bad pcm?? unplugged maf reads 3g/sec KOER???
05-29-2015, 06:35 AM
#1
Staging Lane
Thread Starter
Join Date: Jul 2013
Location: NewHampshire
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
bad pcm?? unplugged maf reads 3g/sec KOER??? I was out with my car the other day( 99 z28), and under partial throttle I was getting a stutter feeling. So I pulled over un plugged my maf (no diag equiptment with me). Drove fine in SD. Its a h/c/I 408. 247/251 624 112lsa cam tfs215 heads 11.5/1 comp. So I swing buy a parts store, and all they had was a cardone maf. I put it in its a little better but still there. I unplugg it and get home and order a a/c delco and put a scanner on my car to check everything out. My maf reads 3g/sec engine running unplugged??? It only reads it running. KOEO it reads 0 but as soon as its running it goes up to 3. I checked continuity in all the wire and thats all good. My long winded question is this normal? Or could it be part of the tune? Thanks for reading if you need any other info let me know
Last edited by 408-99-f; 05-29-2015 at 08:55 AM.
05-29-2015, 08:04 PM
#2
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,604
Likes: 0
Received 6 Likes
on
6 Posts
What's the lowest g/sec value you see in your MAF table?
And are you seeing a real frequency (1-2kHz) at the PCM
under these conditions? If frequency is low, but above MAF
fail minimum, you'll probably be seeing the leftmost value
in the table.
For reference, an Oreo 75mm MAF table I have handy, has
2.42g/sec at 1500Hz, that's the minimum (MAF reads higher
freq, even KOEO, in my scans). For an 85mm I see 1.48 g/sec
@ 1500 leftmost column. So your 3g/sec might just be a clip
value, or maybe you (like I) have a higher MAF freq at zero
real airflow (MAF still has to keep the wires hot, against the
thermal conduction and other heat losses, so should pulse at
lowish freq - how low depends on the thermal situation).
And are you seeing a real frequency (1-2kHz) at the PCM
under these conditions? If frequency is low, but above MAF
fail minimum, you'll probably be seeing the leftmost value
in the table.
For reference, an Oreo 75mm MAF table I have handy, has
2.42g/sec at 1500Hz, that's the minimum (MAF reads higher
freq, even KOEO, in my scans). For an 85mm I see 1.48 g/sec
@ 1500 leftmost column. So your 3g/sec might just be a clip
value, or maybe you (like I) have a higher MAF freq at zero
real airflow (MAF still has to keep the wires hot, against the
thermal conduction and other heat losses, so should pulse at
lowish freq - how low depends on the thermal situation).
05-29-2015, 08:26 PM
#3
Staging Lane
Thread Starter
Join Date: Jul 2013
Location: NewHampshire
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
What's the lowest g/sec value you see in your MAF table?
And are you seeing a real frequency (1-2kHz) at the PCM
under these conditions? If frequency is low, but above MAF
fail minimum, you'll probably be seeing the leftmost value
in the table.
For reference, an Oreo 75mm MAF table I have handy, has
2.42g/sec at 1500Hz, that's the minimum (MAF reads higher
freq, even KOEO, in my scans). For an 85mm I see 1.48 g/sec
@ 1500 leftmost column. So your 3g/sec might just be a clip
value, or maybe you (like I) have a higher MAF freq at zero
real airflow (MAF still has to keep the wires hot, against the
thermal conduction and other heat losses, so should pulse at
lowish freq - how low depends on the thermal situation).
And are you seeing a real frequency (1-2kHz) at the PCM
under these conditions? If frequency is low, but above MAF
fail minimum, you'll probably be seeing the leftmost value
in the table.
For reference, an Oreo 75mm MAF table I have handy, has
2.42g/sec at 1500Hz, that's the minimum (MAF reads higher
freq, even KOEO, in my scans). For an 85mm I see 1.48 g/sec
@ 1500 leftmost column. So your 3g/sec might just be a clip
value, or maybe you (like I) have a higher MAF freq at zero
real airflow (MAF still has to keep the wires hot, against the
thermal conduction and other heat losses, so should pulse at
lowish freq - how low depends on the thermal situation).