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My new-used Maxima has developed a problem over the last couple days. I first noticed that the idle sounded different yesterday morning. It was surging a little in Park before it was fully warmed up, RPMs moving up and down a little. Right after that, on the way to work, the motor would bog whenever the throttle was pushed more than 3/4 down. When it bogged, acceleration would go completley flat, RPM wouldn't increase even if I floored it. If I let up on the throttle, it would usually recover in a couple seconds and revert to moderate acceleration. I also think I felt it missing a couple times on the freeway while cruising at 70-75 mph.
Any idea what this might be or easy things to try? It hasn't hit 45K miles yet, but I know that lots of things can fail with age.
sounds exactly like what my car was doing 3 weeks ago, and it ended up being the coils. I didn't test them or anything, but I had a spare set lying around. Changed those and the spark plugs, and it's run smooth ever since. It'll likely get a little worse as time goes by, and it might throw a code. I can't remember what code that was, but it indicated a cylinder misfire.
OK, so it might be the MAF sensor or the ignition coils/plugs. I don't have any spares for this car, so I need to make a decision whether to buy/try them or just take it to my corner mechanic. Guess I have a few questions about each of these items...
About the MAF sensor, Rock Auto shows the OEM-quality complete assy at more than $100 (Cardone is about $180). OTOH, the sensor itself is less than half that (Walker is least expensive, about $40). Is there a reason to buy the whole assy, or do I only need the sensor?
The ignition coils are too expensive to replace all six for a test, OEM grade are over $50 each. So, I'm thinking about how I could test them on my workbench (lots of non-automotive electrical test gear). Does anyone know if the schematic below (from the FSM) is accurate? If I remove the coils one at a time for testing, is it safe to apply constant 12V between pins 3 and 2? I could connect a spark plug using clip leads, and probably activate the transistor with a pulse generator. I don't think any of the coils are completely dead, but maybe I'd be able to see if one throws a weaker spark than the others. Is this worth doing, or should I just have it analyzed somewhere?
You would only need the sensor, not the whole assembly. Don't cheap out on the MAF sensor either. Only buy OEM. You could try snagging one off a junkyard car if you can find one if you really need to save money.
You would only need the sensor, not the whole assembly. Don't cheap out on the MAF sensor either. Only buy OEM. You could try snagging one off a junkyard car if you can find one if you really need to save money.
I can afford to buy one new, although I'm not sure a quality sensor is available locally. O'reilly only shows a "remanufactured" Cardone (the whole assy), which probably means a used housing with a Chinese sensor in it. Darn, my car is pretty much disabled at this point, hate to wait for something to ship. I'm really frustrated by this influx of Chinese garbage.
I called my local mechanic this morning, learned something new. First thing he asked was whether the Check Engine light had come on. I said no, to which he replied "Oh Lord," meaning, in that case, he can't diagnose it without replacing parts. When I asked if he could just put a scope on the ignition, he laughed and said "I haven't used a scope in more than 20 years." Guess all the shops now just rely on the computer codes in the car.
He did say I should check the MAF first, maybe remove it and clean it with carb cleaner. Was he just thinking about it in general terms, or can ours actually be cleaned?
I forgot to ask... shouldn't the MAF, MAP and bad coil all throw a code? My SES light isn't on. Is it possible it's stored a code, but not activated the light?
I tried the following procedure, but nothing happens:
1. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
2. Repeat the following procedure quickly five times within 5 seconds.
a Fully depress the accelerator pedal.
b Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the MIL starts blinking.
4. Fully release the accelerator pedal.
5. ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).
I forgot to ask... shouldn't the MAF, MAP and bad coil all throw a code? My SES light isn't on. Is it possible it's stored a code, but not activated the light?
I tried the following procedure, but nothing happens:
1. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
2. Repeat the following procedure quickly five times within 5 seconds.
a Fully depress the accelerator pedal.
b Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the MIL starts blinking.
4. Fully release the accelerator pedal.
5. ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).
No, a bad MAF sensor will NOT always trigger a code/CEL. In fact, most of the time, it won't. I know this from my own hard-learned experience.
I always have a spare MAF sensor in my car, one that I know is good and that had proven itself to work in my car. Don't buy the whole assembly - buy only the sensor, preferrably Hitachi (that's the OEM).
No, a bad MAF sensor will NOT always trigger a code/CEL. In fact, most of the time, it won't. I know this from my own hard-learned experience.
I always have a spare MAF sensor in my car, one that I know is good and that had proven itself to work in my car. Don't buy the whole assembly - buy only the sensor, preferrably Hitachi (that's the OEM).
OK, sounds like good advice. Before I spring for a MAF, let me add another detail to the symptom. I decided to drive up to the parts store this evening and have the codes read. When I started it up, the idle was a little more unstable than usual. Out on the street, I couldn't initially nudge it above five or 10 mph. Pressing the pedal to go faster would cause it to bog, and every few seconds there was a muffled pop from the exhaust. At one point, I thought I'd have to get out and push. The problem cleared up after driving about two blocks. It still had a mild flat spot during harder acceleration, but it was running smooth like it did a week ago.
So... the problem has gotten much worse in just the last two days, and it looks now like it's aggravated by a cold engine. Does that sound like a MAF sensor? MAP? Coil? I've seen spark plugs act like this, but not at 45K miles. Maybe they're all corroded from being in the block for 16 years, but then why wasn't it acting up when I bought the car a few weeks ago? Damn, I hate problems like this, especially when the only way to troubleshoot is to replace parts.
Incidentally, the code reader came up with nada, no codes. Pretty incredible considering how badly it was running on the way over there.
OK, sounds like good advice. Before I spring for a MAF, let me add another detail to the symptom. I decided to drive up to the parts store this evening and have the codes read. When I started it up, the idle was a little more unstable than usual. Out on the street, I couldn't initially nudge it above five or 10 mph. Pressing the pedal to go faster would cause it to bog, and every few seconds there was a muffled pop from the exhaust. At one point, I thought I'd have to get out and push. The problem cleared up after driving about two blocks. It still had a mild flat spot during harder acceleration, but it was running smooth like it did a week ago.
So... the problem has gotten much worse in just the last two days, and it looks now like it's aggravated by a cold engine. Does that sound like a MAF sensor? MAP? Coil? I've seen spark plugs act like this, but not at 45K miles. Maybe they're all corroded from being in the block for 16 years, but then why wasn't it acting up when I bought the car a few weeks ago? Damn, I hate problems like this, especially when the only way to troubleshoot is to replace parts.
Incidentally, the code reader came up with nada, no codes. Pretty incredible considering how badly it was running on the way over there.
With the way our cars are, you need a spare MAF in your car (or the ability to borrow it on short notice). You can try to clean your MAF but the result is hit and miss. You can get a new OEM MAF here https://www.rockauto.com/en/moreinfo...359222&jsn=398 (yes, unfortunately you have to buy the whole assembly ..... ).
That's a good price at Rock Auto, but I still hate spending this much without knowing the part is bad. Maybe I should clean it first. That might not do anything, but if it does, I'll know the MAF is the culprit. Of course, this had to happen with the weather turning really bad. It's no fun doing this work in the rain. Does anyone happen to know what size the screws are holding the sensor in the housing (thread and length)?
Wow, I think it's fixed! We caught a break between storms this afternoon, so I did some minor inspection/maintenance work under the hood. First, I pulled apart a few sensor connectors (including the MAF) and greased them with white lithium grease. There was one at the front of the motor that had its electrical tape wrapper pulled back (really a crappy way for the factory to weatherproof these plugs). It looked like the wires might be turning a little green where they go down into the plug, so in addition to greasing the contacts, I greased the upper end at the wires.
Next I drove to the parts store for some MAF sensor spray (CRC) and the security star bit to remove the MAF. By the time I did this, it was too late to know if the car still has the cold idle problem, but it did still have the bog. With the accelerator floored in 2nd, it would run up to about 4,000 RPM, stop accelerating, drop down to 3,500, then slowly climb back to 4,000 and repeat. When I got home and pulled the MAF sensor, I noticed the little wire inside was brownish-black. This was the first MAF sensor I've ever seen, didn't know if that was normal, but one quirt with the spray and it turned shiny silver.
Just like the MAF, I also didn't know how well this car should accelerate when I bought it last month. Well, it runs like a scalded cat now! No bog, no flat spot, just runs hard up to almost the 6,500 redline, then shifts. I'll know in the morning if the cold idle problem is also fixed, but I think this was it. Yay!!
Wow, I think it's fixed! We caught a break between storms this afternoon, so I did some minor inspection/maintenance work under the hood. First, I pulled apart a few sensor connectors (including the MAF) and greased them with white lithium grease. There was one at the front of the motor that had its electrical tape wrapper pulled back (really a crappy way for the factory to weatherproof these plugs). It looked like the wires might be turning a little green where they go down into the plug, so in addition to greasing the contacts, I greased the upper end at the wires.
Next I drove to the parts store for some MAF sensor spray (CRC) and the security star bit to remove the MAF. By the time I did this, it was too late to know if the car still has the cold idle problem, but it did still have the bog. With the accelerator floored in 2nd, it would run up to about 4,000 RPM, stop accelerating, drop down to 3,500, then slowly climb back to 4,000 and repeat. When I got home and pulled the MAF sensor, I noticed the little wire inside was brownish-black. This was the first MAF sensor I've ever seen, didn't know if that was normal, but one quirt with the spray and it turned shiny silver.
Just like the MAF, I also didn't know how well this car should accelerate when I bought it last month. Well, it runs like a scalded cat now! No bog, no flat spot, just runs hard up to almost the 6,500 redline, then shifts. I'll know in the morning if the cold idle problem is also fixed, but I think this was it. Yay!!
It's not a hot wire maf. It's the little metal piece hidden by the plastic.
Just wanted to follow up... Cleaning the MAF sensor and connectors has completely resolved all the driveability issues. The car ran great from cold this morning. In fact, the difference is really astonishing, I never would have believed a dirty MAF sensor could degrade engine performance so much. So, it looks like I got lucky. This will be a good, low-mileage car once I get a few more minor issues sorted.
Well, this car is a joker. When it could barely run at 10 mph, there wasn't a code to be found. Now the second day after cleaning the MAF sensor, still running perfectly, it turned on the SES light. Too funny!
A "hot wire" MAF has a thin piece of wire which it heats to a specific temp by running current through it. The the air passing over the wire cools it down. The more air that flows by it the more power it takes to keep the wire hot. The computer calculates the airflow based on how much power it takes to keep the wire hot and adjusts the amount of fuel the injectors release.
If the wire gets dirty it will be insulated from the passing air allowing the wire to stay hot even as more air passes by it. The dirtier it gets, the less air the computer thinks is passing over it and into the engine. Especially when the amount changes quickly like flooring the throttle.
Well, this car is a joker. When it could barely run at 10 mph, there wasn't a code to be found. Now the second day after cleaning the MAF sensor, still running perfectly, it turned on the SES light. Too funny!
A "hot wire" MAF has a thin piece of wire which it heats to a specific temp by running current through it.
Thanks, but I do know what a hot wire MAF sensor is. It was the meaning and context of the post as a whole that didn't make sense to me. Just a miscommunication, I'm sure.
A "hot wire" MAF has a thin piece of wire which it heats to a specific temp by running current through it. The the air passing over the wire cools it down. The more air that flows by it the more power it takes to keep the wire hot. The computer calculates the airflow based on how much power it takes to keep the wire hot and adjusts the amount of fuel the injectors release.
If the wire gets dirty it will be insulated from the passing air allowing the wire to stay hot even as more air passes by it. The dirtier it gets, the less air the computer thinks is passing over it and into the engine. Especially when the amount changes quickly like flooring the throttle.
Makes you think that after many years of MAF related issues, they'd have self cleaning procedures built into them. Like cleaning an oven, you get it really hot and let it burn all the contaminants off. I think they should do something similar with the MAF.
Just to recap, two days after I cleaned the MAF sensor, the SES light came on. Here's the reading from AutoZone tonight:
Definition
Code P0139 indicates that the Bank 1, Sensor 2 O2 electrical circuit was responding slower than required for a predetermined period of time.
Error Codes Read P0139 Heated Oxygen Sensor 2 Circuit Slow Response P0138 Heated Oxygen Sensor 2 Circuit High Voltage
I haven't had time to search for this in the FSM yet, but I'm hoping this is an easy repair.
yes, change out O2 sensors (im guessing, but thiere may be a even easier fix through the org) but simpyl looks like O2 sensors going bad,
you can just get bosch ones from amazon , no need for OEM on those.
I think that might go through the connector at the front of the motor that had the electrical tape pulled back, one of the two I greased. I'll open it up again and use contact cleaner this time. Maybe this is an intermittent problem and someone else was troubleshooting this problem before me. Does this code refer to more than one sensor?
Here's something interesting. There's a paragraph near the top of the AutoZone printout that I missed earlier because it's highlighted with an almost black background.
"ASE certified Master Technicians have seen this issue on your type of vehicle and the most likely solution is: Reprogram Engine Control Module (ECM)"
Is this likely? Does this mean it should go to the dealer?
Here's something interesting. There's a paragraph near the top of the AutoZone printout that I missed earlier because it's highlighted with an almost black background.
"ASE certified Master Technicians have seen this issue on your type of vehicle and the most likely solution is: Reprogram Engine Control Module (ECM)"
Is this likely? Does this mean it should go to the dealer?
Yes.
There is a TSB (NTB02-051a) that discusses the problem, which was common to all A33s (2000-2002). I remember it, because I ran into it, and my ECU was updated some time in 2005 or so.
The question is: Was you car also updated, or was it not because the problem did not show until now?
Either way, only the dealer has the tools to find out, and to apply the update if/as necessary.
No way to know if this has been updated. I have very little history on the vehicle other than receipts for things like state inspections and oil changes. I found the TSB you mentioned, and it says to replace the rear oxygen sensor before reprogramming the ECM. Is that what you did? You know, I just can't get over the fact that this happened two days after cleaning the MAF sensor and taking the connectors apart that go to the oxygen sensors. Seems like too much to be coincidence.
Well, I replaced the rear O2 sensor. After that, the SES light started turning on more quickly than before (fewer miles), each time I erased the codes. I was concerned something might be wrong with the new sensor, but reprogramming at the dealer has solved the problem. Damn, $135 to correct their firmware. I know this issue doesn't affect actual emissions, but the car won't pass inspection with the light on. That renders it legally inoperable in my state. They should do this as a courtesy, or at least subsidize a portion of the cost.
12-02-2016, 08:13 PM
