New install holding back missfire

[crazypolak]

Hi all,

Ive just installed my MJ on my Toyota 4AGE 16v engine all started and installed with no problems which was great engine idles perfect and revs freely.

However I have a problem under acceleration/load around 3500 / 4500rpm which I can replicate when stationary with no load.

Looking on the forum I suspect this could be the VR sensor installation but my bracket (pictures below) is quite heavy duty construction when compared to others 4mm steel with additional securing bracket.

A couple of questions:

My sensor is at a slight angle (follows the angle of the block) not 90 to the trigger wheel can this cause an issue? Ive seen another 4AGE installation were the sensor is at a similar angle.

The centre of the VR sensor or the eye part is not quite central over the teeth again is this critical I havnt found any information to say that it has to be dead centred?

Im thinking of borrowing an oscilloscope to see if the signal goes dirty when the problem occurs but my take me a few days to get hold of it.

Is there anything else Im over looking??

[fenderstrat536]

Not sure if it is just me but it looks like the sensor should be out farther so it is centered on the trigger wheel

[crazypolak]

Not sure if it is just me but it looks like the sensor should be out farther so it is centered on the trigger wheel

This is one of my questions does it need to be dead centre??

[fenderstrat536]

If you look at the tip of the sensor, at least with the explorer sensor that i'm using, there is a metal bit, I put this as close to dead center with the wheel as i could get it.
It would probably give a more consistent signal in case the wheel has any run-out

[crazypolak]

I will make it more central but I was hoping for a more definitive answer on whether it needs to be central, regarding runout there is none or at least its so minimal its not detectable.

[crazypolak]

Well made a new bracket today that allowed me to centralise the VR sensor and guess what...still no good hesitation will not rev past around 3500/4000 when driven holds back no power.
Any suggestions welcome???

[brentp]

Were you able to observe the signal using an oscilloscope?

Also, what material is your trigger wheel made from?

There's a chance that your bracket might be vibrating at that midrane RPM, which is a fairly common problem. a resonating bracket will affect the waveform going to the EDIS module, which causes the EDIS to lose sync, resulting in the misfire condition. A solution is to make the bracket more rigid.

Let us know on the above!

[crazypolak]

Hi Im waiting to get hold of the scope as soon as I do I will report back.

The trigger wheel is stainless steel.

Ive made a new bracket to allow more sensor adjustment and will brace it up and report back.

[brentp]

Are you using a special magnetic grade of stainless steel (known as austenitic stainless) or is it just regular stainless?

If it's regular stainless the magnetic properties are too weak to generate the proper signal for the VR sensor. You will need to replace it with something like a mild steel wheel or special austenitic stainless.

[crazypolak]

I just double checked its steel that's been plated to stop it rusting it came from a trigger wheel supplier and is listed a suitable for Megajolt and others.

[crazypolak]

So I havnt been able to get hold of a scope yet I still have the problem an did some logging and found the problem is occurring around 4600rpm ans you can see in the log.

Ive also made a more robust VR sensor bracket (although Im not convinced the original one was flexing but this one allows more adjustment.






Im booked to do a hill climb on the 19th of Aug so would really to get this sorted.

[crazypolak]

Attatced data log

[eds911915]

thers other things that cuase misfire other then ignition. you should go back to basic engine performance suck- squeeze- bang- blow make sure all the basic stuff is working to spec at 4600rpm.

[crazypolak]

Quick update the MJ install is all fine turned out after cleaning the carbs all is good. They had draged up some dirt from the tank even with a decent filter on there.

Thanks for all your suggestions all going well now.

[brentp]

I'm a bit concerned about the rigidity of the bracket where the sensor is mounted. The bracket between that and the block is *great* - looks thick and rigid - I would extend that bracket all the way out to the sensor mount.