Good morning,

I have purchased a 94’ 850 from a neighbor in hopes of getting it running for my sister in law to use for a few months. It starts up, but idles very low and rough and shuts off, and sometimes it will idle very high (3k rpms+). I pulled the codes 113, 121, and 512. I ordered a new MAF but it doesn’t seems to have changed anything. It idles better without the MAF plugged in. I know the PVC system needs replacing due to the oil on the manifold by the fill cap. But parts have no arrived yet. I have fixed all of the vacuum leaks I could find which were quite a few.

before I play the parts swapping game, does anyone know some tests I can preform to narrow down what the culprit is before I spend too much money guessing?
have new MAF(is there a way to OHM this out?to test?)
have replaced the spark plugs
fixed vacuum leaks

any help is appreciated.

-Jeremy

 

I'd start with some common tests before buying extra parts including a smoke test to look for the more difficult to find vacuum leaks, checking fuel pressure at the rail and measuring the ECT sensor's cold resistance. I'd also check the connector and wiring to the MAF - the 121 can mean the signal lead is grounded/shorted which can be the wiring, or the MAF unit.

Look for the RobertDIY videos on Youtube - I'm betting there is one for testing the MAF :-) .

 

I unplugged the temp sensor and it runs and drives now. It will stumble occasionally and cut off but it is way smoother.