Im having some serious issues with resets/spark blow out with my toyota cops and it seems to me this mod would help. Can some please be a pal and outline what needs to be done to a v3.0 board to get this mod one? I have a DIY MS built by Brain...

Thank you Very Much you may bring me off this ledge by helping me. LOL

 

it'll be easy. as long as you have a soldering iron.

remove the two posts on the little db9 connector, then unscrew the four screws on the opposite side and pull the board out.

If you look on the bottom of the board there are two resistors below the two LEDs. Those right now are 1K resistors, swap them out for 270ohm resistors. You can take one from R32, R30, R31, R36, R34, or R35....you don't need them on the board as long as 1. You have Hi-Res code or 2. You're never going to use the PWM circuit.

I've been building all my latest MSes using 270ohm resistors on the spark pull-up (I'm left with 6 leftover the way I build the board) and been running it myself for some time now.

Mike are you running the Hi-Res code? Do you have the .1uF cap mod performed as well?

 

Mike, just go buy a pack of resistors at radio shack, 1.07 after tax.

I dont want to go over Scott's head, but scavenging parts from other circuits is just asking for more problems. Not worth it.

 

I'm willing to bet 0% of us here use the circuit. I don't even build it anymore, with the hi-res code it's rendered useless anyways.



I just built this yesterday, notice the missing R32, R30, R31, R36, R34, R35, Q12, Q9, Q13 and Q10?

 

I did the spark mod without the .1uf cap a few days ago and still get the misfires at idle a bit, so it is definitely needed with the high res code.

 

yes, the .1uF cap is absolutely necessary when running hi-res code.

 

Yes and yes... Got a more specific picture of the resisters i need to swap?

 

Bottom right corner:

 

aw im too slow.

 

Got it! Thanks guys. I will stop by the shack on my way home tonite. I'm not really optimistic that this is going to solve my issue but hey u never know. Ive had the same ms,cops and chassis with an NA 1.6, a turbo 1.6, and an NA 1.8. now all the sudden turbo 1.8L wants to give me resets like a ************? I don't get it.

 

Switched the resistors for 270 ohm ones and swapped back to stock coils and the car run beautifully. I dont think im going to mess with Cops any more. I just going to sell the two sets i have and run stock ignition...

 

cripes, I've been getting resets as well. Maybe I'll give this a shot if it becomes more frequent. I only seem to get resets off throttle which is wierd. It has never happened with my foot on the gas...

 

AAAARRRRGGGHHHH .... after several days of running better than ever from doing this mod, my car is now running TERRIBLE again. :(

All was well until I sat in bumper-to-bumper traffic a few days ago, for about an hour .... every time I came to a stop the idle went a little bit higher ..... got way up to 1600 before I was finally able to exit the jammed-up highway. Then the idle went back to normal. I did feel some misfires though .....

.... The next morning I drove to work and the misfires were very very very bad. Been that way for the past couple of days.

I can't even explain how frustrated I am right now.

Someone several months ago suggested my car's problems could indicate a bad head gasket. So I searched last night on M.net and found a semi-related post which could be the problem:
MX-5 Miata Forum - View Single Post - No. 2 Misfire Mystery, part 2

Here's the post from someone whose car had similar problems to mine, i.e. if you don't want to click the link:

"It turned out to be a wire in the Injection Harness, which is also the harness that goes to the coil pack. After replacing the Oxygen Sensor and that not fixing the issue we were poking around in the engine bay while the car was running and moved the injector harness to look at something and that cause the car to run fine. Move the wires back and it ran rough. Move the wire... fine... you get the idea. We ended up replacing the injector harness by taking off the top half of the intake manifold (don't forget to plug the bottom half of the manifild with a rag, or you will lose one of the injector grommets down the hole like we did). This DID fix the problem."

I guess that's worth my time to check out. Dumb question, when I open the hood, where is this injector harness? I'm not familiar with that. I'm also not clear what the poster meant by "replace" the injector harness .... is he saying get a whole new harness? What's involved for that kind of thing?

Someone educate me please.

(Sorry for the thread drift.)

 

the only way your idle is going to go up to 1600 is if the stock ecu decided the idle valve needed to be opened more to compensate for something. were you perhaps heatsoaking and you don't have a good corrections table setup?

 

I have no idea if it was heatsoaking. Without a real temp gauge and without having my laptop on, how would I know?

I don't know anything about that topic.

 

Did the log indicate that MAT was rising to implausible levels during this period?

 

What makes you think I was logging? I was only driving home from work.

 

FWIW I log driving home from work on a regular basis. It is a good way to get some real-world data.

 

I checked to make sure my soldering from the spark mod is still intact (it is) and I checked to make sure the MS MAP gauge is working correctly (it is - sitting at 100 with key on and engine off).

Paul says I'm not using a corrections table. He sent a long and detailed email about why such tables are bad.

So right now the idle is a long-shot secondary concern; the misfires are my primary concern.

To reiterate: I previously changed and checked everything there is to change and check, but still had random misfires ... then I did the spark mod and life was heaven ... then a week later the random misfires suddenly returned. I tried the M.net guy's suggestion (linked in a recent post in this thread) of double-wrapping the coil plug wires in electrical tape for a few inches where they're near the spark plug wires .... that didn't accomplish anything.

I suppose it's plausible that the problem is with the injector connections, but if so, then doesn't explain why the problem magically fixed and then unfixed itself with the spark mod!!!

Also on an NB you have to remove the stock top half of the intake mani to even GET to the injector connections. So obviously the engine can't be on while I do that. How, then, will I know if wiggling the injector wires find a bad connection or not?

Thinking aloud: what's the best way to test that each injector is getting the proper voltage supplied to it? And what is the proper voltage anyway?

 

Sorry to resurrect. I have done the mod with 270 ohm resistors, but am now also converting to COPs. Can I just take care of the lower value resistors with dwell settings, and if so what dwell should I use? Or do I need to reinstall the 1Kohm ones?

Thanks