Another diagnoses

[gloverman]

Hello all.

I have another tricky problem for you guys to give your opinions on.

A bit of background.

Its a customers car - he fitted the cambelt and mounted the motor into the car. I wired in a secondhand link , fitted sump , sorted a few general items like trimming and welding the RH tappet cover to clear the brake master cylinder , make the clutch work , fit fuel filter and fuel lines , heater hoses and other lots of stuff like that.

I mapped out the wiring on the car then moved onto a workshop motor on a stand to make the loom then fitted it to the car and terminated it into the car. Completed power checked before plugging in the ECU , checked the configuration of the ecu , confirmed fuel pump prime with ecu powered up and started the car. Little bit of engine start to get it running and away she went.

Warmed it up a bit and tried to rev it - it coughed and spluttered. Many bad word said at this time , didnt help it was about midnight. I did the normal checks. Coils - one was weak and the other was worse. When reving could see sparks jumping out of one coil lead - replaced along with two plug leads on that side.

Checked mixture - adjust more and less but made no difference. Timing light onto each lead - spastic spark when trying to rev.

Double checked my wiring. couldn't find any shorts or grounds. All continuity was good. Checked crank sensor - bugger bent pin - changed with another one but still played up.

Maybe now I should be asking everyone what they think - no out came the scope. Heres the picture that gave me a pretty good idea of what was up.

The pattern is a bit hard to see but it shows the cam signal on the top and the crank signal on the bottom. So what do you guys think is up?. I had three main options and I have now confirmed the problem. Ill let you know what it is in a few days.

Cheers

 

[gloverman]

Another picture

 

[sideshow]

i recon its the link if its an old one hehee

new ones are ok but are anal with needing perfect signals

 

[sideshow]

y is the cam signal height chanigning
is something bent

 

[gloverman]

Hello Jim - Bottom one is the crank signal. 24 signals to between the single cam pulse. Cheers

 

[cribbj]

If that crank pulse is coming from a Toyota setup, it's seriously sick. (I assume it's Toyota because you said 24 crank pulses between cam pulses)

Since you're generating square crank pulses, it looks like a Hall effect pickup is being used? But because there's a sinusoidal component, I'm guessing either

1) the 12v supply to the Hall has cratered, and/or there's no filtering of it

2) The Hall sensor itself is very sick.

 

[gloverman]

John very good guess but the signal is a standard lexus crank signal. They are reluctor type. Im using my bashed up workshop handheld scope so the definition is a bit crap but you get the idea of the changing pattern. Cheers

 

[cribbj]

If it's a standard VR setup, then it's even weirder. The only thing I know that would cause the sinusoidal changes in amplitude like that would be either the teeth worn down on one side of the trigger wheel, or excessive runout of the wheel (warped crank?)

 

[gloverman]

Jim - I had another spare link from another vehicle and that didnt change it.

Yep both of you got it. Bent trigger wheel. I whipped the crank sensor out and managed to get my head down there to watch as the engine was cranked over. Ill try and get the video up.

Cheers

 

[sideshow]

i never was a fan of the old links
stupud tiniest hand controller

but the new g4s are so user freindly
the software setup is so nice to use