SR20 Setup Tips

On this page

• 1. IGN timing adjustment
• 2. Throttle Position Sensor
• 3. Fuel Pressure Regulator
• 4. Idle Adjustment
• 5. Vacuum Lines
• 6. Fitting a Consult Port
• 7. Z32 Airflow Meter fitment
• 8. Fuel Pumps 101
• 9. Cleaning your Airflow Meter
• 10. Changing Injectors

Sounds simple but it's amazing how many people mess this up. Firstly there are two different ways to place the pickup. Nissan have provided a loop in the wiring loom that drives coil No. 1. You'll find it hanging out of the loom right at the back of the head - near the firewall. Try this one first - just hook the sensor of your timing light through the loop. I've got an old crusty timing light and this loop works fine with it. Other people have had trouble using the loop and prefer to sense directly off of No. 1 plug by making a plug lead extension.

Nissan say to disconnect the TPS to lock the timing but I've not had a lot of success using this method. The other way is to hold the throttle open very slightly to increase revs a bit. So timing light in one hand, throttle in the other. You'll see the timing mark jumping around at idle and then when you increase revs to 1100 or so it will suddenly stabilise. This should be 15 degrees and this is when you take your reading. Don't rev it too much or you'll see timing start to increase.

But the only really reliable way is to monitor the timing directly from the ECU via the Consult Port. You'll need a Consult Cable, a laptop and some monitoring software. I use Datascan software of course, but there are others around. Then you just watch the reported timing value live on the screen and adjust your Crank Angle Sensor until what you're seeing on the crank pulley (with your timing light) matches what's on the screen.

Once you get a reliable reading, set it to 15 degrees. This is a critical adjustment - particularly if your engine has been tuned for more boost etc. Less than 15 degrees will make it very sluggish. More gives extra power but may lead to detonation and engine failure. Note also that the timing marks start at -5 degrees so 15 is the 5th mark from the left. It pays to mark it with some white-out or brightly coloured paint. Base timing on most SR's is 15 degrees - a notable exception is the RNN14 which uses 20 degrees.

2. Throttle Position Sensor

As the name suggests this lets the ECU know how far open the throttle is. Although this is not the primary load sensing device (as it can be with some aftermarket ECUs) it can upset things pretty badly if it's faulty or not adjusted correctly. It consists of a potentiometer (just like a volume knob) that rotates as the throttle is opened and closed. It has 3 pins. The ECU feeds 5V to one, 0V to the other and a voltage somewhere in between is picked off and sent back to the ECU.

Adjustment : This can either be done manually with a multimeter or by plugging into the Consult Port with a laptop and reading it straight off the screen. If using a multimeter it must be done with IGN ON (engine does not need to be running) and the connector fitted to the TPS. You'll need nice sharp multimeter probes to pierce the insulation on the wires - it often pays to give them a quick sharpen with a file/grinder etc. Carefully probe the 0V wire (Black) and the signal wire (White). Don't use chassis GND. With throttle closed you should be seeing 0.5V. The spec is 0.35V to 0.65V but it's nice to have it right in the middle. Adjustment is done by loosening the 2 screws that mount the TPS - NOT by using the throttle stop screw.

Another handy thing to check is that the ECU is actually seeing "TPS Closed". It monitors the TPS position and when it's in a certain range (normally 0.35 to 0.65V) it assumes the throttle is closed. This triggers a flag in the ECU which makes it go into idle mode. You can monitor this via the Consult port using Datascan. If your throttle is closed but the ECU doesn't see it then idle will be all over the place. I've actually seen an SR that wouldn't idle with TPS at 0.5V. It had to be adjusted down to 0.4V before the "TPS Closed" light would come on in Datascan. As soon as this light came on the engine idled perfectly.

Checking : While you're playing with the TPS it's a good idea to check it across the range. Slowly open the throttle - you should see the voltage increase smoothly to just over 4V. If you see any sudden changes (to 0V or 5V) then I'm afraid she's knackered and it's off to Mr. Nissan with you. The Consult Port is extra handy for doing this check as you can log the TPS value while you drive the car - and then check the trace for any drop-outs later.

Autos : These use a different TPS. It has 6 wires. Half of it still functions the same as the manual 3 pin TPS so all of the above still applies (but wire colours are different - you'll need to measure between the Black and White wire). The other half of it goes to the auto trans to aid in determining shift points. For some reason the TPS in auto vehicles is notoriously unreliable. When the auto trans half of it goes faulty the auto will have trouble shifting. Unfortunately the main TPS part also goes dodgy very quickly. They seem to suffer from moisture ingress. Once this happens it's all over.

3. Fuel Pressure Regulator

Not much to this one - but it's quite important. What you need to know is that the FPR regulates the fuel pressure based on manifold pressure. So it relies on having a "sense line" so it can see manifold pressure. This is just a short length of hose. So far so good. So as boost rises, so does fuel pressure. If you think about this, it has to - because the injectors are firing their fuel into the manifold. The system is set up so that the injectors deliver their fuel at 3 bar (43.5psi). But if they are firing fuel into a manifold that has been pressurised to (say) 10psi by Mr Garrett then they are facing an uphill battle. So what happens is that with 0 psi boost the fuel pressure is 43.5 psi. For each psi of boost, the fuel pressure increases by 1 psi - keeping the pressure difference across the injectors constant. So at 10 psi boost the fuel pressure should be 53.5 psi

Where this all goes astray is if something happens to that little 4" piece of hose. This is why it is recommended to take the source for your boost gauge/EBC from somewhere else. If you tee into the hose going to the FPR and a leak develops somewhere in your boost gauge/EBC then the FPR won't get the correct boost signal. Then fuel pressure will be low and your SR will lean out. Then bad things happen - combustion temps increase, detonation starts and the next thing you know you've got bits of SR all over the shed and you're pricing engine components.

4. Idle Adjustment

If you've just installed an SR and the idle speed isn't right then you may be tempted to go for the idle adjustment. Before you do consider this : unless the engine is a real clunker then there's a pretty good chance that the idle was spot on before it was removed. So the idle problem is more than likely due to a fault with the installation. By trying to adjust the idle you will just cover up the symptoms.

Adjustment is not as obvious as it might seem. If you're used to old school carby engines then you'll probably get it wrong. See the throttle stop screw on the throttle body? Don't touch it. The idle is controlled by the IACV (Idle Air Control Valve). This valve simply bleeds air around the throttle body. It's mounted on the inlet manifold and (on S13) you will find an adjustment when you peer down between the runners of the manifold. Idle speed should be 800rpm. Check out the section on TPS adjustment too - this can dramatically affect idle.

5. Vacuum Lines

Details vary between models but the basic concepts are the same.

1. One line from boost source to wastegate actuator as mentioned above. Keep it pre-throttle body as the WG actuator doesn’t really wanna see vacuum.

2. One line from inlet manifold to Fuel Pressure Regulator. This one is very important. Don’t tee anything else off of here. I even put clamps on each end. If it comes off your engine will lean out under boost and you’ll kill it. (see FPR)

3. One line from inlet manifold to BOV. Either of the fittings under the TB will do.

4. One big (15mm?) line from pre-TB to Idle Air Control Valve. This may or may not already be hooked up. You basically just need an air source that has been through the airflow meter into the IACV. On these engines the TB is totally closed at idle. All idle air gets to the engine via the IACV. So if you need to adjust idle (you shouldn’t have to) then do it on the IACV – not the TB. Usually there’s a fitting in the factory plumbing that hooks this line in just before the TB.

5. Some of the hoses you'll see will be for the factory charcoal canister. On the S14 I think the canister is over the LHS and so you have a bunch of lines that run across the top of the rad from the RHS of the engine. Only required if your conversion needs to pass emissions regs.

6. Consult Port

Usually when you buy an SR wiring loom it will be missing the Consult Port. This is because the Consult Port is part of the body loom - the plug will normally be around the fusebox inside the car. You really need this part if you are serious about having your SR run right. Without it you are really in the dark.

They are not hard to fit either. The easiest way is to grab one from a wreck. Most Nissans from around 1990 to 2000 had them. Snip the plug out with about 200mm of wire if possible. Then it's just a matter of wiring it into your loom. You need 5 wires - 12V, GND, CLK, Receive and Transmit. For S13/S14 the Consult wires can be found on the main ECU connector near the bolt in the middle. They will run from here to a small white plug about 200mm away. This plug normally plugs into the body loom and contains signals that go from the ECU to the instruments.

OK, snip the wires near the white plug. You need the Green (Transmit), Green/white (CLK) and Green/black (Receive) wires. On the S13 there's also a black GND wire already on the white plug in the picture so snip it too. Now you just need a power wire. You can get this anywhere but the easiest place is to just splice into the ECU power. There are two of these (in the pic they are up towards the right side of the blue plug. Second from the end) and the wire colours are Black/white. Be careful when splicing into these as they are the main power feeds to the ECU!

Now it's just a matter of getting the signals in the right place. If you've snipped a plug from a wreck then you may have different coloured wires. Don't worry too much about that. As long as you get the wires from the ECU in the right place on the Consult Connector.

Now you can plug in and see exactly what's going on in your SR. For more info on that have a look here.

7. Z32 Airflow Meter fitment

It's actually very easy to change your AFM connector to Z32. I recently discovered that the pins in the connector for S13/early S14 are the same as Z32. S14a/S15 use different pins, so you'll need to snip off the old plug and either crimp new Z32 pins on - or get a Z32 connector with a length of wire on it and join the wires. For S13/early S14 all you need to do is :

• remove all the pins from the Z32 connector and slip the rubber boot off
• same for the SR connector
• slip the rubber boot from the Z32 connector onto the SR wires
• click the 3 pins on the SR loom into the right positions in the Z32 connector backshell
• re-fit the rubber boot to the connector backshell

Result : perfect job that looks like factory. Not tape, no soldering. 5 minute job.

Downside : the pins can be a bugger to remove if you don't know what you're doing. Use a small jeweller's screwdriver to depress the little locking tangs - and be patient. If you pull too hard on the wires without pushing the little tang in from the other side you will wreck the backshell and the pin. Double check that you have the wires in the right place. Get 'em wrong and you'll fry your ECU.

Pinouts:

S13
B = 12V (blk/white)
C = GND (blk)
D = Signal (white)

Z32
B = Signal
C = GND
E = 12V

Tip for young players : Z32 AFM's can be finicky buggers. The plumbing between the AFM and the turbo inlet can be critical. Keep the AFM as far as possible from the turbo. And keep the plumbing nice and smooth - no sudden changes of diameter or sharp bends etc. Use an air filter with a bellmouth entry if possible. If using a recirculating BOV then have it enter the pipe closer to the turbo and aim it away from the AFM. If the AFM is too close to the turbo and/or the plumbing is sloppy you may experience very poor running at idle and low load. This is not some internet rubbish trawled up from a forum - it does happen!

A useful chart of Nissan AFM's here.

*** THIS AREA UNDER CONSTRUCTION ***

8. Fuel Pumps 101

Why your fuel pump is critical: It's easy to think that if your fuel pump is faulty then the engine will just run out of fuel and stop. If you're lucky then this is what will happen. If you're not then your fuel pump will just get "lazy". This can be real problem for your SR. If this happens then the pump will still operate but fuel pressure will be low - resulting in lean mixtures (usually at full load). In the case of a non-turbo engine power will be down and if the engine is used continuously at full load it may suffer damage due to detonation and/or valve damage from high combustion temperatures. Often you'll get away with it. Turbo engines are a different story. Mixtures are much more critical with turbos so if they lean out while driven hard then engine damage will happen very quickly.

Often the pump will start making more noise than usual. Power will feel a little down - the whole power delivery just becomes "soft". As if the engine isn't really trying. If you can get hold of a WB AFR meter then check the mixtures. Under load a standard SR will run very rich - often richer than 10:1. This is normal. Tuned engines usually run around 12:1. Anything leaner than 12.5:1 should be considered dangerous unless the engine has been specifically tuned for lean mixtures.

The other obvious thing to do is to check your fuel pressure. This is as simple as tee-ing a gauge into the fuel line where it enters the fuel rail.

Make sure you get the line that is supplying the fuel rather than the return line to the tank. Here's what you should see:

Idle = 36psi (this can vary a bit as vacuum at idle sometimes varies)
Atmospheric = 43psi (+/- 1psi)
10psi boost = 53psi

To do the "Atmospheric" measurement you just pull the sense hose off of the Fuel Pressure Regulator (FPR). Pressure with boost applied is calculated by starting at 43psi for 0psi (=atmospheric) and then pressure should rise by 1psi for each psi of boost. So 15psi boost should see 43 + 15 = 58psi fuel pressure. This will either need to be done on a dyno or else you can temprarily secure a pressure gauge to the car (keep it OUTSIDE the cabin!) and have the passenger watch it as you drive.

Often a lazy fuel pump will be capable of supplying the correct pressure at idle and even atmospheric. It's only once boost is applied and the pump is asked to supply higher pressures that they will be found wanting.

9. Airflow Meter Cleaning

Dirty airflow meters are becoming quite common now that most SR's have quite a few k's on them. They become dirty due to normal airborne crud and from oil mist that naturally occurs in the inlet tract. Oiled foam air filters will dirty them quicker than anything else. But nobody uses them anymore (ahem...).

Symptoms can be hard to fathom as sometimes they will cause the engine to run lean, other times rich. I've seen both. Fortunately the sensing elements in SR AFM's are easily removeable and quite easy to clean. R32/Z32's can be cleaned but not quite as easily because the sensing elements are not a bolt-in job. Most contamination can be removed using a fine brush (as used for painting models etc.) and solvent such as acetone or contact cleaner.

	Remove clip		Remove connector		Unscrew element		Remove element

Clean element using a fine brush and solvent. Acetone is good. Or almost any contact cleaner will do. Be careful not to damage the sensing elements.

Inspect the two elements under a really good light. An eyeglass helps here (about $5 from Jaycar - the one used in the photo is actually a lens from an old scanner!). They should look like a shiny glass bead with a fine wire wrapped around it. There's often black crud evident.

Crud = bad.

Put it all back together, congratulate yourself on a job well done and shout yourself a beverage for being smart enough to clean your AFM. Instead of declaring it broken and throwing it in the bin like workshops all over the world do.

10. Changing Injectors

Removal: SR20 injectors can actually be quite difficult to remove if you don't know the technique. Which can result in damage to the injectors, damage to fingers and general bad language. To avoid these nasties try the following technique:

Bleed fuel pressure from the system by removing the fuel pump fuse, relay or wiring to fuel pump with the engine running. It should take a couple seconds before pressure goes to zero and the engine dies.

Remove screws and retaining cap.

Replace screws - screw them in until they just bottom on the fuel rail and then back them off a turn.

Using 2 small screwdrivers and the screws as jacking posts, lever the injector out. You may need to back the screws out and use the screwdrivers several times before they pop out.

Replacement: Make sure the O rings are in good condition before replacing the injectors. It's usually recommended that they are replaced. The top O rings are usually fine. The bottom ones sometimes need to be replaced. Take a close look at them - if they haven't bounced back to a nice round section or have cracks/nicks/perishing then don't even bother trying to re-use them as they will leak.

Once you have a set of good O rings then you need to go mad with the lube. You can buy lube specially for this job but if you don't have it then use either Vaseline or engine oil. Lube up the areas on the fuel rail where the O rings seat, as well as the O rings themselves.

Then press the injectors into place. It takes a fair amount of force to get them in. Rotate them back and forth as you push. All this lubrication and rotating is an attempt to avoid damaging the lower O rings. This happens quite easily.

Testing: Once you've got them all in place, fit the caps and it's time for testing. Firstly, turn the IGN on and let the fuel pump prime the system. Then check carefully for external leaks. This part is usually OK. The problem is if the bottom O rings haven't sealed properly. Unfortunately this is quite common. You can usually tell by the way the engine idles. If it starts up and settles into a smooth idle then things are fine. If the idle is uneven (power is down on one or more cylinders) then there is a problem. Sometimes idle will only be slightly affected and the car will drive fine otherwise. Sometimes they will barely idle.

Diagnosis: The next thing to work out is which O ring is damaged. This isn't usually too hard to work out. Remove the injector plugs one by one as the engine is idling. You should get a definite change in idle. The one that gives minimum change is the one that's leaking. It gets a bit harder if there's more than one. Another (preferable) technique is to use the "Power Balance Test" in Datascan. This allows you to knock out one cylinder at a time from a laptop connected to the Consult Diagnostic Port.

Stuff you don't even wanna think about: Another problem associated with leaky bottom O rings is fuel leaking into the cylinder after engine shutdown. EFI systems maintain high fuel pressures after the engine is shut down (as you will know if you've ever removed a fuel hose/injector without fist bleeding the system pressure). If a bottom O ring is leaking then the potential exists for fuel to dribble into the cylinder over time (usually overnight). In the morning the engine will start on 3 cylinders and it will take awhile before the affected cylinder clears. Worst case the cylinder will have enough fuel in it to hydraulic lock. So when it is cranked it simply locks solid. This CAN cause serious engine damage - I've seen bent conrods. This is rare but can happen.

Random general interest article on oils. Not many people properly understand the oil they use in their engines. Not good. This is a particularly well written article because it's written at a level that anyone can understand rather than going into full-on technobabble. Enjoy.

Article here

Last modified : Friday, 08-May-2009 03:32:52 EDT