Misfire with no CEL

[ryan8624]

Yesterday my car developed a sputter and back fire just as I was getting home but I am not getting any lights. I stopped driving it, replaced the plugs today and its still there. It is only at low RPMs (1-2.5k) and its intermittent. It sounds like one cylinder will miss three times or so and then catch, sometimes only missing once, but its intermittent. The car also will not die at idle, it stays at normal RPMs and just sputters and will backfire if driven. Any help is greatly appreciated here. The car is going to Honda tomorrow but I would like to save the money if someone had the same issue. Car is a 2000 with 96k on it. Only modifications are I/H/E.

[repiv]

A sputter or even a backfire near idle, with no CEL, is really not so much of a concern that you need to stop driving it. If it runs well otherwise, can climb the rpm band without a hiccup, it's not a dangerous condition. If you've got bad gas, the ECU will compensate and drive around it. Are you using stock plugs? If you're using an oddball plug, then replacing them with the same kind won't solve anything. Is the torque correct?
A "burble" like what you describe can also mean you've got an exhaust leak or a manifold leak, neither of which will hurt the car if you drive it. If it's bad enough, the ECU will tell you. Your Idle Air Control mechanism might also be acting up and again, this won't hurt the car either.
Try checking and zip tying the MAP sensor and maybe run some concentrated injector cleaner in there. The ECU will tell you if you shouldn't drive it by blinking the CEL at you.

[ryan8624]

So you think I might be able to just drive it and it may sort itself out? The only issue is when crawling around at low RPMs it will sputter and buck. It doesn't seem healthy. However if I can take care of this with some engine treatments and not go to Honda that would be ideal.

I did smell some oil in the exhaust and though I don't drive hard day to day I was at a track day about 2 weeks ago. Do you think that may be a factor?

[repiv]

This is a low torque, high rpm engine. Driving at 1 - 2.5K rpm is just asking for trouble. You are on the verge of lugging the thing. At that rpm, especially if the ambient temps are high, there is not enough torque to motivate a 3000 lb. car. The sputtering and bucking may be actually driver induced and nothing to do with the car itself. When driving at such low rpm, the lower you go and the closer to idle rpm, the more you should be clutching. This bucking thing has been discussed at length for years. It's a function of load and available torque and HP, combined with atmospheric conditions and what the driver wants to do with the car (ie, accelerate and how much). If conditions are right, such low rpms is barely enough to sustain slow speed loafing.
If you do nothing, nothing will get resolved. It will not sort itself out. You must either alter the way you drive the car at such low speeds or introduce some maintenance or mechanical intervention (fuel injector cleaner or better gas or attending to the MAP, IAC or valves) or some or all of the aforementioned items. Now, I don't know what condition your car is in nor do I know what year and what mods you have (it would have been good to mention this stuff), but I'm inclined to think that if you begin by altering your driving style when driving so slowly (ie, using your clutch more*), you may need to do nothing else. The injector cleaner is never a bad idea. I recommend using some at your oil change intervals. Put in the cleaner, use up that tankful of gas, then do the oil change.
When you nearly lug the car (and I think that you are getting very close to doing this if not actually doing it), you are compelling the ECU to make a hard decision. It is trying to decide if you are calling for idle or if you trying to accelerate (even a little bit). If it decides you are trying to move the car, then it dumps fuel. That's when you are getting that raw fuel smell smell, mixed with some oil vapours as you are making the pistons ram themselves backwards (that's what happens in a lug situation). The compression stroke happens just prior to the piston getting to TDC and it's not going fast enough to carry through with the stroke before the fuel explodes.

* When you are going at such low rpm, presumably your speed is also low. It's OK to just go steady state (no speed changes), but if you try to move a little faster or try to overcome a slight incline or overcome rolling resistance, you give it more throttle position. If your clutch is fully engaged, you are asking the engine to give you torque it does not have at that rpm. To counter this, push in the clutch and rev it up a bit as you let out the clutch. This will find the torque you need to get the car on it's way. Once you've delivered this power to the rear wheels, push in the clutch again and use the car's momentum to move it along. When you need to move it more or keep it moving, repeat. This will avoid the sputtering and bucking scenario. This is what you should be doing if you are crawling along. You don't have a monstrous V-8 with gobs of torque off idle. You need rpm to get to the torque you need to move 3000 lbs along.

[ryan8624]

I'm not lugging the engine by virtue of slow speeds, that is a very different kind of bucking. This is around 1.5k in second gear at 20mph. The sputter is when the car is idling as well as driving slowly. There is a problem with combustion someone, I am going to start with injector cleaner and an octane booster in the fuel. Thanks for the advice so far, we will see how this goes.

[repiv]

This is around 1.5k in second gear at 20mph.
This is very close to lugging, if not lugging, especially if you try to give it a little more gas. 1500 rpm with this engine is not enough to do anything. When you are lugging or near lugging, this is a problem with combustion. It cannot use the fuel at the proper moment. Good luck with the cleaner.

[ryan8624]

This is very close to lugging, if not lugging, especially if you try to give it a little more gas. 1500 rpm with this engine is not enough to do anything. When you are lugging or near lugging, this is a problem with combustion. It cannot use the fuel at the proper moment. Good luck with the cleaner.

In over a year of ownership the driving habits have not changed but the cars behavior has. The answer cannot be so simple as simply need to keep the RPMs up.

[repiv]

As you wish. I'm not there to hear the car, to feel the car or to drive the car. I can only give advice based on what information you give. Have you considered that driving at such low rpm for a year has created this problem? When you drive so close to lug, things get gummed up. Things wear abnormally. It may take a year for stuff to show up. If you don't believe that the simple answer may be the one, your only other alternative is to take it to the dealer. Many people have forgone the simple answer in favour of more complicated and costly avenues. Not driving it at such low rpm is free and is only a matter trial. At 1500 rpm, the engine might be putting out 20 lb/ft of torque. If you think that this is enough for your car to go from 20 mph to 22 mph easily, then I can't put forth any further explanation without actually being there to get hands on with your car.

BTW, I just checked and for an AP1, at 1500 rpm, you are going 11 mph in 2nd. You should be in first at that speed. At least then, the engine will have a bit more torque to deal with the demands you ask of it.

[ryan8624]

Update, now I do have a CEL. Right now the ECU is draining and I tried the "MAP whack". In about 10 min I will hope its alright.

[ryan8624]

No success, it still is missing and it even once died at idle. Any help would be great here.

[repiv]

Update, now I do have a CEL. Right now the ECU is draining and I tried the "MAP whack". In about 10 min I will hope its alright.

In some ways, this might be a good thing since you can now go pull the code. With the code, a more targetted approach might be taken. Unless, of course, it's a misfire code, in which case, the diagnosis may be long and difficult. Still, so long as the CEL is NOT blinking, you can still drive it.
In preparation for the misfire code, you might be wise to do the concentrated fuel injector cleaner and to also double check the gaps and torque on the sparkplugs. You never mention what kind you're using. Stock ones are best. Swap them around and swap around the coilpacks, too.
But most important is to get the code.