Kingman Posted March 9, 2009 Share Posted March 9, 2009 I noticed that if I take my battery out of my truck (had to put it in my buddy's Datsun to get 'er runnin) that when I put the battery back in and start it, it runs pretty bad for a few min and driving around. What it does is sputter at idle, the RPMs are very low in park, read 400, and that barely changes in drive. It doesn't die, though. Any throttle application and it runs perfectly fine. These are learning ECUs, correct? So the few min that it runs bad the ECU is finding some way to make it run right? After a few min, like I said, it begins to run perfectly fine and the problem is gone until I remove the battery again. The ECU doesn't give any codes, however. And if I remember, some air valve opens up further to raise the RPMs when, say, the brights are on or the rear defrost is switched on, correct? Well, turning either of those on doesn't affect the RPMs the slightest bit when it's acting up. Could this mean that the valve that controls this is malfunctioning? Because once it starts running right, everything else starts working fine as well. Is the ECU covering up for some sensor or something that's malfunctioning? Would this point to a bad o2 sensor? I know if I take it out, the truck runs exactly the same. Can't quite find out if this means the sensor is good or bad. Any ideas? Link to comment Share on other sites More sharing options...
Precise1 Posted March 10, 2009 Share Posted March 10, 2009 These are learning ECUs, correct? So the few min that it runs bad the ECU is finding some way to make it run right? After a few min, like I said, it begins to run perfectly fine and the problem is gone until I remove the battery again. Yes Would this point to a bad o2 sensor? I know if I take it out, the truck runs exactly the same. Can't quite find out if this means the sensor is good or bad. Look at it this way. If you remove/disconnect the o2 sensor and it doesn't change how the truck runs, then the ECU isn't getting any info from the o2 sensor anyway. Right? B Link to comment Share on other sites More sharing options...
Kingman Posted March 22, 2009 Author Share Posted March 22, 2009 This must be related... I've been searching for close to an hour now, and most things I type in come back no results or are 100% NOT what I need. I even managed to find the cooler center console thread before anything to do with an engine. I fail. Starting a few days ago, on cold starts the engine idles around 800 RPM in park, and runs somewhat rough. Off idle it runs perfectly fine. If I rev it up, and let off, the RPMs drop very low then pop back up to about 800 again. In drive it's about 400. When it's warm, the idle is smooth at 1100-1200 in park and I'd guess around 700 in drive, but that varies within 100 RPM on different stops. In drive, the needle usually sits just above the not-centered line below the 1000 RPM mark. And when it's warm, after it's been idling a while, the idle slowly starts to drop down to 1000 in park until I blip the throttle and it goes back to normal. I have set the idle to where I want it to, but when it's cold it's not behaving the way I've set it. No codes from the ECU. No vacuum leaks as far as I can tell. MAF is clean. This problem is no where near as severe as what I posted above, though. Link to comment Share on other sites More sharing options...
94extreme Posted March 22, 2009 Share Posted March 22, 2009 mine never does that and i have removed my battery pretty often. hmm Link to comment Share on other sites More sharing options...
Kingman Posted March 25, 2009 Author Share Posted March 25, 2009 Any takers? It's getting slightly worse now. And the ECU still isn't giving any codes. What the hell? Link to comment Share on other sites More sharing options...
Simon Posted March 25, 2009 Share Posted March 25, 2009 x2 on what B said. If unplugging the O2 doesn't change anything, then it's not working properly. I've had them go and not throw a code. Link to comment Share on other sites More sharing options...
Kingman Posted March 25, 2009 Author Share Posted March 25, 2009 x2 on what B said. If unplugging the O2 doesn't change anything, then it's not working properly. I've had them go and not throw a code. Is it something that will cause a cold start to be really crappy? I have a universal Bosch O2 sensor, but I need the stock hole drilled out to fit and then I just need to splice the wires. Link to comment Share on other sites More sharing options...
nige Posted March 26, 2009 Share Posted March 26, 2009 (edited) I've had them go and not throw a code. this has also happened to me. mine would start fine, but as soon as you step on the gas it would sputter. didn't matter if the motor was cold, it would get the same problem. I unplugged it and it ran much better. once i replaced the sensor, it ran fine again. it would probably be easier to trade/sell your universal o2 and get the proper part for our trucks. Sometimes the problem can lie within the wires connecting the sensor to the harness. The only way to know for sure is to use a voltmeter to test them. A good OEM replacement o2 sensor should include new wires and a connector like bosch, denso and oem nissan parts. try factorynissan.com and see if Alkorahil will help you out with one. i use the oem nissan or bosch if it helps at all. i usually get a couple years from them if i can manage to keep water out of the tail pipe Edited March 26, 2009 by nige Link to comment Share on other sites More sharing options...
nige Posted March 26, 2009 Share Posted March 26, 2009 oh yeah, loopy idling can be cause by bad vacuum lines too. be sure to check them all for cracks, pinches and snugness. Link to comment Share on other sites More sharing options...
Kingman Posted March 26, 2009 Author Share Posted March 26, 2009 (edited) Thanks for the input. The truck runs perfectly fine off idle when it's cold. It's just at idle when it runs funny. It's not a loopy or loping idle, or sputtering, just not as silky smooth as usual. The slightest bit of throttle and it clears right up. It also should rev up to about 1500-2000 RPM when it first starts for a second and then settle, well lately is has only been revving up to about 1200, if that. When it's cold. When it's warm, again, it runs fine. Edited March 26, 2009 by Kingman Link to comment Share on other sites More sharing options...
Precise1 Posted March 26, 2009 Share Posted March 26, 2009 You get terrible gas mileage and when you disconnect the O2 sensor, the truck runs the same. Time for a new one and I'd replace it with one made to fit the pathfinder bung. B Link to comment Share on other sites More sharing options...
Kingman Posted March 26, 2009 Author Share Posted March 26, 2009 You get terrible gas mileage and when you disconnect the O2 sensor, the truck runs the same. Time for a new one and I'd replace it with one made to fit the pathfinder bung. B Hmmmm that part makes sense. But I was under the impression that as far as runability goes, it either doesn't affect it or it makes it run like total ass, sputtering under load, dying out, etc. I'll find a way to make a hundred bucks and buy a direct fit sensor, but it won't be for a while. I don't even see why a universal one won't work. The wiring is the same... Link to comment Share on other sites More sharing options...
nige Posted March 26, 2009 Share Posted March 26, 2009 maybe it has something to do with the EGR system. It recirculates some of the exhaust gas to the intake when the engine is cold. There are a bunch of valves and vacuum lines in that system that need to be operating properly for the truck to run smooth. a clogged or leaky pcv valve will also cause driveability issues so check that too, it's quick and easy. you can use your universal o2 sensor, it's just a lot of extra work to drill and tap the bigger hole it requires, plus the current sensor might be working properly but the wires are faulty so replacing your sensor will not solve the problem. I wouldn't go replacing it yet because it sounds to me like your problem lies within the egr system because of the different symptoms when the engine is hot and cold. for reference, my truck never revs above 1500rpm regardless of how how cold it is outside. around1200 is normal for a cold (-10-0 C) day. once its warmed up, it should hang around 725rpm. Link to comment Share on other sites More sharing options...
GrimGreg Posted March 26, 2009 Share Posted March 26, 2009 I'll find a way to make a hundred bucks and buy a direct fit sensor, but it won't be for a while. I don't even see why a universal one won't work. The wiring is the same... IIRC, even though it is the same wires, so to speak, the resistance levels are different causing the universals to send the incorrect data signal to the ECU. Link to comment Share on other sites More sharing options...
fleurys Posted March 26, 2009 Share Posted March 26, 2009 so to speak, the resistance levels are different causing the universals to send the incorrect data signal to the ECU. not sure about this one...if the universal is not a wide band sensor, then the signal should still be between .2 and .8 volts.... S. Link to comment Share on other sites More sharing options...
Kingman Posted March 26, 2009 Author Share Posted March 26, 2009 Didn't drive it at all yestertday, but today it ran 100% WTF... I absolutely hate intermittent sh!t. Never had a vehicle that did this so much... Link to comment Share on other sites More sharing options...
GrimGreg Posted March 26, 2009 Share Posted March 26, 2009 I absolutely hate intermittent sh!t.Never had a vehicle that did this so much... It's old and abused, what do you expect? Link to comment Share on other sites More sharing options...
Kingman Posted March 26, 2009 Author Share Posted March 26, 2009 It's old and abused, what do you expect? When something goes bad, to stay bad and not play games with me. Maybe it's too old to remember if it's broken or not... But it is of legal drinking age. I wonder if it would run off Jack... Come to think of it, I never have checked my EGR valve, but all the vacuum lines are a-ok. I really don't think it's O2 sensor related either, and that it's a separate problem all together. But stranger things have happened. The revving up for a second, literally, has to do with the AB valve I think and the vacuum it causes. I took it off and when it started it wouldn't ren at all and there was a second or two gap between the engine starting and consistantly running. After I put the valve back on it started revving up like it does. I like it much better that way, instills a little more confidence. Link to comment Share on other sites More sharing options...
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