New MAF, black smoke and stalling.

Moppman · Post by **Moppman** » 16 Feb 2017, 11:59

Alright, so I'm a first time Volvo owner. I bought this 98' S70 GLT for $2K in perfect condition with 123,XXX miles and was serviced regularyly until 75K. When I bought it, it ran fine but I noticed the MAF was disconnected and looked odd. Tried to plug it in and the car wouldn't idle longer than a few seconds and you couldn't hit the gas at all. So I left it unplugged. The car ran fine without it for the last 2 weeks while I waited for the new MAF, the default values kept it running smooth but was getting awful mpg (12ish). So I replaced the MAF then cleared the ECU by holding the terminals together for about 10 seconds. I started it up and now it idles but very roughly, also has some form of surge. Sounds similar to a cammed car and stalls as soon as you hit the gas. There's quite a bit of black smoke coming out indicating it running rich. I've looked all over and can't find any disconnected hoses, besides the very front of the intake which is behind the grill and looks like it should be connected to something but not sure. So it seems in the end I'm having a problem running way too rich. I have an OBD scanner coming in the morning so I can test the O2 sensor. Would really appreciate any help.

Post by **abscate** » 16 Feb 2017, 12:34

There are probably several things to put right, so lets start with

Cap Rotor plugs wires

Idel Air control valve - probably needs cleaning
Thats a turbo car, right? If there is the slightest leak in the induction hoses, after MAF but before throttle body, it won't run well with the MAF connected.

Post by **misha** » 16 Feb 2017, 14:48

The most important thing is ......is replacement MAF oem Bosch 0 280 217 107 or something aftermarket?
Is check engine light ON and if it is,what are the codes?

Post by **erikv11** » 16 Feb 2017, 16:37

Moppman wrote:... the very front of the intake which is behind the grill and looks like it should be connected to something but not sure...

Just to confirm, this is not an issue, since this part of the intake is before the MAF.

RigsPGT · Post by **RigsPGT** » 16 Feb 2017, 18:32

Did you get an NA MAF or a turbo one? I'd rather trust a used OEM unit than a no name cheap eBay one so if that's the case, get another one asap. Basically your problem started happening right after installing the new one, have you tried unplugging this new MAF? I drove for 3k miles on my 98 NA with the sensor unplugged and that's why you found yours disconnected as the car still runs although not in optimal conditions.
Codes?

Post by **erikv11** » 16 Feb 2017, 20:11

I agree, basically every used MAF at the junkyard is totally fine. Just make sure it is Bosch.

RigsPGT wrote:Did you get an NA MAF or a turbo one? ...

They are the exact same part.

Moppman · Post by **Moppman** » 18 Feb 2017, 02:13

misha wrote:The most important thing is ......is replacement MAF oem Bosch 0 280 217 107 or something aftermarket?
Is check engine light ON and if it is,what are the codes?

Nope, it's an OEM Bosch and no check engine lights when connected, only service light.

Moppman · Post by **Moppman** » 18 Feb 2017, 02:15

abscate wrote:There are probably several things to put right, so lets start with

Cap Rotor plugs wires

Idel Air control valve - probably needs cleaning
Thats a turbo car, right? If there is the slightest leak in the induction hoses, after MAF but before throttle body, it won't run well with the MAF connected.

Well, when the MAF is disconnected it runs fine so not sure about the rotor, cap, plugs or wires. Not sure about the leak before or after the turbo but will check. No obvious sign of one but I'll crawl under it tomorrow and have a better look.

Moppman · Post by **Moppman** » 18 Feb 2017, 02:16

erikv11 wrote:
Moppman wrote:... the very front of the intake which is behind the grill and looks like it should be connected to something but not sure...
Just to confirm, this is not an issue, since this part of the intake is before the MAF.

Didn't think so, just odd that it's randomly placed and not connected to anything.

Moppman · Post by **Moppman** » 18 Feb 2017, 02:18

RigsPGT wrote:Did you get an NA MAF or a turbo one? I'd rather trust a used OEM unit than a no name cheap eBay one so if that's the case, get another one asap. Basically your problem started happening right after installing the new one, have you tried unplugging this new MAF? I drove for 3k miles on my 98 NA with the sensor unplugged and that's why you found yours disconnected as the car still runs although not in optimal conditions.
Codes?

With the old one connected it runs worse. Will not even maintain an idle. With the new one it'll idle but is just very rich with black smoke and giving any gas stalls it. It is authentic. No codes when connected, only when unplugged which is obvious and runs fantastic unplugged just bad mpg and not optimal power.