nisscan.com

Thanks, i relooked at the factory manual and will go and check it out myself, could even be the O ring?
The VVT timing is controlled via the Intake valve timing control solenoid valve, which controls the camshaft sprocket?

Do i understand this correctly?

This could also explain why at Nissan after cranking the motor, the timing was out as it was still under pressure, but back at repair guy, timing seemed fine because motor had stood and oil pressure subsided.

Im feeling positive, hold thumbs

Thanks
Wayne

There is a mistake in what I said before. The vvt sprocket will not cause a mistake in the cam timing but the cam chain tensioner can - normally 1 tooth out. It depends on whether the timing is set by using the marked links on the chain (that may not be there in aftermarket parts) or by the position of the sprockets. Anyway, I still advise verifying the correct cam timing particularly now you mention Nissan reckoned it was out. Can you read the error codes out of the ecu? It will be throwing a code on cranking over.
The O-ring you mention could be a problem (if it is not there, blocked with gasket sealant or incorrectly squished) only after the engine starts and the cam fails to advance.
The intake valve timing control solenoid valve does control cam advance using a pulse width modulated signal to vary the amount of advance. It is either filling chambers in the vvt sprocket, holding the volume or bleeding the volume down.

Thanks Jaf,
Error code is P0340, which relates to the cam sensor, the repair centre has rechecked the timing over and over, and are sure it is correct. I am going to ask them to strip off the little cover plate over cam gears, to confirm this alignment and also the valve timing solenoid.

Will let you know again
Wayne

Hello Jaf, spent all this time trying to get repair guys and nissan to sort out timing. Exhaust cam was out by one tooth, this is all correct now, but sadly i still only have spark on number 4 cylinder, i am at my wits end, no idea what to check next, no error codes at all, any advice..... please

Hi Wayne,

Can you put a scope on the input signal to the coils to see whether the coils are getting a signal and power? (5V logic pulses and 12V DC supply)
Maybe swap the coils around to see if fault follows the coils?
Very strange to still have no spark and no error codes unless the coils or wiring is faulty. How are you determining the presence or absence of spark on each cylinder?

Jaf, i have measured at the ECU output with a scope for ignition pulses, only number 4 has a signal, i have swopped out coils, all have spark on number 4, i am earthing the plug and checking spark across the plug, i have swopped out plugs, i have checked earth and 12 supply to coils, measure continuity from signal terminal back to ECU, all ok, scoped cam and crank sensor signals, measured supply voltage, all ok, even continuity to ECU.It must be something in the system that is blocking firing, injectors seem to have signal as fuel is pumped into cylinders. Natis light goes off when you turn the key, What could this be? i am not sure where to check anymore. Nissan SA tell me there is no way of putting my ECU on another vechile to test, is this true, is there a way to override? thanks wayne,

If all error codes are now clear then rule out wiring problems. Each coil connector should have continuous +12V on one pin and earth on another when the key is turned to IGN. If this is not the case, then look at your FSM and sort it. It could be a ground wire not hooked up. The trigger signals may not be visible if there is no power to the coil (may be open collector/drain style output from ECU) Other than that, it is looking like a component fault inside the ECU. There is one IC that drives the IGN coils and injectors as discussed earlier in this thread. Your ECU will be different to the 04 and later ones so careful what you buy if you have to. Sorry, can't be much more help than that.

Is the SA South Africa or South Australia?

John

Hi jaf,
I've done a wee bit more work on your ROM (I'm telling you, this throttle hang is driving me nuts, even more so now that I think I have a thin chance of finding the problem in the ROM)

I've actually just realised that the Nissan J2534 software uses by-the-book ISO14230, with short address-less headers. I didn't think those were valid in 14230 until I re-read
the spec yesterday. I found the main piece of code that decodes the 14230 Service ID requests, and found a few mfg-defined SIDs :
0xA0, A1, A3, A4 and AC.
I was really hoping to see SIDs 0x23 and 0x3D (Read / WriteMemoryByAddress) in there, but no luck.

[EDIT - I came to a wrong conclusion regarding SID 32 01 to calculate the checksum, so I removed a part]
I was wondering, how did you find your checksums at 63E4 and 63EC ? And how are they calculated / verified ?

Hi fenugrec,

The process to figure out the checksum addresses was simple: download 3 ROMs from the same model car but with slight variations in code. Look for the bytes that always change and there is your checksum. The Nissan checksum algorithm has been around for quite some time unchanged so that part is not too hard. It took me around 2 years to go from wanting to reflash to being able to do it and it is still a very crude process.
I could delve into what happened on many other forums such as Subarus, Mitsubishis and of course the 350Z forums where people commercialized what was the joint and freely given efforts of forum members...... that is why I stop short of giving away anything that could be used to offer a commercialized product.
I think there might be a major error in one or two of my definitions - I was getting random error codes relating to accel position vs throttle position which had no genuine cause. This coincided with making aggressive changes to the AFR tables or what I thought were AFR tables. I had wondered why the load axis appeared to be backwards, now I think it is because these are not AFR but something throttle related. There is another map that always looked like an AFR map from older cars and I think that is the real AFR map. I have put all 3 maps in question back to factory for now until I have more time to figure this out. If the 16x16 maps are throttle related, they could be the answer to the throttle hang problem - one map for accelerating, one map for decelerating - they look about right for that. The other throttle maps look like torque delivery maps.
Are we going to see a SpecV ROM uploaded here soon?

John

Hi John,
thanks for the info. When I posted that last message I had just discovered that the Nissan repro software sent SID 31 ( 31 01 01 00 00 06 ff ff ck1 ck2) to make the ECU verify it's checksum after reprogramming, sending the expected 16-bit checksum and waiting for a positive answer. I interpreted the "06 FF FF" part of the request as the number of bytes to sum, but I could find nothing in the code to support this and it didn't match the checksums you had flagged.
Good thinking on reading 3 different ROMs, I didn't know you had access to three otherwise-identical X-Trails p-))..

Re your AFR / throttle tables, did the axis info I found in the code a few weeks ago confirm some of your findings ?

"Are we going to see a specV ROM soon" : Yes. I feel SID 0xAC is going to help me... I have time to figure out a few things before I get back home in 1-2 weeks, the weather should also have warmed up by then as well so I'll be able to hack at my garage computer (does anyone else call this a "shoputer" ?) without taking "finger breaks" every 10 minutes.