Spikes in MAF at WOT

[Motors]

Can anybody tell me what they think these MAF spikes are?? They are occurring at WOT. Thanks




17186

[NomakeWan]

Vibration disturbing the MAF connector? It looks like a complete signal dropout. Either the MAF internals are vibrating into a failure mode, or the connector is. That's my guess for why the signal would completely drop out like that at high RPM.

[Motors]

Thanks for the reply... I'll take a look at that. I agree. I just wanted to be sure it wasn't a normal signal before I started searching.

[Motors]

So I checked the wiring to the MAF and I can't cause a drop in the signal. I've included another pic of the drops, this time in steady cruise. I don't see anything else happening when the drops occur. I can include a log file if anybody wants to take a look.

17208

[NomakeWan]

Swap MAFs with a different one to rule out vibration affecting the MAF internals?

[Motors]

Yes that would do it... But I'll need to get one... hey wait what about just disconnecting it....????

[NomakeWan]

What would disconnecting it prove? We know there's a problem with the MAF, and it appears to be a signal dropout. If you disconnect the MAF, you'll just get signal dropout 100% of the time. That doesn't tell us why the signal is dropping out.

[WASyL]

from what i see it seems taht MAF sensor is bad

best regards

[Motors]

Right I guess it would just be null. I was thinking if it were a wiring issue that the spike may remain. The MAF is only a year old and probably doesn’t have 300 miles on it.

[NomakeWan]

Right I guess it would just be null. I was thinking if it were a wiring issue that the spike may remain. The MAF is only a year old and probably doesn’t have 300 miles on it.
The spike is a dropout. If there's no MAF plugged in you won't get any signal from the MAF. So the line would just be completely flat. Even if the "spike" were there it would be invisible because the signal line would be nothing.

[Motors]

Copy... thanks for your help.

[2xls1]

I would see if it occurs with a different scan tool.

[Rocko350]

Look at the pins in the connector plugged into he MAF. Get us a pic of that. Most of the time its a yawning pin. I have had alternators that "leak" ac current do things like this but get us the pic first.

Chris

[Motors]

Ok thanks I’ll do that. That connector with pigtail is new as the MAF location doesn’t coincide with the harness. This is an SS Monte which now has an 86 Camaro TPI setup. The connections between the new pigtail and the harness were soldered and heat shrink. I’ll get a pic back in a couple days having some trans shift adjustments made at the shop right now.

Thanks

[WASyL]

do yourself a favour and switch to OSE 12P code. MAF sensor s a good thing in theory but very faulty, going SD mode saves a lot of trouble.

best regards