Jump to content
SAU Community

Recommended Posts

Symptom - Car cranks but does not start (hot or cold)

There is fuel pressure at the line, pump is operating and priming correctly. There is a good spark.

Now here is the confusing part - on initial start, there is no injector pulse. I thought easy fix, its probably my CAS. Changed with another working unit tested on another car. It starts! Switched the engine off. Try to start again, cranks but no start. Once again, no injector pulse.

When i remove the CAS and spin it by hand, the pump primes and the injectors pulses. Reinstall the CAS and it starts. But when I switch it off, same problem reoccurs.

I've checked all the main wiring loom, make sure there's no short to earth. I've checked all earths and wiring. The battery is new. Measures 12.4Vs and 14.5Vs whilst running (alternator is charging). Whilst cranking it drops to 10.2V which is acceptable.

My theory is that the starter motor is drawing too much current when cranking, causing the CAS not to send the proper signal. Does anyone have any further ideas that I might need to check? I know its hard to diagnose a car over the internet without seeing it, but just want to hear any other ideas just in case I have left something out.

By the way, the car did receive a whole bunch of upgraded bits. Just to name a few that might affect it - Bosch 040 fuel pump and Bosch 363 injectors with R32 GTR ballast resistor, Z32 AFM, 80mm Throttle body. The rest of the mods I fail to see how it could affect starting.

Cheers!

Link to comment
https://www.sau.com.au/forums/topic/274278-starting-issues-need-ideas/
Share on other sites

Get rid of the ballast resisters and put in injectors that suit the car.

Had exactly this problem with a customer with a PowerFC Pro and GTR injectors (Dano4127). ripped out the resisters, made a new loom for the SARD 550's I had laying around and bang, starts every time. It had something to do with the injector driver in the ECU not operating correctly with that particular setup. Spoke in length with contacts in Japan and it turns out some of them have different drivers to others so cannot be wired that way.

That's a fair call about the injectors. I'm running a remapped RB20 ECU with Nistune.

My question is now, what's the difference between me turning the CAS by hand and the camshaft doing it whilst cranking? It should technically still prime and pulse the injectors whilst cranking?

It could be dropping voltage to the injector drivers while cranking. It could be something to do with current issues with the resistors in place causing the drivers to not fire while the starter motor is drawing what it needs.

Just a thought.

I never went into it in massive detail as I could see the most uncomplicated solution so I just fixed it. I would have liked to know exactly why but unfortunately time was not permitting. Let me know if you find out the reason.

If you think your car is drawing too much current, hence the voltage drop, does the car start when you roll start it?

like get 2 of your mates to push the car down the street, and clutch it to life, if that doesn't work that's not the problem then.

try starting the car without the AFM plugged in.

Sounds like the CAS is acting up, my car acted the same, would start in the beginning if you pushed it but it got worse and worse until it wounldnt start at all. Pulled the CAS and gave it a spin by hand, sounded like a peppergrinder :blink: Changed it and everything was good!

That's a fair call about the injectors. I'm running a remapped RB20 ECU with Nistune.

My question is now, what's the difference between me turning the CAS by hand and the camshaft doing it whilst cranking? It should technically still prime and pulse the injectors whilst cranking?

it could be that you have a broken cam (have seen this before in a mates ca18) or there is a short in the CAS so that it is earthing out when bolted to the block.

but i would be looking at other things first like voltage dropping when cranking

Cheers for the input guys.

Just to clarify, the engine does start but only after I have manually spun the CAS. As soon as the injector pulses, I can reinstall the CAS and it starts.

Its not the AFM and its not the CAS. When the engine is running, it receives all signals correctly and runs fine. I've checked the end of the cam to make sure there's no damage to the half-moon shaft.

I've just bought another starter motor and will be installing it this weekend.

  • 1 year later...

thread revival, didnt want to start new one, car wont start, only cranks

what i have tested so far:

fuel pump relay - ok

fuel pump primes - ok

fuses (in-cabin and engine bay) - ok

fuel pressure - 43psi

battery (13v, 11v whilst cranking) - ok

ignitor - swapped with another known working one

ignitor earth grounded - yes

voltage at injector - yes

pfc sensor check - ok

disconnected maf - still no start

spark with coilpack attached - FAIL

R34 CAS, yet to remove, however have read broken locator wont stop it starting

continuity testing to coilpack loom - yet to do

check voltage at starter motor - yet to do

broken cam - possible??

Q:

is cas and ignitor only culprit that would cause no spark issue?? any other things i can look at..

anyone wanna lend a R34 CAS i can test with??

if there is injector pulse than the CAS is ok, the ecu gets its firing order signal for injector and spark from the CAS so if one works then they should both work.

you need to check with an LED test light if theres a pulse on the ecu side of the ignitor when cranking, this will tell you if the ecu is sending the signal to the ignitor. it will be very faint when you check it.

if there is no pulse here the check at the ecu itself, if there is none here than you might need to try another ecu,

will PFC sensor check pickup the issue, as it came back normal

I'll open the PFC to check for burnt tracks and re-check wiring

any specific pin I should be testing?

Is there a relay near the PFC, I remember ages ago of one clicking in that area

update:

swapped in a new odyssey pc1200 battery, still no closer to getting it started

i have voltage at the injector plugs although this is different to injector pulse which i cant hear during cranking with screwdriver

if so, that would point the finger at the CAS right?

when measuring voltage at ignitor, do i have to earth out the E during cranking in order to get voltage reading?

also have re-plugged the ECU and relays near it, yet to test voltages at the pins

btw, car started briefly with the new battery for bout a minute, idled normally, could hear the injectors being their noisy normal self, then on its own it splutter few times and died

question:

assuming CAS is fine, and its the power wire to the coil in the loom thats broken or bad (ie. no spark), will cranking still cause injectors to wet the spark plugs??

i will pull CAS out over the weekend and rotate by hand to test if the injectors click etc

also only one of the relay by the ecu click with ignition on however 12v is present on both relays

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Can you log IAT? Whilst WTA coolers have their place, doing any sort of sustained run is not one of them There are fixes that slow down the heat soak, like ice boxes, which don't last that long, and interchillers, which are fairly expensive, up grades to the WTA cooling radiator, which may require a bigger pump, and upgrades to the reservoir size,  and upgrades to the cooling fans, but, it all still heat soaks, and takes ages to come down in hot weather  For a turbo, that isn't locked into WTA like my PD blower is, can you not possibly swap to a nice air to air intercooler????, it would be better for sustained runs then, and have alot less things that could go wrong in my opinion 
    • So, the other thing I've sorted is a baseline dyno run up at Unigroup's new location. The auto trans was a little unco-operative by both shifting down when the throttle was floored on the dyno (so Mark had to ramp it up more slowly than in a manual) and also by shifting up at 6,000 even in sports mode instead of the indicated redline of 7,000 Still, on a hot day it made 240rwkw at 16psi which seems about right for 300kw (400hp) through an auto at the wheels.  The shape of the curve is not quite right because it was not full throttle to about 4,500 to stop it kicking down, but until I can get a tune on the auto trans control this was the best we could do.....full boost will be well below 5,000 once that is sorted, I'll get some data logs when I can to confirm For comparison, the R32 made 255 at 12psi (at 4,500) on the same dyno with tune, n1 turbos, cam gears, big exhaust but otherwise all standard so the v37 is likely a little better out of the box. One thing that is very clear is that the standard water to air intercoolers are not up to sustained use at full throttle in warm ambient temps. After about 5 runs (so only a few minutes full throttle), it was pulling boost and timing and dropping 10-15% power. Unfortunately I didn't get that printout and the Unigroup guys are away at the moment, will try and get hold of it on their return. So, looks like a healthy engine to start modifying and the only real area of concern is the w2a heat exchangers which the aftermarket has plenty of solutions for    
    • I maintain it actually looked really nice in person. So much so that I thought "No, this is illegal" but there it was, clear as day. I think we can easily call the wing and wheels/height to be transformative. Not saying it's better than the GR Whatever, or the 86, or the WRX STI or anything of that sort (the internet says it all bolts up so you can buy best of all worlds?) but it's still at least a thing and not nearly AS bad as people say.
    • That's less offensive than the previous gen.....except for all that ugly black tupperware around the edges. Blerck!
    • I leant out the window recently and took a picture of this new WRX. It looked real damn fine in person. It's faster around a track (stock) than a (stock) GR Yaris. It's much more practical despite being heavier. It's significantly cheaper. This gen tunes really well, much better than others. .... I think they're probably a lot better than people expect.
×
×
  • Create New...