Cranks, but nothing else (Surprised? no)

Hello,

I thought that I was on the verge of getting the engine started for the first time tonight, but that hasn't happened yet. I know I'm getting plenty of fuel pressure at the fuel rail, it cranks, the ECU is getting power from the battery and from the ignition switch when it's on (pin 20, 57 for bat I think, pin 19 for ignition). The injector and the spark plugs are not firing, however. Everything seems pretty dead, am I missing something obvious and where should I look first? I don't have much experience troubleshooting this sort of system.

Thanks for any help,
Luke

Did you disable VATS?!?! Usually, regardless of VATS disabled, the engine will start for a few seconds and then shut off.

To check:
Pull spark plug.
Disconnect the battery cable completely for 15 seconds, reconnect.
Crank engine and check for spark.

If you cannot watch the spark and crank, spray starting fluid into the intake and crank. If it does start and then shut off, the VATS needs disabling.

If it does not spark or start at all, check the harness grounds and check to make sure the engine block is grounded to the battery. Grounds are very important to the LS computer and harness.

I'm pretty sure that LT1Swap dissabled VATS. I have not checked for spark after disconnecting and reconnecting the battery cable. Would VATS also keep the injectors from firing? I have throughly checked all the grounds and I have a huge grounding cable going from both the car body and the battery. I'm pretty sure that there isn't any spark or fuel at all. I know that my fuel pump relay is working though and there is plenty of pressure.

What does the ECU need to know before it sends out signals to the injectors and plugs? Just ignition voltage and a reading from the crank position sensor?

Yes, fuel should be there. Once powered, the LS computer with enable the fuel pump control circuit, energize your new relay and finally send power to the fuel pump for ONLY 2-3 seconds then shut off until called on again by the computer due to MAF. So thats fine.

To go any further, you must verify no spark and no injector activity. Use a NOID light at the injectors and verify no power at the rail or that, although theres voltage at each pink wire, theres no grounding pulse on the adjacent wire during cranking.


Do you have a scanner?

No I don't have a scanner, and I haven't wired in an ALDL plug yet anyway. I can hear the fuel pump run momentarily like you said. I pulled the injectors out and cranked the engine and none of them fired at all. To test spark all I did was pull a plug and ground the casing while a friend cranked the engine, is not good enough? Could a miss-wired MAF cause all of this? Usually cars will start without a MAF at all, they'll run very poorly but will at least fire.

I'm still tinkering but really need anyone's help, please! Thanks 944-LT1. I guess I'll confirm that there is voltage at the injectors but no ground pulse. Also, I had to re-mount one of the drivers side coils. I'm not sure if there is a good ground between it and the firewall, could that be the problem or would it just cause that one cylinder not to fire?

Check your fuel pressure, Just cause the pump is running doesn't mean there is enough pressure. The injectors will not open without the proper pressure behind them.
Also, how long has you motor/injectors been setting? If they were used , then there is a good chance that if they have sat for over a few months that the injectors are stuck. You'll have to take them out and soak them for awhile and them hit them with a 9 volt battery.

I know that I have enough fuel pressure. I'll try taking them out and soaking (in what, gas?) and then activating with a 9v. What else besides VATS would keep the computer from sending the right signals, what other sensors and inputs does it need besides ignition voltage?

A couple of other things:

In the manual it says to take pin 15 of C2 and run it to terminal "L" of the alternator, this wouldn't be important would it? I have already run a wire for the alternator trip from the two wire plug from the Porsche, the other problem is that the GTO doesn't seem to use pin 15 or have any other pinout that matches.

Do I need to have the VSS hooked up?


Thanks,
Luke

I got a 1/4" tube and connected to a 60ml syringe and backflowed (gas) the injectors while opening them with a 9v battery....cleaned right up.

I also found that the head gaskets (poor conductivity) and head bolts (non conductive sealant on them) was causing a grounding problem as I only had the PCM grounded to the driver's head....After running a ground head-to-head and head-to-block and then Block-to-battery did my erratic non-starting issue go away.....sounds alot like my initial prognosis.

Ok, thanks

1. Clean injectors and make sure they're firing properly

2. Check my grounds between the heads, block and battery



Which sensors are absolutely necessary for the engine to fire?

Luke

MAF is no concern here. LS computer wold go to limp/loop/map mode if there was a problem. If you have checked all grounds at the block and heads (there are a few) and determined all of them are fine, let me ask about the wiring to the computer itself! There are many wires that require +12vdc when key on (these are usually pink wires). When you turn the key to run, you should hear relays click and that should be one for the computer. If you do NOT read +12vdc at the pink wires of the injectors with key in run position and do NOT read +12vdc at the wires of the coils, your computer is screaming no joy.

Please list all indications that you have determined that the computer is on at all. i.e. the fuel pump is controlled by pin 9 "fuel relay enable control". What else gives you a clue? Remember that ew cannot see or hear what your car is doing/not doing. So relay those to us!

Biggest/common diagnosis with these symptoms (after determining for sure no fire/fuel/grounds or power to the computer/engine harness problems) is the crank (CKP) and cam (CMP) position sensors. These tell the computer exactly where each cylinder is and when to inject and or fire. If the CMP sensor is not working or the computer cannot recieve a useable signal, it will solely rely on the CKP sensor but will know nothing of where the piston is on exh/int stroke and so cause long cranks until it re-learns.

Sooooo many guys have left the CKP/CMP connector off, barely on, used the wrong crank reluctor, cut a wire, pinched a wire, scraped a wire, broke the insulation of a wire, etcetera and had the same ill affect. Its a bit difficult to get to the CMP sensor with the starter in the way I know, but, you have to make sure it is fully seated. The CKP sensor is easy enough to get to, right near the harmonic balancer.

After you have made sure both these connectors are fully seated and you still have no spark/fuel, you will have to first make sure there is no +12vdc at the pink wires of the injectors and no +12vdc at the coils. The trigger for the coils and injectors is from the computer after seeing the cam and crank sensor 5v low reference signals or atleast (when cmp is not working) the CKP sensor.

Added some ground cables, although I don't think I need to. All the injectors are completely unclogged, when I install them into the fuel rail and turn the key on to pressurize the system I can apply some voltage to each injector and get a really good mist.

I'm not getting any voltage between the pink wires going to each injector and ground (tried both the block and the negative of the battery) when the key is on, however. Same with the coils. I'm not sure why this is. At least I now know that I can focus on a lack of power first and then I'll look at the trigger if it still doesn't work.

Any ideas for how to track this problem down?


EDIT: Sorry, didn't refresh the page before writing the above so I didn't see the reply. I know that the computer triggers the fuel pump from pin 9, I know that I get voltage to pin 19 when the key is on and I get power to the computer all the time at pin 20 and 57 (all C1). I spent half an hour getting the cam position sensor in place, I'm pretty sure it's good but I'll double check.

You should have ignition power to the injectors on the pink wires. The coils should be the same, The negative wires of the injectors will be the out put from the computer. That is the signal that fires the injectors. Same with the coils. Do not ground the injectors as you will burn them out. Most only have about an 80% duty cycle.

Ok, I've got the plug behind the starter; but there is nothing plugged in near the harmonic balancer and I don't see a plug anywhere. That must be my problem Could you give me details on it's location because I can't seem to find it.


Thanks a million,
Luke

Ahhh.

You should have 4 wires at each coil within the connectors:
A - Ground
B - Low Reference
C - Ignition Control Signal
D - Hot +12vdc PINK

I do not have a 2004 schematic. The above is from a 2002 schematic. Regardless, with the key on run, you should have +12vdc at the pink wires of each coil and a ground as well. Make sure this is true on you engine. If not, trace the pink wires of the coil/injector harness back to the computer. These wires are not going into the computer but should be fused to battery hot. The grounds of each coil should terminate on the side of the engine or head. There should be many pink wires at the end of you harness that are recieving fused (15A) battery hot when the ignition relay is energized.

The only places that I have powered the harness are: Pin 20 of C1 with 12v from bat, pin 57 of C1 with 12v from bat and pin 19 of C1 with switch 12v. I have tested all of these connections and know they are working. That must be my problem then, I'll trace those pink wires back after lunch (they're actually orange for me) So there should be 8 pink wires from the injectors getting a direct hot connection to switched 12v and another 2 hots and 2 grounds for the coils?

Sorry for my ignorance about this, I knew that the wiring was going to be my downfall.

Ok, I've got the plug behind the starter; but there is nothing plugged in near the harmonic balancer and I don't see a plug anywhere. That must be my problem Could you give me details on it's location because I can't seem to find it.

Well, wait. Im not sure if your engine has the sensor on top rear of intake or near the starter and I dont know where you crank sensor is on this engine. Sorry, I was thinking my engine. Use your manual to find where they are on your particular block.

The only places that I have powered the harness are: Pin 20 of C1 with 12v from bat, pin 57 of C1 with 12v from bat and pin 19 of C1 with switch 12v. I have tested all of these connections and know they are working.

Yeah, you should have many pink (orange) wires that need power.

.....Just how many wires do you have hanging around not terminated???

too many apparently! I knew we'd get there in the end, I was pretty sure I was missing something fairly obvious!

Thanks guys, I'll let you know how it goes.

SUCCESS!!!!

I'll post a video of it running later when I have something besides dial up internet! Thanks so much to everyone who has helped me out on this. I just needed to apply power to two wires (+12v to right and left bank). Started up almost instantly! It idles smoothly, revs well, sounds good, no overly pronounced valve noises, love the exhaust note. At first glance everything seems to be in good working order, but I'll have to make double sure before I do anything more. This is even using the MAF with the mail-order tune and self wired sensor that no-one thought would work. I'm not saying it won't end up being a problem down the road but right now I couldn't be happier with how it's working.

I know I have oil pressure, but I think my electronic sending unit and gauge combo aren't happy together. The sending unit seems to peg the meter immediately once the engine starts. When I have faster internet I'll post the PN and see if you guys might be able to offer some insight

Temperature gauge seems to work great though, and that was the sending unit I was worried would be inaccurate. I confirmed its readings with a IR temp gun.

I have to head back to school for the week but hopefully I'll get to take it for a test drive next weekend!

Thanks again,
Luke

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Sorry that I haven't been keeping my build thread up to date, for now getting the car done and keeping up with schoolwork is a priority. Hopefully I'll get it on the road this weekend, I'll let you guys know.

Hey guys,

I got to take the car on the first test drive yesterday! This car is going to be nuts when I get the bugs worked out.

There's a weird acceleration problem only when I have it in gear. Just sitting the engine revs great and sounds great, it's responsive and seems like it would happily go to the red line (but I don't go that high). I don't think it's running lean, but I can't tell for sure. However, when I had it on the road yesterday it refuses to accelerate past maybe 2,000 rpm when it's in gear. I can get that high and it's like it hits the rev limiter or something, it sorta bogs and then bucks. If I'm going up a hill it's worse.

Do you think not having the VSS hooked up yet could be the problem? It would be nice if that's all it is. Hopefully I can answer enough questions away from the car while I'm at school this week.


Thanks,
Luke