Crazy Adaptives

[Hawkeye1922]

Has anyone seen adaptive maps looking like this?

This appeared after an hour or so of driving and, unsurprisingly, the car is undriveable. The laptop can seemingly read the MBE data normally, and everything else looks normal (engine will idle). The ECU won't take the reset-adaptives command either.



Is there any explanation/resolution other that "ECU F , buy a new one"??

[Hawkeye1922]

ukkid35 said:

My MBE can suffer from heat soak, causing the car to be almost undriveable, however, once it cools down again it's fine

But since you can't reset the map, that sounds more serious

Even so, I would try reseating the chips, and looking for water damage as already suggested

My symptoms seem to seem to appear after a period of driving, and then go away again after several hours (at least 3) stopped. Is that what you experience when you say "heat soak"?

Have you ever tried plugging diagnostics in whilst its undriveable?

[Hawkeye1922]

Englishman said:

Yes, looks like an ECU fault, but worth checking the map on the odd cylinders before you start spending.

Well, yesterday, the odd cylinders map was identical
This morning I have switched on and plugged in again. Haven't started the engine. The odd bank seems to have recovered its original adaptives. The even bank is all zeros

My current hypotheses are:
1. UKKid's heat soak phenomenon
2. The NVRAM chip is on its way out, either because its internal battery is dying, or it's just old, causing it to give erroneous values SOMETIMES
3. joints/chip seating as suggested
4. Other difficult-to-diagnose ECU fault, causing the NVRAM chip to be incorrectly read SOMETIMES

So I'm going to invest £25 in a replacement NVRAM chip, and while i'm changing it, check for other obvious dry joints. My issue is then testing it - I think I've run out of my 5 breakdown recoveries this year...

Anyone got a spare ECU they can lend while I'm testing it??

Edited by Hawkeye1922 on Sunday 30th June 14:58

[Hawkeye1922]

notaping said:

Hawkeye1922 - Are you using the correct cable to connect the MBE to your computer? The MBE has 2 data modes - Broadcast mode, & Byte mode. All varieties of diagnostic software available will only run in Byte mode. This is set when connecting the recommended TVR configured cable.

I only ask because I don't know what the software would display if it queried the adaptive memory range in Broadcast mode. Also the reset functions won't work in Broadcast mode.

Just a thought.

Thanks - good thought. My cable is well over 10 years old, probably came from China in the first place, worked well with the original TVR diagnostic software for years. I've only recently started using it with the new software, but it has been dependable so far.

I think what's leaning me toward ECU fault is:
- when the adaptive maps are bonkers, the engine behaves exactly as I would expect according to those bonkers maps (complete fuel cut in the blue areas), so I think they are "real" in RAM, and the ECU onboard software is operating the engine correctly
- when the maps aren't bonkers, I can successfully reset maps and fault codes
- even when the maps are bonkers, the diag software is still able to read all other ECU parameters, and they look normal

Would be good to know how to determine whether the unit is in broadcast or byte mode

[Hawkeye1922]

Juddder said:

On borrowing an ECU - I have a spare full-functioning Speed 6 ECU but sadly these refuse to boot when they are swapped in with V8 EPROMs (*there must be something different with the revisions on code start jump point or something like that) so I'm not sure if it would be much use for you to test, but you are of course more than welcome to borrow it.

Finally, I'm pretty sure I have a few of the Dallas NVRAM chips as backups which I am more than happy to post one out to you and you can try it to see if it fixes / changes your problem before having to spend out cash on a new one

Greatly appreciated - thanks. These goodies arrived today





So the patient is coming into surgery in about half an hour...