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Gav's 200sx RPS13 1JZGTE of race car.

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Thanks guys. Really appreciate the extra eyes on trying to figure this one out.

Just had some time now and the first thing I checked is the sense wire on the alternator plug. Pulled back the covering and the sense wire outer layer has split! The inner core looks ok so may not actually be a problem. This plug and three wires I had kept from the donor jzx100 body loom. One of the only plugs on the engine I didn’t replace with new.

The core of the wire looks ok, I hoped it would be obviously corroded but it isn’t.

Im going to buy a new plug and pins and cut the wire back to some fresh stuff. This plug is brittle like most old Toyota ones are.

It may not be the issue but it needs sorting out anyway.


It is currently getting its sense power from a  shared constant power wire which is original to the Nissan chassis. I’ll try wire it directly to the positive cable from the battery in case there is some resistance giving it incorrect voltage and making it over charge.



It’s worse now that I have removed the pin.



Also fitted a turbo beanie thing:


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On 09/07/2020 at 12:32, ~Slideways~ said:

 Just before that point I was engine braking for a couple of minutes around 30-40kph down hill in slow traffic when I noticed it sounded wrong. So I decided to test if ign off and on would fix it, which it did. This is strange because the ECU would have still been on since it has ECU hold power enabled. 

This will be the bit I was looking at, and scratching my head. Ididn't think about a long downhill, I assumed it was all idle.. 

It might be worth reviewing the fuel cut on over-run to see if its enabled, and maybe switch it off for a test.. 

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Just now, mjrstar said:

This will be the bit I was looking at, and scratching my head. Ididn't think about a long downhill, I assumed it was all idle.. 

It might be worth reviewing the fuel cut on over-run to see if its enabled, and maybe switch it off for a test.. 

Definitely worth checking, although the misfire thing can happen at part throttle like on the motorway sitting at 100kph for a few minutes and its fine then with no change at all, it just happens and goes away by itself.

I'm hoping its going to be something simple like a bad earth or the bad sense wire. Or even if the new alternator is stuffed, at least I'd have an answer.



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Fitted new alternator plug, new pins and moved the sense wire to a better power source (theoretically).

At idle it’s fine. A little more revs and it’s going to 15.3v. 

Balls. It must be the voltage regulator. The alternator will be out of warranty now too. It was meant to be ‘all new parts’.

I still have the old alternator which stopped charging. Maybe the reg in that will be ok.

Otherwise I’ll look into whether I can get a new regulator to fit to this refurbished one.


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Fuuuuuuck, I’ve put in a brand new voltage regulator and I thought it was okay because the log in PC Link showed 13.89v at idle. But give it some revs and it jumps to over 16v.

WTF is going on?

My multimeter reports 14.4v at idle and it’s not showing any higher when I rev it.

Either the Link is some how reporting incorrect voltage readings or my multimeter is wrong.

Is there no voltage problem at all and there is some other problem causing the misfire?






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Good suggestions guys thanks. I had also emailed Link support about the difference in readings between the Link log and a multi-meter and they said it could be due to having a diode in the 12v feed to the ECU, as this feed is also used to return the voltage spikes from the switching of solenoids and relays. (I never would have thought it did anymore than provide power to the ECU) 

So if a ISC or boost control solenoid is switching, and a big one would be the injectors then this back EMF will build up and pump up the ECU voltage. 

I had asked about the diode since I had installed one after not being able to find the source of the power back feeding. It sounds like it's more complicated than simple wiring since he's talking about EMF's. 

Anyway, late last night I removed the diode and now the log shows the same voltage as the mutli-meter plus it seems like it is a steady 14.7v even when rev'd to 4000rpm (directly below sleeping children...). I didn't have time to drive it, so I'll try do that tonight after the kids are in bed.

Bit of a frustrating thing but it looks like I'm getting to the bottom of it.

In saying that, it may not having anything to do with the misfire. It does sound feasible that the ecu is getting confused with incorrect voltage though.

Maybe one day I'll actually be able to 'finish' this one!....


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  • 2 months later...

Still chasing this misfire, currently have injectors out, which were new xSpurt 1000cc's when put in some time over a year ago. 

They were tested and it sounds like one was a little iffy on a low pulse, but was then fine which is frustrating. But it does actually match the intermittentness of the misfire. I'm not sure its enough to explain the behavior I'm seeing, but maybe since it only happens at idle/low throttle cruise which would be a pretty low duty cycle on big injectors, it could fit.

Getting them ultrasonically cleaned, if that doesn't do anything then maybe I'll just have to buy one new injector and hope for the best.

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  • 3 months later...

Can't remember the sequence of things that happened but in a nut shell, multiple dyno visits and some teething issues:

- Had boost control issues due to heat melting a vacuum hose, tried extending the fitting by getting it braised but wasn't enough, then found that Turbosmart now provide fittings in their annoying thread and size that no one else uses or stocks. Used some of those to get it away from the heat. Added a bunch of heat shielding and some of that gold tape stuff.


- Over fueling in higher revs, theory was that the Xspurt 1000cc's have a single narrow spray pattern and the 1jz vvti has quite a wide casting/wall in the centre of the intake port. So the fuel must have been hitting that and just flooding the walls with little atomization. So I went back to 540cc Toyota injectors, from an ST215 with plug adapters to test the theory as these have the exact same 4 hole pintle cap jobby as the original 1jz vvti injectors. Should be enough for 300kw atw on 98, I originally went with aftermarket Xspurt 1000's in order to be able to run ethanol later. But that's much harder now that e85 is gone.

- The night before dyno booking the cam cover gaskets decided to leak like a sieve when I went to fill up on 98. Ordered Toyota genuine  and did that.

Back on the dyno just before xmas and the injectors appear to have helped because now as soon as you give it any more than 10psi the clutch lets go. Looks to be limited to 450Nm, previously it didn't slip at more than 14psi, now it can barely handle 10psi. On the other hand it was probably also getting hotter than before. Drove home perfectly fine but made a plan to upgrade the clutch, which I had not been looking forward to doing. 

Wasn't looking forward to taking the box out, because its in a chassis it was never meant to be so was expecting it to be a right bastard of a job.

Google tells me the R154 is 110kg?! I've done many myself but all probably half the weight. 

So I bought a transmission jack, even my wife said I should after I said how heavy it was. 


Turns out it wasn't too bad of a job to get out. Managed to get the driveshaft out through the two driveshaft loops without removing them and the only thing getting in the way of pulling the gearbox all the way back and off was the starter motor bulge hitting the tunnel.

Next time I'll unbolt the pressure plate from the flywheel to give a bit more room. Left it on because I wanted to see if it was possible for when it goes back in.

The piece of wood is tilting the engine back a bit with the jack.



I've now massaged the tunnel a bit with a hammer to help.


Managed to get the flywheel machined even though everyone is closed. Drews Automotive is closed but the guys a bloody legend, was not working and was going away the next day but still got it machined and tested the old pressure plate and the new upgraded one to compare.


Old PP was 1800lbs

New one is 2600lbs

Clutch plate is a 6 puck sprung centre jobby.


Old clutch plate had plenty of life left in it, just not enough




Fitted Toyota Genuine rear main seal and spigot bearing. Totally forgot I need to replace the flywheel bolts since they are meant to be torque to yield. Have ordered some ARP ones now.

I'm sure I've reused flywheel bolts before but for the little bit extra I thought I'd better change them since I don't know their history.

Aim now is to go for 300kw atw, should be able to get there hopefully, intheory the only thing holding it back was the clutch, which had previously held 260kw atw (for one run on the stock Toyota ecu). Bloody scope creep, this was meant to be running the stock 1jz engine/ecu/turbo....




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