Pele

iTrader: (28)

Just as the title says. Swapped engines and I have no spark and no fuel injector pulse... I don't thing I have the fuel pump turning on either.


Bought 1988 5 speed GTU With dead (overheated) engine. Almost pristine body.
Bought 1987 automatic Base with running engine. Front end wreck, but drivable and strong engine.

Pulled the complete longblock from the 1987. Quickest way to do this was to disconnect the engine wiring harness from the ECU and take it with the engine. Then sent the body to the scrap yard... Can't have lawn ornaments.

Pulled the complete longblock the same way from the GTU and removed the clutch and flywheel.

Removed the flexplate and counterweight from the automatic engine, installed a new pilot bearing and seal and put the flywheel and clutch on.


Upon installing the good engine in the 1988 GTU, I started reconnecting the harness and other stuff and found an extra connector that was not present on the original harness. It's sort of oval shaped. What does it go to and was it important? (It's now in the form of a cube.)


Possible solutions:
1.) Dismantle the original GTU engine, take harness off and install this harness on the good engine.
2.) Find a 1987 car and take the mystery part. (Is this mystery part on manual cars as well or only automatics?


I know the 1987 Automatic had an N326 ECU. The 1988 GTU has an N327 ECU. What is the difference?

AFAIK both cars have high impedance injectors. S5s have low impedance. Am I mistaken? My friend seems to thing that this part has to do with injector impedance.

misterstyx69

iTrader: (142)

could be a safety Neutral switch that was on the automatic but not on the Manual.
take some Pics,Post up the connector,and Location.
If it is at the passenger side Corner,at the FRONT,then it could be the Resistor pack connector..strictly guessing though as you didn't say where you found it...More info,better Input from the guys..

SonicRaT

iTrader: (6)

is it near the afm? Could be the resistor pack connector for low imp injectors (86-87.5)

88verttop

oh dear i hope i dont run into any problems pics would help!!!

rx7_FREAKKK

iTrader: (1)

Try using your ecu that worked. and try all electrical you used before. You should not need to change anything but the engine block.

SonicRaT

iTrader: (6)

It's a lot more work to swap the harnesses than to try to locate a resistor pack if that's what's missing. That's the only tricky part about swaps from 86-88. And also, the 86-88 ecus are all interchangeable for NA the only difference was in the harness and injectors. Those are all that need to match. If you swap harnesses you may need to swap injectors too. Check the impedance to make sure.

Pele

iTrader: (28)

****, my bad... It was near the AFM, behind the right headlight...
When did the impedance change get made? Shall I assume that these are low impedance injectors and that 1987.5+ cars have high impedance injectors?

Will missing this part cause no spark and fuel pump as well? I'd assume I should still get fuel pump, spark, and just no injector pulse.
Tach did NOT bounce on cranking.

Anyone have this resistor pack from a parts car for fairly cheap?

SonicRaT

iTrader: (6)

I'm not certain, I'd have to see if I have a wiring diagram of how that things wired. The change from what I recall was the middle of the year in 87, I've never seen an '86 from the factory without it, and I've never seen an '88 from the factory with it. I'll see what I can dig up.

SonicRaT

iTrader: (6)

HAILERS to the rescue! (Sort of). From the wiring diagram provided by HAILERS, it doesn't appear this would prevent anything except for the injectors firing. What happens when you jumper the fuel pump test connector? You can start checking for voltage at the ECU/coils/etc just to make sure everything seems to be connected properly. Hell, check the fuses while you're at it too. In particular the EGI(hood) and MOTOR(foot panel) fuses.

Connector looks like this:


Here's the wiring diagram:

Pele

iTrader: (28)

^ That's the connector.

I'll check power to the coils and jumper the fuel pump test connector and see what happens.

SonicRaT

iTrader: (6)

Might as well start there, I'll see if I can dig out the pins to check on the ECU.

FelixIsGod29X

iTrader: (50)

That plug goes to the solinode resistor pack. You need that to make your injectors fire. I have a recent thread in which i was having the same problems. I will add the link in a minute.

EDIT: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/help-get-my-car-turn-over-821295/

Hope this helps!

HAILERS

Either ECU will work just as good as the other.

No fuel injector power because the solenoid resistor isn't there. Just solder all five wires of the solenoid resistor together and your done. IN your case all five wires of the plug that goes to the solenoid resistor. One wire is black/yellow and is power and the other four feed the fuel injector plugs. Just solder all five together or crimp/solder all five together. Done.

That won't account for lack of spark or lack of fuel pump action.

Key to ON. Jumper the yellow fuel pump check connector. Pump should run. Does not run? Find a piece of electrical wire and ground one end of it. Put the other end in the yellow two socket connector at the top of the TEE so to speak. The BROWN wire is at the top of the tee. Pump should run if the ENGINE fuse is good and key ON.

Turn the key to ON. Do the turn signals work? Wipers work? No? Then it's likely you have no power to the ignition switch from the engine bay fuse box. Main fuse, both EGI fuses must be good and the single wire, black, connector six inches below the engine bay fuse box must be connected up.

And or does the starter work? I mean go to start and just see if it engages. Nothing more. Just that. IF the starter turns over and it's stock wiring to the starter, then the ignition key is getting power from the engine bay fuse box and you can ignore the above paragraph.

Pele

iTrader: (28)

^

Well if it didn't crank, I'd definitely not be worrying about spark or fuel injection pulse.
But as it turns out, I failed.

The car belongs to my friend and neighbor, Molotovman... He spotted my mistake, as I was the one reconnecting the harness while he was tightening engine to transmission bellhousing bolts...

I missed one brown connector way up in the passenger kick panel.

Fired right up without the resistor pack. (EDIT: Now looking at that diagram, it still shouldn't be getting injector pulse without that resistor pack... What the ****?)

Regardless, now, we work on the idle, which may have to do with the intake manifold gasket. We pulled the intake to replace the fire hazard pulsation dampener.

SonicRaT

iTrader: (6)

Yeah, that one's a real pain to troubleshoot if you forget about it. I usually check that one if I don't have voltage at a lot of various sensors/etc. Least it was an easy fix!

Pele

iTrader: (28)

As it turns out, Molotovman had a resistor pack in his shed...

Car is running fine on the N327 ECU. Idle was erratic at first but after running for a while, it became good, and now starts up and holds and idle perfectly at 1000 RPM. Drove it around the block a few times.

Now to work on other things. Like putting on a catback. (Yeah the neighbors aren't happy.) and bleed the rear brakes.