V8S - ECU and air-flow meter problem?

[seb400]

On a test a couple of years ago it was pointed out to me that the ECU didn't store fault codes. The car was serviced last week and a note made that the air-flow meter wasn't working correctly. It revs too highly at start-up and takes too long to settle down to idle.

What I'd like to know is the best solution to fixing both the above. Are ECUs fixable? If I need a new ECU and air-flow meter should I go to Mark Adams and get it set up properly - if so, what's it likely to cost?

Steve

MTIA

[greenv8s]

Have your TVR specialisrs already diagnosed the air flow meter as the cause of the idle problems, or are they just guessing? There are plenty of common faults which cause these symptom, but I'm not aware of a faulty AFM being one of them.

[shpub]

Triued cleaning the stepper motor? As far as I know, all V8S have the 14CUX ECU and store error codes. They can be wiped if the battery is disconnected or the ECU unplugged.

As Pete says a lot of other potential causes as well that an ECU fault code reader should find.

[kevin Secker]

Hi guys,

We had exactly this fault on our V8S. It reved up to about 2500 RPM after start and sat there for up to five minutes. Neighbours hated us and I don't think it was doing the engine any good either.

Please take everything that follows with a big pinch of salt as I am no Mark Adams, however:

1) Our throttle butterfly was worn meaning that it didn't shut properly (67000 miles!!!). This didn't cause the problem but made setting the engine's base idle near impossible. A poorly set up engine will exhibit the traits you describe.
2) IIRC the 14 CUX logs faults codes but doesn't store them....i.e. it will tell you if a sensor is f****d but won't tell you if it has an intermittent fault but is fine when you plug in the reader. I am however quite happy to concede this point to Steve Conversely I think it is correct to say that the ECU is quite capable of thinking a sensor is fine when it is most definitely not!!!
3)ECUs can be repaired but this is expensive (approx £375 plus VAT) and I would try all the other avenues first. Mark Adams would be my first port of call. What he doesn't know about Lucas injection isn't worth knowing.

If it helps we have an airflow meter that is currently not in use. If you wanted to borrow it to eliminate your airflow meter from the equation then you'd be more than welcome. If your ECU turns out to be stuffed we have one for sale in the adverts section......sorry, shameless plug.....I'll get me coat.

Kevin and Emma

[shpub]

The ECU should be the same one as fitted to Griffs and Chimeras and that does log faults but intermittent ones can be difficult though especially when the data the ECU sees is within its normal range but incorrect. e.g. temp sensor saying it is 90 C when it is 25. ECU won't detect that as a fault because 90 is a valid temp however there is a problem.

[shpub]

"The Lucas14CUX have diagnostic
functions, the Lucas 4CU does not.
The 13CU was only used in some export markets.
The later electronic control modules have a
self-test capability that continually examines
the signals from certain engine sensors and
actuators, each signal is compared to a
table of pre-programmed values. If the diagnostic
software determines there is a fault present, the
ECM stores one or more fault codes in it's
memory. Codes are only stored for a limited range of
components.
The Lucas 14CUX generates 2-digit fault codes
for retrieval by a dedicated fault code reader."

From the I-spy book of V8 ECUs...
The 4CU unit was fitted to the earlier Wedges.

[seb400]

Guys - thanks for all the suggestions.

I have cleaned the throttle-pot before which did improve matters.

Would the general concensus be that 'the fact that the ECU doesn't store any fault codes' isn't anything to be unduly worried about?

The car has got a Kent 214 cam which makes it lumpy low down which could be upsetting things a little.

[greenv8s]

seb400 said:

Would the general concensus be that 'the fact that the ECU doesn't store any fault codes' isn't anything to be unduly worried about?

Either the ECU is failing to store fault codes because it is faulty, or the permanent power supply to it has failed (in which case you are also losing the adaptive settings), or there are no fault codes because there are no faults, or the person who said it isn't storing fault codes is wrong.

[shpub]

Or all of the above...

[seb400]

Thanks for clearing that one up, if you two don't know then it's probably not worth knowing!