1jz misfire in over all cylinders.

[Alltoy4me]

I have a pestering misfire that has progressed, I am puzzled and am in need. I own an 89 NA to 1jz convert. It has an AEM v2, Bosch 750cc injectors, upgraded rail and pump. I have an extended wire harness that was checked and is good. Fuel pressure is good, coils are well insulated, not sure where to go next. The video on the youtube link shows the misfire. The picture are my plugs (left to right is 1 to 6). I have gone through 3 sets of properly gapped plugs as well. The misfire was scarce when the original tune was being done and only happened while the engine was warmed up. Now it misses on startup. I believe my Duracrap battery is just not holding the power well and the result is a weak signal to the injectors from my battery thru the ignition switch but I have not checked it yet. It has been sitting for a few weeks at a time for a while now so I have had to charge the battery to run it each time. Does anyone else have any ideas of what is going on? Any help is greatly appreciated.
Thanks,



https://youtu.be/Id3DBLq1uTM

 

[Alltoy4me]

Spark plus are from 1-6 from bottom to top. 1, 3, and 5 are clean. 2, 4, and 6 are fouled.

 

[hvyman]

Have you pulled the boots off the coils and checked for cracks?

 

[Alltoy4me]

The boots have all been shrink wrapped twice over.

 

[RacerXJ220]

Compression good?

 

[Radial]

Sounds like clogging of injectors to me
The ones with white powder on the sparkplugs are most probably clogging, causing lean condition.
The black ones are over-fueling because they are not clogged yet.

I must say that your tune is most probably incorrect, if it was tuned with the misfire.
Misfires gives you totally incorrect AFR readings.

Tip:
You need minimum 10 micron filtering before shipping the fuel to the injectors... We see waay too many installs with just a aftemarket 100 micron filter on the racetrack. They burn pistons every year...even though their buddy did the same mistake last year:nono:

 

[Alltoy4me]

Racer, yeah the compression is great thankfully. Radial, I hadn't thought about the injectors clogging. When the tune was done it was running perfect, the misfire started happening very intermittently at the end of the tune when he was just doing some minor things. We considered it done so I could ship the car West. A fuel filter is easy enough to prevent it from becoming a worse issue so I'll swap that. But I'll still need to clear the injectors. Thanks for the help so far.

 

[Radial]

From memory injector 1-2, 3-4 and 5-6 are all fired in pairs on the stock 1j wiring/ecu. Unless you have changed that with the AEM, there is no way 1,3 and 5 can run different from the others, if not clogged. (with ignition ruled out, of course)

 

[miekedmr]

does the aem work with the stock ignitor and coils or something else? if so have you checked the ignitor?

 

[hvyman]

its your coils. cannot just shrunk wrap them. boots need to be pulled off then the coils need to be plastic epoxyed and then shrink wrapped and then the boots can go back on.

You are experiencing ignition break up that is very common on 1j old coils.

 

[Radial]

If coils really are suspected, just flip them upside down and install some regular sparkplug wires in between the coil output and the plugs.
That way, the cracks in the coils will not short the spark to ground inside the head.

But i'm still guessing on fuel.

 

[Alltoy4me]

Radial: The injectors are wired as 1&4, 3&5, and 2&6 together. I think the fuel filter still should be improved for the current setup. Good call on the bypass.
Miekedmr: The AEM does work with the stock ignitor and coils, I had another ignitor and swapped it out with no difference.
Hvyman: As far as the boots on the coils, I actually have (2) new coils on it and they apparently aren't showing any change on the video. However it does seem like some ignition break up, that is what lead me to think it had something to do with the power feed to all the injectors since they are all fed from a mostly common source.

 

[Alltoy4me]

Got it fixed, it turned out to be low power supply. Looks like I'll be needing a better setup. Glad to have it running good and thanks for the help.