[SOLVED!] 2JZ-GTE Swap into MA70 - Misfiring issues - Will PAY for a correct answer..

[richardjeffries]

pre-obd2 toyotas are connected to a laptop via very simple 2-transistor adapter. There's some free software on the web to run diagnostics for them

Always nice to know what ECU actually "sees". These values may differ from the ones you test with your multimeter

Beautiful idea. Any link to info on this? I will search also. Thanks!

[richardjeffries]

http://www.mafak.com/2008/08/making-...-obd1.html?m=1

[richardjeffries]

Repaired and made no diff. Gonna try a different ecu soon.

[richardjeffries]

*** = todo
^ = done

[George]

I use this software
http://primavistalab.com/myengine/
at the very bottom of the page there's English version of it

Cable can be any rs232 to k-line or usb-kline
the 2-transistor design as per your link is most likely to be ok

[richardjeffries]

I'm going to construct one soon. This will be very useful in testing to see what the conditions are like at the time the misfiring/sputtering occurs.

This is just driving me insane .. the car starts, runs perfectly until the idle drops. Smooth as glass at 900-1100 while warming up. The misfire/sputter is completely consistent with the dropping of the idle. Then after that it sputters/misses every rpm and everything. It clears up a bit at higher RPM but I think it's just being covered up by the high rotation speed of the engine.

[George]

the sooner you make it the sooner you know the answer

CAS related troubles are clearly seen as inconsistent engine speed reading. There still can be a variety of problems including cracked head gasket, faulty idle control valve or ECU, but a single run of diagnostics will cut away the majority of false guesses

[richardjeffries]

I'm going to run a compression test on it tomorrow to hopefully eliminate the BHG item. However I don't see how it could get a BHG from sitting, but, with this car who knows. I know compression test isn't a definitive test for it but it can also tell me if I have any other issues with my valves or anything.

I think what's got me leaning towards electrical/fuel instead of a mechanical failure would be that it is smooth as glass upon first start (30 second or so) until it's warm enough for the idle to drop .. I'm in Florida here so the weather is around 85-90F daily.

What do you mean by 'seen as inconsistent engine speed reading' .. you mean RPM reading? Inconsistent in what ways? I'd love for you to elaborate on this because until now I've gotten no help as far as diagnosing the CAS.

Also, if the whole OBD reader doesn't solve the issue I will borrow an oscilloscope from a friend to help me check the waveform of the crank and cam position sensors.

Lastly, knock sensors. If they were on the way out.. or one was.. how could I check? Would the scope also tell me about these?

Thanks George, you're a huge help!

[George]

With inconsistency I mean that RPM reading is not stable. For example my 1jz-gegives 648-652 RPM when in P, and I assume that's good. Of course you will read higher deviation of RPM because of the misfiring, but generally faulty CAS will result in more jerky RPM behavior. When still in doubt about the origin of RPM shatter it's best to look at the CAS signal with an oscilloscope. There's nothing fancy about it, any laptop with a soundcard will be enough. But I believe you don't have to go that far at first.

Now a couple facts about knock sensors. Even with both of them disconnected idle speed should remain stable. Now to check if they're fine you should check their output with a scope. You should observe some sort of pulsing noise , with amplitude being of order of tenths of volt. Closer look (magnifying T and V scale) should reveal resonant nature of sensor, with oscillation period around 8kHz.

Earlier knock sensors had 200 Ohm resistors built in them. Later sensors, on the opposite, should not have any continuity from output to sensor body.

[richardjeffries]

Huge help. Thanks a lot. I'm curious about the sound card scope trick. I'm going to google it but what program exactly would you use to view waveform ?

[George]

No problem, I'm always curious about problems that seem to have mystic nature =)

I won't recommend any particular program I'm afraid. Though keep in mind you don't need realtime. 1-2 seconds of record at 44100 Hz is more than enough. Only make sure to set adequate input level. Better if you find a soundcard with high input impedance (which allows direct plugging of a guitar, for example), but I believe that's not a critical requirement, you will see something anyway. That impedance thing relates only to knock sensors, with CAS it's not the case.

I use Sony Sound Forge for recording, but it seems to be an overkill for you. If you want typical waveforms, any Toyota engine repair manual would help. I got one engine electrical repair manual in English, it's for for JZA80 / 2jz-gte vvti.

[dumbass]

have u tried to unplug coolant temp sensor when car is cold
then start it and see if it stays better for longer this will tell ecu engine is always cold

then next day try unplug coolant temp sensor but bridge out the 2 wires
this will tell ecu engine is very hot and see if it does the problem right from the start

does it feel like the miss is spark related or fuel related

has this conversion run properly at all or have u just finished wiring it up
and u have made a mistake somewhere and its got this issue

best thing to do is wire in the under dash diagnostic plug and read live data with a scanner

[richardjeffries]

It's finally fixed.

So I made the cable, and went outside and got lost in tinkering with the car more. Never even plugged the cable in.

When I went out to mess with the car, I decided to check the spark plugs to see how the cyl's were doing. They all looked perfect. No black, but no ash. They were just a nice burn, on all six. I decided to do another spark test (did one a few weeks ago but had different issues then). Turns out #4 wasn't sparking.

I swapped the coil pack and still nothing. I swapped the clip with #5 and got a spark. This made it clear to me that it was the wiring or ECU. I tested the power at the coil and got 12v. I tested the continuity between the wire at the coil and the wire at the igniter and it was perfect. Just to make sure, I went and unplugged the pin on the igniter, and ran a new wire from the igniter straight to the coil for the trigger/ground. Still nothing.

I was about to conclude that it must be the igniter or ECU. What I did to test this theory was switch the signal/ground from #4 to #5 and vice versa. In theory if it were the ECU or igniter causing the lack of signal, then #5 would now NOT fire, and #4 would. To my surprise, I had the same result! #4 still not firing.

I was baffled for all of 15 seconds when I figured it must be the power, even though I tested the power.. it's getting signal/ground, it HAS to be the power. I went to run a new power wire straight from the coil clip to the battery when I noticed that the power wire was on the WRONG pin of the coil clip!

Such a ROOKIE MISTAKE and somehow it got away for weeks! I'm wondering how the spark plug was still used though? Was the fuel piling up, and eventually the air compression ignited the mixture? Maybe it had some sort of weak spark on occasion with the wires reversed? Very odd! Sure enough, fixing that wiring mistake cured the issue and the car now drives great. Slow as all hell because of the factory restrictive exhaust and 5psi wastegate. Whatever, at least I can drive it around!

I find it astonishing that there will be no code thrown when the wires are reversed.. this is a phantom problem that I hope will never again take this long to diagnose for anyone thanks to this thread.

Thanks for everyones help!!!

.. and to think someone could have made $100 if they asked if I had checked for spark ..

[dumbass]

its the forums
as if someone will give someone else 100 bucks hahahaha
coil might have been firing just very weak
old school coils could fire if wired backwards
i guess new ones cant
reason u got no codes is the ignitor has told coil to fire
it doesnt know wiring was wrong
if coil wasnt there u might have gotten code
but codes only go as far as ignitor issues
no codes relate to coil

[richardjeffries]

Gotcha. Is there such thing as an OBDII 2JZGTE Auto J-Spec ECU?