JZA70 wont start...problem is very very wierd

[The Real Roadrunner]

How does the CAS stuff up? its a friggin magnet.

have you been thru and checcked that all items are earthed correctly? as thats what it sounds like and it just gives intermitent faults, it could also be perished wires or dry solder joints.

[Hybrid]

If the CAS was stuffed why would one ECU work and the other not? This seems rather confusing.

Can I unplug the knock sensors to see if this does anything? I can see at least 2 hidden down under the intake mani, or is there a third somewhere?

Only two knock sensors on the 1JZ, both the ones you have found.

[DazbaVBz]

still sounds like a earth related problem or a ecu connection problem, just outer interest does the car have a immobiliser installed, also how many ecu have you pluged and unplugged, is there anychance that the pins in the ecu plug may be not seating on the pins properally, causing a intermittent fault, is there a possibility of a relay being fubar'd, i would start looking away from sensors personally, if it was a knock sensor, it would just retard the timing a few degrees, if it was a map sensor i could possibly say maybe, if it was a tps sensor you would have a shit idle, as well as when you had your foot off the pedal and then stomp on the pedal it would hesitate all the time, not only when it gets hot,

[MR 1JZ]

How does the CAS stuff up? its a friggin magnet.

have you been thru and checcked that all items are earthed correctly? as thats what it sounds like and it just gives intermitent faults, it could also be perished wires or dry solder joints.

changed cas

worked fine after that..

[Jt_70R]

Wiring wise, the car is completely stock. no customised wiring, no alarm/immobiliser installed. ie. 100% unmolested.

Im guessing it has to be some kind of dodgy joint/plug somewhere, the problem is very very intermittent.
It does seem to throw the car into limp mode, it still runs; however very very rich, engine light on, the light will flicker off for a moment and the car will splutter and backfire when it comes back on.

But as mentioned last night i started it up, and it drove around perfectly for a good 15 mins, until it randomly started doing it again.

So in theory, all sensors are working fine, there is nothing intrinsically 'dead' with any of them. So must be dodgy joint/earth etc. somewhere is all i can think?
Unfortunately this is my first JZ so I am not particularly knowledgeble of what goes where and what does what.

However what would explain the regular stock ECU not starting the car at all?

Other option is the car is haunted/cursed.

[Jt_70R]

bumpski

so does anyone else have any other thoughts on my rather weird problem?

please take note, the engine light will flicker on and off randomly, even without the engine running, with everything perfectly still, so i cant see how a dodgy plug/earth could be the prob.

[JZA70R_92]

any bits of wiring inside the DIAG box? clean it out if possible. so you say it after 15 mins it runs like shit...try briding t1 and e1 in the diag box and see if it runs ok.

[fatboy13]

What code does it throw when the engine light is on?

My warning lights were flickering etc when one of my earth leads died on me... and that was with the car sitting still, no engine running etc etc

So a dead earth could be an issue... seeing as my car still ran for a couple of minutes (albeit like shit) until i turned it off

[EldarO]

i had similar problem.

BHG FTW!

(this was with my 1J.)

[MR 1JZ]

no freekin way

[Jt_70R]

haha, yeah no BHG here. Definitely an elec problem.

ECU doesnt want to chuck error codes, the stock one I tried wouldnt either for some reason.

unplugged the map sensor last night (both vac then wires) which didnt seem to do anything. the car does exhibit symptoms of running with the map unplugged, so I might try a replacement map sensor just to rule that out also.

[EldarO]

actually
this sounds very familiar.

i had this prob before the motor blew (months before)

the ignition is sorted into 3 pairs, 1 for 2 cylinders.

one of the ignition wires was shorting on another, and causing it to arse out.

o either check the ignition wiring, or the ground for it.

[Jt_70R]

grrrr arrg this problem continues to get more confusing.

with the blitz ecu, i get ~11.9v at the EFI relay. 12.4v battery voltage.
with the standard ecu (that wont start the car) im only getting around 9.2v on the M-REL (main relay coil line), doesnt seem enough to pull the solenoid over.
whats with that? can i just bridge the relay line to get 12v to B+ on the ecu and see what happens?

P.S. the blitz ecu does throw error codes, all i got was code 21 though, oxy sensor, not suprising seeing how its not connected.

[MR 1JZ]

that lack of an 02 sensor gives you another 3 psi of boost cut le way

[EldarO]

that lack of an 02 sensor gives you another 3 psi of boost cut le way

oh?

10 char.