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Sleeper King
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Discussion Starter · #1 ·
Hey guys,
I'm scratching my head on this. We went to crank the motor yesterday and she cranks, but will not fire. Started doing process of elimination.

Cracked open the fitting on the rail, fuel sprayed out, so we have fuel.
Pulled plug/coil and cranked, saw spark
Pulled plugs and they are bone dry as well as the cylinders.
Thought we "felt" the injectors clicking, but will double check with a screwdriver today and listen again
Checked and rechecked grounds and harness connectors, etc..

The only real major thing we changed on the fuel system is swapped in 1600cc injectors from 1000cc, rescaled map in aem for them, and added a 3rd pump that only comes on when LS1 output says to, the 3rd fuel line routes to the FPR and the other 2 feed the rail ends.

Just tyring to talk through this :( it's SOOOO close to firing. Looking for things to check and double check.

Any help is greatly appreciated!!!

Chris
 

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hhhmm, when my crank position sensor came off i didnt get fuel or spark, but you are getting spark...so im stumped...
 

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Sleeper King
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Discussion Starter · #3 ·
I starting thinking about the cam and crank sensors as well. I did log the cranking and the see it "sync'd".

I put the screwdriver to the injector and it's definitely clicking, so no clue why no fuel is making it through even when they are "firing"
 

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well trace your steps back..is your fuel pump coming on? you FPR not flowing?
 

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Smaay said:
hhhmm, when my crank position sensor came off i didnt get fuel or spark, but you are getting spark...so im stumped...

Exactly...
Did you tried unplugging an injector and do a voltage check?

-Chris
 

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Sleeper King
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Discussion Starter · #6 · (Edited)
I'm going to have to check the voltage to the injectors and see.

I've logged practically every other parameter via the aem (attached file) and everything looks good.
Cam and crank show a value of "1" when cranking
Stat Sync'd is "on" when cranking
No timing errors

Yanked the coils/plugs and I'm seeing spark. I've swapped in another starter and same issue. Had the battery tested, all is good there too.

edit: put some fuel into the cyl and tried cranking, and nothing, not even a backfire. So I'm not entirely sure how I saw the arcing of the plugs to the valve covers when I cranked and thought I was seeing spark.

CT
 

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Sounds like a physical injector problem or injector control problem to me. I cant think of any other reason considering you have feul in the rail......maybe there is something blocking feul :dunno:

1) volt test injectors
2) check FPR out
3) recheck electronics
 

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High Performance WorkShop
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Sounds like a physical injector problem or injector control problem to me. I cant think of any other reason considering you have feul in the rail......maybe there is something blocking feul
he said he has fuel in the rail , so that isn't a problem ,
forget about the pumps , regulator and lines , as fuel is reaching your injectors ,
if you were on stock ecu , i might have a tip or two , but AEM , am not an expert on ,
i'd say check your crank sensor , just open and clean if you can , or swap it out ,
then check your cam sensors , next check your water temp sensor that it's hooked up , the one on the water neck , aaaand least but not least , check your wiring from your injectors to your aem , use a multimeter &/or tester and check for power .
 

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I say check each injector outside the car by giving it direct voltage. We had the same problem with my firends car, came out to be all 6 bad injectors.
 

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Sleeper King
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Discussion Starter · #10 ·
Thanks for the feedback guys.

Tested all of the injector harnesses. They all check out with accurate battery voltage. Showing 10.5volts or so when cranking.

Like it was said, the fuel is making all the way to the injectors, however the cyl are dry. The pumps are working just fine, and I have 40+psi in the lines.

Sadil, I've already swapped in an entirely new set of injectors and still the same issue :(

As for the cam and crank position sensors, could they still be messed up, even though they both are registering and "sync'ing" (based off my aem log)?

Again, thanks for the help guys.
 

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Take the protective caps off the injectors you ****.... and if not "Try doing that dance with your hips and Larry's hands crasping them firmly".
 

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Sleeper King
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Discussion Starter · #13 ·
Wow, I completely forgot about those Jim!!!! ...................................NOT! Now go away and bother your boyfriend.
 

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So just to recap here, you have fuel at the rail and voltage at the injector clips. Well, are you sure you have low impendence injectors and nothing else? Whats the specs on those injector you swapped ?

Chris
 

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Sleeper King
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Discussion Starter · #15 · (Edited)
So the mystery continues

They are in fact low impedance injectors, we tested them (5ohms). I poured just a tad bit of fuel into each cyl to see if I would get something, nada! So I'm not entirely sure what's going on here, since I did see some arc'ing from the plugs to the valvecover (ground) while cranking. I tested resistance on the solenoid resistor, and all came out to factory tolerance.
I'm trying to figure out what the specs for resitance on the igniter are, anyone?

Next up, resistance test the crank and cam position sensors I guess.

Btw, they are precision 1600's

Chris
 

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brother , just swap out your cam and crank angle sensors , and you'll be fine !
check your igniter as well ,
if you want to check for firing , don't pour fuel into cylinders , instead spray some fuel into your intake and then crank . if she fires up , you know your timing and ignition problems are gone and then you focus on fuel .
goodluck !
 

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Sleeper King
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Discussion Starter · #18 ·
Well, I tested resistance on the cam and crank position sensors

Cam sensors cam out ok and within tolerance 1.1kohms and factory manual states 835-1400ohms. Besides, I swapped the 2 back and forth as the aem only uses one of them anyways.

Now, I tested the crank position sensor and factory spec says 835-1400ohms (cold) mine showed approximately 2.1k (2100). Now I'm not an electrically inclined person ;) but that doesn't seem good. I will have to swap in a new one and test.
 

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Hey Chris, Parin told me about your issue and i've just finished my electrical courses in class. Here's my input: high resistance acts like an open in an electrical circuit so it's either a bad sensor or there's an open in the circuitry. I doubt there's an open ..my guess bad crank sensor. Now when you took the sensor reading of 1400hz was the engine cranking or no?

Spark you said fires at the plug/coil
Fuel you said is present and FP is fine via FPR correct?
Is the return line having flow back to the tank?
Is your MAP sensor reading an air figure?
Cam sensor is within specs i'm assuming?
Crank sensor shows higher than avg. reading so thats my guess.

HTH..
 

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Sleeper King
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Discussion Starter · #20 · (Edited)
inco9nito99 said:
Hey Chris, Parin told me about your issue and i've just finished my electrical courses in class. Here's my input: high resistance acts like an open in an electrical circuit so it's either a bad sensor or there's an open in the circuitry. I doubt there's an open ..my guess bad crank sensor. Now when you took the sensor reading of 1400hz was the engine cranking or no?

Spark you said fires at the plug/coil
( I do see some arc'ing from the plugs to the valvecover where I have it grounded, however it seems sparse and weak)

Fuel you said is present and FP is fine via FPR correct?
Corrent, I have 40+psi in the lines at the fpr, and I have fuel in the rail

Is the return line having flow back to the tank?
I'm using the factory return line

Is your MAP sensor reading an air figure?

Cam sensor is within specs i'm assuming?
They tested within factory tolerance

Crank sensor shows higher than avg. reading so thats my guess.

HTH..
Hey Kunal! Hope you're doing well out there.

I took the resistance reading of the cps (crank position sensor) and cam sensors while ignition was off (like the factory manual states)

I'll answer the rest of the questions above
 
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