I'm having problems getting my car to start, but I know it has the compression (80psi Front 100psi Rear, fix that later) and I've got spark. I know it would start if I get fuel in properly because it roared up when I sprayed a bit in the intake and also when I did an injector test on the secondaries, but I cannot get to the primaries. I'm assuming the primaries are fine as well though because I have no reason to believe otherwise.

Anyways, onto my questions. I did a resistance test at the secondaries, at the injector connector plugs, and at the ecu connector for good measure, and I am getting ~18ohms iirc at the injectors but ~540ohms through the connector and back at the ecu. Also, I had a test light between battery positive and the injector connector ground and I am getting ~1.5v drop in the circuit as well. Any suggestions on where I may be getting the resistance?

Also, I am trying to find out where the injector ground is, I may be backwards, but on my wiring diagram from Alldata and Mitchell OnDemand are saying something about a condenser. Where is this condenser and what exactly does it do? I have looked at the S4 FSM wiring diagram pdf page 25, easier to jump that way, but fsm page 50-28 and, assuming the arrows dictate electrical flow, I'm looking at this wrong maybe? I see the condenser on that diagram as well straight up from the first splice at the bottom.

 

Check the voltage w/key to on at pins 3E which is the front primary (Light Green wire) and 3C which is the rear secondary (Light Green/Black wire) and both pins should have 12 volts to it. The Black yellow wire, which is the oher wire at each of the injectors, should also have 12 volts w/key to on. If it does and the injector plugs are good and firmly connected to the primary injectors then the voltage on the B/Y wire passes on to the second wire at each primary injector and this voltage should be present at pin 3E and 3C. This will give you a heads up as to what might or might not be the problem. If you currently have spark then that should eliminate the 30 amp Comp fuse that powers the ECU and the 40 amp INJ fuse that powers the injectors and coils. You also need to initially check to see if the fuel pump works properly. Jumpering the fuel check connector and turning the key to on should turn the pump on. Do this first and tell us if that is good to go.

There are no grounds for the injector itself.

 

Satch, I forgot to mention that I did check for voltage on all the green, 3 with stripes 1 without, wires on the ecu connector and came up with ~12.3v, did not know about the black one. Also, I do have the pump jumped right now as I am trying to also figure out what is wrong in that circuit to give me a 5v drop at the pump, FD pump in case that matters. I think I have narrowed it down to either a corroded circuit opening relay or a bad AFM, but I could be wrong.

 

If you jump the fuel check connector, that will bypass the fuel switch internal to the AFM, so that would eliminate that item if your "main focus" is on the low voltage making its way to the pump. Typically, the voltage drops quite a bit w/key to start, so a drop of 3 to 4 volts or so is to be expected. If you could prove there is ample fuel pressure at startup then that would redirect the focus away from the pump itself to another issue. If you happened to have a spare CAS then you could connect it to the proper harness after unconnecting the installed CAS and spin the bottom cog w/key to on and you should hear the injectors click. If you disconnected the secondary plugs before doing this and heard the injectors click then they must be the primary injectors making the noise.

And the wires you tested at the ECU are the ground wires for the injectors as the ECU drops the 12 volts seen on the checked wires to close to 0 volts when the key is put to start ( at least for the primary injectors). So these are the injector grounds as opposed to there being a constant ground to the injectors which my previous response was a function of misunderstanding your question.

And of course the primary injectors might be clogged in addition to the engine being flooded.

 

At the pump with it jumped I have about 11.5v w/key on, so with that being bypassed would that mean that the AFM is bad or could it still be the opening relay? I had a pressure gauge on in class today after my filter and was ready ~44psi w/key on, but my instructor and I have determined that I may have a clogged filter, which I was getting around to replacing anyways, because we were attempting to measure flow rate and noticed no pressure while it was flowing.

I unfortunately do not have a spare CAS to test that method, I was actually just reading a thread mentioning that but dismissed it because I don't have a spare CAS.

Your second paragraph confuses me a bit, I don't know why, but did my result of ~12.3v, on all four wires, mean anything, injector/wiring condition-wise?

I'm assuming the primary injectors would not be clogged as this was a well maintained vehicle before I bought it and the secondaries opened fine with our injector tester, just could not reach the primaries without tearing into everything, but it has just been stored for about 2 years so I'm trying to get her running again. I also don't think it's flooded as all four spark plugs were bone dry when I pulled them to check for that very reason.

 

The injector is fed two wires such that the B/Y wire supplies the voltage and the other wire eminating from the ECU is the ground trigger. When the car is started the wires leading from the ECU to the primary injectors will have their voltage reduced to create a ground for the injector to create the impetus for it to fire. The ground signal occurs in a rapid fashion to prevent the injector from releasing too much fuel.

 

So, my 12.3v finding means...? Nothing until I test the B/Y wire I'm assuming?

 

No. The B/Y wire feeds the injector w/12 volts. The injector plug being secured properly allows this voltage to pass onto the wires that lead to the ECU. You should see 12 volts w/key to on at the Green ECU wires so this proves the B/Y wires are okay as the voltage on the Green wires are "incoming" to the ECU and not being outputted (sent "from" the ECU).

EDIT: In other words, if the plug was loose you would not see 12 volts on the Green wires.

 

So as for voltage I'm doing good, but why/where would I have ~540 ohms resistance at the ecu and injector plug? Or is my testing wrong? I had pulled the ecu connectors and probed each green wire while grounding to a nearby shiny body bolt and those were my readings, I also got those readings when I plugged the ecu back in and tested at the secondary injector connectors. I figured testing both ways just to be sure it wasn't because the ecu was unplugged.

 

I'm not familiar with the process of taking an ohm reading throught the Green wires as far as what is accepted as a normal reading. If you had the secondary injector plug disconnected and ohmed out both ends of the Green wires then it should give you a low ohm reading.

 

I think you misunderstood my poor explanation lol. For my readings I did two separate tests to look for resistance in the injector circuit, because I knew the injectors should only be a few ohms. My first test was simply unplugging the ecu connectors and checking for resistance between all four green wires and ground which showed the ~540 ohms for each injector wire, the injector connectors themselves were still plugged in. My second test was just the opposite, the ecu connectors plugged in and testing from the injector connector to ground, which showed the same reading on one wire and an open circuit on the other wire.

Again, I may be going about this the wrong way, but my wiring diagram from Alldata showed that the injectors did ground through the condenser, which I still do not know what/where that is.

 

The condenser is a capacitor and is supposed to reduce noise in that particular circuit and it is not a ground.

 

Ah, well that clears that up. Any ideas on how to get at the primaries without tearing everything apart?

 

You can't.

 

Arg, well I'm going to assume that they are fine just like the secondaries. My main focus is that resistance and the 1.5v drop at my secondary connectors, which I'm assuming is also present at my primary connectors.

Are there any common causes or places of interest that I should be looking at for this resistance?

 

The primaries are the only ones which should release fuel on startup so if you pull the sparkplug wires off the sparkplugs and remove one of the plugs and turn the engine over you should see some fuel spray coming out of the plug hole if the primary injectors were injecting some fuel.

Not sure really what you are doing w/the test that indicates a 1.5 voltage drop on the injectors so I can't help you with that.

 

The primaries are not injecting fuel because it was bone dry when I pulled plugs to check for flooding in the first place, after I had attempted to start it for a few days before that.

I got the 1.5v drop figure when I had placed a test light between the injector connector ground and battery positive, which lit, then proceeded to place a volt meter between the test light and the block.

 

I guess you could remove the smallest ECU plug housing the injector wires and place a ground to the Green wire corresponding to either of the primary injectors and do this w/key to on and the injector should fire.

Since the injectors have two wires, either you put the test light to the B/Y wire or the Green wire. Which was it or am I wrong on this account?

EDIT: If the car were to idle and the voltage off the Green wires were to be measured it would indicate about 8 volts or so because the pulsing ground signal from the ECU is too fast for an ordinary voltmeter to catch. Since the voltage in the car circuits drops w/key to start I'm not so sure this test will provide meaningful results though.

 

I could not pull the boot off my injector connecter so I cannot tell you which wire I was on, but it was the only one that lit while the test light was connected to battery positive.

Would you happen to know which specific green wires are for the primaries? If I am reading my wiring diagram right they should be Light Green and Light Green/Black, but I just want to be sure.

I know a DMM wouldn't be fast enough to read the switching, but our school ones do have a high/low hold, maybe wrong name, function.

 

Front is Light Green and the rear is the LG/B wire.

If by chance you tapped into the B/Y wire during the test for resistance then you are including the coils , condenser, and Main relay into the equation.

If you shot some starter fluid into the intake once again and checked the voltage on the ECU injector wires the car might run long enough to see if the ECU was pulsing the necessary ground signal to the injectors in question.

 

if you have a spare airflow meter try tossing it in and see what happens.

 

I used gas in the intake, but same thing. I could also just hook up two injector testers and pulse the secondaries as I know that will work to get fuel in. Maybe if I pulse fast enough I could keep the car running long enough lol.

Edit: Didn't see your message before I posted Karack. I unfortunately do not have a spare afm to test with. I have no spare parts just laying around to test with actually.

 

well, i ask because the AFM also cuts the injectors off if the AFM is faulty but i believe it also cuts ignition. but if you have one laying there, why not.

 

Know of a good place to buy a new one, if the time ever comes?

I'm hoping tomorrow it turns out to just be the clogged filter. Wouldn't she still sputter and attempt to start though? Or do you need a significant amount of pressure behind the injectors?

 

i believe airtex remanufactures them but even the reman ones are costly that i would just try pulling one out of a friend's car when he isn't looking for a few minutes.