Toyota COPs not working well when cold
 

alright I've been tackling this issue for months. I have toyota cops and I recenty rewired them to make sure the wiring wasn't the problem. Here's the deal:

70+ degrees outside: car starts right up and drives fine

50-70 degrees: takes 1-3 tries to start the car, then it misses every now and then for 3 minutes and goes away, presumably when the car warms up a little

now it's gotten to the point where I tried to start it in 30 degree weather, and i had to crank it probably 30 rotations and it finally caught and I had to keep my foot on the gas to keep it running, and it sounds like its running on 2-3 cylinders, but its not constant. the car has to warm up completely before it goes away. before it does, it misses so much that it's pretty much undrivable.

my dwell is set correctly, and as I said I rewired them, made sure they were grounding well, and put some dielectric grease inside the cops. If it was just running on 3 cylinders all the time It'd be an easy diagnosis that one of the packs is bad, but I dont think one in particular is acting up, I think they all operate like shit when it's cold. Would this have anything to do with pulse width settings? any other weird spark cold start settings I should look at? Any other ideas?

Edit: I guess it's also worth mentioning that I've had these installed for two years, and they acted fine last winter.

What do the plugs look like?

they are brown. the tune is otherwise fine, so once they stop misfiring they are ok. i'm sure if i started it cold, ran it like shit for a couple minutes, then pulled them they'd most likely be dripping with fuel.

IRTB's makes this really easy to diagnose. they occasionally blast a fireball out of the runners while i'm keeping it running in that condition.

edit: Also I changed my plugs that were gapped really huge because I thought that was causing the problem. on brand new plugs with the stock gap I'm having the same problem though.

It sounds like cranking pw (fuel) try suggestions from threads like this

i had a bitch of a time to start mine first up, but that was so long ago (everyone was just starting on ms) some searching will help you out with the issues (it has mostly always helped me).

Backfires point to lean fueling. I'd look at Cranking PW's and ASE, After Start Enrichment.

Wideband? What are your AFRs when it catches? Unless it's missing too much, it should give you an indication if your fuel is good. You can always use a spark tester to see if it's the COPs. Did it work fine with stock ignition?

I had the same exact issues with mine...which is why I ended up just running the stock coil and wires for the time being. I'm definitly going to stay tuned to see the outcome so I can hopefully get mine running right with the cops.

i don't think its a fueling issue. it reads a correct AFR about where it should when its running, cold and warm. Also, lets say I am getting it warmed up while its running like crap, and the coolant gauge finally starts to move but its not fully warmed up, i can drive the car at WOT and my afr is good at like 12.0 or so, but i can still feel it miss. Also, I know its getting adequate fuel under startup because if it cranks for long enough without firing, once it does fire, i get a nice loud pop from my exhaust.

also, correct me if i'm wrong but as far as I know there are three stages to startup: cranking, after start, and running. after start only lasts for a few seconds, right? my car will run like shit no matter how long it's been running until it warms up. in the cold weather now, it will behave like shit for 10 minutes. while cold the afr's are at an appropriate level, if not a little rich. I've tried leaning it out, and it shows as leaner on the gauge, but still same result.

right now outside its 30 degrees, and I know if i went and tried to start it it would crank for about 15 seconds with nothing happening at all, then it would start to fire every now and then but still not start (cha-cha-cha-cha-cha-chugchug-cha-cha) then after another 15 seconds of that i can blip the throttle and then it will eventually catch and run like a subaru for a good solid minute. it wont idle by itself for at least 3 minutes.

Maybe the dwell needs to be set higher while its cold?

It seems like to me that all of the coil packs, or most of them, are damaged somehow from two years of use and still work while warm but dont while cold. I have a set of ls1 coil packs lying around, I'll probably swap to those.

I have been having the exactly the same issues with my cops setup. I first tried a different set of COPS and nothing changed. I am having a friend try out my harness soon to see if that is causing the problems. This issue is really annoying because 9psi is SLOW.

update:
i changed my cranking pw to this:
8.9
8.8
8.3
7.8
7.7
7.5
6.3
4.8
3.6
3.1

the numbers were a good bit higher on the colder end of the spectrum, and it started a lot faster (took about 8 cranks in 30 degree weather, i was expecting it to take around 60) and it actually would idle right off the bat, but it was still kinda choppy. I don't know if it misses under load yet. more details after work.

What size injectors?

stock tan tops. 235cc iirc.

ha, nice title change. we'll see if that totally fixes it when I drive to work. I know it helped startup, but i dont know if it helped everything else yet. I suspect that it just helped a little and the problem will still be there. my afr has looked fine through this whole process.

Your O2 sensor might be bad or you have timing issues. You need to check your spark strength and make sure that's even the issue. You might also want to check the voltage at your COPs and make sure you have the 10uF capacitor in there. Most of us doubt the COPs are your problem.

N3v have you switched back to stock coils and seen if you have the same problems? I am highly suspect of people saying it is cold start settings. Mine do exactly the same as yours when it is cold, switch to my stock coils and it runs perfectly. With no change of startup settings at all. I will try to get a video tomorrow morning of how mine runs in the cold.

shuiend, what resistors are you using on your MS for ignition? Do you have the capacitor installed on your COPs? Have you checked your COPs to see if they're good and that the spark is strong?

I'm assuming you at least reduced the dwell time for the COPs.

Which specific resistors do you want to know the values of? It has been 2+ years since I have peaked in my megasquirt so I will have to go look up whats in there.

I have no capacitor installed in the wiring harness. The harness was built well over a year ago before adding them was common. I will look into it.

I have tried out 2 completely different sets of cops. Both have the same issues when they are cold. Yes I am reducing dwell settings when I switch to the cops.

I will hopefully get up a video tomorrow morning.

My dwell time is at 3.2ms for cranking and 2.5 for running if i remember correctly off the top of my head, i looked it up and made sure they were right when i did it. i'm not running any capacitors on my COPs. Do I need to change out the resistors on my ms board?

And hey whoever changed my thread name, this problem is still persisting and is showing to have nothing to do with cold start. :jerkit:

i have fucked with my cold start settings and it makes no difference. It just decided to work a little better when i started the car in the morning. it misfires all the time, i can see it in the tach. now when I say it doesn't misfire when it warms up, it just misfires less. for some reason I dont seem to have this problem in warmer weather at all, but on startup and even on warm cruise this winter i'm having this problem.

i just drove it home from work, it started up better but still i have to keep my foot on the gas to keep it idling for a few minutes before i drive off. also, it still misfired once it got warm. granted, it doesnt make it almost undrivable like when its cold though. but at idle, i could watch my tach sputter and drop every time it misfired. being that the afr was 13-14.5 at idle, and my tach is tied directly to my ignition, it has to be the ignition.

Now I feel like some people are starting to touch on the root of this problem. i'm not running capacitors and all the resistors on my board are the stock ones, whichever ones braineack's walkthrough says to use.

The aforementioned resistors are the ignition pullup resistors, which were specified as 1K until earlier this year when it was recommended to use something like 270 ohms instead. Here's the thread that discusses it, maybe it will ring a bell for you guys.

I'm curious if simply installing the 10,000 uF electrolytic cap on your COPs harness would solve a bunch of this misfire business. I happen to have a couple extras so Lars you can just install one and see if it helps.

he's using 1K ones.

If it's misfiring the whole time, maybe you have a noisy 'input' signal from your cas.
Have you put in the 0.1uF cap between JS8 (input CMP pin) and GND?
Like this thread (I didn't have time to find the right one)