1991 Miata 1.6L Ignition Timing Issues

1991 Miata Long Nose Crank.

A friend(he should be signing up shortly for GRM) has a 1991 Miata with the 1.6L and a long nose crank.

When he did the timing belt a while back he found odd markings on the timing gear and found the teeth count was off the usual 19 teeth between cam gears. He has 21(i believe) teeth between cam gears with marks from the previous owner on the 21 tooth count which is where the car runs perfectly fine. Timing can be adjusted within spec and everything.

So he tried to get it back to OE Mazda(19 teeth) and found that the car wouldn't run. Checked with a timing light and found the ignition timing WAY out beyond the range on the crank pulley - say 20-25 degrees or more BTDC.

So he set it back to 21 teeth again(this is like the 4th time) and it runs correctly. Checked timing and it shows it within range and he can adjust it to 14 degrees without issue. Car runs and drives.

We figured maybe the cams were off another BP engine? Checked them with a known good set of 1.6L cams from a Miata and they are the exact same.

If the ignition timing is that far advanced with the cams properly timed at 19 teeth between cam gears what could it be? There isnt enough adjustment on the CAS sensor to get it back within range.

Could the spout connector not grounding be an issue? I assume that if not grounded(or wire broken to connector) that the ECU will add ignition timing at idle? But 10 degrees or more?

Oddest thing ive heard of and hope someone on the GRM forum could point us in a different direction. Has anyone heard of this? Or dealt with something like this? Any and all help is greatly appreciated. Owner will chime in shortly to add any other information to this thread in hopes that we can get him back to OE specifications.

Stop counting teeth. I don't actually know how many teeth there are supposed to be as Mazda doesn't bother with that.

 Set up the cam timing as intended. Engine at TDC, intake cam with the I mark at 12 o'clock, exhaust cam with the E mark at 12 o'clock after the tension has been set. That last part is where most people get confused, they don't set the tension and things don't completely fall into alignment until that is set. Keep in mind that if it's off, it'll be off by a full tooth. I prefer to use the 12 o'clock method instead of the marks on the timing cover because then the I and E make sense.

Make sure the cam gears are actually installed correctly on the cam - that means the locating dowel is in the slot that lines up with the I (intake) or E (exhaust). If this is done incorrectly, you will not have a good day.

Check to make sure the damper has not slipped. Put the car at TDC (measured by either putting something down the #1 cylinder hole or using the mark on the block for the timing belt pulley) and then confirm that the timing mark is at T. If not, then you have a slipped damper and you cannot use the mark to set ignition timing.

You have to put the car into timing mode in order to be able to set ignition timing. Timing advance is used to control idle speed to some extent.

He is going to check all of them again. Still dont know why he hasnt responded yet...

Damper is good. That is known. He sticks a screwdriver into hole #1 and watches as it hits TDC.

Cam timing he is sure that he is on point and he is sure that the tension is set as needed.

If the cam gears are off, would the timing be that far off to where it would bottom out the CAS sensor?

Also, the spout connector, if it has a broken wire or isnt grounding itself out, what would be the consequences? I assume advanced base ignition timing. But by how much?
 

What is the "spout connector"?

You started off with a bunch of confusion about number of teeth and incorrect cam timing. I'd set the cam timing as per the factory technique and stop fretting about teeth.

If the intake cam (on a 1.6) has the gear installed incorrectly, that will definitely affect the calibration of the CAS. I have not experimented to see how much, but it would be possible to figure it out if this was something interesting to the individual who wants to spend the time. More importantly, if it's installed incorrectly that needs to be fixed.

Keith Tanner said:

What is the "spout connector"?

You started off with a bunch of confusion about number of teeth and incorrect cam timing. I'd set the cam timing as per the factory technique and stop fretting about teeth.

If the intake cam (on a 1.6) has the gear installed incorrectly, that will definitely affect the calibration of the CAS. I have not experimented to see how much, but it would be possible to figure it out if this was something interesting to the individual who wants to spend the time. More importantly, if it's installed incorrectly that needs to be fixed.

Sorry, its an old Ford term that was used for the Mustang w/ a 5.0L to set the distributor timing, its the little connector that you need to ground to put the ECU into "test mode" for setting the timing.

Ah, gotcha. I have to say I was not having any luck trying to figure that out :)

If the spout connector wire is damaged - never seen that, you'd probably have a whole bunch of damage to the harness first - then I'd expect the ignition timing to be moving around. IIRC it also stops trying to control the IAC when it's in "timing mode" so maybe you could try unplugging that if you're trying to determine if the ECU is in that mode. But I'd have to get a long way down the troubleshooting checklist before I got to that point.

In reply to kevinatfms :

Hello!

As Kevin mentioned above, I recently performed a timing belt on my 1.6 long nose miata engine. The white out marks on the timing cover were put there by the previous owner. Prior to performing the timing belt replacement the vehicle was running fine. Each of the cam gears appeared to be 1 tooth off and I wanted to correct the cams at the time of reinstalling the timing belt. I did replace the cam seals when replacing the timing belt and made sure the dowel did line up in the slot before reinstalling the gears. The picture below shows how I reinstalled the timing belt. Cylinder 1 was at TDC, the cams are at 12 o clock, and the crank is in line. I did properly tension the belt after installing before putting everything back together. After putting everything back together the car runs like complete crap and that I get due to changing each cam gear by 1 tooth. As mentioned above, I do not have enough adjustment in the CAS when adjusting the ignition timing. I did put the car in diag mode and brought the vehicle to operating temperature. If I change the cam gears back to line up with the white out marks then the vehicle runs ok. I have checked the damper... twice... and I even tried swapping on a solid lightweight damper just to see if it made a difference. I checked the markings on the cams to confirm that they are factory OE cams which they are. I just can't seem to wrap my head around why it works with the marks applied by the previous owner and not the way it should be set by the factory. My biggest question is... what is this causing? Could it be down on power?

Perspective/parallax in the image may be deceptive, but it appears the intake cam is advanced, looking at the pulley's spokes vs. the top of the inner cover.

Factory timing marks rarely line up perfectly (DOHC Mopar fours are the worst for this) due to production tolerances stacking up everywhere.

I'm not sure the intake cam is off, the index mark at 12 o'clock looks okay in that pic.

Crank certainly seems to be at TDC in that picture, you can see the notch in the timing belt pulley lining up with the notch on the block. That almost never goes wrong. If you install the damper now, does the timing mark line up with T?

How did you set the tension? I don't think that's a problem, just humor me.

Note that the 1.6 and 1.8 CAS units have slightly different housings although they are electrically compatible. The range of adjustment is different. Can you shoot a picture of the CAS so we can see what the back plate looks like?

Just to be clear.  The only way the car runs well is if you turn the intake cam 1 tooth counter clockwise and the exhaust 1 tooth clockwise from the way they are in the picture?

In reply to APEowner :

That is exactly correct

jkarlin said:

In reply to APEowner :

That is exactly correct

Well, that's weird.  And, when the car is running well you have enough adjustment on the CAS? 

Keith typed his response while I was typing mine and the answers to his questions will help get to the bottom of whatever is going on there.  He's also at least as qualified to help you troubleshoot this as I am and he's clearly got a troubleshooting path in mind so I'm going to let him guide the conversation.  He can also claim he's working while he's helping you.

No no no. Then we only get one person's idea. Keep asking questions. A big part of remote troubleshooting is asking the right question.

Keith Tanner said:

I'm not sure the intake cam is off, the index mark at 12 o'clock looks okay in that pic.

Crank certainly seems to be at TDC in that picture, you can see the notch in the timing belt pulley lining up with the notch on the block. That almost never goes wrong. If you install the damper now, does the timing mark line up with T?

How did you set the tension? I don't think that's a problem, just humor me.

Note that the 1.6 and 1.8 CAS units have slightly different housings although they are electrically compatible. The range of adjustment is different. Can you shoot a picture of the CAS so we can see what the back plate looks like?

The damper timing mark DOES line up with the T after installing the damper.

I set the tension by after installing the belt and tensioner/tensioner spring (which i also replaced new)... I rotated thru 1 and 5/6 rotations of the crank around before torquing the bolt for the timing belt tensioner

See picture below. Let me know if this angle works or if you want to see it from a different angle

I'm looking for the shape of the cap on the back. One is squared off, one is very rounded. I think that will do. Let me check my 1.6s tonight.

Keith Tanner said:

No no no. Then we only get one person's idea. Keep asking questions. A big part of remote troubleshooting is asking the right question.

I'm not going anywhere.  What I was trying to say in my poorly worded post is that I don't want to pull jkarlin away from checking the things you suggested.  I've seen too many threads where there's no logical troubleshooting path and some important questions never get answered because everyone is suggesting different things and the OP ends up jumping around trying to answer them.

In reply to Keith Tanner :

Ok, so you had me doing my own research on different CAS sensors. From what i can tell the 90-93 has that adjustment slot at 9 o clock if the plug is at 12 o clock and the 94 - 97 adjustment slot is more at 7:30 ish? Looking at my picture... To me it seems it looks correct?

It's something along those lines. They're close enough that they sorta work, but different enough that you can hit the adjustment limit.

I'm having a hard time explaining why it might work better with the cam gears set wrong. Everything is solid steel, every misassembly scenario I can think of ends up with the car not running. I don't think there's any way for a CAS to slip internally - but just for fun, I don't suppose you have access to another to swap in? I think you can pull the slotted cam drive wheel off the CAS, I wonder what would happen if you reinstalled it upside down?

Unless someone screwed with those cams for some reason. Like redrilled the end of it and moved the locating dowel. Never heard of it though.

In reply to APEowner :

When the car is running well (the cam gears in the white out marks) then it seems i have normal adjustment in the CAS. I can advance and retard within range and set ignition timing correctly... Well correctly to the incorrect cam timing haha. When the cam gears are in the picture i posted.... Which i swear is the correct mechanical time, then the ignition timing is off the chart. At full retard of the CAS range it is still way too advanced but at least i can see the mark in my field of view when using the timing light. 

APEowner said:

Just to be clear.  The only way the car runs well is if you turn the intake cam 1 tooth counter clockwise and the exhaust 1 tooth clockwise from the way they are in the picture?

I gotta say, from the picture, it looks like that would line up the marks properly to me..

Any chance you can get a picture straight on at the cam gears in the "running right" position?

What an I missing?  Sounds like you're over-thinking it.  If you can get the timing set right and it runs well, go do a 0-60 run.  If you're off, you'll be off by like 2 seconds :)

In reply to Keith Tanner :

I do not have one laying around, but if i need to get one then i can work on that. I didn't think it was possible to install the CAS upside down. Isn't it slotted in a way that it only goes in one way?

Yes, the CAS is slotted in a way that it only goes in one way. 

HOWEVER the drive gear is mounted to the shaft with a roll pin. If you punched that out and reassembled it with the drive gear on backwards, you might get this behavior. Maybe. And probably only on an 1.6 with the batch injection, a 1.8 might not run at all. I have not tried this.

Does it run well when assembled "incorrectly"? Do you have any idea of the car's history? 

In reply to WonkoTheSane (Forum Supporter) :

I'm considering going with a stand alone ecu and figure i shouldn't even consider something like that until i can figure out the timing scenario. Especially if after a stand alone if i want to go turbo / sc there is a lot going on with timing. The picture below is before i tool it apart. Was even using the little FM tool to keep the cams from changing.

In reply to Keith Tanner :

It runs very well when its not "assembled" correctly. I don't know the history. I bought it from a college girl who had 17in rims on it!!!! Those went away really quick. It did already have an oil cooler, oil filter relocation, and a racing beat catback. So the car had been modified slightly. Ive owed the car now for 3 years and really drive on nice days, to and from the track, and track days / autocross. Its a 91 with 125k miles. I have put 5k on it in 3 years. It doesn't even smoke when floored or smoke it all for that matter. The car has full bolt ons yet wont pull on another bone stock 1.6 that blows smoke like crazy. Makes me wonder if it is down on power? At idle i swear it almost sounds like it has a slight cam? It has a little lope however not extreme to the point where the idle is affected.

Dumb question, but did you pull the bolt out from the crank pulley and verify that the keyway wasn't buggered up?