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Randomly drops in Idle and sometimes dies. OEM Coil Pack OHM's? CAS?

3K views 7 replies 5 participants last post by  RedemPhex 
#1 ·
Alright I have been trying to install MS on my car and having an idle issue.

After scaring myself I went back to stock until I could make some progress.

Today was the first day I really drove it and during the day it seemed fine, tonight however I found an issue...

Randomly (I can not reproduce it I keep trying to) it will suddenly drop to 500 RPM with the clutch in and sometimes die.
I thought it was because I needed to readjust the Idle Air Screw (I had been messing with closing it while working with the MS), so I did and it came back, so I did it again... and it came back again just now.

But after the first time the car would again randomly (I also could not reproduce this which I also tried too) buck and shake refusing to move while in gear but fine out of gear and then it would go away.

I checked the plug wires and one was popped up and clicked back down and while it has not done it again it did die again (This was also at the same time I adjusted the idle air screw for a third time) it never bucked.


I have come across some threads that say common issues are either coil packs or CAS.
I have one more set of coil packs I know works but I would like to OHM test these if I can whats the factory acceptable specs on the coils? (If possible)

As for the CAS, Where is this? I take it as a Crank Angle Sensor? or Cam Angle Sensor? or am I way off?

Hopefully this will point me to the issue I was having with my MS too... or just show me something I hurt while playing with MS.

Thanks!

2000 Miata, Not Boosted.
 
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#3 ·
Ok I am so used to the KL I have to get the sensor Acronyms and Locations down on this motor too.

I will pull it now since I am ahead tonight and clean it up... probably make it worse and tow the car home lol.
 
#4 ·
So today I pulled the codes and got:
P0113
P0118
P0123
P1141

So I cleared them and they came back shortly.

So I replaced the Coolant Sensor, IAT Sensor, MAF and the whole Throttle Body with both the TPS and IAC sensors.

Made it a block and the car stalled again.

The gentleman I get all my Miata parts from was out of ECU's for 99-00, but he believe the ECU was the problem.

All those codes mean High Out put except for 1141 I believe is MAF related. All pieces have been replaced so I am not sure what to make of it here.

With all those parts replaced I find myself wondering just what could be the issue but this was not an issue before I started MS so either wiring is the issue for some reason (less likely in my opinion), the Stock ECU got damaged some how (More likely) or there is another issue I am not finding.
 
#6 ·
I have a metal hard tube and I had it off today I did not notice any holes. I keep forgetting to take a picture of my engine bay as requested.
 
#8 ·
have you tried manually setting the idle? You should do this in open-loop, by shorting out the GND and TEN pins on your diagnostic port in the engine bay.

Generally, there was a ton of gunk in my IAC. I cleaned it up with brake cleaner (and my intake manifold), then shorted out gnd and ten (with the car running obviously) and then set my idle. It fixed my drooping idle (my car was not stalling, but I have heard of people who had it so bad that it did).
m.net has a nice write up somewhere, let me see if I can dig it out.

EDIT:
Here is what I could find:
http://forum.miata.net/vb/showthread.php?t=138960&highlight=idle+dip

And another important one:
http://forum.miata.net/vb/showthread.php?t=396195

Mostly this post:
POPSTOY had a writeup on here somewhere that dealt with pulling the throttle body and cleaning it thoroughly, including the idle bypass circuitry. You'll need to reset the base dile when you're done (short T.E.N to GRND via the underhood diag port and set the idle with the ECU out of the equasion).

Peter
 
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