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Old 08-29-2017, 06:13 PM   #1
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Default Car won't start after going back to "stock" for SMOG California 96 Miata

So here's the full story (I'll try and keep it short), previous owner turbocharged 1996 Miata with Bell/BEGi kit. Has changed a lot over the years since then, and to my luck I was able to obtain a CARB EO D-349-1 sticker from Begi.
The car was running on MSPNP Gen 1 (I know is ancient) with RC 550 CC injectors (also ancient) but they worked and I tracked the car and loved it... but I need to pass smog for first time here in California.

After swapping everything back to "stock" (see below) car started and ran on MSPNP prior to doing the following:
1) Wired wastegate open on turbo and removed c-clip
2) Installed EGR adapter and egr tube over to intake manifold (this was the biggest b!tch in the world)
3) Swapped Injectors to stock brown ones
4) Swapped injector harness (non soldered connections to the RC 550cc)
5) Swapped stock ECU into car (did this stupidly without removing battery, hoping this didn't damage my coils?)
6) Installed stock o2 sensor in upstream bung (as well as new AEM X-series UEGO Wideband which is in second "primary" bung of downpipe)
7) Installed MAF and taped away IAT sensor (for now)
8) Plugged MAP hose running back to MSPNP

Car starts, runs for 3-5 seconds.. sputters (one time misfired) and dies... throws a code (which my OBDII reader with my stock ECU now gives me the p0335 code. Which is odd because my understanding is this just is used to detect misfire and throw a code... not to actually do anything/stop the car from running.
I am currently troubleshooting a p0335 code with crank position sensor... I looked for it on the front of my 96 miata and... it isn't there. I read up and saw that MSPNP Gen 1 didn't use this, it used a separate sensor for Crankshaft posistion sensor (CPS) and camshaft position sensor (CAS) (on the back). *naming of CAS vs CPS still confusing and apologies if I mixed it up*

I'm thinking the PO installed some way to get the MS to read the CPS differently and removed it... but if he did... I dont know where or what he would be using instead... as I see no wiring harness of any sort to get to... (attached a photo of where it should be... but isn't... no harness or anything) The car is a bit of a frankenstein and (I mix it up) but is using either the block or head from a 2000 or 2001 after a motor went boom boom. Which could explain the different sensor and MSPNP being okay with it... but obviously the stock 96 ecu wants to see the specific variable reluctant sensor (NA) vs the hall-effect (NB). I SHOULD BE ABLE TO FIND THIS THOUGH as from what I've read it is in the same place. by the crank pulley on front of motor..

A side note:I noticed one of the clips on the CAS wasn't good but it still seemed to seat properly (Also on the harness the two plugs to the coil pack are identical, does it matter which one goes to which) I would think this would through a CAS code if it was bad....

Below is where I believe it should be from every post I've read... but I don't see it... anywhere or any harness of any kind. Which from reading, the 99-05 and 96-97 use a different CPS (see below) but I'm not seeing it... again anywhere...





Anyways, any help on this is appreciated. Plans after this thing passes, is to get a MS3x and ID1000 injectors and retune to the unfortunate 91 octane (or just go straight to e85 who knows). I'm running a Walbro 255lph (previous owner) as well through Vishnu dual fuel rail.
Car is so close to running, no other codes are thrown (yet) or are pending based on the very short 3x runs I attempted late last night.
Could something else be wrong that is stalling out the car? Timing that was done on the CAS manually or the coils or NGK wires being bad as I messed with installing the EGR tube and ignition harness?

Thanks,


Kyle
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Old 08-29-2017, 08:52 PM   #2
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Did you unplug the coil pack at any point? You may have reversed the plugs. And I can't see your image so hard to help on the head question, but if you have the cas at the back and it's a na 1.8 valve cover - raised letters- the you should have the cps down at the trigger wheel. Pretty ignorant myself here but I was chasing a po300 for a while on my '97 and got real familiar with those components.
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Old 08-29-2017, 09:28 PM   #3
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Yeah I unplugged and replaced the entire harness. I never touched the NGK coil wires though, just moved to the side while I worked on the EGR etc.
Looking through the history from PO, looks like it is a 01 engine block with a NA head from the original.
I don't see a CPS at all down by the trigger wheel.. no harness or wiring. I'm thinking the MSPNP was happy without having it there, but obviously the stock ECU needs to see it to not throw a code.

Would it be anything related to fuel relay if it is idling smooth for 3-5 seconds and then stuttering turning off?

I know I'll need a CPS at some point and I'm on getting one just not thinking it is the immediate issue sadly. (would love to be wrong)
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Old 08-29-2017, 10:08 PM   #4
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I was referring to the two plugs that go to the coil pack, I doubt it's that your firing would be all kinds of off. When it idles and dies is it choking out due to too much fuel or is leaning out and starving for fuel. What happens when you go to start it again? Too much fuel till you crank it out? Not enough till it has enough in there? Or does it fire right up?

Got to troubleshoot it.

You have a few paths you need to check.

It was running before so it not mechanical timing, you have spark and it does idle smoothly though momentarily so you have spark and firing order is right.

It's not the cps- in my experience but I'm ignorant- I've unplugged mine and it keeps running. How does your stock ecu read air flow and maintain fuel air ratio? Is this all back to stock? Vacuum leak or cool valve cover breather letting more air in pass the mass air flow sensor?
Check your systems and follow the paths back to failure.
Fuel pump likely still works
the regulator is nuts simple it probably works
the harness and injectors are different- make sure they are all plugged in all the way.


Look over every thing again and talk your self through the steps to swap back over to smog, you may find you missed something In the process. If you keep jumping around to different things you will likely keep jumping over the issue.

​​​​​​​Good luck
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Old 08-29-2017, 11:15 PM   #5
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The crank trigger wheel for the NA is only needed for misfire detection - hence, why it's only on 96 and 97 NA's for OBDII compliance. The ECU still uses the signal from the CAS for crank and cam timing. NB is a different animal, using the crank sensor as the crank sensor and a cam signal that only reads the cam. I'd ignore the code for troubleshooting purposes - you'll need to get it solved for smog, but it's not the source of your not running issue.

Does it run with a little bit of throttle? Wondering if there's a diode wired across the idle air valve.
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Old 08-30-2017, 03:30 PM   #6
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Running off MAF through the intake to the turbo.
EGR valve (which is now connected to the exhaust manifold) but both ports are venting to atmosphere.
Good news is... I went out after swapping the two connectors on the cam angle sensor (at the back)... (which misfired and I didn't start the car again after)

The car ran continuously, but ran RICH. Like 1-4 A/F ratio at around 2k rpms.. then try to idle below 200-500 rpm and bog a bit and hunt.. and be around 9-12 A/F which sounds a lot more right. The video for part of it I would press the gas pedal to raise the rpms up to help it get to 2k.
I tried adding a bit of throttle to getting it out of the bogging point... per gooflophaze, went back to the 2k rpms and running RICH

Video link below

https://goo.gl/photos/apJj5VbTDn4bbL8aA

I only added throttle about halfway through the video, sorry don't have the exact points this happened. Regardless it operated the same with/without throttle.
NOTE car never turned off even when bogging down and not touching the gas pedal. Did the same thing when I restarted it as well so wasn't a one time start deal.

I don't want to run it this rich for long because I now have a wideband o2 for the AEM, new stock o2 and a new CARB cat that I know will get toasted if they see that much fuel...
didn't touch out the back of the exhaust I saw what appeared to be fuel on the ground as well... makes sense with how rich it was running.

Might be related to idle control valve... but for now I'm going to disconnect the cat and run from the downpipe until I get this sorted...

Is this (new) behavior typical of the idle air valve/idle position?
Again I agree that on the 96-97 the code for crank pos sensor only throws a code with/without it on the car

Appreciate all the help on this
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Old 08-30-2017, 04:11 PM   #7
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https://www.miataturbo.net/diy-turbo...94-97-a-31595/
Also I know this thread exists, I'm going to try and match it per the attached pdf, I have shown on first sheet how it is currently routed, and how stock is shown for a 96 per this thread.
(now that the car is at least "running") was waiting to modify too much before I got to a point of idle (introducing too many changes without proving them out one at a time leads to a headache of trouble shooting)

Also I have the MAP hose for the megasquirt still connected to the intake manifold but blocked off with a screw in the hose
Attached Files
File Type: pdf Miata Trouble Shoot August 2017.pdf (76.8 KB, 6 views)
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Old 08-30-2017, 04:44 PM   #8
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The afr's you've listed aren't possible. 9-10 is super rich, much more than that and the engine won't run.
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Old 08-30-2017, 05:48 PM   #9
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I brought the AEM UEGO back to the ECU for power, ground, and o2 signal so i'm not expecting to see abnormal values different than what the (unplugged) MSPNP would see.
You are right 9 is running super rich, I'm not sure what it is seeing as the engine is revving up to 2k rpms.
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Old 08-30-2017, 07:37 PM   #10
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Ignore what your AFR is saying - that data is obviously bunk. The stock ECU isn't using the O2 data (closed loop) until it reaches operating temp anyway. It's another thing to get fixed, but isn't the root of your problem right now.

What pipe are you using for your intake tube that connects to the MAF? Is the idle valve plumbed to it?
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Old 08-30-2017, 07:48 PM   #11
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I just have a 90 degree elbow coming off to the filter to a coupler that goes to the MAF just to get it to pass, with megasquirt it just goes from a 90 straight to the filter... wasn't aware there was an idle valve that needed to be plumbed to it....
See photo (older since I'm not at home injectors are in motor)

Last edited by swimomatic; 08-30-2017 at 07:49 PM. Reason: photos
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Old 08-30-2017, 07:57 PM   #12
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The idle air valve is under the throttle body - it has a small pipe that on the stock intake plumbs to the stock crossover tube. If it's open to atmosphere, it acts like a giant vacuum leak since the air isn't being metered by the MAF.
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Old 08-30-2017, 09:04 PM   #13
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Is your smog guy gonna ignore visual orrr are you just hoping?
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Old 09-01-2017, 12:13 PM   #14
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I think that the old begi kits (turbo + fuel pressure regular + timing box) are smog legal in CA, so having a turbo installed isn't an automatic fail.

That being said, when I was living in CA, I saw what the turbo/supercharged guys were going through to make 150-180whp and moved to FL. I actually met Jason C SBB back then (2002).
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Old 09-15-2017, 01:28 PM   #15
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I have a EO D-349-1 CARB approved from Begi for the car, just have to get all codes to clear and get s SMOG tech to sign off on it once this is sorted.
So two things after being back from vacation:
One, had the AEM UEGO in the wrong mode... I am seeing A/F ratios in the 17-20 range when the car is idling. (woops)
Two, there is a hose connecting the throttle body to the IACV, I was able to trace it down. With that said, there is nothing connecting that over to the Intake that is going into the turbo assembly with the MAF.
Option 1: Plug the hose from the throttle body and let it run over to the turbo as it is. Run a hose directing over from the IACV to the intake just after the MAF.
Option 2: Route from dump of BOV and run hose over to the intake just after the MAF (not sure the implications of not having a BOV with my W/G wired open etc).
Similar to what is shown in attached BEGI-S photo of turbo kit


Either way I have to tap some way/somehow from the intake to the IACV for the car to idle. Good news is that, though it isn't smooth the car does continue to run without stalling at this point.

The next step is tackling the CPS, but I'll tackle that after I get this going (believe car is using the 99-05 NB sensor or no sensor at all.. still can't find the damn thing)

Last edited by swimomatic; 09-15-2017 at 01:51 PM. Reason: Remembered the BOV has a dump that isn't hooked up and can route off that instead of removing
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Old 01-12-2018, 07:17 PM   #16
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Quote:
Originally Posted by gooflophaze View Post
The crank trigger wheel for the NA is only needed for misfire detection - hence, why it's only on 96 and 97 NA's for OBDII compliance. The ECU still uses the signal from the CAS for crank and cam timing. NB is a different animal, using the crank sensor as the crank sensor and a cam signal that only reads the cam. I'd ignore the code for troubleshooting purposes - you'll need to get it solved for smog, but it's not the source of your not running issue.

Does it run with a little bit of throttle? Wondering if there's a diode wired across the idle air valve.
So I got the code to clear by getting a trigger wheel from someone on the forums. The car does continue to run while driving it under throttle. When I let off to let it idle, it idles high and blips in rpms.

Is it common to wire a diode across the stock IACV with a MSPNP Gen 1?
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Old 01-13-2018, 06:19 AM   #17
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TLDNR.

If you're still running a MAF check the wiring/etc on that.
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