Any Direct Injected 300gt / 250gt V35's?

[scotty nm35]

We had our 2006 Stag with VQ25DD decarbed at 120K by our local Nissan dealer just over a year ago and it came back with an intermittent miss at idle progressing to a nasty stagger on acceleration a month or so later. It was far worse than before we took it in. It went back to them 3x times and nothing they did fixed those problems and they investigated all sorts of stuff including coil packs etc, but they were sure it was nothing they'd done. Eventually, several months later, after losing all faith in them, we took it to a specialist in modern engine problems. It didn't take long for him to find that one of the new spark plugs Nissan had fitted had a cracked insulator, and was tracking, and was obviously caused when installed. By that time, I'd had enough of the petrol bills, and the lack of expertise by the local agents, so it was sold. I'd recommend staying well clear of the 250DD and 300DD if you can. Apparently injector failures in these motors are common and expensive too - around $3K upwards.

You sold a perfectly good car because your Nissan mechanic couldn't change a spark plug. Don't take it out on everyone else that owns a DD, they are a great engine if serviced correctly, and very efficient if you drive them easy.

Injector failures aren't common, there are plenty of high K example DD's running about that haven't failed. Using low grade fuel in them would carbon up the injector nozzle, as it is inside the chamber. I sold a set of S/H injectors to a guy in Malaysia fairly cheap not long ago. I am sure I can get aftermarket injectors from my wholesaler too, if the stock ones can't be cleaned.

Just because Nissan want to ream you on price doesn't mean you should pay their stupid prices. There is no way I will be giving them another cent after the poor service and attitude I have copped for buying an import.

[o2bfit]

I'm planning to clean the intake soon.

From what I've read in this thread, its the EGR that causes the black crud and its recommended to block this off. However to stop the ECU throwing an error code you need to use a 10ohm resister across the temp sensor. Can some please detail the fix and sensor location?

Also a few people have re-routed the breather hose or recommended to use a oil catch can. Can someone detail the re-routing the breather hose option?

Thanks

[Leroy Peterson]

I dont know much on Nissans Direct Injection design, but do you think these systems are similar to what has been put in to the new Pulsar/Clio running MR16DDTs?

[sonicii]

Direct injection really just specifies the location of the injector. Considering EGR and PCV are emission requirements, newer Di engines are probably just as susceptible to the issues we are seeing in the older VQ DD engines.

The advantages we have today is oil manufactures are now making oils suitable for Di engines which result in less 'gunk' in the intake manifold which should at least delay the problem.

[Deep Dish V35]

Blocking the EGR (by unbolting it and making steel blanking plates for each opening) made a big difference. My plenum is still clean 15000km later. Now all the mess comes from the crankcase breather pipe that joins to the front of the plenum. Its blowing oil directly into the front two cylinder ports, which causes a bit of smoke on startup.

Have been running this long with the engine light on. Makes no difference. Im a bit hesitant to solder in a resistor incase i get it wrong and cause a bigger problem

[scotty nm35]

Trouble is, the engine is most probably in some kind of limp mode if the engine lamp is lit.

Not hard to trick the pyro temp sensor, it's just behind the throttle body. No idea what resistance to throw over it, but you could test it out yourself fairly easily on the stove. Just understand, there are fuel savings from exhaust gas recirculation... Up to you if it's worth the mess.

The issue with direct injection messy intakes isn't just the egr and oil breathing, there is also carbon crap thrown back up the runner 4 inches or so when the intake valve opens. Standard top feed injectors would keep this part of the runner clean usually. I spent 20 hours cleaning an Audi RS4 V8's intake manifold runners, which was so bad after 100,000ks the ports had less than 30% of the original flow, and it was throwing tumbler codes. They don't even run egr. I'm not a fan of direct injection for this reason, unless the engine runs both kinds of injectors, like the new BRZ engine.

[o2bfit]

Hello Scott, is this the temp sensor that causes the ECU to throw a code when the EGR is blocked?

I was hoping that some of the people who have done this would be able to provide details on how they resolved it.

[scotty nm35]

I don't know anyone who has actually bothered. Many have blanked it though.

I would be pulling the sensor, heating it on the stove and measuring the resistance curve with a meter. (unless you can find the resistance graph in the Jap DD workshop manual) You would want to drop a resistor over the wires corresponding with around 3-400 degrees at a guess. Failing that, run a wire from the ecu pins to a varistor of the same range, so you can adjust it until you don't throw a code.

I spoke to my injector wholesaler about the DD injectors, they can and do clean and flow test the stock injectors, as they have a special jig for all direct injectors, diesel and petrol.

[Deep Dish V35]

Nicko_2010 did the resistor trick. He also had ford falcon springs in his sedan. Crazy russian.

[o2bfit]

I would have thought that any poor fuel mileage would only be when the car is cold? I take it when the engine is cold, the EGR is open and as the car comes up to temperature, the EGR is closes. Having a cleaner intake should improve my fuel consumption (its not too bad now)

Presumably, the EGR temp sensors resistance is low when cold and is at a certain value when hot. If I can get to the sensor easy enough, I could disconnect the connector and measure the resistance when its cold and when its hot.

[sonicii]

EGR functions under certain conditions at all temperatures, it is not a method of warming up the car quicker. In fact it may not be used at all when the engine is cold (not sure on this)

I believe the temp sensor is an indicator to the ECU that the hot exhaust gasses are actually entering the intake when the EGR valve opens. If the valve is blocked off, the ECU will see no temperature change in the intake when then valve should be open and throw a CEL.

[o2bfit]

I performed the intake clean the other week. It was pretty bad like most of the picks the in thread. After 30k since cleaning the throttle body, the back on the plate had a fine layer of carbon but wasn't too bad.

Most of the time is taken up in the cleaning so best to use the a good cleaner; I found the Nulon throttle body and carby cleaner the best but went through several cans of it. Others have used Oven cleaner but you have to be careful with it as its caustic and will eat the aluminium (so people reckon)

I PM'd a few people on their solutions for blanking the EGR and using a resistor but got no response so decided to use a small hole in the plate to restrict EGR inflow. Not sure on how much of a difference this will make but will keep an eye on things. No error code so far so may try going a smaller hole.

There are a few new intake cleaners coming on to the market that promise to help address cleaning the intake. Revive Engine Cleaner and Terra Clean are a couple of brands that regularly pop up with good reviews but I'm not sure of the availability in Aus/NZ.

[scotty nm35]

I found heavy duty degreaser worked well, and is much less caustic. It is just too expensive to use carb cleaners, you will go through many cans.

Good to hear the car doesn't throw codes with a small hole, what size did you drill? It may take a while for the codes to show, let us know if it pops up after a while.

I can probably find out the resistance required if I get a chance, I know a few people trying to ditch egr completely.

[o2bfit]

Currently using an 8mm hole. Its been 3 weeks since I did it. I will try a 6mm hole next time.

I tried a CRC degreaser and it was hopeless. Only good enough to clean up the oil rather than the black gum.

It would be good if we can get some accurate details to how to block off the EGR completely without throwing a code.

[spector171]

Hey everybody am new to the skylines. Question I have a 2003 Nissan skyline v35 250gt. Were is the fuel injectors located on this car after your remove the upper an lower intake manifold upon cleaning the carbon buildup

[scotty nm35]

They run direct injectors, they are down in the V under the lower plenum.

What do you want to do with them?

[spector171]

Are they fuel injectors like the Infiniti g35

[Jazzadub]

This is in reply to the original post in 2009.

I don't have a view on the GDI systems, but I disagree that the purpose of EGR and PCV systems are to re-burn unburnt fuel.

The purpose of an EGR system is to effectively reduce the displacement of the engine under certain operating conditions.

It does this by replacing some of the gas with gas that doesn't have oxygen in it (ie exhaust gas).

An analogy would be running your car at the top of Mount Everest - less oxygen, less fuel, less power, but better economy when cruising.

Thus EGR system is for economy, but not primarily by reburning unburnt fuel.

My understanding, of PCV valves, which might be wrong, is that the vacuum in the intake manifold helps draw out the small amounts of blow by that occur in an N/A engine. (Doesn't work with boost pressure). This would help prevent water and fuel vapour contaminating the oil.

By putting a catch can in place is a good fix if it is correctly hooked up. It also stops these vapours venting out to atmosphere.

Therefore, PCV (valve cover breather) systems are for engine longevity, and reducing blow by "emissions". I can't see how it is a method of increasing fuel economy.

Just my 2c on those points!

[scotty nm35]

They are fuel injectors, but nothing like the G35. Your ones spray directly into the cylinder.

Why?

[spector171]

Or ok. Am question my skyline is running rich an the only code am getting is the p0100 is this the reason my I have a engine running rich cuz I dis suspect fuel injectors