My wife's 2k with just over 100k finally got a CEL, related to low EGR flow. I had just made the last payment and the 100k extended warranty on emissions equipment had expired, wouldn't you know. The light came on at 100,007 miles.

Anyway, I popped off the throttle body and found the tip of the guide tube to be completely clogged. I tried digging the carbon out, but it was baked in and hard. So, I got out the trusty saber saw with a hacksaw tip and cut off the top inch of the tube. The clog extended about a half inch down from the top, so that fixed it.

Put the TB back on and it has been CEL free since.

 

Got any pictures so we can see?

How difficult was it to get the throtle body off? Can the tube be accessed without removing the throttle body and just replaced?

thanks!

 

Not too difficult. Once you remove the intake filter box and maf, the throttle body is accessible. The hardest part is disconnecting the coolant hoses from the TB. You need some long handled needle nose pliers to get at the hose clips.

To replace the guide tube altogether, you will have to first remove the TB so that you have access to the lower end of the guide tube.

 

What exactly is an EGR? Does this get glogged in every car?

 

EGR stands for exhaust gas recirculation. It is an emissions control strategy whereby inert exhaust gases are recirculated back into the intake under certain operating conditions. The effect is to lower combustion chamber temperatures below the point at which certain NOx compounds are formed. The problem is that the exhaust gases contain a certain amount of unburned hydrocarbons as well as carbon and soot, and will eventually clog up the egr passages that lead back into the intake manifold.

Incidentally, many newer cars (including the VQ35 equipped vehicles) use late exhaust cam timing along with variable intake cam timing to draw exhaust gases back into the combustion chamber without using an external egr system. This is why pieces of precat that might break off for one reason or another can be sucked back into the engine, with the potential of causing considerable damage.

 

Besides the CEL, did the car display any other symptoms that should be watched for?

 

01s do not have egr along with cali spec 00s.

 

From what I've read, symptoms cover many similarities as a partially bad MAF or TPS. Most likely if you are experiencing any "symptoms" of a clogged EGR it would be something along the lines of slightly sluggish acceleration or slight drops/flat spots in the powerband. I also am interested in what else changes along the lines of driveability. A nissan tech just told me that I most likely have a pretty solid carbon build up in my 00 because my ECU keeps adjusting A/F ratios compensating for something of this nature. He also aimed me down the road of replacing the MAF itself but definetly recommended cleaning the EGR. I am learning as much as I can about our underhoods daily and I am still fresh in this department so I am always open to correction. I should be doing a thorough cleaning of my EGR components pretty soon so look for another write-up.

Kevin

 

I have seen 2k1 VQ30DE-K engines with egr. Why would cali spec cars not have emissions control equipment that the rest of the country is required to have?

The only symptoms I could tell when I was driving the car was a very slight sluggishness at certain rpm. My wife, who does 95% of the driving in that car, said that there were times when the car would idle rough.

 

i think '00 cali spec DO have EGR systems.

question: would there be anyway to TRICK the ecu that the EGR is working properly... sorta like o2 sim?

 

Anyone have the Nissan repair manual for the 2001 model year to see if there is an EGR in the car?

 

What triggers the CEL in this case is a temperature reading from the egr temp sensor that is too low, indicating an obstruction. In this situation you could fool the ecu by replacing the temp sensor with a resistor that has the resistance value that the sensor provides at the temperature it is supposed to be seeing.

The problem is that at times when the egr is supposed to be closed, the ecu looks for temperature readings that are low. So if you use a resistor to give a pseudo-hot value, you will still get a CEL because the ecu will think the egr is stuck open.

 

subscribing

 

Only 00 Fed specs have EGR.

 

01-03 do not have EGR
my cali spec '00 has an EGR, not sure about fed spec.

 

So the exhaust fumes are being released into the engine bay instead of being routed for re-combustion?

 

No, I think he just shortened the tubing taking up some of the slack. The EGR system will still circulate the unused fumes back into the intake. At least that was my impression.

 

I don't think so - the EGR guide tube is a sold metal tube - no way to extend it - there's a flange at the end too...

 

EGR is a problem on alot of cars, I see atleast 2 Acuras coming in a day for the problem. We pull the intake manifold off, and drill out the EGR passage which is clogged with a special drill. Then we insert a SSteel sleeve in the passage to keep it from carboning up. One Nissans they use a tube that supplys EGR gas to the intake manifold- right behind the throttle body. This tube cloggs up with carbon and sets off a flow code. I doubt you can trick the ECU into thinking the EGR is working fine.

My 01 has no EGR valve- its a LATE model 01, one of the last few before the 02s came out. Early model 00 Cali specs had EGR, there is a VIN split.

 

No. The top of the guide tube sticks up an inch and a half or more into the intake manifold behind the throttle body. I just lopped off the top inch.

 

Interesting. That tube is different from the 4th Gens then... in my tube, the end of the tube is flush with the flange that bolts onto the rear of the plenum...

In the 5th Gen plenum, does on the EGR port have an immediate 90degree (curved) elbow in the exhaust gas path? It seems to me, that both the narrow tube size and the immediate elbow (at least in the 4th Gens) contribute to the build up. The elbow just serves as a wall/barrier to slow down the flow of fumes and give them something to start building up on. At the same time a wider diameter tube would probably limit the amount of build up too (or take longer to completely clog). I have pics of my tube clogged (before/after, etc.) if anyone is interested - it's off a 4th Gen though.

 

 

It's almost as though that was Nissan's way of addressing the issue... here is a pic of the 4th gen tube:



Picture of the elbow I was referring to on the 4th Gen plenum EGR port:

 

In the several 00VI setups I've sold, the EGR guide tubes have usually been clogged up to some degree. The worst have been pretty much completely clogged. However, the clog has been generally limited to the top inch or so of the tube (that protrudes into the manifold airflow just downstream of the TB). I suspect that this is because the air coming in thru the TB is much colder that the hot exhaust gas trying to come up thru the tube, leading to solidification.
For anyone doing the 00VI modification to their 4th gen (and using the DE-K EGR guide tube), save yourself some down-the-road headaches by cleaning it out while you have it easily accessible.

 

so what could cause an egr high flow? im thinking its the solenoid or a vac line somewhere.

 

Stephen Max, you're the best! Thanks for posting this. I did as you did and cut the top of the EGR tube off, it was completely clogged however, I had to use a hacksaw blade to cut through top 1" of tube and CEL is now off. You saved me alot of money. Thanks again.

 

Holy hell. I thought Stephen Max started posting again, lol.

(2005 thread)

 

I still post occasionally.

 

I don't see how a clogged EGR can affect performane?

 

It doesn't usually affect peak performance, but a faulty egr can cause some driveability problems.

If the egr valve is stuck open, then it will allow exhaust gas into the intake during idling resulting in a rough idle and a bit of a stumble at throttle tip in.

If it is clogged up, then cylinder temperatures will be higher than normal, and pinging (light knocking) can result at partial throttle operation. If the pinging becomes heavy enough, the ecu will pull timing, resulting in a loss of power.