Intermittent rich issue

turtle1615 · Post by **turtle1615** » 06 Nov 2018, 17:10

So my 98 v70 t5 will occasionally have a running issue at idle usually only happens when it's cold outside. It will start to sputter and spit and puff a cloud of black out the tail pipe it never happens for long enough to test and it's very random. Usually happens like in line at a drive thru. Its died during this before but always restarts and has never set a check engine light. Any ideas?

Post by **misha** » 06 Nov 2018, 17:27

Scan for codes....if check engine light isn't ON it doesn't mean that there are no codes stored(pending codes).
Meanwhile....re-seat MAF connector few times by pluging & unpluging it while the key is removed from ignition.
Check FPR at fuel rail for fuel in vacuum line....there shouldn't be any.
Also...check connector for ECT...from the wiring loom side.They are notorious for corrosion and intermittent contact.

turtle1615 · Post by **turtle1615** » 06 Nov 2018, 17:34

It has no codes. I've had a live data stream up while the issue happens and everything looks fine. I will check the temp sensor. Also the issue is quick but the amount of fuel is large enough that if standing next to the car when it happens you can hear the motor bog down and run rough for 1 or 2 seconds then you can hear the mass of fuel as it hits the cat and then the muffler then out the tail pipe it's crazy as hell, you just can hear it and follow it through the exhaust. It might do this 2 or 3 times a day when cold outside. Never once when its warm or hot out. It did it last winter also but not once since spring and I drive this car everyday, now it's been back for about 2 weeks.

Post by **misha** » 06 Nov 2018, 17:53

Then... MAF & ECT connectors since it's intermittent.
Both can make problems you are experiencing.
I would rule out FPR because if it is bad it would be bad in warm weather too.
Note that....if you used android app for live data....it isn't accurate at all and CAN'T be trusted.

turtle1615 · Post by **turtle1615** » 06 Nov 2018, 18:26

It's a snap on scanner I'm using. I've wiggled the maf connector and cant make it happen. I'll check the temp sensor tomorrow when there's more light

dj_v70 · Post by **dj_v70** » 06 Nov 2018, 19:25

One idea is to get an aerosol can of air. Turn it upside down (will spray colder) and spray on potential trouble spots to see if you can recreate issue.

Post by **mrbrian200** » 07 Nov 2018, 01:02

Also check you throttle position sensor and the harness connections to it. If the sensor falsely indicates that you've stepped on the accelerator pedal, the ECU dumps gas into the mix. When the throttle plate hasn't opened by the corresponding amount, there's not enough oxygen/air to burn the extra fuel which just goes out the exhaust.

Post by **jvl** » 07 Nov 2018, 06:48

I have experienced the same issue. It was a loose MAP (not MAF) sensor connector. The engine would die when fiddling with the connector.

Sommerfeldt · Post by **Sommerfeldt** » 07 Nov 2018, 09:24

Dodgy O2 sensor can also cause this - that was my issue when those symptoms popped up.

- S