1999 Explorer with 150K miles. A couple of months ago, the CE light came on and I checked it with a friend’s diagnostic tool. It gave the code for “Too lean on bank 1”. From what I read, it didn’t sound too serious. We had just had a massive temperature drop from one day to the next and I thought that that might have contributed. The light came on again and now both banks are lean.
I’m not really asking how to get it fixed (but if anyone has any advice, I’d be happy to listen), I just want to know how being too lean is a problem. From inside the car, I don’t detect any performance problems.
Mileage might suffer/performance might suffer, and the polution controls might be compromised. Lean = not enough fuel for the am’t of air in combustion.
You have a less-than-ideal combustion process. I think in this case it makes performance worse. Maybe not noticably. It is possible that this affects pollution controls.
This is why a CE light = an automatic emmissions failure in states that perform such checks.
A logical guess might be that you have clogged fuel injectors, which shouldn’t be terribly expensive to fix. And yeah, it’s probably not performing as well as it might.
Thanks for the info guys. One thing that I should have added, for a long time, the Exploder has “rumbled to life” when starting cold. I’ve seen Rick recommend Techron to other Dopers so I got a bottle of it several months ago and things seemed better for a month or two. I guess it wouldn’t hurt to put another in.
Fortunately for me, I’m in Oklahoma and we don’t have any kind of inspections anymore. Once upon a time we had safety inspections (“Does your horn work? Here’s your sticker.”) but now we don’t even do that.
Lean codes can be set from something as minor as bad vacuum hose to something as major as a faulty head gasket. Whatever it is, it appears to be getting worse. It would be wise to have it properly evaluated.
For those of us that live out in the sticks, that’s easier said than done. The closest trustworthy engine shop to my house is about an hour’s drive. But I know your reputation so I guess that’s what I’ll do. Thanks.
It could also be something as simple as a clogged cat(s) or bad O2 sensors. Regardless of whether there’s actually something wrong with your engine or if the computer just thinks there is, your power, fuel economy, and emissions will all be compromised as long as the CE light is on. It sounds like you’re willing to put up with that.
There’s also the general problem with driving around with your CE light on… if you have a real problem, like a rock punches a hole in your oil pan and you start dumping 7 quarts of oil all over the road, you’ll have no warning that your engine is about to fry.
Point taken except that I haven’t been driving around with the light on. I’ve used my friend’s tool to clear it. It stayed off for a couple of months but now it’s back.
It’s a valid point that with the Check Engine Light always on, you won’t know if another problem appears until other symptoms arise, or the light is reset. Despite its name, however, the CEL is not associated with loss of oil or oil pressure, or engine mechanicals in general. It’s associated with performance (ignition and fuel) and emissions items. There’s an oil pressure gauge or warning light for the scenario you describe.
A plugged cat might be the result of a lean condition (engine goes lean, misfire occurs, cat does a Chernobyl) it is not the cause of a lean condition. Yes, a bad O2 sensor can give a too lean reading. But what made the O2 sensor go bad? If you just replace the sensors without correcting the underlying cause of the sensor failure all you are doing is setting yourself up to buy a second set of sensors when the first replacement set fails.
No. The check engine light is for emission failures. A hole in the oil pan is not an emissions failure.
Your car has an oil pressure warning light, an oil level sensor, an oil pressure gauge, or some combination of the above to warn you of a rock through the pan. The check engine light is not designed to come on under these conditions.
The largest single cause of a too lean condition is an air leak into the engine. The air leak can be on either the intake side, or the exhaust side. Yes, and exhaust leak before or near the O2 sensors will cause them to read lean, and add extra fuel (unneeded) to the engine.
I’m glad you showed up, Rick, since I mentioned your fondness for Techron earlier. Do you have any opinions as to why Techron would have seemed to have helped with starting a cold engine? It helped much longer than the initial tankful when I put the Techron in.
Carbon deposits build up in intake passages and on the back side of intake valves. They can absorb some of the fuel meant to go into the cylinders, leaving the engine with a bit less than it needs to start readily. After it’s run briefly, the deposits have absorbed all they can hold and cease having effect, but then after sitting long enough (overnight) they dry out again. Techron helps clean off the carbon deposits, and it takes longer for them to build up again than it took to clean them off.
Chevron, of course, always heavily markets their Techron additive being in the fuel mix. If there is a Chevron (or some Texaco) station reasonably nearby, switching to that gasoline may help a little bit as well.
I’m always a little skeptical about such claims unless I can get a look at the formulation and all the data (which, of course, is generally impossible.) But Techron seems to be the only additive that apparently actually works.
Well, the reason I said some Texaco stations is because of the Chevron-Texaco merger to bring Texaco (and many Texaco stations) into Chevron Corporation.
As for Shell stations, no. Those are stations that have made a change in franchise affiliation and now get their gasoline (and other marketed oils and the like) from Shell Oil Company.
A mosquito on the mass air flow sensor. I’m not sure how it got past the air filter. The mechanic said either someone installed it improperly so that the seal was compromised or I have really bad luck and it flew in when the filter was being changed.