What airfow meter in a Griff 4.3?

[NicBowman]

Anyone know if a Lucas 5AM airflow meter is used in a 4.3 Griff?

Ta

Nic

[Barreti]

Does it say so on the side of it Nic.
I certainly remember it does on Chim.
I'll trot to the garage for a look if you need me to.

[HarryW]

You would assume so, what is on there at the moment , as I believe some of the early hot wire cars had a 'strange' AFM ouput something like 3Volts fsd instead of the normal 5Volts fsd from a 5AM. Just a thought if you are having issues in this area and hence the question.

[Barreti]

YES ....

[NicBowman]

Mine is 3AM, there appears to be a cheap new 5AM on e bay, but doesn't look like it is suitable.

Out of interest, if a 5AM is fitted to yours Baretti, what is the engine? Is a 5AM bigger or smaller capacilty than a 3AM? Lots of questions!

thanks all

Nic

Edited by NicBowman on Thursday 21st June 22:30

[Barreti]

Mine is a 4.3 Nic. Allegedly of the BV variety.
How will you know, to look at them, if there is a difference. I grabbed a couple of other photos if they might be any help establishing whats what, although I didn't go to the trouble of pulling off the induction pipe and photographing down its throat - I thought I already had a photo like that !

Edited by Barreti on Thursday 21st June 22:38

[K4000JB]

hi guys as far as i am aware the 3am and 5am afm's are interchangeable all that needs setting up is the idle mixture. this is wot i have found with my precat i have been dabling with different afm's to see which ones will work without going to the expense of a remap trying the later larger one at the mo
cheers ant
p.s the internal restrictive size is the same for the 3am and 5am as far as i can see and my car has just been to lemans and back with the 5am on it with no issues

Edited by K4000JB on Thursday 21st June 23:21

[HarryW]

I'm fairly certain that the 3am and 5am AFM's difference are exactly what I stated earlier, 3 volts fsd out and 5 volts fsd both obviously for max air flow through them. The fitting of a 5am for a 3am will confuse 14cux ECU, imagine an ECU looking for a scaled 3 volts max signal to enable it to select the right load site being faced with a 5volt signal, at best it will run rich at worse ... .
I believe they can be exchanged but I'm certain it will involve doing something the ECU too.
I would speak to Mark Adam if I were you.

[griffter]

The Hamill book on tuning RV8s states that 3AM and 5AM are interchangeable. The voltage output from the 3AM at full airflow is way over 3 volts - nearer 4.5. I think they probably are a straight swap, thought I don't why the designation was changed if that's the case.
Any 3AM - eg from a 90's straight six Jag will be OK on the TVR I think, but you MUST set the CO trim up correctly.

[HarryW]

Not sure tbh always thought (and was fairly certain) the 3am output was scaled differently to the 5am. Still worth a call to Mark Adams his contact details are normally in the club magazine for RV8 ECU advice.

[griffsmith]

griffter said:

Any 3AM - eg from a 90's straight six Jag will be OK on the TVR I think, but you MUST set the CO trim up correctly.

What is the correct CO trim setting Griffter??

my spare 3AM meter came from a jag breakers and it worked fine. I agree all readings seem to be the same as stated in SH book / LR manual for 5AM meters, and when I asked the question previously on here no one really could tell me what the differences were and if it would have any effect on my car.. either way i stuck with the type I had and it turned out cheaper that way..

[HarryW]

Give Mark a ring it will cost nothing to hear it from the horses mouth.

when you say you checked all the voltages did that include the scaled/load output whilst under load/driving or just at tick over with no load

Edited by HarryW on Friday 22 June 10:21

[griffsmith]

HarryW said:

Give Mark a ring it will cost nothing to hear it from the horses mouth.

when you say you checked all the voltages did that include the scaled/load output whilst under load/driving or just at tick over with no load

Edited by HarryW on Friday 22 June 10:21

when I did it, I checked static (ignition on) for CO trim, and with engine running and various steady state rpms out of gear not whilst driving. I don't think being under load makes any / significant difference, you are just measuring volume airflow which is dependant on rpm..

[K4000JB]

as i said earlier the 3am and 5am both worked on my car they bothrun an 5 volts or aleast the ones i have do i believe the correct voltage for idle enrichment is around 1.5volts but you would need to get the emissions checked out straight away cos this could differ from engine to engine. i have an lc1 fitted to my car so i can monitor the fueling an as far as i see it the 3am and 5am dont differ enough to make a difference. The 20am airflow meter is not a straight swop, although it fits and it also runs on 5 volts ,you can fit it and make the car idle but you do need to add a potentiometer to give the ecu a base idle setting for idle enrichment(as per the rpi website)but the car wont run because it is getting more air than it thinks and does not inject enough fuel therefore running dangerously lean