1SWEET7

iTrader: (1)

I was having a great day until I went to floor it in fourth and hit a wall. I replicated it a couple more times in diff gears and recognized it was the secondaries. Well I backprobed the front and rear Primaries at the ECU and I got 10V each, which seems too low, then I backprobed the front and rear Secondaries and got 11.7V on my Front Secondary and 0V on my Rear Secondary. I Ohmed my 10ohm 10watt resistors on the secondaries and they were fine. How should I go about fixing this?

Davidov

iTrader: (2)

Injectors are Pulse-width modulated. Your multimeter is too slow to read the injector pulses and will result in an average.

Is your car a turbo model?

1SWEET7

iTrader: (1)

This is with the key to ON and the car OFF. Yes it is a 1988 Turbo and it has been running fine since I installed the injectors 8 months ago. FSM spec says with the key to ON all 4 injectors should read ~12V.

1SWEET7

iTrader: (1)

I notice in the wiring diagrams it looks like there is a 12v wire that goes from the main relay to the injectors then to ECU. I am wondering if I can just run a new wire from the main relay to the injectors then to the ECU? That way I can eliminate that section of probably failed wiring. Or can I wire the Front Secondary to the Rear Secondary so that it sees voltage? I daily drive this car and it is gonna suck to drive on just primaries, so I need to get this fixed ASAP.

1SWEET7

iTrader: (1)

Well after reading through the wiring diagrams a bunch I think I have a lead. I am thinking the rear secondary injector clip is loose. I will pop the manifold off tomorrow morning and check it out. I don't see why the primaries would be at 10v though as they are fed by the same wire (B/Y) as the secondaries coming from the FEM-02 (orange footwell plug). Maybe Hailers will see this thread and chime in for me.

HAILERS2

Plug probably fell off.

Key ON, engine OFF. Pull the plug off the ECU and then check the voltage on all four injector wires in the harness plug. All should be the dame.

Or if new injector plugs and wires were installed in the past on each injector, maybe where *they* spliced the new plugs and wires to the harness, the connection is bad for that one secondary wire.

Yeah. Upper intakes gotta be removed.

If the engine is running the primary voltage will read a bit lower at idle than the secondarys, because the primarys are being used when the engine is running and the secondarys are not.

If you actually drive the car and monitor the voltage of the primarys, you'll see a voltage drop the more you put a load on the engine. The secondarys will read alternator voltage until you put a load on the engine and the rpms hit 3800 rpms, then the voltage will drop from alternator voltage to half of the voltage the primarys were reading just prior to hitting 3800 rpm, then drop more if your really *on it*.

But you had key ON, engine OFF, and if the ECU plug is off they should all read batt voltage. One secondary did not, so it's plug is off or??? a wire is loose coming or going from that plug.

Did I type enough? Yeah. Too much.

Some automotobile meters have a DUTY CYCLE feature, where you can backprobe the injector wires and read the duty cycle while driving. Like a Fluke 88 and I think at one time I've seen a Radio Shack meter with that feature.

1SWEET7

iTrader: (1)

Thank you Hailers. Yes the Rear Secondary plug was loose. Now I get 10v on both Primaries and 11.7v on both secondaries. When I tested for voltage I had the key to ON and the car off with the plug still attached to the ECU then I backprobed and got the above voltages. When I unplugged it I could hear a relay clicking back and fourth in the bay so I plugged it back in. The clips are stock. So it is safe to assume that 10v on the primaries is fine? It has run fine for 8 months. I will take my manifold off ASAP and see why that clip came loose.

HAILERS2

The ten volts with key ON, engine OFF does not sound right to me. All four injectors should be reading the same voltage.

TEll you what. Later today I'll go look at a series four Turbo and non turbo car and write back. I'll do it like you did. All plugs on the ECU......key ON, engine OFF.

I don't own a series five but imho the voltages should read the same. Later.

EDIT: I got off my bottom and went to the turbo car. Key ON, engine OFF. All plugs on the ECU and everywhere else. All four injector wires when pricked by a sewing needle show 12.19 vdc. That's on a car that hasn't been run in several days. The batt itself under the same conditions read 12.28 vdc.

What your seeing is abbynormal , as Marty Feldman said, in the movie Young Frakenstein with Gene Wilder.

RotaryEvolution

iTrader: (30)

if you're getting voltage at 3 of the 4 injectors then you need to start cutting open the wiring harness near the injectors and probe the wire to find out where exactly the voltage is dropping.

mazda had a horrible habit of simply crimping wires together with a brass crimp and simply wrapping the connection up with electrical tape in the looms. i've found these connections corroded from water intrusion on more than a few occasions.

1SWEET7

iTrader: (1)

Ok so I probed the FEM 02 connection and I got ~12v on both the B/Y wires, so then the problem must be in the wiring going to the injectors from the FEM 02 or from the injectors to the ECU correct? I feel like just rewiring the whole crap setup. I could just run a power wire from the B/Y wire on the FEM 02 connector to all the injectors, then run a single wire from each injector back to it's appropriate ECU plug if I have to correct? Thanks for all the help guys.

HAILERS2

The two black/yellow wires at FEM-02 are joined together into one wire just after the EM half of that plug.

I'd pull the plugs off the injectors and see what the voltage is on the injector plugs. The black/yellow wire that is. Should match FEM-02 to a tee.

Sounds like bad aftermarket crimps on the injector pigtails as mentioned above in another post.

1SWEET7

iTrader: (1)

Ok I pulled everything off and I got 11.97v on all the injector clips. Testing the same thing at the ECU results in 11.57v on the secondaries, and still 10v at the primaries. In which direction should I head now? Should I just go ahead and rewire it so I can be sure, or pull apart the harness and find the culprit?

EDIT Ok I just had a thought, I took the secondary injector clip which I was getting 11.57 on at the ECU, and switched it onto the primary injector. Well it now read ~10v. So that would mean there is a problem with the primary injectors then right? I ohmed the injectors and got 12.6 on each which checks out. I don't think rewiring is going to help. Can someone clarify this for me. I hope I don't have to get new primary injectors.

HAILERS

Try a fully charged battery. Your cars readings should ape the readings I got in my post above......all the same voltage at the ECU even with the plug on the ECU itself.

No ten volt stuff on one and 12 on the other stuff.

1SWEET7

iTrader: (1)

The battery was fully charged. If the injectors are getting 12v at the clips that is the main thing right. The wires running to the ECU are just for ground so it shouldn't matter that much I am thinking. Like I said above I switched one of the secondary injector clips with the primary injector then I probed it again and it read ~10v. So that leads me to believe it is related to the injectors not the wiring, but the injectors ohmed out to spec so I am just gonna run them. I have driven it for 8 months without problems so I can't see it doing anything now.