X83 1jz

[KARTS]

I am after some advice, I am in the final stages of a 1jz conversion from a JZX81 front cut. The front cut was already a manual converson and I have used the complete wire loom, Dash, ECU and hydro fan. I had the ECU checked and the caps replaced mainly due to its age. Put it all in and swapped the L/H body loom plug to suit the jzx loom. The car originally started o/k but it did run rough and after several starts the engine stopped. Now it wont start, it turns over ok but will not fire. Its got fuel at the rail and flow from the return line. Pulled one ignitor out and it had spark. Did a diognostic and got three flashes and then one, I guess thats 31 which I think is MAP sensor? Can the MAP sensor stop it running? any ideas?

[JP]

31 is the map sensor signal, and yes it can stop the engine running. Have you checked its all connected properly?

After that, check the sensor is getting it's 5V input from the ECU, that it's ground is good back to the block and that you have voltage at the middle output pin from the map sensor plug.

The voltage on the middle pin should drop when the engine is cranking. It should have about 2.6V on the sensor output wire with the igniiton on and engine not running, then drop down around 1.8-2.2V during cranking (can't remember exactly how much vac a 1J pulls while cranking...)

[KARTS]

Hi JP, thanks for the reply, I did check voltages on the weekend and I do have the 5v at the map sensor which is the same as the TPS I think, cant remember the other voltages but they were low and I will check tonight. I have checked every conceavable wire and connector and all fuses and relays. You mentioned it should have a good ground back to the block, how is it grounded as I cant see how it could get a ground through the mounting bracket? The engine did run albeit rough so it did have a connection. A friend who has the same 1j conversion mentioned that when he did his they put ignition power to the TPS momentarily for some reason to get it to run, any ideas what that's about?

[JP]

do not put ignition power to your TPS unless you want to damage something.

The Map sensor ground is on the 1st wire of the plug, and runs back to the ECU sensor ground E2(common to TPS, air temp, water temp and MAP sensors).

Pin 3 on the map is +5V from the ECU (VCC), the middle pin is the signal back to the ECU (PIM), the 3rd is the ground.

The TPS also utilises ECU's 5V sensor power.

If the ECU's engine ground is poor (where the brown wires bolt to the intake manifold) then you can get intermittent running problems and sensor issues.

[KARTS]

Thanks JP great info, I will check out the bits and pieces tonight and appriciate your help

[KARTS]

Checked the voltages and I have 5v and 2.6v in the middle and a ground, when cranking it stayed at 2.6v with no drop? I swapped the MAP sensor accross from a friends car and mine ran o/k in his car. I looked at his TPS and it has a 12v wire spliced into the green wire on the TPS plug taking its power from the ICSV power and I dont know why?

[JP]

try a different vac port on the plenum for the map sensor. If the voltage doesn't move during cranking then the map sensor is not reading vacuum. 2.6V is atmospheric pressure on a 1J map sensor.

[KARTS]

Well after checking all the components including the ECU in another car and they all worked o/k. In desperation we pulled the spark plugs out and cleaned them put them back in and some cylinders momentarily fired then nothing so then we changed the spark plugs and the friggen thing started and ran perfectly. Now I know this doesn't sound right but all 6 platinum plugs that look like new simply wont fire.

I did need to run a 12 volt wire from the ICSV connector to the TPS which solved the 2000 RPM cut. The engine runs idles and drives fine.

[JP]

something in your wiring is wrong if you need 12V to the TPS. The toyota TPS does not use any 12V feeds.

[PlacentaJuan]

yea dont hook up 12v to map sensor, it blows the ecu (have done this twice)

i would have said tps is the same deal but if you have done it with no problems then that is really interesting.

if you have a FCD somewhere then that might be your problem if it has malfunctioned or not wired up with enough koala-T

be aware of the gapping and temp rating of platinum plugs, as they can not be re-gapped (as far as i know or is that iridium i am thinking about?)

when i switched from copper to platinum or iridium the car had trouble running while cold, next time i will go back to copper because i dont like the idea of leaving plugs in there for years.

[JP]

The green wire to the TPS is your Idle switch, as I posted in your car's other problem thread at toyotacressida.net, when this wire is permanently grounded you end up with an early revlimit. Connecting 12V to that wire is no good for your ECU.

[KARTS]

Hi JP, Yes I agree it doesn't seem to be logical and I'm not comfortable with jumping power to any ware but it does seems to work. The two other local conversion have the same wire jumped to the TPS. If the green wire is getting a permamnent ground any ideas where to look? I would have thought putting 12v to a grounded wire would have burn something, but nothing got hot and no fuses blew. This problem must be common and there probably is another way to overcome it but what? As I said earlier this was a JZX81 wiring loom transplant and the other two local cars are the same with the same problem, if this wire is not jumped they are rev limited to approx 2000 rpm also.
I did a diognostic and have no codes now, well I think its no codes as the eng light just continually flashes with no pause.