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After failing smog I checked the EGR system and found this......
Dudes,
A bit hard to see but I apparently have a JDM 2JZGE cylinder head installed on my '95 SC300. The EGR port is plugged about two inches into the block. Factory casting, never drilled out.
No exhaust is reaching the EGR valve obviously, which is why I had high NOX numbers per the smog test. Does anyone know if I can simply drill this out with the head still on the engine and in the car or am I screwed?
I don't think you can drill that out. US spec cars have a EGR chamber on the back of the head while JDM motors have a blockoff plate. It would look that your car has this same plate.
The good news is you can replace this chamber. The bad news is you'll either need to pull the head or the whole motor to do it.
Part #7 (and gasket #8). I don't know the exact part number, but now you know what you need to ask for at Lexus.
Actually, try Toyota too. 2JZ-GE Supra. It's probably cheaper from them.
Okay, I verified that because my cylinder head is JDM, I would need the mentioned EGR cover plate (thanks for the information) for the rear of the head. I would also need to drill at least at two points to open up the exhaust passages as well as tap eight holes for the EGR cover plate screws. There is no JDM plate. It's simply a blank area of the cylinder head that hasn't been machined for the U.S./North America EGR system.
It looks like this (not my photo)
It may be easier to simply find and install a U.S. 2jzge cylinder head. It will depend on the price and how difficult it is to drill the two EGR passage ways.
Okay, I verified that because my cylinder head is JDM, I would need the mentioned EGR cover plate (thanks for the information) for the rear of the head. I would also need to drill at least at two points to open up the exhaust passages as well as tap eight holes for the EGR cover plate screws. There is no JDM plate. It's simply a blank area of the cylinder head that hasn't been machined for the U.S./North America EGR system.
It looks like this (not my photo)
It may be easier to simply find and install a U.S. 2jzge cylinder head. It will depend on the price and how difficult it is to drill the two EGR passage ways.
.
Great research. To add, what ECU do you have? If you have NO CEL, I believe you may have a JDM ECU. If you have a USDM ECU, I believe you should have a CEL for EGR malfunction since it's not drilled out and would have failed smog due to a CEL. Depending on the number of O2 sensors, you may need a Federal or California ECU, both of which should pass Cali smog.
The ECU he needs should be determined by the chassis. If the hood label is still there it should say which emissions spec the car originally was. If it's a Federal chassis, there's no reason to get a Cali ECU. If a Cali chassis, then it's a must.
If you don't have it already, this recent list I created may help to source the right box. It's only a partial list so far:
The cylinder head is the main trouble. People have discussed drilling out the EGR passages on JDM 2JZGTE heads but this isn't easy stuff and I haven't heard of anyone actually getting it done successfully. Same applies to a GE head. Unless you're an ace machinist and want to try your luck it would be a far easier to find any USDM 1992-1997 SC300 or GS300 cylinder head in good shape and swap everything onto that which isn't already in place. Your intake manifold, fuel rail, sensors and other bits which might be emissions specific for Cali by year should be swapped over.
It's frustrating to see that the previous owner slapped on a JDM head. If it's a Federal car that originally came from out of state then I can see how this might have been reasonable thinking. But it never would have passed smog normally configured like that.
Even if you were to bolt all the correct EGR gear it would never pass without that system functioning. When you get a smog test done the EGR isn't usually checked unless there is some indication from the dyno numbers that it might be malfunctioning. In this case, it likely would be checked for operation.
I know this isn't what you wanted to hear, freakness. How much time do you have before your next smog test is due?
1995 Federal SC300 5-speed - Began life in Atlanta Georgia, then spent a few years in Texas
Federal ECU
Currently in California, not sure how many years
Cylinder head is JDM, perhaps the entire block is
Car was stolen at some point and pieced back together which explains the Frankenstein details on the car such as '92 wiring harness, early transmission, tons of Pick-n-Pull parts (they like to mark parts in fluorescent pen in case of returns)
Previous owner didn't attach the fuel line to the fuel rail correctly and had a small engine fire and in frustration, sold it (to me). I had to replace a number of hoses, wiring, sensors, etc.
I replaced the JDM intake manifold and brought the car to standard Federal level
After a lot of work, the car currently runs very well; factory idle, vacuum test reveals 21 inHg of mercury, everything works engine-wise except for the JDM cylinder head not having the USDM EGR ports drilled. There are two passage ways as far as I can tell; one is easy, a short angled bore on the left side from the back of the head to the EGR boss. The other side is still a mystery. I'm hoping its a straight bore from the number 6 cylinder exhaust port to the rear of the head. I don't know at the moment. Yes, it may be easier to simply source a used USDM head; the bummer is the current JDM head is in great condition. Since a JDM head is useless in California, it doesn't bother me to drill it out and possibly ruin it. If I purchase a used USDM head I'll want to test it and possibly rebuild it since I don't know its history. This is my project car; I purchased it six months ago and I don't care if it sits another six months. It was just a bummer to get so close to being able to register it then finding out this JDM issue. Oh, well....
Easy way to figure out if it's a JDM ecu: There's no MAF
I suspect you've got a USDM ecu and wiring harness and the jdm block. There's probably a resistor wiring into the wiring harness for the EGR, hence the no codes.
However, I've read that some members don't get EGR codes when they delete their EGR, so that might only be a code on cali-spec OBD1 and all OBD2 cars
I think it's probably easier to source a usdm GE head. Maybe find someone to swap heads with. Someone doing a NAT build would probably want your head more than the typical GE head
I managed to find my solution to the JDM cylinder head issue.
I began by pulling the JDM cylinder head.
It barely fit in the vertical position on my drill stand
For each bore I drilled a pilot hole followed by the final hole. This is the initial marking and pilot hole drilling from the rear of the cylinder head to the number six exhaust port. You can see the passageway is cast; it simply needs to be drilled out.
Pilot hole is complete
Here is my 12mm bit after starting at the rear of the cylinder head and exiting inside the number 6 exhaust port
The rear of the JDM cylinder head with only a slight angled depression giving any clue as to where to drill
A total of ten holes needed to be bored. The large 12mm bore on the left goes to the intake side of the head where the EGR metal pipe bolts on. This is at an angle and I could only do it by hand with a drill so it looks rough but it's, "fully functional." The large 12mm hole on the right is to the number six exhaust port and is approximately three inches long. The smaller eight holes are for the EGR cover plate/gasket and have to be tapped for screws. I drilled to a depth of 12.25mm. Any deeper and you risk penetrating the coolant passageway.
The final product now appears completely USDM OEM.
Stock replacement OEM head gasket, new engine bolts, and the head was re-installed on the block. New coolant, new oil, the engine ran the same as before.
The original smog test fail with high NOx
The retest is a success. The NOx numbers are still high and that probably means one of the catalytic converters is dying. But it's now a street legal car with current registration.
On the journey home from the smog shop the odometer read this...
A lot of fun, not really, and now I can think about the car's suspension which is shot to hell.
11-17-15, 03:44 PM
After failing smog I checked the EGR system and found this......
