KahnBB6

iTrader: (5)

Well guys I made a little progress today but still no cigar.

With the new fan clutch in the car idles VERY smoothly now. The power loss issue I noticed as a result of it locking up is gone and the engine drives silk smooth again. That's part of what makes this so frustrating: the car is in terrific tune and it feels like it's operating just fine now that all the non-emissions related fixes have been done! It's acting near perfect again.

...

The original EGR valve was replaced by my shop with the Standard Motor Products / Intermotor part (EGV 867) I'd bought weeks ago. I actually thought I'd heard some odd hissing noises at cold startup but I could not be sure. Ali, I didn't feel any leaks back there when the engine was warming up.

Anyway, even if the original one is still good (I kept it of course), now the car has a brand new one. And the night before I replaced the good working used EGR VSV with the brand new one I'd bought.

The first thing I did was get onto the highway and take a very long drive. I had planned to rack up 100 miles to ensure that this fix actually solved the EGR code issue.

Nope. Now it came on at a mere 49 miles on the trip odometer from the ECU reset. I confirmed it was a Code 71 when I got home.

...

Today I called Carson Toyota and asked about the Y-shaped manifold part (17860-46070). There were a few on order for customers and one was available locally so I bought it and I'll pick it up tomorrow or Friday. Carson did not say they were discontinued btw.

I will be installing that once I have it in my possession. A brand new, never used Intake-Y manifold.

Gerry, I still believe the manifold you sent me is good since mine had no flow and yours does but I am pulling out all the stops and trying everything at this point.

...

Now the two other things I have thought of is replacing the steel vacuum line assembly that bolts underneath the Y-Intake. It popped into my head on the way home tonight that it *might* be possible that it has become clogged... since my original EGR vacuum modulator got clogged up with carbon and may have contaminated it.

I never checked those steel lines for clogging. I'm not sure it would be an easy job to clean them out. I'm going to see if that is available too.

...

Lastly, I am strongly considering sending the ebay 1992 SC300 M/T Cali-Spec ECU I snagged a couple of months ago into Tanin Auto for them to recondition and then, as a last resort, try that in the car assuming its in good shape when they're finished with it. The Toyota Reman ECU I have covers the ECU P/N's for 1992, 1993 and 1994 Cali-Spec M/T models so it should work.

I'm skeptical of the Toyota Reman ECU actually being the issue but I'm not ruling it out at this point.

...

Other than those last couple of things I have NO IDEA what else I can replace to make the damned light go away other than building an entire engine from scratch in the same manner I've pieced together the pile of 2JZ-GTE parts.

.....

Gerry, sadly I am in agreement with you about registering in Florida if none of this works out or if I can't get an exemption by proving with numerous receipts just how much money I've spend attempting to correct the stupid emissions light.

But that would completely change the use of the car and it would just sit outside for months in the salty air and begin to rust. Not to mention I'd be out of a car in Los Angeles which... doesn't really work in Los Angeles.

KahnBB6

iTrader: (5)

I put in a work order with Tanin for the 1992 M/T Cali ECU and will send that out tomorrow. It can't hurt to try later as a last resort and it will be a good spare compatible ECU at the very least.

Awaiting the new "Y" manifold from Carson Toyota.

I found one vacuum line going into the throttle body area on the "Y" manifold seemed to have hardened so much it may... may... not have been completely sealing. Replaced that hose.

I also tested the metal vacuum tubes going from the EGR VSV to the EGR Vacuum modulator to see if, in fact, they might have become clogged. When I used my vacuum hand pump on one end and used my finger to tightly cover the correct tube(s) on the other end I got them to hold pressure... and release pressure once I let go with my finger. I'm not convinced I need to try ordering one of those assemblies too.

I am going to buy more of the correct inner diameter vacuum line in a spool and identify the little vacuum check valve(s) underneath the "Y" manifold. When I put the new one on I will replace any of those little vacuum connections that seem appropriate.

Ali SC3

iTrader: (10)

I think checking the ecu is a good idea. off the shelf toyota reman's do not have the best track record I am not sure they actually test them fully and you know at some point it was not working and then repaired... and who knows where they do that reman job. still it just affecting the egr seems odd to me, normally would be other symptoms but your issue is eluding everyone so far.

as for the metal lines, just test them as you said, maybe if you have a compressor blow them clean, havent had one clog up yet over here. make sure the check valves are facing the right way... but I want to say the check valve is on the vacuum lines that are related to the charcoal canistor purge system (so you cannot pressurize the charcoal canister under boost), not the egr but its been a while. its funny the canister itself has a checkvalve built in, but the vacuum lines for it also have a check valve I guess its like a double safety thing.

did you do anything with your exhaust recently? what did your last emission numbers look like?
I only say this because lets assume nothing is wrong with the actual egr on the engine, but its triggering from the exhaust temp out of range on the egr probe in the exhaust passage.
This could also be due to changes in the exhaust like say a clogged cat, more or less backpressure or maybe a leak at the exhaust manfiold or exhaust flange. I would give the exhaust side a quick lookover because I can tell you that even though you are not turbo, exhaust issues can trigger the egr as well cause it changes the temp of the exhaust gasses.

Like when I went na-t for the first year I was on the stock ecu with a piggyback, I could never get the egr code to go away even though the egr was hooked up like stock, and my car never through an egr code for the whole year before that I drove it n/a. it would always be tripping the egr due to the change in temps. so if you go through everything on the egr and intake side, my advice is take a little time and check over the whole exhaust side next.

I don't think the passages in the head are blocked, or the new Y will solve anything because you said when you put vacuum on it the engine stumbled, which tells me its all working.
But it can be working and exhaust temp out of range will trigger it if that makes any sense.

KahnBB6

iTrader: (5)

I agree with you. I was skeptical of my mechanic suggesting it at first but now I'm beginning to wonder about the health of the Toyota Reman ECU in the car. We have no way of knowing if Toyota has ever been as in-depth as Tanin with ECU repairs. From what you say, they may not be.

I just sent the 1992 M/T Cali ECU out today with adequate insurance. We'll see what Tanin says about it next week. I went ahead with that now because it will take time to actually get it back in my hands and as soon as I have it and can confirm it works I might send the Toyota Reman ECU out almost immediately to make sure I have both computers reconditioned before my deadline.

Annoying because I still need to send the USDM 2JZ-GTE 6-speed ECU out for reconditioning also and now it's just going to sit and wait even longer before IT is inspected.

I am NOT certain of this but I have recently had some half-baked suspicion that there is just a smidgen of cold startup issue still there. It absolutely had gone away earlier after installing the new TPS sensor.

I'm not sure at all but I've noticed it still hasn't been 100% perfect in the last couple of days. Today for instance it may have been ignition timing pull due to the heat or it may be the spark plugs being prematurely worn again (which I will be replacing with the new Y-Intake anyway) but there was some lack of power abve 4,000 RPM this afternoon. *Not* hesitation but just a lack of 4800-6000 push. And yet the engine has been revving beautifully since the TPS sensor change and especially since I've replaced the fan clutch. Driving on the highway yesterday also seemed fine to me other than the 2JZ-GE's natural lack of horsepower and torque at higher elevation.

Good info there, thank you! Based on my initial test at the EGR VSV and intake vac-line connection that goes back to the EGR Vacuum modulator connection I'm not as concerned about that right now.

The only thing touched on the exhaust recently was that the #2 cat and rear mufflers were temporarily removed by my mechanic when I had the car in to get a new clutch installed last month.

I had planned to get some new OEM exhaust pipe gaskets all around but I haven't done that just yet with all of this other recently.

Wow. Okay, I'm going to have to bring that one to my mechanic to double check. It's beyond what I am able to do in a small shared apartment garage... other than trying to feel for any gas leaks while the car is starting from cold.

I don't think it is either but I have to try everything I can at this point. This EGR code issue is well beyond the point of being ridiculous.

So I guess I will order the exhaust pipe gaskets anyway and perhaps have those installed. Then I'll install the new Y-Intake and once I have the '92 ECU back I'll try that in the car and see if the car acts any differently.

And we'll see if a 1992 ECU actually is the same as a 1993 and 1994 ECU after all. I never actually tested it in my car because I figured it is so old at this point it's better to have Tanin work on it before even plugging it into my SC. Since Toyota specified that my Reman ECU covers the Cali-Spec M/T computers for 1992-1994 I'm assuming it has exactly the same programming and emissions function.

Airbag function is not tied to the engine ECU in our cars, correct? Since 1992's have no passenger airbag and 1993+ models do.

I still have the incorrect 1995 M/T Cali ECU I can plug in and drive with as as well to see if there is any difference (it worked just fine other than the permanent CEL due to being too new for the car)... but that has also never had its capacitors serviced.

t2d2

iTrader: (8)

The airbag system has its own computer below the stereo. I can't imagine there are any secondary functions shared with the main ECU.

KahnBB6

iTrader: (5)

Okay, good. That's what I thought. I knew about the separate Airbag ECU but I was not sure if its signals tied into the engine ECU in any direct way.

I think I'll be fine since it does appear both 1992 and 1993-94 and 92-94 Reman are all the same ECU.

KahnBB6

iTrader: (5)

I am definitely becoming suspicious of the ECU again. I was considering splitting up the EGR-related pages of this thread from this one to create a new thread (I'd call it "The SC300 EGR Code 71 From Hell") but if the ECU is in question again it feels like it's come full circle.

So much has been replaced and it has been running fine but in the last couple of days I have felt as if startup once again isn't perfectly smooth (although this is very, very minor compared to what I've described a few pages back), and I swear there is occasionally some rich exhaust smell during some (but not all) startups.

There also hasn't been perfect acceleration feel above 4000rpm in the last day. As mentioned before, the highway drive felt fine when the ECU was still fresh from a reset but now it's not precisely the same. Hard to describe because this is all very, very minor and I'm questioning if I am looking for these symptoms or if I am actually noticing real quirks. I feel it's the latter but I have no second opinion.

Yet: the engine is much smoother and more rev-happy than it has been in months. It's just that upper end of the powerband that isn't stumbling or anything but occasionally feels... anemic. Then other times I get fairly normal power upon full throttle acceleration.

The spare ECU should get to Tanin over the weekend. New intake should be in and ready for pickup tomorrow. In the meantime I'm seriously thinking of swapping in the '95 ECU to see what happens.

I'm beat tonight though.

KahnBB6

iTrader: (5)

It has been suggested to me today that I should consider replacing my O2 sensors again since they may have been compromised during all of this troubleshooting.

On top of that, apparently my using an OBD1 1995 ECU that requires heated O2 sensors on a pre-1995 car that has no heated O2 sensors may have caused the O2 sensors to have been wrecked a bit since the 1995 ECU may have caused the car to run overly rich to compensate for the heated O2 signals it was not getting.

So... I've ordered a new set of Denso O2's to install on top of the rest.

I won't be trying the 1995 as a temporary ECU any longer.

t2d2

iTrader: (8)

^ Er, I've been running a '95 ECU on my '94 for several months now and haven't noticed any such issues, including mpg changes.

KahnBB6

iTrader: (5)

Well then....

*Throws up hands* (and not at you, t2d2)

However, in my case it may be a Cali-Spec ECU quirk. Aren't your car and ECU Federal type?

t2d2

iTrader: (8)

Thanks for clarifying. At this point, I'd be understanding if you were throwing punches.

Correct. Your guess is as good as mine whether that makes a difference.

KahnBB6

iTrader: (5)

^^ No, that was definitely not directed at you. Just my general frustration in trying to nail this down.

I am inclined to believe the Cali 1995 ECU does make more of a difference. At the very least it might explain why my previous plug/cap/rotor/wire job may have only lasted a few thousand miles before I had issues with the fairly new rotor (and possibly the new plugs which I will inspect soon): the '95 ECU may have been giving more spark, changing timing(?) and especially dumping more fuel than normal to compensate for what it assumed was a lack of correct temperature range in the O2 sensors.

Since 1992-1994's never had heated O2 (Lambda) sensors even in Cali-Spec models.

I used the 1995 ECU on two main occasions during this whole saga:

-- Once to test another ECU in the care *before* I sent my original ECU in for capacitor service (before it was lost/stolen in transit). I drove on that '95 ECU from late September (I think) until very early January when I installed the correct type Lexus Reman ECU.

-- I think I tried it one more time after that and went back to the Lexus Reman ECU permanently.

If I'm wrong, I'll have to check the previous pages of this thread.

What I hope is that I haven't hurt my cats as a result of using the 1995 ECU which may have run the car too rich.

I have no rotten egg smell from the exhaust so I think I am fine on that front.

Frustrating to learn of this possibility only yesterday.

.....

--The 1992 ECU arrives at Tanin later today.

--Y-Intake delivery delayed until Tuesday while another in national inventory was sourced from a Florida dealer.

--New Denso O2's ordered.

--New cat #1 and cat #2 exhaust system gaskets ordered just in case. Those were mentioned as being old when I had the clutch done recently.

--New Spark plugs, distributor cap and rotor on standby for when I take the manifold off again.

--It's also been suggested by my mechanic to order a new OEM fuel pressure regulator. Not sure if that's really necessary or not unless it has to do with the funny startup issue that's come back.

--It has been recommended that I check the continuity of the harness connection that goes to the EGR temperature sensor and the continuity between those pins and the ECU. I'll have to look up how to do that.

gerrb

iTrader: (34)

huh ?

Craig - there is a difference between the ECU of 1995-1996 group and the 1992-1994 and consequently their wiring harness. I don't think using a 1995 ECU into a 1994 car would get your car to run as expected (optimally) especially in California who are so strict on emissions . Exactly the reason why I believe they were sub grouped into 92-94 95-96 97 and above so changes in their physical looks and other functionalities like wiring , ECUs , etc can be better classified to which group / version they belong.

Just by looking at their wiring diagrams, you can tell there are differences on their engine wiring harness and ECUs. One example .... on the 95 ECUs.... the pin OX3 is on Pin 30 and pin HT3 is Pin 36 of the ECU where as on the 94 ECU , that pin which is OX3 will be on Pin 61 and the HT3 will be pin 71 of the ECU. Consequently their wiring for the 80 pin connector of the engine harness where those pins are located would follow. So plugging an ECU to the other group model wont get a component to run as expected because of different pin configurations. I have every year's electrical wiring diagram from 1992-2002 for SC300 / SC400 if you want them Craig so you can further do your research between years.

At this point I have no idea what else is different but when I have more time, I would check more on their wiring / ECU pinning differences between 92-94 and 95-96. But one thing sure they are not exactly the same so some functionalities differ and a 95 ECU wouldn't function exactly the same as a 94 ECU . Not saying it won't run your car . What I am saying is it won't run your car in the best or optimal condition. Like in the example above , a component of a 94 car wont be running because it is not properly wired in a 95 ECU.

Craig , what year is your SC300 and is it a Cali-spec'ed car ? What about the ECU and harness you are using ?

KahnBB6

iTrader: (5)

Absolutely agree with you. I knew only of the change to heated O2 sensors for 1995 Cali-Spec SC300's and when I bought the 1995 Cali ECU last year I mistakenly assumed that the permanent CEL was related only to the absence of the heated O2 circuitry on my car. I naively assumed that this CEL was a passive side effect of using the ECU (ie: the 3rd O2 sensor on Cali models has no bearing on ECU engine control and adjustment. It's just a check light).

I naively assumed using the 1995 Cali ECU would, other than the CEL, operate the car the same way a 92-94 Cali M/T ECU would. Everything drove just fine at the time. I was fully aware I would need the correct ECU and that it was a temporary stop-gap until I could find another correct 92-94 ECU. I never intended to test the car with it. The plan was to drive with the '95 computer only as long as it took Tanin to ship my original repaired computer back to me.

And that never happened.

Needless to say that as a result of what was suggested to me the other day AND your post there is no way I will be plugging in the '95 computer again.

Gerry, that little bit of information right there is all I need to understand that I shouldn't have tried using the '95 ECU a few months ago even as a temporary measure. It sounds as if even a 92-94 Federal ECU would have been a better "temporary" ECU to test the car with.

At the time I didn't know just how different those ECUs were since 1995 is still OBD1 even in a California-Spec :/

No, no. What you've posted here is totally fine. Thank you. I don't want you to go to that trouble. It's more than enough information for me to understand that at least for Cali models it's not going to help anything by putting a '95 SC300 Cali-Spec ECU into a 92-94 SC300 Cali-Spec chassis. Regardless of the fact that it won't pass smog with a CEL, it's almost certain to not be operating the engine correctly on an older model. I did not realize that until later.

I thought it would be okay as a temporary ECU back in November of last year since it was an OBD1 Cali-Spec computer into an OBD1 Cali-Spec car. Apparently not so.

My car is a 1993 SC300 Cali-Spec original 5-speed model.

Harness is the original one. It has never been changed. Cali-Spec and M/T for the year.

My original ECU was the correct 89661-23421. That is a 1993 SC300 M/T Cali-Spec computer. That's the one Fedex allowed to be stolen while in transit after Tanin repaired it.

The ECU in the car now is a Toyota Reman 89661-24322(84). That one is Toyota's superseded replacement ECU number for 1992, 1993 and 1994 SC300 M/T Cali-Spec cars.

The ECU I have currently sent off to Tanin Auto for repair is an 89661-24320. 1992 SC300 M/T Cali-Spec computer.

From my research into ECU part numbers:

89661-24320 -- 1992 SC300 M/T Cali-Spec

89661-24321 -- 1993-1994 SC300 M/T Cali-Spec

89661-24322(84) -- Reman Replaces all 1992-1994 SC300 M/T Cali-Spec ECU's according to Toyota's system.


This week I will myself install the brand new Y-Intake, new Denso O2 sensors, new spark plugs/cap/rotor and double check (from the routing diagram) and replace any remaining older hoses in the vacuum system under the Y-manifold. I will also attempt to test the harness connection wires for the EGR temp sensor.

I will swap in the 1992 ECU when it comes back from repair.

My hope is that all of the bad running during this saga plus the previous temporary use of the '95 ECU for a couple of months prior to about January 10th of this year (when I changed to the correct Toyota Reman ECU) didn't do any harm to the cats.

gerrb

iTrader: (34)

Correct me if I am wrong .. looking at the 93 diagrams which yours should belong , you have two Non Heated (single wire , front / rear ) O2 sensors and the SUB sensor is heated (3 or 4 wires) .. .is that right ?

Looking at the 1995 diagrams , for California .. all those 3 oxygen sensors are already heated oxygen sensors( 3 or 4 wires) thus consequently wired as such . That is another difference on the 1995 ECU / Wiring from the 92-94 .

This emphasizes the fact that a 95 ECU will somehow perform differently into a 92-94 car and vice versa because of wiring / functionality differences. Your car may run because the differences are not something that would stop the car from running (notably some emission components) but they affect the car in how it should run OPTIMALLY or in the way it was meant to be. And before you know it , I haven't seen the internal diagrams of the ECUs , maybe affecting something else in their circuitry because of different pin configurations between both groups.