Carrera Backdate project - Sladeys hotrod

[sladey]

I had a very generous Ben (Smallspeed) ready to lend me his sensor but in the end I plumped for buying a new one - meant a lunchtime mercy-dash to Leicester but it's all there ready to rock and roll if the installed ones doesn't play ball

Tomorrow is D-Day!

[Darren65]

Tomorrow is D-Day!

Good luck, hope all goes well.

[Uk911]

What he said.....mark

[sladey]

Still at Wayne's .....

[sladey]

[hot66]

Late night ! All going ok I hope

[sladey]

Have got an issue with the rev limiter cutting in too soon - something to be looked at.

Wayne's found a way of reducing the problem so it not too much of a hindrance at the moment.

We (Wayne)'be done one session then had a brew to let everything cool down. Now doing another session and it's currently 23:50

[hot66]

Are you home yet ?

[sladey]

Yes - finally!

Left Wayne's at ten to one this morning

It was quite a day. It's still not perfect but he has found more power. Best estimate at the moment is 270bhp+ Cant be more accurate than that at the moment as the rev limiter is still kicking in lower than it should (but I hope I've got an answer to that)

I left the car with Wayne at around 10:00 yesterday morning and went off to sample the sunny delights of downtown Warrington. When I left it with him he mentioned someone was bringing in a racing M3 for checking after he'd done my job.

I came back at 2pm to find my car in the car park and the M3 being loaded onto the rollers. Wayne said he'd been unable to cure the rev limiter cutting in early and this was messing up everything as it was cutting in at around 5500 - so could do proper power runs. He'd phoned thyme MD of Canems and talked the problem through with him. They felt it could be the crank sensor (which is on the flywheel) being too close and sending too high a voltage through' the ECU doesn't like it and eventually the says 'Whoa, big boy'.

He said the M3 owner shouldn't take very long at all as he was just checking a couple of things and then he'd be gone.

As I knew these things always take longer than expected I said I'd walk into town again and be back in a couple of hours - at 4pm.

Turned up at 4 to find the M3 in full swing on the rollers.

I sat around for a while (eventually moving my seat away from the front of M3 while it was screaming at 8000 rpm ) and then went next door to the go kart place for a cup of tea and bit to eat. I kept popping back. Wayne apologised and said it was taking much longer than expected.

They guy didn't finish until 7:30pm

Cars then had to be moved around so mine could go on the ramp to move the crank sensor out. Wayne did that. Tried it all again and everything was to pot - the revs weren't showing properly at all - so that wasn't right. Wayne then moved it back to the original position.

He then did various checks which seemed to show that the actual voltage coming through wasn't that back so couldn't really cause this problem. However he then tried adding a resistor in series to the engine speed sensor. That helped quite a bit. He therefore made up a proper connector (initial one was bodged just to test it) to increase this resistance. This seemed to have sorted the problem.

By this time it was gone 10pm, and it wasn't until about 10:30pm that it went onto the rollers. I took some videos. The noise was incredible - I had to walk out. Then I got my noise cancelling headphones on and was able to stay there. He was on that session until 11:30 when he stopped to let the rolling road air brake cool down and have a brew.

We talked it through and he said the rev limit problem had come back. As the engine got warmer it seemed to be cutting in at a lower level. He'd only experienced something similar years ago on an escort which had everything new - it eventually turned out to be the crank moving in the journals which in turn caused vibration at higher speeds. I was skeptical about this and he wasn't offering it as a likely explanation.

At 10 to midnight he started a second session which went on until about 12:45am. At then end of it all I got the readjust - I'll post them shortly.

The engine cutting in meant that the graph spiked at the end which gave a false high reading for that spike (335bhp!!). If you ignore the spike at about 6400 it's giving 270bhp It hadn't leveled off at that stage either so may be able to give more if the spike hadn't cut in.

Torque is coming in at 230 ft lbs at around 5500

[sladey]

Obviously I've got mixed feelings. The car feels fantastic (but I wasn't able to properly give it some on the way home due to ice and snow) but I'd like to bottom out the problem. I don't believe the loose crank idea. I know the care with which it went together and Mike's experience so I can't buy into that one.

However I had a lightbulb moment this morning. When I was doing the sills I managed to cut through a load of the ECU wires. Ian soldered them back together while lying on his back under the car. If one of those joints wasn't good or starting to fail then potentially this could cause 'noise' at higher voltages.

I'be emailed this theory to Wayne but it sounds the most likely. If so then it's quite easily fixable (may involve a bit of cutting and rewelding inside the car but nothing major.

Can't wait to give it the beans 270 and it weighs about 1180Kg.

When I was last at Wayne's, with a single out exhaust I was getting 230.

[sladey]

Bhp only graph - you can see where it spikes



And with the torque added - that's a bit wavey - no idea if that's part of the same problem

[Nige]

Keep at it Mark and you'll get there. Maybe next time, drop the car off and catch the train back and collect it the following week, I hate hanging around when things go like when there is nothing you can do.

[DustyM]

Was the lambda sensor an issue in the end?

[sladey]

No not really - it was actually wired up wrongly which probably fried the suppressor. He changed the wiring round and it worked. We didn't have the correct cables to recalibrate it but he logged it's settings against the actual. Settings across the rev range and was therefore able to compensate for the misreading.

Overall I'm really happy - just been out in it and took it to 6200 without incident. Wayne's responded and if we've broken the crank sensor screen then that would/could cause the problem.

Obviously I want to sort the problem, but in real-world driving it doesn't affect anything as I wouldn't normally be taking it over 6K revs

[sladey]

Keep at it Mark and you'll get there. Maybe next time, drop the car off and catch the train back and collect it the following week, I hate hanging around when things go like when there is nothing you can do.

Yep fair enough - I had to do that last time. If the M3 guy hadn't butted in I would have probably been away by 6