Alright ive been struggling with this code (P1512 - Intake Manifold Runner Control Bank 1 Stuck Closed) for over a week. Theres not much on any Miata forum related to this issue.

I have no clue what to do next aside from replacing parts (that appear to be working fine) so before I do that I figured I should ask some of you experts.

Car is a 2001, engine was replaced and has around 120k on it. I bought it 2 weeks ago, and am starting to question how good of a deal i got.

So far I have :
~Checked all vacuum lines going to the VVT solenoid (all of them coming from the back of the intake) and they all appear good
~Connected a high end scan tool to my ECM and manually activated the VVT solenoid (which I could hear clicking)
~Seperated the top half from the bottom half of the intake manifold and checked to see if the rod the VVT solenoid turns would move, and it does
~Tested the signal wire from the VVT solenoid to the ECM and the wire appears good


Im thinking about replacing all the vacuum lines just to rule them out completely. Then the VVT solenoid.

Could my ECM be bad? From searching about replacing the ECM, can I reprogram it or do I have to take it to a shop?

Are my check valves facing the correct direction?

Anything look wrong? Aside from the purple valve cover...

Any suggestions?

 

I believe i'm making progress...

Replaced all vacuum lines to no effect so I started looking over the oil control valve on the top of valve cover.

Looks like i'm missing the OCV Filter (screen) that goes into the oil control valve assembly. My oil was very dirty when I bought it (since been changed). Starting to think that the VVT actuator maybe sticking due to the dirty oil.

 

The error seems to be with the intake manifold plates - the VTCS system, not with the VVT.

 

agreed, look into the vtcs system.

 

Sounds like Scott needs to make you a ms3x sooner rather then later.

 

If that could help solve this, ill order one from him immediately. Emissions is due and this is complicating passing.

If I know that my VTCS vacuum switch works(on back of intake manifold), the bar inside the intake manifold attached to the VTCS actuator (under throttle body) rotates, and all vacuum lines are new what else should I be checking? I cant find a schematic of a miata's VTCS system anywhere online.

 

Post 43:

https://www.miataturbo.net/engine-pe...s-85172/page3/


With the info you have given, I'd be pulling off the manifold, and confirming full opening of the butterflies. Additionally, confirm that the check valve is still okay (not obviously damaged). Engine was replaced, good chance vacuum lines could be reversed. Has the code been cleared, and reappeared? What is coolant temp (approx) in the freeze frame?

 

That was it. Vacuum lines were not routed correctly. I cant get code to come back (before this it would come back almost immediately after reving car to 3k rpms) Ill take it for a drive to confirm once I finish everything else and get it off of jack stands.

Thanks for your help

 

I have the same issue but the diagram isn't helping me could u post a picture of the actual hoses and engine to see exactly where they are routed to

 

I also might have this same issue...
Consequently very little power under 3k. I inherited the car as a basket-case and had to put it together with no references.