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Old 07-15-2011, 12:42 PM   #1
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Default COP running really bad.

I have all my Cops installed and it does run however it has a misfire at low revs which I cant hear or tell if its there at higher revs/70mph. Every so often the exhaust will bang as if fuel has ignited in the exhaust.

My Tach has also stopped working. Do I still need to do the 1K resistor MOD even though im running a DIYPNP?

Also I couldnt understand where the 2.5ms dwell rating was entered on tuner studio. I changed cranking to 3.5 but where do you cnage dwell to 2.5?

Would that cause it to run like a bag of s**t.
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Old 07-15-2011, 12:51 PM   #2
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the dwell rating is as measured at 14v, so you should use 2.1ms and then tune your battery dwell correction table to match the curve that jason has mesaured.

that will bring up back up to ~2.5ms when running


yes on resistor.


running like **** = bad wiring job? did you gap the plugs out too large?
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Old 07-15-2011, 01:02 PM   #3
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0.8mm gap
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Old 07-15-2011, 01:15 PM   #4
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try gapping them out to .11mm
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Old 07-15-2011, 01:18 PM   #5
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0.11 thats tiny.

Just searching for the graphs from Jason and I found a page which lists some dwell setting but not sure if this is it?https://www.miataturbo.net/showthrea...ighlight=dwell

These figures?
10V: 5.9 mS
11V: 5 mS
12V: 4.25mS
13V: 3.75mS
14V: 3.3mS
15V: 2.9mS
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Old 07-15-2011, 01:34 PM   #6
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i meant 1.1mm or ~.040"


yep, so you gotta do some math assuming the dwell number in the spark settings is based around 14v and you know you run at Xvolts when cruise around, you need to convert his final numbers into a percentage and plugged into your battery-dwell curve to get your desired output.
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Old 07-15-2011, 01:38 PM   #7
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Quote:
Originally Posted by Braineack View Post
i meant 1.1mm or ~.040"


yep, so you gotta do some math assuming the dwell number in the spark settings is based around 14v and you know you run at Xvolts when cruise around, you need to convert his final numbers into a percentage and plugged into your battery-dwell curve to get your desired output.
You have lost me there.
So based on what you said at 14V that should be 2.5ms. Then im lost sorry.
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Old 07-15-2011, 01:56 PM   #8
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i dont know what curve you just posted but Jason measured the ideal dwell curve for the Toyota COPs at:

9v = 3.4ms
10v = 3.1ms
11v = 2.8ms
12v = 2.6ms
13v = 2.4ms
14v = 2.2ms
15v = 2.0ms
16v = 1.9ms


so under your ignition settings you should use 2.2ms as the dwell value.

But what is your voltage when the car is running? 13.5v as reported by the MS?

So your correction curve needs to make sure that at 13.5v you dwell-battery correction is 105% and 140% correction for 10v.

makes sense now?

if 2.2ms = 100% then 3.1ms = ~140% and 1.5ms = 68%

so:

9v = 3.4ms = 154%
10v = 3.1ms = 141%
11v = 2.8ms = 127%
12v = 2.6ms = 118%
13v = 2.4ms = 110%
14v = 2.2ms = 100%
15v = 2.0ms = 90%
16v = 1.9ms = 86%
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Old 07-15-2011, 02:07 PM   #9
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Brain why would increasing the gap help the misfire?
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Old 07-15-2011, 02:14 PM   #10
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i dunno, but that's where it should be at now with these coils; but i fear the issue is a bad coil and/or wiring.
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Old 07-15-2011, 07:06 PM   #11
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Thanks for the figures that explains it much clearer. Just need to get my laptop sorted out now and then change the dwell settings and my ignition table.
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Old 07-21-2011, 05:37 PM   #12
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As I suspected the car is still running very lumpy. I change some of the settings in the dwell correction table. Only problem I had is that there wasnt enough points to set each of the values set above so I nevr had the dwell correction set for any lower than 10 volts. Is there a way of adding more points to the graph so I can input all the figures above.

I fear I may have damaged some or all the cops. I hope not but still the car runs very lumpy
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Old 07-22-2011, 03:19 AM   #13
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Is there a way to add all the figures to the dwell correction table? If not what voltage should I start at or shoul I just leave 13v and the odd numbers out and assume that when the curve passes through that point then it's the value above.
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Old 07-22-2011, 08:32 AM   #14
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I mean I just did the math for you, if you cant figure out how to apply that to a table...hint, you don't need all the data points.

The dwell is not your problem, it's either wired incorrectly (eg. firing order) or the coil(s) themselves are bad.
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Old 07-22-2011, 05:19 PM   #15
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I appreciate as always your help Scott, Just wanted to be sure so I can eliminate that as the problem. My wiring was ok. It wasnt the best but I would think its fine. Only things I did a bit crappy was I never had full lengths of wire for each wire on the cop and then solder them to the correct points on the connector. I joined the cables that could be joined with as short a wire as I could get away with. That might mean that 4 wires where soldered together and then 1 wire went from that to the connector. Other than that I cant think of an error with wiring. The CAP is in and must be right as its not blown up

COPS yes they could be damaged. I have 1 spare so I could do a swap on them all and see if it goes.

Assuming I input the figures above I assume the COPS shouldnt now get damaged (Yes if they are already damaged they will still be)?

I need to use the car tomorrow to travel 100miles. Just hope it gets me there and back.
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Old 07-22-2011, 05:30 PM   #16
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My revs are up and down like a yoyo any suggestions on what this could be. I have changed max dwell to 2.1, cranking is 3.5 dwell table is
6V =200
9v=154
10v-142
12v=118
14v=100
16v=86

Ok so I left it running for a while and the revs seemed to stay constanta fter a minute or so. I have chaged the gapos to 1.1mm up from 0.8mm. When holding a constant rev the engine idle drops then recovers. I have took a small clip to try and show you. i will upload in a sec.

Last edited by ronniebiggs; 07-22-2011 at 05:54 PM.
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Old 07-22-2011, 06:58 PM   #17
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View My Video
It may not be the best footage but you can here the small miss as it ticks over then when I rev it and hold it at the same revs you can hear the engine tone drop then recover and do that several times.

Any suggestions?
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Old 07-23-2011, 05:34 AM   #18
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I tried swpping all the coils 1 by 1 with my spare new cop and the engine note still drops. TBH I think this may have been there before going to COP as I remember when the crap tuner was tuning the car and he held the revs at certain revs and then adjusted the timing/fuel the same sort of thing been there.

Any suggestions from watching the video?
Is it normal or does anyone else have a similar thing where if you hold the throttle constant at certain revs the engine dips the revs then recovers?
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Old 07-23-2011, 09:51 AM   #19
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Quote:
Originally Posted by ronniebiggs View Post
View My Video
It may not be the best footage but you can here the small miss as it ticks over then when I rev it and hold it at the same revs you can hear the engine tone drop then recover and do that several times.

Any suggestions?
Quote:
Originally Posted by ronniebiggs View Post
I tried swpping all the coils 1 by 1 with my spare new cop and the engine note still drops. TBH I think this may have been there before going to COP as I remember when the crap tuner was tuning the car and he held the revs at certain revs and then adjusted the timing/fuel the same sort of thing been there.

Any suggestions from watching the video?
Is it normal or does anyone else have a similar thing where if you hold the throttle constant at certain revs the engine dips the revs then recovers?
These "problems" can be due to all sorts of things not necessarily related to your COPs. Stuff like AFR, airflow wierdness, idle valve, vvt.

What happens when you actually drive the car?
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Old 07-23-2011, 11:28 AM   #20
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Anytime I've ever held the rpms constant and it did that it was because that area of my fuel map was highly untuned.

the engine idles like they are all firing.
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