We'll after hours of searching, testing and trying I'm stumped.

I'm having some really bad ignition breakup after the car has been driven for a while or heat soaked.

Car pulls great if it comes out of the garage cold and isn't heat soaked. If i drive around for a while and get into some stop and go traffic then romp on it it will miss badly. Its even worse if I have the lights and fans on. It can take up to 25 min of driving for the problem to come up.

If I give it about 1/2, to 3/4 throttle it pulls no problem to redline but WOT it doesn't like me unless its not heat soaked.

So far I've swapped the coils packs, ignitor, new plugs, new plug wires, and the coil harness. I've also tested the resistance of the wires from the ignitor plug to the plugin for the coil packs. All good. Alt is putting out 14v (I rebuilt it when I built the motor) Battery is less than 1 year old, interstate 51r. I've done all new grounds, and extra grounding throughout the engine.

After changing those things out the ignition miss is exactly as it was before.

AFR ratios are great at 11.2, and they will stay there when it misses so I know its not fuel cut.

Even if the air intake temps are the same hot vs cold it still misses.

Power fc is running the stock map with the PIM volt adjusted to the afr I wanted. I will do proper tuning once this issues fixed.

Motor has less than 3,000 miles on it. (plugs and wires only have bout 200 miles on them)

My mods are Street port, PFC, intake, full exhaust (wrapped dp), full non seq, larger smic, under drive pulleys (no airpump) stripped rewrapped the stock engine wiring harnesses and removed unneeded wires. About 12psi. And premixing.


The unknown. I bought this car as a shell built the motor for it and put it back into a whole car so I don't know the history of this car, but I do know all the parts for the engine came from one of my spare good known motors from back in the day.

I've finally gotten the motor broken in and fixed lots of other issues so this is the first I've really been able to romp on it hard, so I don't know if this is something that has came up all at once or if its been a problem since I first fired it up.

If anyone can point me in the right directions I'm all ears. Thanks!

 

We're the new coils brand new? If not, did you measure their resistances? Looks like you've checked all the usual culprits.

 

1. Swapped with another Power FC? ECU may having issues heating up.
2. When you swapped coils, were they with KNOWN goods or new?
3. Tried swapping different pick-ups (by the main pulley)? They could be failing from the heat.

 

I haven't swapped the PFC with a known good working one but I don't think that would be the case everything works perfectly out of it and it came from a local guys fd that was being put back to stock to sell.

Coil packs are known to be good, they look great visually. And even after swapping them zero change happened to the missing issue.

I was thinking about swapping the pick ups. But the car runs perfectly unless its under WOT. But its something to try.

 

What plugs are you running? Also how much premix?

 

When I've experienced break up it's on single turbo cars and it's plug related so in your case I'd start with spark plugs but I seriously doubt that's the problem.

Have you tried running some 10 plugs leading (you can leave the 9s in the trailing)

Next I'd lean toward your engine harness or coil pack harness and swapping in a stock ECU couldn't hurt to rule out the PFC as a problem.

Have you tried turning the boost down to say 8 or 9 to see if the problem still exist? If it goes away I'd guess it's plug, coil or AFR issue.

 

Running 9s, they are very new plugs. I did a resistance test on both of my coil packs and the L1 L2 didn't even do anything on either packs. I'm going to order a new leading coil pack and go from there. The coil packs I have came from good cars but they have been sitting for years.


I wish I could turn the boost down but it creeps to that, I ported the crap out of the wastegate just like I've done on all my other fds.

I would like to plug in the stock ecu but I've got zero emissions stuff on it and I know it would go right into limp mode.

Premixing 1oz to a gallon, no omp.

 

spark plug gap

 

I'm guessing he's running the standard NGK rotary type plugs so gap won't be an issue.

Have you tried going 3 quarter throttle to keep the boost at 10 psi or lower? If not try it and see if you still have break up.

 

I have had a few cars that break up at 12PSI on the dyno, HKS twin power always solved the issue. Ignition Amplifiers 93+ RX-7

 

im having the same problem, its fine up to about 10psi then starts breaking up.. im using LS2 truck coils with NGK 9's

 

It's rare but I've seen coils test fine when cold but then become out of spec as they heat up. It sounds crazy, but put them in the oven on the lowest setting to heat them up and then re test them.

I'd also re inspect all grounds and if all else fails buy a ignition amp.

 

Brand new coil pack is on the way. I will post results after install.

Yeah 3/4 throttle is just fine, its WOT that gives me troubles.


This makes the most sense and I've read a bit about that happening. Its exactly like what my car does. Once it gets hot it starts to fail, the hotter it gets the more it fails. Hence the new pack on the way

 

Assuming that you are going to go down the path of a hotter spark, I highly recommend looking past the Twin Power:

https://www.rx7club.com/3rd-generati...nstall-992444/

The twin power isn't bad however for the same $$$ you can have what I believe is a better setup.

 

New coil pack came in today. Problem is still the same. Car runs slightly better so it wasn't a complete waste of money. Although it might be a placebo effect haha.

I guess I'll order a twin power and see what happens after that.

I dunno though its so strange that it misses only once its hot and heat soaked, not before.

 

What's your EGT temps when cold and hot? It might be something fuel wise as well.

Is your AF the same when hot and cold?

JT

 

It's worst case but compression could be low. Is it hot starting with ease?

Also have you tried colder plugs like 10s?

The twin power is known to cure these problems but with twins at 12psi it shouldn't be needed of course neither should the colder plugs.

Possibly it's just tuned too rich and once it warms up and the compression comes down the AFR is way off. OOOPs I think I remember you saying according to the AF gauge it's around 11.3.

 

Sounds like the tune is too rich at high rpm. I had a similar problem at high rpm with my old M2 stage 3 ecu. A properly tuned PFC fixed the problem.

 

Hot start, zero problems. Motor made great compression last time I tested it.

A/F ratios are exactly the same hot vs cold about 11.3. They stay the same when its missing too. Its a brand new innovate wb.

I haven't tried colder plugs yet.

It takes about 25 min of driving for this problem to come up.

 

I should of read your 1st post more carefully throughout my replies lol.

Anywho good luck with it. Hopefully a Twin Power will fix it and obviously a tune should help as well.

 

haha thanks, I'm going to try and figure out why my boost is creeping too. I've ported many a wastegate in my day and this is the first that's creeped this much.

Hopefully I can get the boost down and see if it still misses at a lower boost setting.

I'm wondering if the alternator isn't putting out enough amps. Its showing 13.8v on my commander. Under heavy electrical load it misses more though so it makes me wonder.

 

Your boost may be creeping due to the ignition problems. Incomplete burned fuel is great at spinning the turbine wheel

 

Have you checked your injector duty? If you have stock injectors, they may be fine during warmup, when the pfc is limiting your boost. Once it warms up you may be hitting 100%. Have your injectors been cleaned? Do you have a stock fuel pump?

 

I have a similar TT car tuned at around 11.3 AFR and it will see approx 90 to 92% duty cycle at 12psi on a 4th gear pull and makes about 300 on a dyno-max.

See what your car is doing in regards to duty cycle when running 4th gear all the way out.

 

All 4 injectors were cleaned and flow tested by rc when I built the motor. Injector duty cycle is about 93% little more if it creeps past 12psi.

When its miss firing the afrs are still the same.

Stock fuel pump.