So I did all the work under the intake, 'new' injectors, new plugs, dbl checked all the connectors and hoses, etc. darn thing will not start. Sounds like a no-spark engine, or no fuel at the injectors. All the fuses look good, new fuel pump relay, etc.

The fuel rails did go dry when removing the injectors, so do the rails need to be purged?

So, what can it be?

I wonder is the the spring in the bottom end of the cap-coils are not touching the plugs. Plugs are identical in length as the ones that cam out, but I did notice when installing the coils there was not spring push back on the coil itself. I recall when I 1st did plugs in 2008-2009 when you installed the coils they would be held up off the valve cover an 1/8" or so (due to the spring in the bottom) and then the coil bolt would push it down into position when tightened. This time though the coils seem to just fall right down onto the valve cover flat, w/o any bolt install yet, so this make me wonder if the springs need to be pulled out some?

Your thoughts?

 

Well, I stretched all the coil-pak springs, feels better being bolted down, can feel a little push back.

But, I disconnected the fuel line closest to the brake master cylinder (the one near #3 & #5 plugs), turn ignition on and got no fuel. Hmmmm, why is that?

I am hoping nothing shorted in ECU somewhere. While servicing I did have fuel pump relay out but batt was still connected, fuse box top cover off, and while removing a long extension from cyl #1 spark plug the back of the extension touche the corner batt bolt down terminal and the tip of the plug socket grazed the top of valve cover. I did get a few sparks from that. Hoping the ground path through the valve cover back to batt neg terminal did not fry any electronics. Would not seem plausible, but as of now I don't know why no fuel pressure. I check all fuses too.

 

Verify fuel pump in tank is working (get someone under there to listen when you turn the key to the run position)

You might need to go through a few key-turns to get fuel back up the rails. There might be a tech-stream function to do this.

Chip H.

 

I tried 4 starts, each with a 1-2min break between them. Should of had pressure by then.

And duly noted, after that spark incident I took neg off the battery, vehicle sat w/o power for 3 days.

 

Odd, no power on any of the Fuel Pump relay connectors, with ignition in run or off positions, but the rest of the fuses have power.

 

Here's the wiring diagram, two relays for fuel pump. C/OPN Relay is the one that provide power to pump relay. My C/OPN relay is not working, meaning it appears the ECU is not allowing C/OPN relay coil to flow mA to energize that relay.

w/o IGN-off there's no power on C/OPN, but w/ IGN-run the C/OPN relay coil has +12v on both relay coil contacts, which mean no current flow. The relay is good as I tested it outside the fuse box, etc.

Fuel Pump Relay isn't actually a on/off relay, it's a relay that switches between direct to pump, or via the pump resistor. My guess, direct to pump to get it started, then less amps in pump after running via the pump resistor.

So, why is C/OPN relay not energizing? I am not 100% where that relay coil connections go, my guess is to the ECU, but you can see it in the electrical wiring diagram sticky, "Engine Controls2.pdf".

But if it's a ECU issue, how is it just this C/OPN relay? Makes no sense.

 

I can't find anything causing this issue. If the ECU went south because of that short I mentioned, why just the C/OPN relay, and everything else seems ok. I must be missing something.

 

More info to this mystery.
I jumped the fuel pump at the relay connections (fuel relay) to +12. The pump runs and I can feel fuel gushing through the fuel line that enters at the rear-driverside corner of the intake manifold (where the fuel clip-on is). While the pump is running I tried to start it, but it simply did a few "trying to start" sounds, almost as if there's pressure on the rails, perhaps spark is ok, but injectors not opening.

 

Possible the security system is preventing injector pulse?

 

Immobilizer maybe?

Same key that I have always used.

When I get near the vehicle the red car logo with key in middle starts to blink.

My key can lock/unlock using the remote, etc.

 

I reprogrammed my key, didn't fix anything.

 

Can someone verify for me. After your GX has been sitting for a few hours, when you turn the ignition key to RUN position, do you hear the fuel pump in rear of vehicle pumping (a kinda whine sound). When my GX was all good I never heard the fuel pump just with key in the RUN position.

I may be wrong about the C/OPN relay, the ECU may latch that 'on' only when trying to start and then stays 'on' once engine running is sensed. The 'fuel pump' relay is a selector relay, +V directly to the pump, or +V through the ~1ohm pump resistor (that aluminum heatsink just behind the engine bay fuse box). Not clear to me if the pump needs more amps at start time, or after the engine is running (or if the ECU changes that as needed, like ez hwy driving vs heavy on pedal from a full stop). The ECU would control that selection via the 'fuel pump' relay.

That (last paragraph) may be std operating code (not sure), but maybe I am running up against an immobilizer issue? Car with key light does disappear when I insert my key.

 

Still more mystery here. The ECU is logging DTC P2118, and randomly a P2135. <-- this after removing EFI 20A fuse which provides power to the ECU, letting it sit for about 5min, then put fuse back. The code reads as 2118 and 2118 Pending. Maybe that's a test after it's running? But, even if I clear the DTC stuff the ECU will not power on the C/OPN relay.

Throttle body actuator issue? Contacts are clean. Anyone have the ohms test procedure? The motor connections are 2.1ohm, seems low no?

This code would put vehicle into limp mode, or not allow engine to start. But duly noted, if I clear the DTC I still do not get C/OPN relay to power up the fuel system.

I am a bit baffled, everything else seems ok though, well, I cannot test to see if injectors or spark is working if it wont power the fuel, etc.

Fried ECU ??

 

The procedure you went through with your key is for remote lock, and has nothing to do with the immobilizer. The key has a remote lock/unlock module in it, but also has a RFID chip that identifies it to the immobilizer system (there is an antenna near the ignition switch that challenges the chip). You will need a top-level tech-stream subscription to code a key to the vehicle, so locksmith, dealer, etc.

When I first turn my key to run position, I do hear the fuel pump. I haven't investigated it, but I believe you're correct in that the ECU commands it to run at full speed to prime the rails, then routes it through the resistor once the engine has started to run it at a slower speed.

I don't really have anything else for you, other than to investigate the codes. Dumb question - you did plug everything back in, and don't have a pin that got pushed out of the connector body or got bent?

Chip H.

 

All the connectors snapped in like normal. The only connectors undone were a few sensors, injectors, spark, and the big one behind intake (the higher of the two). I dont see any missing connections.

Even if I jump the fuel pump to run, it won't start, which seems like ECU is not running injectors or spark.

The only thing close would be limp mode which can cause ECU to not run EFI at all. But I have no DTC's for being in this mode.

Notes: throttle body works fine, moves in-sync with gas pedal.

What does the immobilizer do? Would it cutoff EFI?

I find it odd that just EFI seems to be affected. But then again, that's most of the ECU stuff.

Shorting batt to top of valve cover, is ground loop nightmare. Some of that current will travel through all the gnd wires, and if there's common path inside the ECU then some of those track could possibly burn up. It would of have to taken out a gnd track on the transistor that controls the FC pin on ECU. FC is the gnd side of the C/OPN relay coil.

Also odd that I am getting no DTC's for no fuel pressure when trying to start it.

Unless I missed a really important connector, this looks more like a goofed ECU.