SDL with new hyperflows, new rear o2 sensors, changed oil and reinstalled right temp

Swap the thermocouple with an ecu and read again. That will verify ecu or thermocouple


Is your bypass stuck open by any chance?


How is your Y pipe?

 

Seems strange. First, we know that the TCs connected to the TCUs that are staying at 0.54V must at least be completing the circuit because if there was no connections the TCUs go to 5 volts as was verified. Second, we know the TCUs are getting the 12 V power. Based on this and the bench testing, it suggests the TCs are bad or the leads are internally shorted.

As Tim said, you could swap either the L or R (green) TCU with the center (black) one. If the center remains working it would further confirm the bench testing and be another indication of bad TCs in the L & R cats. If the working signal moves with the TCU then it indicates that there is a problem with the green TCUs in spite of the bench testing.

The funny thing here is that the green TCUs are suppose to be the good ones. But, all the TCUs which have been sent to me, and were supposed to be bad, were green, yet tested good. But this is good as the code you had, 1449, indicates a problem with the TCUs not responding.

When you tested the TCUs did you also test all 3 TCs or just use one TC in all the tests?

[edit] I see you responded before I got my post together.

[edit 2] I would not worry to much about your bypass valve just yet. Even if opened your L and R cats should come up to temperature.

 

Bypass-

Drive car pull into driveway leave running. pull the vacuum hose off and see if the valve closes. You may have the lines crossed to the bypass

Y pipe you need to pull it out and check it. It should have a Cat in both sides. You can see in.
I have a spare here I will take a pic of if you need to see.

It's something basic wrong here, you are getting "auto diagnostics 101"

 

Agreed that it is something basic but the problem seems to be with the L & R cat circuits, not the center. 2.2 V is only a little over 1200*F, well below the first warning temp, or 3.75V according the FBB.

 

I really don't know. But my logic is that if the main ECU does not see a TCU reporting anything above 0.5-0.6V it may throw the code (1449) and turn on the SLD. It may be Ferrari's way of trying to tell you that the CEL is possibly due to a cat over heat problem. I.E. it should not be ignored.

Regardless, it seems your L&R TCUs should be reporting more than 0.5-0.6V. That is the output cold. The cats work best at 750*F or higher. The exhaust gasses exiting the cats should be at least that, or higher. So you should be seeing at least 1.5V from the L&R TCUs.

 

We know what the sensors "should" do but the ECU is the uncertain here. Possibly they use a delta % to trigger a code besides a set point. These are primitive Italian programed ECUs to say the least


The connections at the ECU are borderline at best, a place to take a look see also.

 

10 pages later are you still working on problems from your 1st post or has the thread evolved exposing new problems to sort?

 

Bob, if you want my spare ECU again to swap and try, let me know- I can ship Monday.

 

He's learning hands on

 

My 2c. Lotsa talk about lights and voltage. How does it run?
Don't bother to flame me, I know I'm an idiot....

1. Take it out and warm it up with codes cleared.
Have somebody follow you.
2. Run it up to redline in at least first 2 gears a couple of times. Sitting idling or putting around afraid of hurting something proves nothing. Does it pull hard all the way to redline in 2nd gear? (If not, you've got blockage.) Check all 4 cat temps inlet and outlet immediately. Hot in front, cooler in back? Is it smoking black? If so, go to redline a few more times. Still smoking black? White?
3. Drive directly to friendly smog pre-test guy.
4. Have pipes sniffed. Whassup?
5. Read codes.

OK, now just ignore this post.

 

Summarize.

A) Car did not have problem before cats and O2 sensors were replaced.

B) None of the TCUs is sending a signal to the ECU that the cats are over heating.

C) All TCUs and TCs were bench tested and found to be working.

D) In the car two TCUs are not registering any temperature in the exhaust.

E) SDL comes on with code DTC 1449, "TCUs voltage out of range".

Possible causes:

1) Bad TCs.

2) Bad TCUs.

3) Blocked/collapsed cats. (Car would run like s*&t.)

4) Bad signal wire connection to ECU.

5) It's a Ferrari and they all do that.

I'm assuming that once the problem with the two TCUs not reporting a suitable operating temperature to the ECU is corrected the SDL will go out and the code will not reoccur.

 

P1451 is secondary air pump ground problem. I think you had this before. May be a result of messing around with the wires near the pump when fooling with the TCUs.

P1449 is as you say, Bank 2 cat temp. But this code relates to the TCU not working correctly.

I really think the best bet is to start swapping wires between one of the greens and the black TCUs. It appears that we know the black TCU is working in the car. So start with just swapping TCs between the green and black. If the green TCU still outputs 0.5 - 06. V the TCU should be the problem. If the green TCU now outputs about 2V and the black drops to 0.5 - 0.6V then the TC is bad. Don't worry about the SDL and codes. They may or may not be different.

[edit]

Understand, I look at this totally as an electrical problem: The TC should get hot and the TCU should output an appropriate voltage. The green TCUs are not doing that. So either the TCs connected to the green TCUs aren't getting hot (unlikely if the car runs anywhere near correctly), the TCs are shot, or the TCUs are shot. The tough part is that the bench testing seems to contradict what's happening in the car.

Also, you can't assume that the Audi DTC means the same as the Ferrari code. It's a manufacture specific code.

 

So if you assume you really don't have a true fault with codes then :
you got 6 general things in play for the answer to the problem:
2 TC
2 TCU (SDECU)
Motronic ECU
wiring/connections between all

If you read post #2 10 pages ago my quote is above. To spell it out more clearly you can use a 1.5V AA battery and a few wires to temporarily completely bypass 4 of the 6 i.e. 2 TC and 2 TCU's. If after bypass you still get the SDL your problem is either in the wiring/connections or the Motronic ECU.

 

I put money on the integrity of the wiring, including ground.

 

It would be nice if one of the experts could answer the question; will a P1449 code (pending or otherwise) turn on the SLD?