1998 S70 GLT Starts then dies, drive with MAF unplugged

Post by **rspi** » 19 Mar 2014, 21:01

Grrr, this is my daughter's car about 1,600 miles away. It all started on 3/12 with P0243 & P0171 codes. Searched around a there were no clear answers but about 75% of the threads lead to a bad MAF. So I shipped her a MAF and after the MAF change, the car did NOT want to start. Start, run for a second, then die. So she pulled the MAF and the car starts and runs rough.

Thinking that used MAF may have been bad, I sent her one that I test on my turbo 850. Same thing, the car will not run with the MAF plugged in but will run rough with it unplugged.

So I had her reset the system by pulling the battery connectors and holding them together for several seconds. Then I had her unplug her ECU and plug it back in a few times while the battery was disconnected. Connected everything back up and has the same issue.

After driving the car a little, the only code now is the P0102 MAF code because she is driving with it disconnected.

Any suggestions before she takes it to a shop?

Post by **erikv11** » 19 Mar 2014, 22:04

Maybe a problem with the MAF connector.

https://www.matthewsvolvosite.com/forums ... =1&t=24655
http://volvospeed.com/volvo_repairs_how ... ensor.html

Post by **jimmy57** » 19 Mar 2014, 22:26

Air leak between MAF and throttle or MAF and Turbo if it is a turbo engine. A measuring MAF misses the air through the leak and the ECM is miscalculating based on low MAF signal. unplugged MAF makes it a throttle angle based computation and it runs OK but the fuel trim functionality is inhibited so a host of other codes will not be set due to the default running program.

Post by **erikv11** » 20 Mar 2014, 00:16

Wow, nice post Jimmy, that makes perfect sense.

Post by **rspi** » 20 Mar 2014, 04:57

Thanks. I told her to check for air leaks but if it is GROSS she probably missed it.

I also had her fool with the plug a little but that didn't help. The little post on VolvoSpeed was hard to understand on my phone but it looks like they zip tied the wire harness to the backside of the MAF.

Post by **rspi** » 20 Mar 2014, 06:19

Would/could a seized turbo cause the car to start & die like that?

Post by **rspi** » 20 Mar 2014, 07:17

I told her to plug the MAF back in, clear the code, start the car and keep it running until it pops a code.

Post by **jblackburn** » 20 Mar 2014, 11:50

Going along with Jimmy's theory - sounds like a classic blown-off clamp on a hose, usually either at the throttle body itself (held under that black plastic cover) or intercooler.

Post by **rspi** » 21 Mar 2014, 03:27

Well, she could not find anything loose or leaking. Not sure if she had help.

She hooked up the MAF, got it running and kept it running for about 5 minutes by keeping the motor rev'd up but it would NOT throw a code so she gave up.

She has an appointment to have it checked out Tuesday am. Any other suggestions are welcome till then.

Post by **abscate** » 21 Mar 2014, 09:37

Is she close enough that one of our non-serial killer members can take a look? Maybe send out a help request in that forum?