Peanuts

iTrader: (15)

been really enjoying the car recently, had a few teething issues and they had all been put to bed.
nice.

Sunday morning I go for a drive round a mates and at part throttle I get a knock count in the low 40's
thinking about it, I cant think what it would be....
I added a 1/2 bottle NF in case of fuel, I changed to another MAF (spares but not 100% theyre spot on) yet this morning, although no high knock spike/count it was more sparkly at the lower levels, sometimes a constant count of 6 on boost.
is there a way of checking the voltage on the MAF?
is it on the same screen as the o2 sensor voltage, but at the top marked afl?
what should the voltage be on the MAF?
hhmmm, sure its only a small thing but being a 99 owner the MAF is always in the back of my mind
any ideas please
Andy

Andy.F

Andy

The maf voltage is read from the Airflow in the monitor menu. 1300 means 1.3 volts for example. Normally warm idle is somewhere between 1000 and 1300, if it reads 1600+ then its u/s.
Beware that the 99 maf does not like being handled !

Andy

Peanuts

iTrader: (15)

getting about 1310/1315 on warm idle so not too far off the mark there.
lambda still reading 0.84/6 at boost
other than straighten out the fins on the tmic and wait for a fresh drop o' juice cant see what it could be
maybe time to smarten up the waterspray a bit

Andy.F

A value of 6 on boost (this is on a 0-100 noise scale) is just background noise, anything up to approx 20 depending on the particular engine is just mechanical, not combustion related.
The 40 value on light load is not normal ? Light load is not prone to creating det conditions however, are you sure there is nothing rattling around in the engine bay ?

Andy

Peanuts

iTrader: (15)

<off to have a poke about>

Jolly Green Monster

iTrader: (4)

part throttle.. bit of the map it has not been on before??

Peanuts

iTrader: (15)

what you saying Simon
Im not a full throttle hooligan you know

mapping was done specifically for my needs which means an awfull lot of point and squirt motorway work, at varying loads/throttle positions, just came on suddenly on sunday morning, had been in fine fettle for the friday beano home as well

Jolly Green Monster

iTrader: (4)

probably just some dodgy fuel then..

was it lowish rpm and high gear, say 3000 to 4000rpm in 5th?

Peanuts

iTrader: (15)

thats what I figured Simon.
When I got back on Sunday morning after a bit of det I decided to add a drop of NF.
allowing a little run to get it mixed up and running round through the critical bits I saw a better picture on the trip home tonight.
still a little sparkly at low revs/cruise but made a top count of 8 (background).
managed a full throttle spell and made 1.32bar all within that 8 count.
will be empty tank by tomorrow night and will be filling up with fresh.

managed to change to another MAF and was flashing 1.30/31v at warm idle so not unduly worried there now.
have got another MAF to play with and will try that if fresh optimax isnt the ticket.
cheers guys for looking in

Andy