Fuel Problems

Sommerfeldt · Post by **Sommerfeldt** » 13 Mar 2019, 14:05

Yeah, you can’t just unplug the O2. The Long term fuel trim will get all crazy, and do exactly what OPs problem describes. There’s been some theory running around for a long time that the rear O2 just checks the health of the cat, but it seems pretty clear that both of them influence the LTFT. A spacer could work, but fixing the exhaust and getting a cat in there would be the only real fix.
Or modify the programming.

One thing that is concerning, is the throttle lag. It kind of points to an air leak somewhere, when there’s not enough correction in fuel trims to account for it at some specific load point. OP; have you read error codes, and if so, what were they?

- S

Derilas · Post by **Derilas** » 13 Mar 2019, 16:09

The codes are as follows: P0172- too Rich Bank 1 (I don't think it has banks), P0300, 302, 301, 303, 305 (misfire codes), and one interesting code I can't figure out, a P1310. My car has a cap & rotor, so I'm not sure what that's about, maybe you more experienced users know something. The car isn't throwing any cat codes, despite there not being a cat, as well as despite the fact that the O2 sensors don't appear to have been tampered with, but this obviously could be caused by the massive exhaust leak at the base of the manifold

Derilas · Post by **Derilas** » 13 Mar 2019, 16:09

The codes are as follows: P0172- too Rich Bank 1 (I don't think it has banks), P0300, 302, 301, 303, 305 (misfire codes), and one interesting code I can't figure out, a P1310. My car has a cap & rotor, so I'm not sure what that's about, maybe you more experienced users know something. The car isn't throwing any cat codes, despite there not being a cat, as well as despite the fact that the O2 sensors don't appear to have been tampered with, but this obviously could be caused by the massive exhaust leak at the base of the manifold

Sommerfeldt · Post by **Sommerfeldt** » 13 Mar 2019, 17:13

The 1310 is a random misfire code, as far as I can remember - just means “oi! misfire, bud!”. The rest point to where they are.

With that amount of misfires, you’re running super rich, but we knew that. I’m still not convinced there isn’t an air leak somewhere, but your best bet is still getting the exhaust fixed and fuel pressure checked. Your O2s are probably working fine - it’s their environment that’s off.

You’re supposed to have a cap and rotor - no fun without them. The banks are referring to the ECU data banks, me thinks? Someone correct me if I’m wrong.

- S

Derilas · Post by **Derilas** » 13 Mar 2019, 18:00

**Normal** cars are set up, usually, with two different rows of cylinders, with different exhaust manifolds. Bank 1 or 2 refers to the two different rows. the in-line 5 I have doesn't have that, there's only one set of O2 sensors. Do you know how I can test for / find an air (do you mean vacuum?) leak?

Post by **abscate** » 13 Mar 2019, 18:34

If your bank 1 is too rich the Volvo dealer will fix that.

Derilas · Post by **Derilas** » 13 Mar 2019, 18:59

Abscate,

put simply, thanks, but no thanks

Derilas · Post by **Derilas** » 13 Mar 2019, 19:35

Sommerfeldt,

What do you mean by an air leak? I'm pretty new with cars and so I'm still pretty unsure what you're referring to. I know the basics of how vacuum and air flow work in a car, are you recommending that I check all of the vacuum lines and intake manifold gaskets? After that, which I fully intend on doing, is there anything else I need to check for "air leaks," excluding, of course, the exhaust? Please let me know what you mean, thanks in advance.

Post by **abscate** » 13 Mar 2019, 20:14

Do yOU have a leak at the base of the manifold? That will mess up your OXS.

THE OXS upstream will see too much oxygen And try’s to jam more fuel into The cycle.

The down stream sensor will see excess O2 and report the Cat isn’t working right

Sommerfeldt · Post by **Sommerfeldt** » 14 Mar 2019, 02:22

Derilas wrote: ↑13 Mar 2019, 19:35 Sommerfeldt,

What do you mean by an air leak? I'm pretty new with cars and so I'm still pretty unsure what you're referring to. I know the basics of how vacuum and air flow work in a car, are you recommending that I check all of the vacuum lines and intake manifold gaskets? After that, which I fully intend on doing, is there anything else I need to check for "air leaks," excluding, of course, the exhaust? Please let me know what you mean, thanks in advance.

Yeah, negative (vacuum) or positive pressure (boost) leaks will do super weird things, but mainly they'll make you run rich or lean. In your case, it's the hesitation that makes me think there might be more than the O2 sensor(s) and exhaust. If air is leaking in or out after the measurement from the MAF (airflow mass sensor), then fuel trims will be off. It'd have to be somewhat substantial in your case, so you should check for leaks using starter fluid or something like it, spraying lightly around intake manifold and hoses when the car is idling. See abscate's reply as well.

If the car revs up, you found a leak.

As you say, there's only one row of cylinders here, so my understanding of the reference to "banks" in these cars are the 2 separate parts of the ECU "storage" in Motronic 4.4 ECUs. That might not be accurate, but it also doesn't much matter. "Too rich bank 1" should in any case refer to the "front" O2 sensor, i.e. the one before the cat.

Get a handle on the exhaust, check for vacuum leaks, check your fuel pressure, and also make sure that the throttle cable isn't binding anywhere along its travel. I know you said there wasn't any slack, but it can (in rare instances) bind at places in its sleeve, if it has been neglected. Check your throttle body, that the valve travels freely and isn't full of deposits. In that order, kind of.

- S

Fuel Problems

Re: Fuel Problems