[urq] MAC 02 Pressure Transducer failure?

fdekat fdekat at sentex.net
Fri Jul 8 17:16:54 EDT 2005

Hello All:

Last month, I spent a lot of time replacing the head gasket in my MC motored
urq.  Thanks for all the tips!

I ended up pulling out the manifolds and head separatly, but dropped the
whole mess back in as one piece. WAY easier...

Now Mr. Bill Bennet pointed out that there was a good chance that my head
gasket failure was from 'pingin', and that I had to fix that, or I'd have the
problem again..

THat man is a genius, because unknown to him, I HAD been hearing light
pinging before the head gasket failure. Now that I have replace the head
gasket, I've been really listening for pinging. I find if I drive near
concrete walls or guard rails, I can hear the pinging if I'm on it fairly
hard in mid range revs (3500 to maybe 5000).

SO the next thing is, how do you get pinging, if the computer adjusts

Martin P tells me about the known 'pressure transducer failure'. 

So today I wired up some leads to the transducer, so I could measure it's
output while driving.

Surprisingly enough, there was no output. I assume that means the ECU thinks
it's seeing full vaccum all the time.

 That cold explain the pinging..!

So my questions are:
1) What's the chance that replacement transducers are available? 
(Probably unobtanium, so I may as well go to a MAC 11 ECU and harness, as I
already have the block, head and turbo..?)

2) I'm sure I've seen a spreadsheet somewhere, that shows transducer output
vs transducer pressure. Anyone else know where to find that?

I could then substitute the pressure transducer output with a fixed voltage,
closer to what the ECU would want to see for near full boost. At least then,
It won't ping so much (But have other side effects of never changing value

3) Or any other ideas?

It's the MAC 02 with the 'yellow' label, if that makes any difference?


=Frank de Kat=

More information about the urq mailing list