denley Posted June 13, 2011 Share Posted June 13, 2011 my 94 pathfinder le 4x4 auto 3.0l got buried in a mud hole pretty good the other day, water leaked into the passenger side really bad due to it being sloped that way. The ECU was under water for a while and was filled with mud causing it not to start, so i bought a used ECU to try. It worked as far as getting it started but now it runs terrible. It feels as if it idles at 300 rpm and almost wants to die until given gas very slowly, after giving it gas it seems to run fine except a roaring noise from the engine. Would a faulty used ECU cause it to run very rough and make an awful noise? Is there any way to test the ECU to see if its an internal engine problem instead? Oh also there is no check engine light or and other hazard light on the dash. Any help is appreciated. Thanks!! Link to comment Share on other sites More sharing options...
sewebster Posted June 13, 2011 Share Posted June 13, 2011 Don't really have enough information here... go back to basics, check your ignition system etc. What is this roaring noise? Find where it is coming from. My engine always makes a "roaring" noise Link to comment Share on other sites More sharing options...
denley Posted June 13, 2011 Author Share Posted June 13, 2011 Ignition checks out, distributors fine, new distributor cap and rotor, plugs and wires are good. Besides a dead battery it seems to start and get ignition fine. The roaring I'm referring to is in the engine bay, almost like engine is running without oil but I did a fresh oil change before I ran it. That's why I was asking if the computer could be making the engine run rough and not ignite right or get proper fuel mixture and cause the engine to make this noise. Figured if computer was faulty it would throw an engine light. Link to comment Share on other sites More sharing options...
ejin4499 Posted June 13, 2011 Share Posted June 13, 2011 Ignition checks out, distributors fine, new distributor cap and rotor, plugs and wires are good. Besides a dead battery it seems to start and get ignition fine. The roaring I'm referring to is in the engine bay, almost like engine is running without oil but I did a fresh oil change before I ran it. That's why I was asking if the computer could be making the engine run rough and not ignite right or get proper fuel mixture and cause the engine to make this noise. Figured if computer was faulty it would throw an engine light. Vacuum or exhaust leaks? What condition are your rubber lines in? when you changed the oil was there water/gas/anything that didn't belong? go through page 127 - 132 on the service manual check all your electrical connections to the ecu. Make sure you didn't bend or break any pins on the ecu connection harness. check that you don't have any obviously damaged wires in the harness under the water level. You mentioned that it was in mud did you clean out the wireing harness ? If you got water and crap in there it could be shorting something out. I recomend 90% isopropyl alcohol( available at a pharmacy) distill white vinegar (this is not the stuff you use in salad dressing) then distilled water. DO NOT USE TAP WATER!!!!! Use each to gently rinse your ecm harness connector inside and out then allow to dry. The drying period is two days minimum with a fan blowing on it at all times. This is the process I use to clean keyboards and laptops when they get crap spilled on them. You may have spun a bearing if you over worked your engine getting back out of the mud. Link to comment Share on other sites More sharing options...
sewebster Posted June 13, 2011 Share Posted June 13, 2011 Alternator complaining about getting dunked? Link to comment Share on other sites More sharing options...
denley Posted June 13, 2011 Author Share Posted June 13, 2011 i messed with it some just a min ago, checked the oil and it still had some gas in it so i changed it again and started it and the roaring noise was almost all gone, but the rough idle was still there. i started messing with vacuum hoses and i unplugged the hose from the intake manifold to the fuel pressure regulator. rough idle almost completely went away.....what would cause it to run better when unplugged versus it plugged in like it should be? Link to comment Share on other sites More sharing options...
sewebster Posted June 13, 2011 Share Posted June 13, 2011 The vacuum on the fuel pressure regulator drops the fuel pressure when at idle. Did you plug the hose when you pulled it off? If not then you would have had a vacuum leak. Anyway, assuming you pinched the hose, this seems to indicate some kind of fuel problem. Gas in your oil means some kind of injector leak. What do you mean "still" had some gas in it? Did you have this problem before? Link to comment Share on other sites More sharing options...
denley Posted June 13, 2011 Author Share Posted June 13, 2011 i tried both, when plugged it ran rough, with open leaking it ran great. I had gas in the oil due to the computer going out and flooding the engine trying to start it therefore gas from the cylinders running into the crankcase. Link to comment Share on other sites More sharing options...
ejin4499 Posted June 14, 2011 Share Posted June 14, 2011 (edited) i messed with it some just a min ago, checked the oil and it still had some gas in it so i changed it again and started it and the roaring noise was almost all gone, but the rough idle was still there. i started messing with vacuum hoses and i unplugged the hose from the intake manifold to the fuel pressure regulator. rough idle almost completely went away.....what would cause it to run better when unplugged versus it plugged in like it should be? Just for giggles try disconecting you O2 sensor while your at idle. That might fix the rest of the rough idle. My vote is still on a dozen small vacuum leaks from the old hoses or dirty connections. Edited June 14, 2011 by ejin4499 Link to comment Share on other sites More sharing options...
sewebster Posted June 14, 2011 Share Posted June 14, 2011 i tried both, when plugged it ran rough, with open leaking it ran great. I had gas in the oil due to the computer going out and flooding the engine trying to start it therefore gas from the cylinders running into the crankcase. So, when you have a vacuum leak it runs well, ok. So one thing it could be is it not getting enough air at idle. Check the AAC valve connection and appropriate pins on the ECU? idle adjust screw? Or it could be that the vacuum leak just causes it to increase in engine speed enough that you are away from your problem condition... Link to comment Share on other sites More sharing options...
denley Posted June 14, 2011 Author Share Posted June 14, 2011 well i got bored and decided to do a diagnostic check on the ecu. i read the thread here on npora on how to do it but it seems odd. i did exactly how the instructions said to and i got the follow codes in this order. 22-Fuel pump 33-heated oxygen sensor 44-ECCS normal operation 55- no malfunction 11- Crank angle sensor/ camshaft position sensor. just thought it was odd to get codes in perfect 10 number intervals almost in perfect order. Link to comment Share on other sites More sharing options...
WarehouseRat Posted June 14, 2011 Share Posted June 14, 2011 nope lol those are the mode codes ie mode 1 mode 2etc etc wait till you see both leds flash 3 times then turn the knob all the way clockwise then write the flashes down first flash means tens the second flashes are the ones which corespond to a tdc code Link to comment Share on other sites More sharing options...
sewebster Posted June 14, 2011 Share Posted June 14, 2011 Yeah, you didn't actually enter diagnostic mode 3. Link to comment Share on other sites More sharing options...
denley Posted June 14, 2011 Author Share Posted June 14, 2011 Gotcha now I got it, got 55 no malfunction so that's a relief, seems the more I run it the better it's getting, I'm getting a new battery and fresh oil for it today, I'll take her down the highway and see how she does down the road. Link to comment Share on other sites More sharing options...
adamzan Posted June 14, 2011 Share Posted June 14, 2011 Maybe change the fuel and air filters while you're at it. Link to comment Share on other sites More sharing options...
WarehouseRat Posted June 15, 2011 Share Posted June 15, 2011 if it sat in standing water far any length of time i would check the tranny and tranfer case fluids for water/etc just to be safe axles should be fine breathers are high enough Link to comment Share on other sites More sharing options...
denley Posted June 16, 2011 Author Share Posted June 16, 2011 Ok i changed the battery, oil, oil filter, air filter, fuel filter, and put seafoam in the gas to dry up any water that might be in there. The new battery wouldnt even turn the engine over.....i had to use the 300 amp jump start setting on a charger to even turn it over. After starting it the engine ran fair but i noticed that it hesitated from takeoffs and was sluggish just driving around my neighborhood, it never died or threw any codes but i still did a diagnostic on the ecu, it gave me code 34 Knock sensor. Why would it just now give me that code although i have ran it multiple times throughout the week? Also why would a new battery that tested 12.8 volts not turn over the engine without the jump start charger EVERY SINGLE TIME!?!?!? Any help? Im getting very frustrated at this thing lol. Link to comment Share on other sites More sharing options...
WarehouseRat Posted June 17, 2011 Share Posted June 17, 2011 even new battery's get dead cells if its a new good battery it should have a voltage higher then 13 volts, bad batterys can make all kinds of issues Link to comment Share on other sites More sharing options...
sewebster Posted June 17, 2011 Share Posted June 17, 2011 bad battery connection... Link to comment Share on other sites More sharing options...
denley Posted June 17, 2011 Author Share Posted June 17, 2011 I changed the battery terminals and no change, still had to have the jump start, also where about is the knock sensor located on the vg30e? Link to comment Share on other sites More sharing options...
sewebster Posted June 18, 2011 Share Posted June 18, 2011 I changed the battery terminals and no change, still had to have the jump start, also where about is the knock sensor located on the vg30e? On top of the block, under the intake manifold. Link to comment Share on other sites More sharing options...
denley Posted June 19, 2011 Author Share Posted June 19, 2011 I've seen a lot about relocating the knock sensor with a maxima harness, is this method reliable? Also do you think it's a waste of time for me to change it? It ran rough and terrible for a week before it gave me this code so I don't really want to spend the time and money doing the relocation if it's gonna do nothing but clear a code. Link to comment Share on other sites More sharing options...
sewebster Posted June 19, 2011 Share Posted June 19, 2011 I've seen a lot about relocating the knock sensor with a maxima harness, is this method reliable? Also do you think it's a waste of time for me to change it? It ran rough and terrible for a week before it gave me this code so I don't really want to spend the time and money doing the relocation if it's gonna do nothing but clear a code. My guess is you're only getting the code because your engine is running rough and terrible and tripping the knock sensor...Umm, there is a way to fool the ecu into thinking the sensor is always good by wiring up a resistor or something. If you could do that you could check if it solves all your problems and if so then you can relocate your sensor. If not, go back to finding some other issue. Maybe someone remembers where that resistor thing was written up? Link to comment Share on other sites More sharing options...
thehuntersam Posted June 19, 2011 Share Posted June 19, 2011 You could also try cleaning the MAF for kicks, changing out the fuel filter, or running some sort of cleaner through it as a last try. Like Marvel Mystery Oil, Sea foam, injector cleaner etc, just to see if that will clear some stuff up out of the engine. More than likely your electrical is not happy somewhere. Link to comment Share on other sites More sharing options...
denley Posted June 21, 2011 Author Share Posted June 21, 2011 I think I would rather just replace the knock sensor rather than try wiring up a resistor, I found a good deal on the sensor at a local parts store but where can I find the maxima harness? Also what year maxima does it need to be from? Link to comment Share on other sites More sharing options...
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