AFM swap - what should I expect?

AFM swap - what should I expect?

Author
Discussion

FlipFlopGriff

Original Poster:

7,144 posts

246 months

Friday 31st July 2015
quotequote all
Right, finally checked my AFM. Initially when ignition on the reading jumps to 4 then quickly drops back to around 0.35 (after 5 seconds). Start it and the reading is 2.11 then drops to around 1.87 after a minute.
Swap AFM (another Griff AFM). initially higher around2 then drops to 035 after a few seconds. Start is up and 1.90 but stopped it after a few seconds as it didn't sound as smooth as the original meter.
Conclusion - no clue.
Car is a 430BV.
Am I just wasting my time and the original AFM is good?
FFG

PH430

147 posts

127 months

Friday 31st July 2015
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Swap to a 20AM AFM and a new MA chip. The 20AM are steady and have a better breathing and more BHP on top if the revs.

blitzracing

6,387 posts

219 months

Saturday 1st August 2015
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The power on values sound OK- the idle values are a little more difficult to assess as they will vary if the car is not rock steady at say 800 rpm, - a shift of 50 rpm will make a significant difference, so that could be all you are seeing if its not running right. Why are the values dropping after I minute- is the RPM shifting? Typically a failed AFM voltage will be much higher than the values you have, and also dont forget the ECU will need to relearn its fuel trim if the AFM voltage is slightly different before the idle will smooth. Id expect to see very high long term trim values if the AFM value is higher than spec'.

FlipFlopGriff

Original Poster:

7,144 posts

246 months

Saturday 1st August 2015
quotequote all
RPM around 900 when warm. I wasn't in the car when tested so only at the revs it started at which are generally higher than 900, say 1100 before it warms up and drops back down.
I've got a new 5am (copy though) which i'll try.
Was planning on going 20am but along with some other mods at the same time but Mrs FFG out of work at the minute so this is on hold.
FFG

Hoover.

5,988 posts

241 months

Saturday 1st August 2015
quotequote all
Pual.... no idea what is going on with your car, but would say need to sort problem before moving on/up grading ...otherwise will not get to bottom of

as for 20am.... have a chat with me when we meet in a few weeks as got 20am and all relevant wiring etc smile

davep

1,141 posts

283 months

Sunday 2nd August 2015
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blitzracing said:
The power on values sound OK- the idle values are a little more difficult to assess as they will vary if the car is not rock steady at say 800 rpm, - a shift of 50 rpm will make a significant difference, so that could be all you are seeing if its not running right. Why are the values dropping after I minute- is the RPM shifting? Typically a failed AFM voltage will be much higher than the values you have, and also dont forget the ECU will need to relearn its fuel trim if the AFM voltage is slightly different before the idle will smooth. Id expect to see very high long term trim values if the AFM value is higher than spec'.
FlipFlop's car is a pre-cat (4.3 BV) so will be using Map 2, hence open loop, hence Long Term Trim is skipped. Therefore, I'd check the respective CO trim values of each AFM unit as well.

stevesprint

1,114 posts

178 months

Sunday 2nd August 2015
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davep said:
FlipFlop's car is a pre-cat (4.3 BV) so will be using Map 2, hence open loop, hence Long Term Trim is skipped. Therefore, I'd check the respective CO trim values of each AFM unit as well.
Dave, Very good point.

Paul, Set the new AFM CO trim screw to the same voltage as your original AFM voltage. I'll also load the original TVR 430BV map into my ECU so when I'm out next I can workout the correct CO Trim voltage for you.

Steve



FlipFlopGriff

Original Poster:

7,144 posts

246 months

Sunday 2nd August 2015
quotequote all
CO trim was at 1.39-1.4. It does adjust up and down. The car stinks when I put it in the garage and it only passes the MoT if the throttle is blipped a few times to bring the idle figures down and then only just passes.
Steve, are you saying to adjust the CO trim to 0.35? The testing info I have states it should be between 0.8 and 1.4 so it is, just. What impact does lowering the CO trim have?
FFG

blitzracing

6,387 posts

219 months

Sunday 2nd August 2015
quotequote all
The CO trim is not different to tweaking the idle mixture screw on a carburettor- wind it out and it goes rich- and in it goes lean- (check this on your AFM- according to MA not all AFMs are the same way around !) and it affects the mixture noticeably up to around 2500 rpm. You could set it up on a CO meter or gas tester, or I do it by winding it in until the engine starts to idle poorly as it becomes to lean, then back it back far enough to get a sooth ticker, and no further.

stevesprint

1,114 posts

178 months

Sunday 2nd August 2015
quotequote all
FlipFlopGriff said:
CO trim was at 1.39-1.4. It does adjust up and down. The car stinks when I put it in the garage and it only passes the MoT if the throttle is blipped a few times to bring the idle figures down and then only just passes.
Steve, are you saying to adjust the CO trim to 0.35? The testing info I have states it should be between 0.8 and 1.4 so it is, just. What impact does lowering the CO trim have?
FFG
I think we are confusing the air flow reading with the CO Trim screw reading.

My CO Trim screw is set to 1.4v for smoothness (13.5 AFR) but with the later ECU code, I just want to check its the same for TVR original 430BV map. I always remember clockwise increases the volts and the fuel. It is perfectly legal for a 1992 vehicle to raise the idle to pass the MOT. In fact the MOT machine actually tells the operator to raise the idle after the first attempt, alternatively you could reduce the CO trim voltage (anticlockwise)for the MOT.

FlipFlopGriff

Original Poster:

7,144 posts

246 months

Sunday 2nd August 2015
quotequote all
Steve,
So 1.4 is the ideal?
What happens above 1.4?, say 1.6?
FFG

stevesprint

1,114 posts

178 months

Sunday 2nd August 2015
quotequote all
FlipFlopGriff said:
Steve, So 1.4 is the ideal?
Please let me check on my AFR gauge its the same for your map, hopefully I'll use my Griff tomorrow (Monday)
FlipFlopGriff said:
What happens above 1.4?, say 1.6?
Richer, smoother and smellier.

stevesprint

1,114 posts

178 months

Monday 3rd August 2015
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Paul
Hopefully this screen shot of my 430SV (Small Valve) running the factory 430/430BV map answers your question, you can see at idle with 13.5 AFR (for smoothness) the CO Trim voltage is set to 0.93v. I remembered it was different for the earlier Precat ECU software but not sure why it’s different.

If you’ve got RoverGauge please check your checksum is the same “BF” if not is your Tune “R2422” and Multiplier “6B6C”?

Good Luck with that 5AM copy, I won’t tell you what Mark Blitz thinks of them.
Steve

FlipFlopGriff

Original Poster:

7,144 posts

246 months

Monday 3rd August 2015
quotequote all
Thanks Steve. So if I set the CO trim to around 0.95 and see how it goes? I don't have Rovergauge but I need to. Got an ECU mate but no idea how to use it.
Do I just need the cable (from Mark on the bay now) and the software? and a laptop obviously. No idea what all the letters/numbers mean but presume if I get Rovergauge I can drop a screenshot on here.
FFG

blitzracing

6,387 posts

219 months

Tuesday 4th August 2015
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stevesprint said:
Good Luck with that 5AM copy, I won’t tell you what Mark Blitz thinks of them.
Steve
banghead

Podie

46,630 posts

274 months

Tuesday 4th August 2015
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stevesprint said:
Good Luck with that 5AM copy
Agreed!

Seriously, FFG don't waste your time.

FlipFlopGriff

Original Poster:

7,144 posts

246 months

Tuesday 4th August 2015
quotequote all
Podie said:
Agreed!

Seriously, FFG don't waste your time.
Bought a couple at the time a few years back and have one on the 500 - it runs like a dream!!
Maybe I should mothball mine and drive that instead.
FFG

Podie

46,630 posts

274 months

Tuesday 4th August 2015
quotequote all
FlipFlopGriff said:
Podie said:
Agreed!

Seriously, FFG don't waste your time.
Bought a couple at the time a few years back and have one on the 500 - it runs like a dream!!
Maybe I should mothball mine and drive that instead.
FFG
Had nothing but trouble. If yours is working, don't touch it! hehe

A900ss

3,245 posts

151 months

Tuesday 4th August 2015
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I bought a 5 AM copy and it run fine.

That was until I put it on a rolling road and discovered just how lean it was running above 2.5k. I couldn't feel it but it could have been major damage to my car.

I went to Joolz. New larger AFM fitted, rolling road re map, £450 and an extra 30hp from what it was delivering before.

Good luck.