1987 3.2 Carrera Backdate project - Sladeys hotrod

[Gary71]

Sorry to hear it didn't work out... Did you sell all the standard bits?...

[Mike]

100 pages Mark and fascinating stuff, well done on your perseverance and ability for diy work, an inspiration to us all!

[impmad2000]

Hi Mark,
I think now it is time for you to really understand the system. You need to start using the system diagnostics and the data logging. I have taken a quick look at the Canems manual and it looks like it offers a few tools to help you see what is going on. I suggest you start with data logging and look at the crank sensor diagnostics as well as the general diagnostics.
If you find a fault in the diagnostics, then I can take a closer look for a probable cause.
In the mean time I'll take a further look through the manual. Talk to the Canems people too, They will definitely have more ideas than I will.
It doesn't matter whether it Megasquirt, Emerald or Canems, at the end of the day, the owner never gets to see the hoops that the installer jumps through to make something work. It is usually dismissed to make the installer look like an expert... It just took a little longer than expected !! Poke around yourself and you will learn so much, all useful for maintenance and tuning going forward, especially when you go ITB.
Is the car still on a dizzy ?
Tim

[sladey]

Gary - I've sold the Barn door but still have the other bits. Wouldn't consider going back though - current ECU is night and day compared to the old ECU and although I want to sort this problem out - having a 6200 redline doesn't affect my driving - even when I'm pressing on.

Mike - thanks - and yes 100 pages Still enjoying the journey

Thanks for that Tim and I think you're right. I'll get some data logging and diagnostics running and speak to Canems initially - that should give me more information and more to work on.

I've gone dizzyless- installed their DIS ignition conversion kit, their MAP conversion kit, and their ECU

Cheers

Mark

[bjmullan]

Yes 100 pages and still a great read. Hope you sort this problem out and keep this fab post going

p.s. I would be no help, once wired the horn to the brake light circuit on my GP Spyder so it would only work when I had my foot on the brake

[Bruce M]

What value is the resistor?

10k to 20k ohms appears to be the "recommended" value.

[sladey]

Hi Bruce,

From memory it was around the 20 mark - he tested it first with 9 and then went to 22 (I could well be misremembering those numbers)

Recommended by whom? Is this a common thing to do then?

[tea boy]

Why don't you ask David from Canems if he'll have a look at it?

Scunthorpe is not that far from you.

[sladey]

I'm going to contact him this week - work's a bit hectic at the moment.

I did some data logging on Sunday night with and without the problem - can't see anything obvious. I'll share that data when I get a chance

[Jonny Hart]

Why not switch the rev limiter off completely in the software?

Perhaps the problem you've got, isn't the problem you think you've got!

[Bruce M]

Hi Bruce,

From memory it was around the 20 mark - he tested it first with 9 and then went to 22 (I could well be misremembering those numbers)

Recommended by whom? Is this a common thing to do then?

It's mentioned in the mega squirt manual that high tooth counts with VR sensors can suffer from noise interference and a resister in series usually sorts it out.

As per:
http://www.diyautotune.com/tech_article ... _index.htm

You might want to try fitting a resister in the TDC sensor wire. Although there is only a single pulse per rotation, it will be similarly narrow at higher revs.

[sladey]

Hi Bruce,

From memory it was around the 20 mark - he tested it first with 9 and then went to 22 (I could well be misremembering those numbers)

Recommended by whom? Is this a common thing to do then?

It's mentioned in the mega squirt manual that high tooth counts with VR sensors can suffer from noise interference and a resister in series usually sorts it out.

As per:
http://www.diyautotune.com/tech_article ... _index.htm

You might want to try fitting a resister in the TDC sensor wire. Although there is only a single pulse per rotation, it will be similarly narrow at higher revs.

that's brilliant - thanks for that - found this on the page

Bosch 60-2 wheels and high RPM breakup (Can also apply to other high tooth count wheels)

This happens most often with V3.57 boards, but can happen with V3.0 boards too. We've seen this most often on BMWs and Hyundais, but it can happen on any Bosch Motronic system, or with Electromotive trigger wheels as well. With some sensors, it can apply to 36-1 or 36-2 wheels. What starts as a small noise spike at low RPM becomes a very large noise spike right in the spot where the missing tooth is, causing the ECU to lose synch. You'll see this problem manifest as the RPM signal suddenly spiking downward at high RPM, and the car acting like it's hit a rev limiter. Putting a 10K to 20K resistor inline with the crankshaft position sensor wire generally clears this right up. Below is a tooth log showing this problem happening to a 36-1 trigger wheel.

Looks to be exactly my symptoms. I'll look into secondary resistor and/or higher resistor in the speed sensor as well

I'll post a couple of data logs from when the problem happened

[sladey]

Here's some data when the problem was occurring - the rpm is the red line and I start hard acceleration at 547 until about 548.5 (if anyone's interested I can tell you what each colour means)



and here is the same chart with just the rpm and the voltage shown



I can see the voltage is spikey just before it cuts out, but it's also spikey later on when it's accelerating OK. It was also spikey elsewhere to the same level when it was accelerating OK without cutting out.

[impmad2000]

What is the blue?

[Gary71]

Are you using the screened cable from the crank sensor to ECU? I noted you said you had one but not that you'd tried it yet.

I think the blue line is voltage. Where's that measured?