Cam Sync - AEM Infinity - Starting Issues - Cam Sync

[mikedsilva]

I've been running an AEM Infinity 506 with no real issues. I recently had the motor out to swap back to a set of cams that I had initially used and wanted to experiment with again. The cam/crank sensor which mounts in place of the distributor was not removed, and nor was the crank pulley.

First start was not an issue. Fired up, did the cam break in, etc

After that, it was very difficult to start. I played around with my cranking afr and timing etc but couldnt understand what had changed so much. Even fitted a new set of plugs but that didnt make much difference.

I managed to get the car running and bed in the engine and change oil etc, so all good there. But I was scared to park up anywhere but home... it was taking 20 plus tries to get started.

Today I sat with a friend who looked at my diagnostics tab in the AEM software.

While cranking, I quickly got sync state 100% and it would try to fire and bang (like gunshot) and carry on but not run. When it eventually did fire up, it ran fine. We noted that the "Cam 0 Timing Degrees" on the Diagnostics tab, was reading 475 degrees. We turned off, and tried to restart.. this time, when it wouldn't start (even thought it said I was in sync) the Cam 0 Timing Degrees was showing 116 = basically 360 degrees out.
He thought that perhaps my crank pulled sensor was 'noisy'... but again, it was running well up till this point. He altered the noise settings in the wizard and it did seem to be easier to start but was far from repeatable. We had to use an auxilliary battery.

Looking at the cam/crank sensor, it is designed in such a way, that the sensor is not perfectly over the middle of the toothed wheel on the pulley. So I removed the cam/crank sensor from the motor and was careful NOT to rotate the pinion. I elongated the hole in the housing slightly with a dremel, then reinserted the cam/crank sensor and made sure it was centred over the toothed wheel, and also 1mm or a fraction less distance from the teeth.

I rechecked my ignition sync anyway... with ignition lock in the wizard at 0, and the fuel pump and injector relays removed, I cranked the motor with a timing light and got 0deg at top dead centre. Does this support my efforts to not roate the pinion on the sensor while it was out of the motor?
I went to fire up the motor and it did not fire. I still got all green boxes to say I was in sync, but this time the "Cam 0 Timing Degrees" was reading 296 (earlier today it was 116) = ie, 180 degrees difference.
Turn key off, and on again, and this time, it syncs showing 655 and it fires right up.

So I don't understand why it sometimes syncs 360 out from when it should?
And also, how I managed to be 180 out on the reinstall, if my ignition sync did not need to be altered? Does this mean I must have knocked the pinion? But if so, wouldn't that mean I would need to make adjustments on my ignition sync?

I'm confused...

Here's a short video
https://youtu.be/A_xwB9m0GN0

[Harpo]

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[icarp]

Mike , it sounds like the pick up sensor in the unit is going bad or the wire .
just a thought
Ian

[mikedsilva]

Originally Posted by icarp

Mike , it sounds like the pick up sensor in the unit is going bad or the wire .
just a thought
Ian

possible...
looking at the Rasant Manual I got years ago, it talks about ignition sync but that was when they had the EPM module..and I got the later updated cam/crank sensor.
Back then, they said the EPM module had two discs inside the EPM: one has 24 “teeth” which provides the crankshaft position signal to the ECU, while the other has 1 “tooth” and provides the camshaft signal.

I'm a bit basic when it comes to electrical things.. I got the cam/crank sensor and use a 60-2 tooth gear on the crank pulley. I'm assuming my 60-2 wheel replaces the 24 teeth in the old EPM.

Is the coarse timing adjustment (CamSyncAdjustment) in multiples of 30 degrees? ie, if you put a "1" in the box, does that mean 30? I'm thinking I need to go back and re do this as I have "36" in mine.

[mikedsilva]

Originally Posted by icarp

Mike , it sounds like the pick up sensor in the unit is going bad or the wire .
just a thought
Ian

But which sensor... the one on the flywheel? or the one in the cam/dist sensor housing?

[dannobee]

If you didn't mess with the cam sensor or the crank sensor, that leaves the wiring as the most likely suspect. Validate with a multimeter and the wiggle test. While I'm not familiar with the 506 specifically, most ECMs, both factory and aftermarket, only need to see the correct sync for one revolution for it to fire the ignition correctly. If the failure occurs during a drive cycle, it just won't start on the next try. Which is pretty much what you're experiencing.

[Mr Beau]

Can you ignore the cam sync and run in waste spark?

[mikedsilva]

Originally Posted by dannobee

If you didn't mess with the cam sensor or the crank sensor, that leaves the wiring as the most likely suspect. Validate with a multimeter and the wiggle test. While I'm not familiar with the 506 specifically, most ECMs, both factory and aftermarket, only need to see the correct sync for one revolution for it to fire the ignition correctly. If the failure occurs during a drive cycle, it just won't start on the next try. Which is pretty much what you're experiencing.

Not sure I understand "failure occurs during a drive cycle"... ?

For some reason, during crank it syncs 360 out of phase sometimes and of course will not start. Could wiring or connection cause it to sync incorrectly?
Also, the Cam0_SyncError1 and Cam0_SyncError2 are incrementing while the engine is running = that isn't normal is it?

[mikedsilva]

Originally Posted by Mr Beau

Can you ignore the cam sync and run in waste spark?

Don't know and not sure I should?

[mikedsilva]

Spent some time checking my grounds. The wiring harness from Rasant has 2 grounds in the engine back that are spliced into the coil harnesses.. they ground onto the top of the engine into the cam housing location. Also double checked my ground on the trans strap where the ecu ground attaches.
I cleaned everything and tried again.

This time, I got 1 or 2 failed starts and then it started several times in a row.
Ie the cam sync was picking up correctly.
But 10 minutes later, I was getting failed starts and it was trying to sync 360 out of phase.

A friend is going to loan me a scope and I guess we will see what signals we are getting.

What can cause an "erratic" sensor? and also, if the sensor was indeed faulty, why does it run perfectly fine once it actually does start?

[Harpo]

Have you asked Andrew and /or Infinity?

[stownsen914]

Random thing - I had an issue setting up a car with a Motec, not sure if it might be possible with an AEM. During cranking the ECU needs a certain minimum voltage to power it. It's not uncommon for voltage to drop to 8 volts or less during cranking, which in my case was causing the ECU to not work properly. Easy enough to check in case AEM has a similar minimum voltage. The solution for me was a more substantial battery.

['78 SC]

Originally Posted by mikedsilva

possible...
looking at the Rasant Manual I got years ago, it talks about ignition sync but that was when they had the EPM module..and I got the later updated cam/crank sensor.
Back then, they said the EPM module had two discs inside the EPM: one has 24 “teeth” which provides the crankshaft position signal to the ECU, while the other has 1 “tooth” and provides the camshaft signal.

I'm a bit basic when it comes to electrical things.. I got the cam/crank sensor and use a 60-2 tooth gear on the crank pulley. I'm assuming my 60-2 wheel replaces the 24 teeth in the old EPM...

So you're using just the sync (cam) signal from the EPM and getting the reference (crank) signal from the 60-2 crank pulley wheel? Are there two connectors on the EPM? Are you using the correct (cam sync) one?

just spitballing,
Steve

[mikedsilva]

Originally Posted by Harpo

Have you asked Andrew and /or Infinity?

yes
no reply as such yet

[mikedsilva]

Originally Posted by '78 SC

So you're using just the sync (cam) signal from the EPM and getting the reference (crank) signal from the 60-2 crank pulley wheel? Are there two connectors on the EPM? Are you using the correct (cam sync) one?

just spitballing,
Steve

hi Steve
yes, there are 2 sensors. They have different plug types and cannot be plugged in incorrectly. Here is the setup I am using. https://rasantproducts.com/collections/engine-sensors/products/rasant-products-cam-crank-housing

As mentioned, this system was working perfectly a few weeks ago, before I pulled the engine to swap camshafts.
Thanks for the suggestion though.

[mikedsilva]

Originally Posted by stownsen914

Random thing - I had an issue setting up a car with a Motec, not sure if it might be possible with an AEM. During cranking the ECU needs a certain minimum voltage to power it. It's not uncommon for voltage to drop to 8 volts or less during cranking, which in my case was causing the ECU to not work properly. Easy enough to check in case AEM has a similar minimum voltage. The solution for me was a more substantial battery.

Hi, yes thought this might be something. I have had the battery on a charger and also using a portable jump pack. Cranking speed is strong and battery level is good.
Today it went form syncing correctly every so often, to now where it is not syncing correctly at all. It will not start. I have borrowed a scope tool to try to inspect the signals coming from the sensors.
I'm hoping it's a failing cam position sensor as that is relatively easy to replace.....

[mikedsilva]

[dannobee]

"Drive cycle" starts when you turn the key and it fires up and ends when you turn the key off. There are different strategies in the ECM to address failures, like when the cam sensor signal is lost. But often the ECM "remembers" the last correct cam sensor signal (it is firing the ignition and injectors, after all) and can keep the engine running without the cam sensor signal. It only needs the cam signal on initial cranking, to properly fire the ignition and injector sequence (if it's sequential injection and not batch fired).

Since this started after cam replacement, what changed? Wiring? Was the cam sensor bumped or damaged? Is the crank sensor gap the same?

[icarp]

Andrew and Rasant /or Infinity? were having trouble with the sensor for a while .
This could be the same gremlin. It had to do with the 60-2 and the sensor specs .
Ian

[mikedsilva]

Originally Posted by dannobee

"Drive cycle" starts when you turn the key and it fires up and ends when you turn the key off. There are different strategies in the ECM to address failures, like when the cam sensor signal is lost. But often the ECM "remembers" the last correct cam sensor signal (it is firing the ignition and injectors, after all) and can keep the engine running without the cam sensor signal. It only needs the cam signal on initial cranking, to properly fire the ignition and injector sequence (if it's sequential injection and not batch fired).

Since this started after cam replacement, what changed? Wiring? Was the cam sensor bumped or damaged? Is the crank sensor gap the same?

Hi
the cam/crank sensor housing and its sensors were left in the case and not removed while the cams were swapped. Also, the crank sensor gap was exactly the same since the pulley was also not removed from the engine.