1JZ code 13 has me baffled.

[Guest AlanHutchinson]

Hi Everyone,

 

I'm not usually one to post on here, usually one to lurk and read .

 

Anyway I know there are a few that know the 1jz and the electronics surrounding it on here quite well and would like some advice if I may.

 

The car's an early JZZ30 Soarer auto 100% stock.

 

Ever since I've owned the car, it's thrown up the check engine light about 5 seconds after starting it only if left at idle in park or neutral. If I switch to drive or reverse before this 5 seconds it doesn't come on until it's back in either neutral or park at idle when stationary (I tested whilst driving down a hill by knocking it into neutral and allowing it to coast and the light doesn't come on). It's never been a cause for concern as the car has always run fantastically....

 

...Until just recently when I noticed it leaving a nice amount of unburned fuel out the back when setting off from cold (minor accelleration) and smelling a bit rich when cold. It's also just failed an MOT on emissions.

 

Now I've spent a lot of time researching this kind of issue and have not found another one that matches mine exactly, but it seemed like it was likely to be an issue with the capacitors on the ECU leaking onto the circuit board. By chance, I had a spare good ECU that I could try available to me and that has made no difference, so we can rule that issue out.

 

I did the paperclip trick on the ECU to find out what is causing the light to come on (perhaps it's related to my running rich issues?) and it came back with a code 13 which I know is related to cam sensor circuitry.

 

Having read up on the cam sensor issues on the 1j and 2j, it seems people report a misfire or even the car dropping into limp which this car is not doing, there's no misfiring at idle and it drives perfectly.

 

I also understand that the cam and crank sensors on the JZ engines are so sensitive to things like worn cam belts/tensioners which I can rule out as it's a reasonably recent cam belt and I checked the tensioner this evening which is fine.

 

I have noticed this evening that if I hold the revs on for a length of time and let them drop off back to idle I do in fact get a misfire and the car will then idle at around 400rpm, if I give it a bit of gas it then begins to rev up perfectly smoothly before dropping back to its 400rpm idle. Switching the car off and on again it goes back to normal idle and perfect running.

 

I don't particularly want to start throwing loads of money at new parts that won't solve the issue as I'm planning on selling up shortly after it's sorted but at the same time I want it to be correct for the new owner and be able to get it through its MOT.

 

So yeah. Has anyone come across this issue before?

 

Also forgot to mention if the light does come on before I set off, there is no noticeable difference in power. The fuel consumption is also pretty bad.

 

Thank you in advance to anyone who can help me and apologies for the essay.

 

Alan

[Swampy442]

How much would the car be with this issue?

[Guest AlanHutchinson]

How much would the car be with this issue?

 

Not for sale with the issue unfortunately. Unless you want to pay full money for it

[Konrad]

I would check Idle Control valve for any dirt inside

[Chris Wilson]

Did you check if the crank cam belt pulley had a loose trigger disc on it when you did the cam belt? Someone good with a scope might be able to pick up an anomaly with the crank or cam signals, they'd probably need one that logged data though. Frankly you could pay a lot to get this diagnosed, it would be far cheaper to leave it alone until it does something more obvious (like won't start or runs chronically badly). I agree that cleaning the idle control valve is a good idea, so is cleaning the throttle body inside where the throttle flap seats. DO NOT turn any throttle stop screws, nor the throttle position sensor!!!!!!