1jz won't start

[George]

see my post dated april 19th. your boost sensor may appear disconnected from ecu. figure out ecu terminals involved and check wires for continuity

[dumbass]

map sensor wont make it idle that high

find the inlet hose to the idle motor and crimp it with long nose pliers
if there are no inlet manifold leaks there is only 2 spots that will put extra air into motor to make it idle higher
thats the idle motor or the throttle butterfly so also check for fully closed butterfly

adding extra fuel due to bad map sensor or wiring will not make it idle high only extra air will make it idle high up to 2000 rpm

[doommachine]

Or the ECU caps being rooted and causing the idle motor to open and close. The car, again, won't start. I pulled out all the coils and plugs and wired them together to see if they were sparking in the correct order - it sort of does, but often cylinder 2 sparks twice (ie, as I keep rotating it it sparks a second time).

I have checked the boost sensor and there is continuity.


I think I'll just send the ECU off for repair and if that doesn't fix it, I'll have to pull the injectors. Hope not, it looks like a PITA on the 1j (on a VR4 you can literally unbolt the fuel rail and remove it from the car in about 5 minutes.)

[BEVANI]

The inlet makes this weird whistling sound too.

Any open vac lines/ ports on the manifold? Done that before... LOL

[doommachine]

Any open vac lines/ ports on the manifold? Done that before... LOL

Nah I think it's just a normal inlet manifold noise, I don't really have the right rubber pipe so it's basically open at the moment.

After I installed the fuel pump today it started like a champ, (idle still about 2k though - although if I block off the inlet it basically stalls out, pretty sure its the ISC being stupid. When I swap out the TRC throttle body I'll pull it out) but I started tapping the ECU case and it started to run a bit funny.. so I grabbed the connectors and started wiggling them slightly and it really cracked the shits then. It only looks like a single layer PCB.. possible dry solder joints on the connectors?

[dumbass]

pull covers of ecu and check the capcitors
instead of fuking round with the other things
the issues u have are so random and each time its a different thing
which sort of points towards ecu
if u had a faulty sensor u would think it would do it all the time
some guys on here fix em for afew bucks
otherwise take your car to an expert

if your ecu has been plugged in and out many many times u can get loose terminals
which ive had once or twice before
but ive never ever had bad solder joins on a toyota ecu on the main ecu terminals
these are toyota denso ecu so are pretty well made
not dodgey vn vp delco shit which have issues with joints

[BEVANI]

AMEN to that!

[doommachine]

AMEN to that!

Yeah I know.. it's exactly like DSM forums.. any problem with car = ECU caps. I'm sending it off this week.

[doommachine]

OK so as mentioned before my ECU seemed to have parts missing - confirmed that it does. If anyone has a spare jza70/x81 ecu, would you kindly open it up and tell me the values of/ take pictures of the resistor at R348 and the transistor at T316? It's on the bottom board (board with the ECU connector). Cheers!

[big_zop]

With my reference photos, R348 is the same as R338 near it. I dont have a clear line of sight to T316 (its behind T311 in the pic) so cant get that till later if you need it. Its from a JZX81.

Does it look like they were never installed or were removed later on? I can see that there are a number of resisters labelled on the boards that arent installed, like R353 which is right next to T348.

[doommachine]

With my reference photos, R348 is the same as R338 near it. I dont have a clear line of sight to T316 (its behind T311 in the pic) so cant get that till later if you need it. Its from a JZX81.

Does it look like they were never installed or were removed later on? I can see that there are a number of resisters labelled on the boards that arent installed, like R353 which is right next to T348.

Nah they've definitely been unsoldered. Pretty sure Terra-operative has worked it out, if I need anything further I'll respond to the thread, cheers!

[doommachine]

So I received it back and still has the same issue, although it never has a "non start" issue now.

However, there is a difference - when I unplug the map sensor now the idle is stable, albeit still high at 2000 rpm. The cars hot now so I can't pull the ISCV out yet.

I was testing the MAP wrong, looking at voltage drop between the PIM and actual earth, but between PIM and sensor earth with just the ignition on I get 2.6 v and 1.76v when the car is running.. looks like the MAP is fine darnit. ISCV? I'll have to pull that... or maybe the ECU is absolutely fried??

[doommachine]

OK so today when I went to start it (After painstakingly ensuring the TPS was in the correct place) - it still gave me a really ridiculously high idle. I replaced the ISCV entirely.

After a while I tried to put it into gear to see if it would pulse the idle under load (just seeing what would happen really) - then after that it started running really badly. Now when I start it, the idle is low but very very rough, and if I open the throttle it doesn't rev - just sort of dies and sputters.

So now we have

- New fuel pump + filter
- replaced ECU caps
- replaced ISCV
- tested TPS
- Tested resistance of every sensor - they're all ok, CPS, both cam sensors...

Pretty much even though I have replaced the ECU caps.. it sounds like a screwed ECU right?

Oh, also, I tested the connection between the diagnostic ports and the ECU - no problem there. Even after replacing the missing resistor and transistor the ECU still won't throw a code.

Also, now sometimes my fuel guage flashes.. and sometimes it reads empty? Not sure how it's tied in with anything else or if it's in any way relevant.

[JZA70R_92]

Digi dash? if so that would be the cause of the empty and sometimes full reading will be a dicky sender. how bad was the ecu caps? tracks on board stuffed? anyone in SA able to maybe stick your ecu in there car to confirm if its an ecu problem? sounds crazy try bridging the FP +B in the diagnostic box see if any difference

[doommachine]

Digi dash? if so that would be the cause of the empty and sometimes full reading will be a dicky sender. how bad was the ecu caps? tracks on board stuffed? anyone in SA able to maybe stick your ecu in there car to confirm if its an ecu problem? sounds crazy try bridging the FP +B in the diagnostic box see if any difference

Made no difference... pretty sure I know what it is now.. the 16 pin connector which has lots of the important sensors attached is pretty sloppy in its socket. So, TPS, MAP, water and air temp sensor.. plus it has the TE1 and T circuits (diagnostics). When the car is running, if I wiggle each individual connector they're ok, with the exception of the 16 pin - sometimes I wiggle it and the car comes really good, sometimes the idle drops and it stalls. Earlier today I pushed it a little bit and fuel started to bellow from the exhaust.

I've already tested the entire circuit and all of the wiring for the connector is correct, but the question is, really, how do I improve the connection of an ecu socket connector? I'm thinking take every single pin out and squish it a bit with pliers? Or maybe put a dab of solder on each of the ECU pins/ tin them a little bit to make the pin slightly bigger?