My 1998 s70 T5 is running like crap, sputtering like crazy, and it seems to only happen after driving 30-40 minutes. It will barely get out of its own way and small little puffs of black smoke out of the exhaust while the car is running like this.

I got the car scanned and here are the following codes:
P0172-too rich bank 1
P0131-oxygen sensor bank 1 sensor 1, circuit low voltage
P0102-mass or volume air flow sensor circuit low input
P0455-evap system leak detected
P0300-random cylinder misfire detected
P0301-cylinder #1 misfire condition
P0303-cylinder #3 misfire condition

Can anyone help me diagnose these by any chance? Don't worry about the EVAP code, it's probably because there is no gas cap, getting one today.

My plans are as follows:
Install new gas cap.
Clean MAF.
Clean throttle body.
Check all vacuum lines for leaks or broken hoses.
Pull spark plugs to inspect and check the gap. 0.028 correct?
Install brand new MSD Blaster coil I have sitting around that I never used.
If this doesn't fix my issue, get new oxygen and MAF sensors. Does this sound like I'm headed in the right direction?

Little back story to give you guys a little more info. I bought the car last week for somewhat of a deal. When I test drove it, the car ran fine and had no misfires. My test drive was not 30-40 minutes long so the issue hadn't come about.

I have a receipt from some work the previous owner did in November. On the shops invoice it says "customer states car not running good. Not staying running. Has misfire codes & black smoke from tailpipe. Spark plugs filled up & wires cap rotor resistance out of specs."

Work order on same shop receipt from November:
New distributor cap.
New distributor rotor.
New ignition wire set.
New spark plugs.

They changed all the ignition components except for the coil pack, seems strange. Obviously none of this fixed the problem since I am having the same issues as before the work was even done.

Discuss. . .

 

Sounds like a good plan. I'd probably start with the vacuum line check since a break there can cascade a set of codes. I'd also clear all the codes after you put on the gas cap then see what stays. Typically coils are not part of a tune up kit - If you have a single coil design then they don't have an expiration date (my 95 850 is on its original coil with 200K+ miles). For the newer cars with the coil packs (ie one coil per cyl or two), I've seen recommendations to replace at 100K miles. The vacuum tube set up is similar to the 850s so check out some of the postings and Youtube videos for common vacuum line faults (ie the vacuum tree, and some of the other elbows). You may need a smoke test to find the more obscure breaks.

 

I pulled the distributor cap and saw some oil around the edges. There was no oil on the rotor tip, so I'm not sure if it is a cause of the issue I am having or not. I will be changing that cam seal and the valve cover gasket since they are both leaking a tad.

There are 3 nipples on the front of the intake manifold on the driver side(2 big nipples side by side, and 1 smaller nipple underneath the 2 big ones). I had 2 split hoses, 1(big nipple top left) that led to the hard line for the fuel pressure regulator, and the other(small nipple underneath the 2 big ones) that leads to the bypass valve. I replaced both and cleaned the MAF with 91% alcohol.

I took the car for a 30 minute ride and all was well, I thought I had fixed the issue. Not quite. A few blocks from home the car started to sputter again so I pulled over. It was idling really low(400-500rpm's) and then it stalled. I started the car, it idled low and stalled again. This happened about 3 more times. On the 4th re-start, it idled fine so I took off and drove it home and it did not sputter along the way. Weird

While I was digging around in the engine bay, I saw another hose/line that was not connected to anything. It was on the driver side of the fan and ran down under it to the passenger side.

Does anyone know what it is or goes to?

 

I believe that hose is the cause of your EVAP leak. It should connect to an EVAP valve although the picture is too close for me to know for sure.


The first three DTCs are the root cause. Your comment about black smoke and these codes tell us it is running rich (too much fuel). The MAF measures incoming air and the O2 measures the oxygen content (or lack of) in the exhaust. The P0172 DTC is just confirming what you know so that leaves the other 2.

Both DTCs are suggesting electrical faults rather than low readings. If you have a generic reader you could connect to the DLC (data link connector) you could monitor these readings as you drive and try to determine which item is out of limits.

Something to try, if you disconnect the MAF and drive the car the car should run OK based on an emergency program in the ECM. This is an unscientific way to determine what is going on. Any DTCs (other than the MAF disconnected) set would suggest an issue with that system so if the O2 sensor comes back I would think the O2 sensor was defective. If no DTCs other than the MAF come back then I would start there.


Once you fix these DTCs the misfire DTCs should be cured as the mixture is now good.

 

I was told there is a filter that goes between that open hose in my pic and the purge valve.


I dont get what you are saying. at first it seems you are implying that I have an electrical problem, then you say it can be my MAF or O2. not sure what you are saying.

whats the data link connector? the obdII port in the center console? if so, I dont know of any generic code reader that reads live data, just codes when the car is off and the key is on the on position

 

It is only air from the fuel tank that goes to the EVAP (with some fuel vapors) so no filter needed.


Data Link Connector is the OBD11 port. Yes, there are code readers that display information as well as read / erase DTCs so it appears yours does not have that function.

We have to determine if the root cause of your issue is an electrical issue or an air leak or similar. The sensor gives information that the ECM acts upon by changing the amount of fuel injected, which in turn changes the air fuel ratio so we need to determine if that information can be trusted or if that sensor is defective.


Try unplugging the MAF ad driving the vehicle. It should run fairly well. Then read the DTCs and see if your O2 sensor DTC returns.

 

gotcha! Unfortunately, my code reader does no do live data, just read and erase codes.

I will take the car for a spin tomorrow, if it acts up again(most likely scenario), I will pull over, shut off the car, unplug the MAF, start the car and see if it is fine or still acting up. I'm also going to go over all the vacuum hoses and check for cracked, dry or any disconnected lines.

 

did a voltage test with a mulimeter today on my maf. on idle, its between 0.80-0.94 volts. when revving the engine it goes to 2.0 volts. I think these #'s are low, are they? should I order a new MAF?

 

wanted to inspect the plugs and the gaps, found oil under the black cover on top of the valve cover. looks like its from spilling oil when refilling the engine. plugs look good too

 

just for a piece of mind, I also did a compression test today.
190 across the board except cylinder 2 which was at 185. im pretty happy about that. not bad for a 17 year old car