S70 Wont Idle, replaced MAF, idle fine without MAF connected

UCONNs70GLT · Post by **UCONNs70GLT** » 08 Nov 2011, 19:10

Hey everyone,
Id like to start by saying thank you for all of the very informative posts on this forum which have helped me troubleshoot so far. I have a 1998 S70 GLT which i love to death. Two mondays ago I drove my car to school and then when I got back to it after class it refused to idle and would just stall after turning it on. I got it to Autozone by reving it on start and it stalled many times on the way, luckily my university is on the same street as my local autozone.

Codes pulled from autozone OBD scanner:
Secondary Air sys malfunction
Turbocharger wastegate solenoid A malfunction

(I have been back to autozone this week by unplugging the MAF in which the car runs fine, the turbo just does not kick in. Theses codes do not exist anymore which makes me think that it may have been a result of it running with the bad MAF so the air info is not being passed to the ECU confusing it into throwing those codes. When i scanned it this week a new code P0102 Maf circuit low input came up, and this is the only code currently.)

This is what i have tried:
Cleaned throttle body, IACV and MAF.
Replaced MAF with OEM BOSCH MAF from FCP.

Car will idle and run fine with MAF unplugged but once it is plugged in it will stall.
Today I cleaned the IACV which was quite dirty, it would not move and make clicking sound when shaken before i cleaned it as I read it should. After cleaning it slides back and forth making the sound I am understanding that it should make.

I put it back in and replaced the oem clamps with hose clamps. Result: Same issue, car will not idle and stay on without MAF unplugged. Any suggestions?
Thank you so much, all help is appreciated

caz2773 · Post by **caz2773** » 08 Nov 2011, 19:22

replace the maf with a good one

UCONNs70GLT · Post by **UCONNs70GLT** » 08 Nov 2011, 19:26

So do you think the brand new one I just purchased was faulty? It was a new OEM Bosch MAF from FCP with the same S/N.

Post by **jblackburn** » 08 Nov 2011, 19:37

I doubt this is a mass airflow sensor issue and is moreso a blown off turbo/intercooler hose or loose vacuum hose.

UCONNs70GLT · Post by **UCONNs70GLT** » 08 Nov 2011, 19:51

Ahh that sounds very possible, would you mind naming a few hoses that I can look up and check?
Thanks
Oh and the MAF i replaced it with was brand new, I forgot to mention.

Post by **jblackburn** » 08 Nov 2011, 19:56

Follow all of these up from the turbo, down to the intercooler, then back up to the throttle body. They tend to like to blow off where the rubber hoses connect to the metal pipes or throttle body. Sometimes the hose to the idle control valve (silver cylinder near the throttle body) can blow a hole in it at that connection to the smaller hose.

UCONNs70GLT · Post by **UCONNs70GLT** » 08 Nov 2011, 20:06

Alright, I'll be sure to check that tomorrow morning!
Thank you very much

Post by **cn90** » 09 Nov 2011, 08:44

Your symptoms are very classic for bad MAF. These were the symptoms I had when my MAF went Sotuh!

Glad you got the Bosch OEM MAF. However a brand-new MAF does not mean it is good. It might have been dropped during shipping etc.
- Get a similar car in your city and swap the MAF, if you car now runs fine, then the new MAF is bad.
(Search forum for members with similar car in CT and PM them to see if they can do you a favor).

- Once confirmed bad, you can contact FCP for an MAF exchange.

Post by **Choguy03** » 09 Nov 2011, 09:38

MAF Circuit Testing

Use a suitable scan tool, a Graphing Multi–Meter (GMM), or a Digital Volt–Ohm Meter (DVOM) in order to view the MAF data.

MAF Sensor logic is relative to the scale of resistance: when the intake air volume is low, the voltage is decreased. When the coolant temperature is high, the voltage is increased (See Figure 1).

Inspect the air intake tube, the engine air filter, and the MAF and/or IAT sensors for contamination and physical damage in order to verify that the air induction system is in proper working order. If an air induction system fault is evident, repair as required before continuing.

If a DVOM is being used, additional information may be acquired by taking measurements at the sensor connector as well as the PCM connector. If a significant voltage drop is measured (greater than 0.5 volts DC), check the wiring harness and connections for corrosion, poor pin connections, or damaged wires.

If all engine wiring and pin connections are confirmed, disconnect the MAF Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the MAF Sensor.

: Figure 1: MAF Sensor Range Chart; MAF.gif (26.58 KiB) Viewed 3537 times

Post by **misha** » 09 Nov 2011, 15:16

Is there a posibillity for an air leak in hose which goes from maf to a throttle body?

Inspect it carefully.