I have a 1997 Nissan Altima that has started having an irregular idle. It is almost like someone is hitting the gas and releasing and it jumps between 300-1000 rpms. it was throwing codes for the stupid knock sensor, multiple cylinder misfire and the O2 sensor. I changed the plugs and wires, fuel filter, air filter, front O2 sensor, both belts, distributor cap and rotor, spray cleaned the MAF and replaced a cracked manifold. I also ran a bottle of Gumout fuel injection cleaner through it. The idle has actually gotten a little worse after doing all of this. Next i'm going to check all vacuum lines. But i think it may be the dreaded MAF sensor. Any other suggestions?
The description sounds like a technical Service Bulletin Nissan came out with on your car. It fits your description to a "T".
However, the codes you are getting are not what the service bulletin reports. The code they say it sets is DTC 0400 which relates to an irregular EGR operation, causing a problem where it will not maintain an idle or Will idle roughly. There is not a recall campaign on this item.
As far as misfire problems: Nissan had a service bulletin out on problem ECM's which caused this problem. Check with your local dealer. This may possibly be covered under warranty.
The reference number is NTB97-026 The bulletin was issued March,12,1997 There was no recall on this item.
Good luck to both of you.
cutch1965: WHOA!>>>>>>>>>>DON'T just start throwing parts at the car to see if it will fix the problem, let me see if I can help and save you a few bucks! Maybe you'll owe ma a happy meal or sumpten (I write real good huh?)
Before you go replacing the egr, had you recently had a state inspection? If you had passed, the egr was working fine. The egr is not a high failure rate component on that engine. Running an exhaust gasses analysis two symptoms would be apparent. A high H/C level and possibly a NOX level out of parameters.
An egr valve, when it is not seated, will cause the engine to idle rough, like you pulled a vacuum hose off of it. It can be tested with a small hand held tool which can create at least 12-15 inches of vacuum. If vacuum is applied to the egr while the engine is running and there is an appreciable difference in how it idles, (it starts running very rough), you release the vacuum and it should return to normal. The egr's can be cleaned in many cases.
The throttle positioning sensor can be checked and adjusted using a digital volt/ohm meter. If you are going to be doing work on you cars and other things about the house, whether it be fixing an outlet or the dryer, the DVOM, is a worth every penny! They can be bought very cheap, at Radio Shacks, Fry's Electronic's and more. All you need is a basic one which measures ohms, volts, both AC and DC.
You will be able to use this meter to check all of the other sensors on the car as well as do pin outs, voltage drop checks and more! DOESN'T THAT SOUND LIKE FUN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Make sure all of the electrical connectors are clean of corrosion and on the real small connectors it's not a bad idea to put some dielectric grease on the connections to eliminate an potential problems of electrolysis. A lot of people forget about fuel filters and I have run into one case where the filter was actually in a kind of "limbo "state, where it created a lean condition so bad that the exhaust on the toyota truck were were working on would glow cherry red. The gas mileage had dropped severely. The customer never really put his foot in it so he never really would have picked up on a fuel starvation problem unless he were to go on a real hard run. The quality of parts can also affect the performance and mileage. Cheap ignition parts will definitely differ from quality when it comes to performance. You want a compromise or you want what was designed and engineered for the car? You mentioned that you has sprayed Mass Air Flow Sensor.. The kind of raised a big red flag for me! That is a real delicate component an is not really designed to be cleaned. If you look inside the meter, you will see some small wires. When the engine is shut off, those wires actually heat up to in excess of 1,000 degrees Fahrenheit! So, the unit is actually self cleaning. Your intentions of cleaning it may possibly, unknowingly damaged it. Now cleaning the throttle body is ok. Look at the large hoses which connect the MAF to the throttle body for any types of cracks. Any places where "False air" can get in (unmetered air) will affect the performance and fuel mileage.
OK, this should give you a starting point before you go throwing money away. I don't know where you are in the country, but if you can get your hands on some, there is a product made by "LUBROMOLY" (they are out of Germany) it's called "Injectron". It's a fuel additive which I now buy by the case and sell to my customers. It cleans injectors better than some of the injector cleaning equipment I have seen. All you do is dump a can in the fuel tank! BUY THAT DVOM and it'll save you a fortune if you are serious about learning to fix you own car as well as save money!
Keep in touch GUY! GOOD LUCK>
×
3,473 views
Usually answered in minutes!
I'm having the same problem. The 4th cylinder misfire, knock sensor, crank shaft sensor and some other manufacturer sensor came up for the engine light. So far we have tried all of the sensors and no change whatsoever. We took off the valve cover and found a whole bunch of carbon build up in it which is not good and we don't know where it came from. Also the 4th fuel injector is leaking, we tried switching 1 with 4 to see if it would change and it's still 4 that's leaking. There is gas in the oil. We also replaced the intake manifold gasket because that was leaking. Soo right now we have a car that won't start, has oil in the engine and the 4th fuel injector is not working so we're thinking of a new engine and possibly the o rings on the injectors? We 1st cleaned the injectors and that helped a bunch with the idle but now we can't get her started. Email me if you want [email protected]
We had the leaking intake manifold gaskets replaced which helped with the idle alot. The car runs pretty good now with just a few minor issues and the check engine light is still on. Advance auto ran the codes and I believe one that came back was the irregular EGR operation but there was also another code which they said could be multiple things including O2 sensor, MAF sensor, a vacuum leak of some sort, and a couple of other things that I can't think of right now. The tach is also jumping rpm's randomly at times when driving on the freeway but the engine does not change. I was told this may be the throttle position sensor. Amongst all of this there has been a significant decrease in fuel mileage. When we got the car 3 years ago it was getting about 325-340 miles per tank and now it is only getting about 185 to 200. A big difference that i really need to get fixed. It seems like a lot of the sensors are deciding to go bad all at one time. I am going to clean the injectors, replace the EGR valve and maybe the throttle position sensor along with some vacuum lines and see what happens.
Thanks for the info, I will check into some of these things as well.
Yeah, I'm having pretty much the same problem. My AC compressor went and was making a terrible racket. Next thing you know my engine light went on. After removing the belt from the AC, the noise stopped and I had the engine light reset. Well it kept coming on again and again. I kept getting codes for the knock sensor, O2 sensors front and back. The O2 sensors had already both been replaced. Like you, my cars rpms is jumping around the same range as your own. I've noticed a significant decrease in performance and fuel economy. The car actually feels like it is bogging. In researching info about the knock sensor, it actually screws up your timing. I guess what I want to know is if the knock sensor can cause your O2 sensors to act eradically which could be why I'm getting codes for these as well. The guy showed me on the diagnostic device how the numbers were jumping all over the place. I won't be doing the work myself and I hate to pay for something it doesn't need. Or to fix it and it be something else. I've seen this happen to many people when dealing with sensors and codes.
×