When you did the lifters (not an engine guy!)
Could you have swapped the intake and exhaust cams by accident? I know its possible on neons, don't know about miata. (At least bp powered ones. My only remaining miata has one cam)
When you did the lifters (not an engine guy!)
Could you have swapped the intake and exhaust cams by accident? I know its possible on neons, don't know about miata. (At least bp powered ones. My only remaining miata has one cam)
In reply to Dusterbd13-michael :
Not possible. The exhaust cam has an extra price that drives the cam angle sensor.
Wild for no reason thought.
Is the cat clogged?
In reply to noddaz :
Not that I can see. Had the exhaust off for a driveshaft swap and nothing obvious from the engine side.
It’s not really possible to put the CAS in 180* off, by design.
I assumed that and then looked up pics of it and convinced myself otherwise. Swing and a miss.
So what else can cause the ignition timing to be so far off? When the 99 miata i fixed had these symptoms they were created by the timing belt being off. That in itself wouldn't have stopped the engine from running (and didnt, it technically ran) except that the cam position sensor was triggering off the wrong part of the cam gear and causing a double spark on the 2-3 cyls like a heartbeat that was also out of time, so the engine ran like E36 M3 and kicked back so hard during cranking that it stripped the teeth off the flywheel.
If the coils are wired correctly (one goes to 1&4, other goes to 2&3) and you switch the connectors between them and it gets worse, then the problem is upstream of that and has to do with the timing of the triggering. If that is solely triggered by a CAS that can only be put in one way onto only one cam that is correctly timed both at the dowel pin and at the sprocket...
Will flipping that trigger wheel for the crank sensor cause a timing problem (like 180 out...) ?
Anyone ever hear of the screw that retains the trigger wheel to the indexed shaft in the CAS coming loose?
I've seen the trigger on a 2001-05 VVT cam come loose, that was hard to ID.
The rule is always "what did you just do?". The odds of another failure happening right when you do something else are really, really low. So it has to be something that was just done.
To be sure I've got this right - since the last time the car ran, the following has been done:
- cams and cam sprockets removed and replaced
- lifters removed and replaced
- timing belt changed
- CAS removed and replaced and aligned with indexing marks
- driveshaft removed (and replaced?)
- coil harness plugs swapped (what? hang on, this is wrong if I understand it)
I'm almost positive the crank trigger shouldn't cause a running problem as a result on a 1997, but what if the trigger wheel is on backwards? I know it can be done on an NB and it's a bitch to figure out. Air gap to that sensor should be 0.040" or less.
I was at the track today so didn't get anything done. Yes, Keith, what you have stated is correct.
As for the coil wires, I removed them when I replaced a missing screw. I thought I may have put them back incorrectly so I tried swapping them. It didn't work.
Trigger wheel was not removed. The crank pulley and trigger wheel were removed as one with the big bolt. I will check the air gap next time I work on it.
I do appreciate all the advice! Thank you!
Have you done a compression test?
In reply to wvumtnbkr :
Not yet but the car was running fine (other than noisy) when the lifters were swapped. I have no reason to believe it would be bad. Why do you recommend checking compression? I may be missing something.
Thanks!
It's possible to hold the valves open slightly with improper lash (which trashes compression). I know your valve lash isn't 'adjustable' but an assembly problem could conceivably cause something like that to happen.
Long shot........Any chance you reversed the firing order?
Not according to what he’s posted before.
Miata firing order is easy. 1 and 4 get attached to the same coil, and the one furthest to the outside. 2 and 3 attach to the other one. Doesn’t matter which of the two posts you use on a coil. So 4123, 1432, 4132, 1423 all work for a 1.8.
In reply to Vigo :
Got it. I will try and check next time I work on the car. I'm back to work this week so progress is going to slow a bit.
The other thing I'm going to try is moving the belt one tooth each way on the sprockets to see if the car runs any different.
Keith, how would I check the oil pump spring and over pressurization?
PMRacing said:In reply to wvumtnbkr :
Not yet but the car was running fine (other than noisy) when the lifters were swapped. I have no reason to believe it would be bad. Why do you recommend checking compression? I may be missing something.
Thanks!
Because you have a no start condition after tearing apart the valvetrain. I would verify I had compression before chasing everything else. It's easy peasy.
Don’t bother to move the belt on the sprockets, they’re obviously correct. I know there’s all sorts of panic about timing belt installation on the internets, but it’s really really simple.
To check oil pressure, get an oil pressure gauge. I don’t think that’s it, I had a Miata that made 100 psi cold and it ran fine. But the 1996 pumps are known to stick open. Dunno if I’ve heard of one sticking shut.
BTW, I'm disappointed. No one has said the solution is an LS swap yet. 
When my pulley let go on the highway it bent the crank position sensor WAY out of the way..... I've only just got it close to fixing it. Anyways, the car still drove fine and started, albeit slow.
PMRacing said:BTW, I'm disappointed. No one has said the solution is an LS swap yet.
LS Swaps are so 2018. Subaru EJ25 swaps are where it's at now.
Fueled by Caffeine said:When my pulley let go on the highway it bent the crank position sensor WAY out of the way..... I've only just got it close to fixing it. Anyways, the car still drove fine and started, albeit slow.
Note that an NB would not run in this scenario. It’s only the 1996-97 cars that consider the crank sensor to be for diagnostic purposes instead of a fundamental sensor.
So here is going to be my plan of action, albeit in small bursts of rare spare time...
1. Comp check - make sure new lifters aren't sticking open somehow.
1a. Leak down - if issue with 1, I will throw a leak down tester on to see if I can pinpoint problem area
2. If 1 and 1a are OK, oil pressure check. I assume I just thread into the factory port? I'll need to locate a guage to do this...
3. Put old lifters in and deal with noise and see if it runs right?
PMRacing said:3. Put old lifters in and deal with noise and see if it runs right?
I would continue with the basics here, check fuel and spark.
Yes, it's almost certainly related to something you did during the swap, but it could be something peripheral. Maybe there's a marginal wire in the harness somewhere and moving the harness around resulted in it making intermittent contact, so you're getting a bad cam angle sensor reading or a bad ground or something. Maybe bumping the fuel pressure regulator disloged a piece of gunk that's clogging an injector -- something weird like that.
NickD said:PMRacing said:BTW, I'm disappointed. No one has said the solution is an LS swap yet.
LS Swaps are so 2018. Subaru EJ25 swaps are where it's at now.
Dual port SOHC y0!!
k24 and just be done with it..... :) This thread has me totally double checking everything since I just took my 94 down to the block and basically rebuilt or replaced everything from the block up and removed a ton of stuff from the engine compartment like AC, PS, and Cruise. I'll know this weekend if I did it right.
Could the cams themselves be installed 180 out? Or is that not possible?
Comp test results would be interesting.
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