still no spark and no injector fires, 91 q45??????

[navyman_98_99]

I replaced the ecu, the power transistors, the crank angle sensor, the fuel control module and still no spark and the injectors dont fire. the crank angle sensor has continuity to the ecu on all wires. what else causes no spark.I can spray starting fuid in the intake and it starts up for a second then dies. so maybe it is getting spark but it isnt much if it is. I took out the coils and tested them to ground and they dont seem to be getting any spark.

So what is next. what can I do next to get this thing running again.Thanks Mike

[navyman_98_99]

dang, no one has any ideas huh? I still dont get it!

[maxnix]

Might be better if you posted in Infiniti Mechanic. Tell us about the fuel pump and fuel filter.

[navyman_98_99]

the fuel pump and fuel filter are also new.the fuel pump when turning on the car you can only hear for a second or two then it shuts off. after cranking the engine you can also hear the fuel pump for a few seconds then it shuts off. Thanks Mike

[Jesda]

Do a search for FPCU, as this may or may not be the cause of your problem. It can burn out over time and make its problems present after installing a new pump, as it did for me. A few FPCUs are for sale for cheap in the classifieds, I believe. I keep an extra one in the glovebox.

You said your Q will start however, when you spray starting fluid. I dont know what that means, and I dont know if that rules out the FPCU. Someone with more knowledge should chime in, or perhaps you want to post this, as Brian said, in the Infiniti Online Mechanic section.

[maxnix]

The OEM fuel pump should be heard only when the ignition key is rotated to the run position initially (before rotating it to the starter engagement position) as the pump runs at it's top speed until the fuel system is pressurized.

Hearing it run after an attempted start makes one wonder if it is OEM or the FPCM is fully functional. What pressures are you getting in your fuel line after the filter?

[navyman_98_99]

about 48 psi, if I remember correctly is the fuel pressure I am getting. and the fpcm is brand new, I also checked it in my buddys q45, and it works perfectly.

[maxnix]

Well, this is perplexing if you have adequate fuel pressure after the fuel filter and are getting spark. Not flooding it, are you? If you have a couple of failed injectors that are leaking, I suppose they could wash the cylinders enough to get no compression.

Hmmmm.....

[CoastyAV8R]

If it will start with starting fluid, that would lead me to believe it's a fuel problem. Now there isn't much between the fuel filter and your injectors except the fuel rail. I'm not sure if there is a way to check the fuel flow at this point. If you do have a bad injector and it's washing your cylinders, you may be able to smell the excess fuel in your oil.

Something else that you may want to consider is the condition of your battery, if it's weak I've seen cars not start because the ECM wasn't getting enough voltage to get everything going and if you look in the service manual all the sensors and computers rely on the battery before start up.

Do you have the factory service manual? Wes sent it to me on the internet and it has an incredible amount of useful info in it that can help you narrow down your problem before you spend anymore money. The service manual states you should be seeing 34 psi with the regulator valve vacuum hose hooked up and 43.4 with it disconnected. Hope this helps, atleast it confirms you have good fuel pressure.

[navyman_98_99]

I can't smell any fuel! what makes the injectors fire. the crank angle sensor or the ecu. I have a manual also, and its online I just cant read the schematics, the are all blurry on the site I use. I need to see what fires the injectors. any info would be great. Thanks Mike

[navyman_98_99]

Ok, I changed the fuel injectors, the fuel rail and the wiring harness for the injectors today and my injectors still dont fire. I dont get it??? what else would cause my injectors not to fire. I can manually gorund one of the wires to each individual injector then the one I ground, fires. Maybe my ecu's ( I have two of them now) are both messed up. From what I can tell from the schematic is that the ecu tells the injectors to fire, and I have continuity from every ground wire that goes from the injector to the ecu like I should and I have the 12vdc on every injector like I should. So I am not getting the signal from the ecu telling the injectors to fire! What tells the ecu what cylinder is ready for some fuel so the ecu knows when to fire the injectors? I would think the cas but not for sure.any more help would be great!! Thanks Mike

[elwesso]

Ok, I changed the fuel injectors, the fuel rail and the wiring harness for the injectors today and my injectors still dont fire. I dont get it??? what else would cause my injectors not to fire. I can manually gorund one of the wires to each individual injector then the one I ground, fires. Maybe my ecu's ( I have two of them now) are both messed up. From what I can tell from the schematic is that the ecu tells the injectors to fire, and I have continuity from every ground wire that goes from the injector to the ecu like I should and I have the 12vdc on every injector like I should. So I am not getting the signal from the ecu telling the injectors to fire! What tells the ecu what cylinder is ready for some fuel so the ecu knows when to fire the injectors? I would think the cas but not for sure.any more help would be great!! Thanks Mike

+

There is an injector fuse/relay that I *assume* youve checked? ECUs RARELY fail!

[Q451990]

I think you should check your crank angle sensor... but even if it fails, isn't there a sub-crank angle sensor that lets it run in "limp mode"? Don't have the manual with me...

I remember one of the injector tests was to remove the CAS and rotate it while listening for the injectors to "click"... What was the car doing when it stopped working?

I think there's another very unfortunate possibility, and that's that you're not getting compression for the worst of all reasons (timing chain guide failure) - if the chain isn't intact on the left bank it can't turn the CAS... no CAS and no signal to the ECU...

Heath

[navyman_98_99]

What was the car doing when it stopped working?

I think there's another very unfortunate possibility, and that's that you're not getting compression for the worst of all reasons (timing chain guide failure) - if the chain isn't intact on the left bank it can't turn the CAS... no CAS and no signal to the ECU...

Heath

I know for a fact that the crank angle sensor is turning while turning over the engine and I have tons of compression. when I take the cas out and turn it with the key on, I dont get any clicks from the injectors, this is my second cas I have tried and they both do the same thing which is nothing. The wierd thing is I checked the wireing schematic and all the wires that go from the crank angles sensor and sub crank angle sensor to the ecu have full continuity, So I know that the wires are going to the right place and they are not broken. I dont have 2 volts on the position wire to the crank angle sensor when the schamtic says I should. I dont know where that 2 volts come from yet. I have security light going off and on when truning over the engine or closing the door I wonderr if that has anything to do with it? thanks Mike

[navyman_98_99]

Wess, I cant find the relay for the injectors but I checked the fuse in the enigine compartment and its fine. My manual doesnt show a relay for the injectors, if you could help me out that would be great. Thanks Mike

[maxnix]

Two dumb questions. Is the main fuse intact? Is it possible for the CAS to be installed out of phase, say 180°?

[navyman_98_99]

Yes, the main fuse is intact, or I wouldn't be able to turn it over and I wouldn't have no dash lights, I dont even think the ecu would come on if the main fuse wasn't intact and no the cas cant be installed 180 out. There is only one way the cas can go in. I have given up, I am going to take it to someone that has a diagnostic scanner for nissan's, I don't even know if that will tell the exact problem or not, will It? I have replaced every thing I can think of and then more. I have continuity on all the wires going from the sensors to the ecu, all my relays that I can find and that my schematic shows, are all good. I have tons of compression, tons of fuel pressure, my crank angle sensor is reading what it should at the terminals going to the ecu. My injectors still dont fire, unless I manually ground the wire going to the ecu for each individual injector. All I need is fuel to the cylinders, then my car will run again. I have an electrical engineering background and this car has me stumped. I just don't get this dang thing!!!! Any one that has any more ideas, I would love to hear them and try them out, before I take the easy way out and get a diagnostic reading.Thanks every one for the help, I will get this thing going again!!!!Mike

[Jeff Williams]

Here is a couple stupid questions:

Have you checked the throttle position sensor?

When you get the car to start with starter fluid, can you keep it running, by squirting it in the throttle body?

Have you checked the plugs, to see if they are fouled?

[navyman_98_99]

No, I havent checked the throtle position sensor yet, I didnt know it had anything to do with the injectors. the car will stay running if I keep spraying the starter fluid in the throttle body. The plugs are brand new and not fouled, I changed the plugs and that was the last time the car has run! Yes the plugs are the right ones, I have tripple checked. If the throttle position senser has anything to do with the fuel injectors not fireing I would like to know more. Thanks for the help, Mike

[navyman_98_99]

I just checked the mass airflow sensor and it seems to be reading more volts then the fsm saysit should read, so it is probably bad. the maf shouldn't stop te injectors from firing. My throttle position sensor and the wiring going to the ecu is all good. so it's not that. I am missing something somewhere and it is driving me crazy!!!Thanks Mike

[3Q Jay]

i know you may have been thru this before...but, how do you know you've got nothing at the injectors?you did all 8 new oem injectors? did you ohm them before install? have you ohmed them thru the 8-wire harness on top of the right vc? next might be to setup the ecu end [to a scope would be ideal-or analog meter] of the 8-wire and see if you are getting any signal coming out of the ecu.

was there anything amiss when you pulled the old injectors [like the rails are completely clogged of sumpin'?

where are you measuring fuel pressure?

[navyman_98_99]

The injectors are fine. before I put the injectors in I actually grounded one of them with fuel pressure to the fuel rail and sure enough one of them sprayed fuel like no other, but when I got in the car and cranked it over no fuel came out. i am measuring the fuel pressure on the output of the fuel filter like the shop manlual says. I don't know what else to do. Thanks Mike

[Jeff Williams]

When you grounded the injector, was it a ground on the engine, or the chassis?

Could it be a grounding problem?

Have you put a meter on an injector, to see if it is getting positive voltage when you try to start the car? It sounds like a broken wire in the harness somewhere to me.

Try calling T3 in Atlanta, to see if they will spend 20 minutes on the phone with you. Byron might have some insight into the problem

[3Q Jay]

i think Jeff might be on to something. the thought i had this morning was to try grounding the ecu. i know you may have already measured ecu chassis to frame with your meter, but at least temporarily, i'd rig up a ground wire 18awg minimum, and go from an ecu hold down screw to the bare car frame.

might also still have some gremlins in the harness between the ecu and injector subharness connector. i don't recall if you said you measured that already. don't overlook possible position sensitive open in the harness [wiggle it].

[maxnix]

Still no Ohm readings?

Are injectors leaking? Does the fuel system hold pressure over time?

[navyman_98_99]

I ground wire to the injector on the engine even when the key is in the off position and it still fires the injector. The injectors always have positive battery voltage to them on one wire, all together there is two wires going to the injectors. The wire that doesn't have the battery voltage going to it I ground it out, and it fires the injector that was ground out. But when turning over the engine it does not fire the injectors like it should all the wires that I can ground out also go to the ecu and I hav continuity on all the injector wires going to the ecu. I am also positive I have no spark, when i spray the starting fuid in the throttle body, the compression is igniting the starting fluid. I took the coils out and did like the shop manual says and I am not getting any spark from the coils. They all ohm fine. the injectors all ohm fine and the car does hold fuel pressure over time. So I am stumped!!!Thanks Mike

[Jeff Williams]

I would concentrate on the spark issue. The injectors not firing may be a byproduct of no spark.

Did you ever find out where the 2 volts to the CAS comes from?

Have you checked the igniter packs? I am shooting in the dark, because I have not had electrical problems with either Q (yet). Have you posted in the Infiniti Online Mechanic forum?

It is probably some cheap part or conector or broken wire. I wish I was closer, or was more help.

Keep us posted.

[elwesso]

So you replaced the spark plugs, did you possibly reverse the connectors on the ignitor packs, or leave them unplugged or something.....? Try that..

There was a thread by "walnuts" in the online mechanic and he didnt think he was getting spark either when he did the test...

[navyman_98_99]

I replaced the ignitors with brand new ones, I have them plugged in. Oh ya when I push the gas pedal just a tad, I hear a humming noise. I checked it out and it is coming from the transmission, I unplug the throttle position sensor harness and it goes away, but my led screen in the left hand corner of the speedo cluster says transmission failure. I plug the tps back in and the faiulure goes away, but I hear the humming. I wonder if that humming in the transmission has anything to do with it, does anybodys car have the same humming noise coming from the transmission, with the key in the on position. and the gas pedal just barely pushed. Let me know, please.Thanks Mike

[maxnix]

Are you sure about the humming in the transmission? Can't think what there is to hum in there if the engine is not turned over. Some relay, perhaps? Sure it is not the fuel pump you hear?