Hi. So this problem has boggled a lot of people that i've talked to and I'm finally going to be posting up the situation to see if anyone can help! First things first I will reply relatively frequently. I do have a camera and I can take photos of whatever is needed to help clarify the problem.

The Car its History
1993 Mazda RX7
Bought salvage title rolling shell, was an automatic originally, previous owner swapped to manual. Purchased a JDM engine/transmission from a 94 rx7 dropped it in. Car ran fine until I pulled out engine/transmission to replace twin turbos which were leaking oil.

Current Modifications
HKS downpipe
Apexi Intake
Blitz 4" Exhaust
Viper Alarm System
Walbro Fuel Pump

The Problem
Car will not start, it will crank fine, no spark, no fuel. Self Diagnostic Tester will not work (CEL stays ON), fans turn on as soon as ignition 2 is turned on.

Checked Fuel System:
fuel pump will turn on, just fuel speed relay will not turn on.
Checked terminal 1k on ECU, it has power (2 voltsish I can check again)
Checked speed relay, circuit opening relay, and main relay, relays respond when terminals tapped

Checked Ignition System:
spark plugs won't fire, power at ignition coils

Checked Crank Angle Sensor (as per manual):
No continuity between Ground and 4G (ecu harness side) and Ground and 4H
Resistance between 4G and 4H is within spec
Replaced ECU with known working ECU still no start

So yeah I'll be sitting here intently waiting for your guys thoughts!

 

Fans turning on with the key usually mean the ECU harness isn't grounded out. There is a ring terminal on the ECU harness that bolts to the top of the rear rotor housing - is that connected?

Also, there is a blue and a white connector from the ECU harness that plugs into the dash harness inside the car, make sure those are plugged in.

Checked all the ECU fuses?

Does the fuel pump run and system build pressure when you jumper the F/P and ground in the diagnostic terminal?

Dale

 

Check the yellow relay in the fuse box next to battery apparently that relay stop spark and fuel delivery, and like Dale said check the egi fuse, also check the connections points at the ecu to make sure no pins is bend inside the ecu.

 

Thanks for the reply Dale! I just checked the ring terminal from the engine harness that bolts to the UIM right above the rear rotor housing. its connected and i checked it to battery ground and chassis ground, full continuity.


The white and blue connectors you're talking about (i think its X-05 and x-07) are both connected as are the 4 yellow ecu blocks




I'm not sure which ECU fuses you're talking about. The fuse block with the engine 15a is fine as are the fuses in the engine bay.

The fuel pump does not run and build pressure when you jump the f/p to ground in the diagnostic terminal. It does work if you bypass the fuel pump speed relay by completing the relay's circuit allowing 12v to pass thru, activating the fuel pump.


sorry for the large sizes XD i figured bigger is better! =]

 

The relays inside the fuse box in the engine bay are actuating when the F/P to ground is jumped as well as when the ignition is turned on. I've pulled them as well, given them 12v as per FSM and they have all actuated like they are supposed to.



I've checked the connection points at the ECU on both ECUs to check the pins and they seem to be okay.

 

A lot of that loom wrap on your wiring harnesses isn't factory. I think you need to address your harness integrity.

 

To dguy:

I actually did that myself when i dropped in the engine the first time (its an auto chassis harness to manual engine harness) Before I dropped the engine back in I also checked continuity for all the pins on the harness and verified that there is full continuity on there. If there's something specific that you think I should check for I'm all ears. I've already checked the grounds, the fuel pump relay, and the CAS.

 

The reason I know it stop the spark is because I this happen to me last week, same situation as you car will crank, but will not start-up. I check for fuel & spark and it's there, I decide to a compression test and I happen to remove that yellow relay and I notice my spark stop. Also did you hook up the right connectors for the crank angle sensor and what ecu are u using? Anyway my situation turn out to be 2 things, when i connect my ecu with the harness i did not align it accurate so I bend two pins (cramp area) which apparently ground out the ecu which kill my data logger that was connected. On good side my my power fc is good.

 

on your advice! =] i decided to bypass the EGI and Main relays (green and yellow) and the fan clicked off fuel pump engaged and self diagnostic started working. code 11 is appearing and I haven't gotten it to start yet so i'd like to keep this thread open until everythings sorted out. but thanks for the tip. I don't yet know if its the relays that went out or if theres a wiring issue thats not engaging them

 

to rx7aholic:
the CAS was never touched when removing the engine and putting it back in so theres no chance the wires got flipped. they stayed plugged in the entire time.

Update on the Car
Engine is still not starting. Cranking, there is fuel smell on plugs with some oil. No spark on plugs.
However now I'm having a fairly decent oil leak (new oil) from where the turbochargers bolt onto the rotor housing. All the bolts attaching the turbo to the rotor housing are tightened but a steady stream of oil will leak/spurt out from behind the turbo manifold while cranking. Don't know if this complicates it, but ECU is also throwing code 11 the IAT.

 

Just to be sure, there a ground wire which attaches on the US driver's side of the engine block (lower part of the engine by or on the A/C bracket). Is this connected? Typically if that ground is not connected, you get no spark.

 

Have you lost spark AND injector pulse or just spark?