SR20 Wiring Looms

We're spending a large part of our time supporting the NIStune system at present - building and testing boards, further development, customer support and of course dyno tuning. So wiring only gets done as time permits. Unfortunately wiring jobs are very time consuming. If you're desperate drop me a line and I'll see what we can work out but I can't promise anything.

What’s involved?

The looms are NOT "made from scratch". Just sourcing the connectors would be nigh on impossible. Rather, the existing SR loom is disassembled and a series of relays and fuses are added to ensure that all parts of the EFI system are fed power correctly.

*** NEW *** All relays and fuses are now mounted on a bracket inside the cabin. The igniter can also be moved inside the car for some applications. If you're a Datto 1600 owner then you may wish to take advantage of our new mounting tray setup. Details here

Details

1. All relays are configured as per the original vehicle to ensure your SR runs just like it did from the factory.
2. All sub-circuits are fused correctly so that in the event of a failure everything is protected and if necessary an analysis can be made using the factory wiring diagram.
3. All wire joins in the loom are insulated with heatshrink for maximum reliability before the loom is re-assembled.
4. All relevant wires are clearly labelled and any parts that are not required are removed to tidy things up.
5. A diagnostic Port is added to the loom. More details below.
6. Once the loom is complete we assemble the whole EFI system and test it on the bench. We have set up some electronics to simulate CAS and speed signals - as well as all the minor sensors, injectors etc. This ensures that the ECU, Airflow Meter and the loom itself are serviceable.
7. The Airflow Meter sensing element is cleaned.
8. Detailed installation instructions are provided - as well as a sheet of "SR20 startup tips and traps" to help ensure a trouble free first start.

Basic completed loom

What vehicles are catered for?

The most common conversions are the Datto 1600 (510) and Bluebird (910). But most vehicles can be catered for provided you can supply a few basic measurements. We've done looms for Gazelles, 180Bs, Stanzas, Clubmans, Toyota Sprinters and many more.

What’s left for the owner to do?

There are only 4 basic wires to connect:

• +12V from Battery positive (via a fused source)
• "START" signal from the Ignition Switch
• "IGN ON" from the Ignition Switch
• Fuel Pump positive

Wires for Tacho and Temp Gauge will also be labelled so you can use those in your car if you want.

Which SR20's do you support?

We do them all. DE and DET. Prices vary - see down bottom of page. We do not do CA18's - it's not that we don't like them (they're a real gem of an engine), it's just that most of the wiring is getting very old now, which makes it very difficult for us to supply you with a reliable product.

Which SR20 should I buy?

We get asked this all the time. It often comes down to what's available. If you find a good clean engine at a reasonable price then don't worry about what model it is. All the SR20's are good solid engines. Having said that, here are some notes on each of them:

• S13 SR20DE: Can be had very cheaply. 270cc injectors, 9.5:1 compression. Make a terrific base for DE+T jobs. Just add a turbo, ex manifold and injectors from a DET. Std ECU can be tuned for DE+T duties no problem. They come with bigger cams than DET and 9.5:1 compression, so once a turbo is added they make for a very responsive unit, although you need to be sensible with max boost levels. Ideal for budget jobs - particularly in lighter cars.
• S13 SR20DET: Without doubt the most popular for transplants. Largely due to price. Although popularity has kept prices up somewhat and many S13 DET's coming in have quite high km on them, so beware. 370cc injectors, somewhat undersized T25G turbo. These turbos are very responsive but will only give around 11 - 12 psi max at mid/high rpm. Great turbo for DE+T conversions. ECU easily tuneable. In fact they are so popular that we now have a good library of proven tunes for bigger turbos, injectors and AFM's available for people who purchase the NIStune system.
• S14/15 SR20DE: Terrific engines for Clubman type applications. 10:1 compression and VCT makes them a much better choice than the S13 DE if you intend to stay non-turbo. 270cc injectors. We currently cannot tune these ECU's, although the standard tune is actually pretty good compared to S13 DE. Some guys have been using S13 DE ECU's to tune these and this works fine but you need to control VCT separately as S13 ECU's never had VCT control.
• S14 SR20DET: Good engine. Still come with 370cc injectors but got VCT and turbo upgrade to T28 - which means that instead of being restricted (by turbo) to around 150rwkw like the S13, you can go to nearly 200rwkw without changing turbo. Same 8.5:1 compression as S13 DET, so you can pile the boost into them. S14 and S14a are basically the same engine. ECU's are different but both are tuneable. VCT gives them a major advantage over S13. Dyno testing has proven that VCT brings boost on about 500 rpm earlier and keeps the power going about 500 rpm later. VCT mechanisms can be become troublesome once km's increase.
• S15 SR20DET: The best RWD SR20. Basically the same engine as S14 DET but got an injector upgrade to 480cc. So your can tune the ECU for around 200rwkw with plenty of injector headroom. JDM S15's came with ball-bearing turbo. S14a and S15 both had proper factory boost control, so if you run the NIStune system you have the option to control boost with the factory ECU. It's fully mappable against RPM and throttle position. Nice. Came with 6 speed gearbox which can be an issue for some conversions. Also has "dual mass" flywheel which can be troublesome. Speed signal driven from diff instead of gearbox, so beware of this when planning your conversion. Australian delivered S15's came with NATS anti-theft system. See below.

The problem with S15's - NATS

Australian delivered S15's have the Nissan Anti Theft System (NATS) built into the ECU. This needs to be taken into account if you intend to fit an S15 SR20. Japanese delviered (JDM) S15's don't have NATS. If you've got an Aussie delivered S15 then your options are (in order of preference):

• Remap the ECU to JDM by fitting a NIStune daughterboard (we can do this if necessary)
• Source a JDM ECU (re-wiring of some ECU pins required)
• Source the original IGN key and NATS unit and wire into the ECU (never seen this done)

When the Aussie delivered ECU has a NIStune board fitted (with JDM maps) we can do tweaks like tidying up the IGM maps and total removal of the speed limiter. The ECU is then effectively tuneable, so if you wish to upgrade turbo, injectors and/or AFM it's just a matter of having it re-tuned at any tuner who uses the NIStune system. See the Ordering section of the NIStune website.

Tuning

Using the factory ECU no longer means having to keep everything totally standard. Quite the opposite. These ECU's can be tuned to cater for most modifications. Many owners get us to fit a NIStune realtime board to their ECU when the wiring is done. Often with standard maps programmed. Then later when it's time to upgrade, they just need to fit the new shiny bits and re-tune the ECU via the diagnostic port.

There are some examples of what can be done here.

What parts do I need to run an SR20 with the factory EFI system?

Most importers know which parts need to be supplied with an engine package to get it going, but below is a checklist to keep 'em honest (parts shown are for S13 DET):

• EFI wiring loom (uncut!)
• ECU
• Airflow Meter
• Igniter

The following parts should still be mounted on the engine, but sometimes they go missing or get damaged, so it's worth checking when you buy your engine:

• O2 Sensor You should find this mounted in the section of exhaust just after the turbo. They are easily damaged so check that it's OK. There are two types - bigg'uns (18mm thread - usually found on the later "black top" S13 SR's) and small'uns (12mm thread - usually found on earlier "red top" S13 SR's).
• Speed Sensor. These are fitted in the gearbox where you'd normally expect to find the speedo cable. Normally treated as "optional". See more on this below under "Speed Sensor Interface".
• Crank Angle Sensor (Dizzy). Another one that is easily damaged. Check the connector on the loom that plugs into this one too. It is right at the front of the engine making these the most often damaged part.
• All factory engine sensors (TPS, 2x water temp sensors, detonation sensor). It's rare to have problems with these. The detonation sensor is nestled down under the inlet manifold mounted to the side of the engine block so it's well protected. Water temp sensors are a similar story. They are both mounted in the thermostat housing just next to the throttle body. One is for supplying a temp signal to the ECU (the 2 way one) and the other is for the temp gauge (single way).
• Coils and coils sub-loom
• Throttle Position Sensor (TPS). Strangely enough this is to be found on the throttle body! Responsible for really messing up an SR if it is dodgy or adjusted incorrectly. The one thing to watch out for here is that the auto and manual versions are different. See below.

Are there differences between the manual and auto looms?

Yes, but they are of little consequence. The main difference is that the auto looms have a 6 pin connector on the Throttle Position Sensor (TPS), while manuals use a 3 pin connector. You can still run an auto loom and ECU if you have a manual transmission, you just have to make sure that the TPS connector on the engine matches that of the loom ie: if the engine has a 6 pin TPS then you need a loom with a 6 pin connector.

Can I run an Auto ECU with my manual trans?

Yes, but idle speeds may not be quite right. Some (50F11) also run "milder" maps (= less HP) than the manual ECU's so it's recommended that they be re-mapped to a manual. Email me for details - see below.

Manual S13 SR20DET ECU's will have a 50F0X PN (eg: 50F00 or 50F05 are the most common ones). Auto PNs start at 50F10 (eg: 50F10 and 50F11 are the most common ones). Same numbering system for S14/15 ECU's - if the last two digits are less than 10 then it's a manual, if it's 10 or above then it's an auto.

What about the wiring on the right side of the engine?

This is not part of the EFI system and is not part of the service. There's actually very little to do anyway. The usual stuff you'll find on any engine - Starter Motor, Alternator, Oil Pressure Switch and the Neutral Switch on the gearbox. Much of the wiring in this area needs to be done with the engine in the car to get lengths correct, but if you send this loom with the EFI loom we'll pull it to bits, remove all the stuff you don't need and label the stuff that you do - for free.

There's some information HERE to show what you how it works.

Diagnostic Port

We've been working with the diagnostic port on the SR for some time now. But usually it's forgotten about when it comes to engine conversions. Because the connector itself is hidden away over the other side of the car it isn't included in an engine package. And even guys with front-cuts tend to forget about it as the wiring goes through the dash loom.

But it doesn't have to be like this! All you need to do is source a connector from the wreckers (most Nissans have them) and wire it in. Wiring details here. Any diagnostic scan tool can then be plugged in to access a whole range of things including diagnostic codes, sensor data (in real time), active tests and a heap more. If you have access to a laptop then you only need a Consult Interface cable and you are ready to get intimate with your SR!

The diagnostic port connector is now a standard part of all SR20 loom jobs - supplied, fitted and tested.

Speed Sensor Interface

If you want your SR to run JUST like factory then you may want this. The SR turbo engines will usually run fine without a "speed" signal going to the ECU. This signal is used to hold a high idle when coasting to a stop - so they may have a tendency to stall without it. Many guys simply turn the idle up a tad in an effort overcome this.

The SR20DE engines are another thing altogether. Depending on exactly which engine/ECU you have the symptoms may vary - but usually involve a hard cut when the engine is run at full load and high RPM for any length of time. This is usually around 6 seconds (S13) or 10 seconds (S14/15). This problem is very annoying and can be fixed by either wiring in the factory speedo or fitting a Speed Sensor Interface so that the ECU gets the correct signal.

We build these up on a custom made circuit board which is then wrapped in heat-shrink (about the size of a match box). We fit about 300mm of wire to allow connection to your wiring - instructions provided. It's usually best to mount them on the lid of the ECU so that you can easily tap into the necessary wires. If purchased as part of a wiring loom job the unit will be wired up of course. All units tested before dispatch. $AU50

More details here

Options

I tend to be pretty busy so you may have to book in advance - please email me and I'll let you know what the current workload is.

Last modified : Friday, 13-May-2011 16:38:15 PDT