1JZ Swap into Miata - No Start, no fuel, no Injector Pulse ... Expert Suggestions Pls

ChrisPackit

New Member
Jan 10, 2014
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UK
Guys

Looking to seek some advice from the 1JZ experts on here, with a engine swap project that is driving me nuts!

A bit of background... The donor car was a Lexus Soarer with a 1JZ GTE and a R154 manual box and the recipient car was a 1994 Mazda MX5 (Miata) - All of the swap has been completed, all of the fabrication done and just now need to get it running.

Donor car was bought running and I drove it back from the guy I bought it from about 2 years ago so know all the bits worked OK.

So original ECU and wiring harness has been used, though stripped of any P/S, A/C, TEMS wiring etc. Upgraded injectors to 560cc Mitsubishi Evo top feeds, upgraded fuel system operated manually on a switch panel. The car is being used for Drag so has no Idle Control or O2 either (May add O2 back in), only circuits left are Crank sensor, MAP, Cam Sensors, TPS, AIT sensor, Water Sensors, Alternator etc.

My problem is I am getting no spark or fuel...

The story so far of things I've done and checked.

- Wired ECU to ensure that the B, B+, IGSW have 12V. M REL gives me 12V but I've wired the fuse box off a switch through the Main EFI Relay rather than through the key. I'm happy with this part.

- STA has 12V on crank. ECU B, B+, IGSW retains the 12V on crank, doesnt drop the voltage.

- The 2 Black / Orange wires in the loom have 12V, to injectors and Coils etc.

- Engine earths on E01, E02, E1, E1 have earths (according to continuity test on multi meter) - Earths terminate on the tab on the head near the front and both rings use the same earthing point due to it running an aftermarket inlet manifold which has no M6 / M8 female points to attach to.

- Running an Optima Red Top battery in the passenger compartment, earths onto a welded on bolt to the chassis on the trans tunnel, extra thick earth from the battery to the engine block, and small OEM earth from the head to the firewall.

- I have tried to use temporary jump leads as extra earth straps to see if this would resolve, but no.

- When activated, the ECU gives 12V to one wire on the coils, and both wires on the injectors as it should (I beleive), just no pulsing on the node light or spark to coils. Tested with a plug grounded on the rocker covers and no spark.

- Crank Sensor, Cam Sensors, Ignitor all have continuity on wires to ECU.

- Crank Sensor removed, cleaned up the end, checked the 12 point disc that it rotates with the crank, with my finger

- Crank Sensor and Cam Sensors have a resitance of around 1050 ohms which I believe falls within range.

- Receiving IGF signal from the ignitor to the ECU, which has continuity to ECU and voltage raises to 0.3 volts on crank.

- Ignitor has 12V and earth to it on the 4 pin connector. The R / Y is IGF signal I beleive, not sure what the other wire does.

- All TPS and other sensors have 5V supply (might check this again though!)

- Checked Cam Sensors for voltage, but I didn't realise they were Resonance effect sensors. Guess I could do with scoping the Cam and Crank Sensors?


So my thoughts are if I have havent got either spark nor fuel then it is something affecting both and I beleive you only need the Crank Sensor, at least 1 of the 2 Cam Sensors and an IGF signal minimum to crank. So in my mind that would rule out the ECU and Ignitor being bad, unless both of the are gone which I don't think is the case.

I'm leaning towards either of the following areas:

- Bad earths
- Bad Crank Position Sensor
- Wiring fault around Crank or Cam Sensors (though I have checked these a dozen times!)

Anyone got any suggestions on what to try next?

Thanks for your help!
 

MightyAl

New Member
Jun 5, 2005
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Chesterfield, MO
1jz ecus are notorious for going bad. Have you seem the Ecu run an engine? I would try a known good Ecu before chasing ghosts. Usually it is the injector side that goes bad and the ignition is fine. I have run into several 1jz ecus with faulty fuel control.
 

ChrisPackit

New Member
Jan 10, 2014
11
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0
UK
Thanks for the reply guys.

The earths are on the head rather than the inlet manifold as the aftermarket manifold has no where to earth to. Do you think this would make a difference?. I will wire up the clocks and the CEL circuit and pull codes though I would expect many codes to come up having quite a few circuits not plugged in, i.e. the Idle control and O2.

The car was driven back on the ECU a couple of years ago. It may be worth opening it up and seeing if there's any evidence of blown Caps in there.

Any more suggestions guys? Would you try a Crank Pos Sensor first, as they're only quite cheap to try rather than ECU?

Many Thanks
 

ChrisPackit

New Member
Jan 10, 2014
11
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0
UK
OK - I've had another hour on the car last night, still no joy - Looking like I'm going to hire a scope out to check the signals next. One thing that did strike me though that I'm hoping you electronics experts can confirm, is that Ive notived that all of the 12V supplies to coil packs, injectors etc have 12V but ALSO they are showing continuity to ground?! This isn't normal is it? I took off the whole engine loom and appears that the issue still occurs when just the fusebox is powered up from the ignition. So the main black/red wire from the fuse box has both 12V and ground with very little connected. This could explain the poor signals to ignitor, coils etc and poor earths I guess.

Can someone confirm that I'm not going mad, and there shouldn't be continuity between 12V and ground?

Thanks
 

ChrisPackit

New Member
Jan 10, 2014
11
0
0
UK
So I'm on with the electrical issue with the 1JZ in the Miata / MX5 and now Ive found that with nothing attached on either terminal with the exception of one earth strap from the negative to the chassis, that I'm still getting continuity to ground to the 12V positive terminal. I tried to call Optima "Technical" support, who were anything but Technical !

So any thoughts on this? Even though the battery cranks the car, could it be bad ? I tested the stock battery just for my own sanity, and even though it was flat, it gave no continuity with the same set up.

Has anyone got an Optima battery that could test for me ???

You thoughts are much appreciated !
 

tlo86

Ninja Editor 'Since 05'
Jul 24, 2005
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Colorado
if it cranks you have juice.. even though optimas are junk it is probably fine and not your issue when in doubt undo what you just did -