SpecialWarr Posted March 27, 2014 Share Posted March 27, 2014 After having spent a good part of my free time last summer under the hood, the transmission, the suspension, the brakes and the body of the new-to-me '90 Pathfinder (and first Nissan) I have run across something that is beyond my my to cope with..... I cannot figure out what is not working. To recall what I have done to the truck so far: new plugs and wires, cap and rotor, rear brake pads, one rocker panel and welded the rear sway-bar link back to the body. Replaced the TPS, added an additional ground to the MAF on the black center wire (not soldered yet, just Union-style twisted contact) and installed a Grant steering wheel. Earlier this week, I was taking an exit ramp off of the highway, I shifted into 2nd and used the brakes to slow down from 70km/hr, when I got to the stop light at the bottom of the hill the engine speed was at 950 to 1000 RPM while in gear at a full stop. I shifted into neutral and it jumped up to about 1500 and started to skip cylinders (I'm guessing that what it was since I'm not a mechanic) it sounded like a low-speed air compressor mixed with regular motor sounds. It stopped at the next light and the idle returned to 700 and jumpy, bouncing from 650-ish to 725. The motor sounds okay at speed, has decent power throughout the rpm range and still gets about 515 kms to the tankful with consistent consumption on my daily commute during the week. I took the timing light to it last night after I arrived home and while it was doing this phhhutt pphhhutt sound the idle was jumping from 700-ish to 1200 and the timing that I could see was going from -22 BTDC to +2 ATDC. I watched it for a few seconds and it switched back and forth from 700 RPM and -22 BTDC to 1200PRM and +2ATDC.... What am I not getting? I can't find anything on here about this particular problem so I hoping that someone can point me in the right direction.... I don't know what to look for or what to look at first, second or third. Please help a broke bicycle mechanic with an FSM that he doesn't know how to read (what is this H.S. and T.S. in that thing anyway!??) Link to comment Share on other sites More sharing options...
bushnut Posted March 27, 2014 Share Posted March 27, 2014 from one broke bicycle mechanic to another, from what I've been reading quite a lot of idle problems start with vacuum lines. that rough idle is often the engine not breathing proper or not getting regular fuel supply, so I would also check your exhaust manifolds for cracks. fuel pressure and filter. I'm not all that familiar with the vg30 engine so I'm guessing here as well. could be faulty knock sensor....just a few ideas to help you find a direction. in any case go through it one system at a time, just like when you're fixing a bike and it is calling you a Bit*$, take a brake walk away, come back and you usually find its a kinked cable, not a worn derailleur return spring like you feared. Link to comment Share on other sites More sharing options...
adamzan Posted March 28, 2014 Share Posted March 28, 2014 (edited) The timing is probably fine, it should advance when the revs go up. I would check for loose wires or connectors. Wiggle them and see what happens. I go to Montreal frequently so if you ever need a hand let me know. Edited March 28, 2014 by adamzan Link to comment Share on other sites More sharing options...
fixinto Posted March 28, 2014 Share Posted March 28, 2014 clean your MAF. also if you replaced the TPS, use the wide open throttle pins, and get out a multi meter and feeler gauges and make sure it does what is supposed to. after you get it where you want it, Plug everything back in and start it up. if the idle is hunting, let the warm up to operating temp then shut it off. Unplug the TPS and start it back up, let the idle settle down then plug it back in. Snap the throttle a few times then give it a week or so to learn the new idle set position. Before you do all of that be sure that the Fast idle cam isnt flaking out and is functioning properly or at least set to where its always at the lowest throttle position. hmmm thats about it, hopefully this puts you on the right track. Pat Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 28, 2014 Author Share Posted March 28, 2014 Thanks guys! Vacuum tubing is now done and no change, MAF was cleaned while I was doing the vacuum tubing tonight. The TPS was installed months ago and has been working flawlessly since. The only thing that I found suspect was #1 fuel injector connection was loose ( I repaired that last week just before this whole thing started). I pulled plug wires while idling and every one chaned the rhythm of the motor, the plugs are in since July last year when I set the gap by eye at 0.034".... :-) I've already ordered a fuel pressure regulator since it costs as much as the tool and I'll get another fuel filter to install at the same time (oops didn't mention that I installed a new sending unit in the tank two months ago); an IACV is also on the way from rockauto. Geez I sound like in worse shape than Mr.eViLdEaD.... at least he has real trouble. ...I just have a truck that sounds funny at idle. If anyone has any more ideas just throw them out and I'll happily take a run at it (blind enthusiasm and tools are a dangerous thing in my hands)!! sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
fixinto Posted March 29, 2014 Share Posted March 29, 2014 check clean or change your PCV valve. .....the issue is a "stumbling idle"? drops below normal and kindof hunts for the proper place? does it do it when its parked and you dont have your foot on the brake? or is your foot on the brake? or dont matter......turn your steering wheel hard one way while sitting still and watch your rpms u should get a couple of hundred rpm bump in it if your IAC is working. its like the quick dirty check so to speak. ......k running out of ideas.....may wanna revisit that injector wiring, was the wires damaged? or just a loose connector. hope somethin i said helps, at this point im kindof blindly throwin stuff out there that could even remotely effect the idle lol. pat Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 29, 2014 Author Share Posted March 29, 2014 (edited) The PCV is new-ish but I'll check it again, maybe it doesn't like the downshift off of the highway?fixinto: thanks for the ideas and help! The injector was just a loose connection, now the injector works.I had a terrible sleep last night but a moment of DOH! this morning!!! It occured to me that all of this started after goofing around with the truck two weeks ago. I wonder if I might have dislodged some junk in the gas tank?? Bunged up the fuel filter?? bushnut you are a genius! Now I just have to find a fuel filter.sent from under Ernest the Pathfinder Edited March 29, 2014 by SpecialWarr Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 29, 2014 Author Share Posted March 29, 2014 Alrighty, fuel filter installed but there is little change in the motor it still appears to be missing on at least one cylinder. The IACV drops the revs about 100-ish RPMs when the steering is at full lock and pulling on the wheel. Maybe one of the new plug wires is bad? 10-14 ohms says the Precise 1. ...so off to check those right now. sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 29, 2014 Author Share Posted March 29, 2014 Plug wires 123 and 5 are between 5.5 and 9.5 ohms..... 4 and 6 however are 1.25 ohms each..... I suspect that may be the funky mis-fire. And there goes another paycheque into truck parts. sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 30, 2014 Author Share Posted March 30, 2014 I see that these trucks are not common.... I can't get any parts at any of my usual places! I ordered NGK ignition wires from Rock Auto today and changed the new wires for 4 and 6 for my old ones which still work but I'm not hearing any real change to the tone of the motor, it doesn't mis-fire anymore though! BUT the truck appears to have lost power with the addition of two more operating cylinders. I think the next thing is to look for air leakage between the MAF and the O2 sensor again since I don't really know what else to do. I don't know if this is going to help but I pulled the neg. battery cable and I'm going to reattach it tomorrow. Maybe I can ask the ECU to do what I want. Link to comment Share on other sites More sharing options...
Precise1 Posted March 30, 2014 Share Posted March 30, 2014 Alrighty, fuel filter installed but there is little change in the motor it still appears to be missing on at least one cylinder. The IACV drops the revs about 100-ish RPMs when the steering is at full lock and pulling on the wheel. Maybe one of the new plug wires is bad? 10-14 ohms says the Precise 1. ...so off to check those right now. sent from under Ernest the Pathfinder I hope I didn't say that, the 10-14 ohms refers to the injector resistance test! Look in the FSM in the EC section, have you checked the ECU for stored codes? If so/there aren't any, keep reading under the diagnostic procedures, there is a whole series that talk about engine hunting, stumbling, etc and what diagnostic steps to take. Ask about anything you don't understand, but please reference a page or diagnostic... B Link to comment Share on other sites More sharing options...
adamzan Posted March 30, 2014 Share Posted March 30, 2014 Here are the specs for most things, including the ignition wires. Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 30, 2014 Author Share Posted March 30, 2014 Sorry for the misquote Precise 1. You are correct, 10-14ohms was for the injector resistance NOT the wire resistance.... I was pulling that from memory from the other topic. My bad! I seem to be missing that page from my FSM .... unless it's somwhere that I haven't read yet! I'm going to reattach the ground and take the truck for a short drive and see what codes I can get out of it today. I'll post up later this afternoon with some results. Thanks again for the help and pointers! sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
SpecialWarr Posted March 30, 2014 Author Share Posted March 30, 2014 Survey says: not a single code to be had after the drive around the city. Time to visit the rest of the injectors and check their connections but I'll wait until the IACV and fuel pressure regulator arrive for that.....or maybe I just think it sounds "off"?? I don't know. sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
fixinto Posted April 2, 2014 Share Posted April 2, 2014 (edited) U say that ur rpms dip 100ish lock to lock? I can put my pathy in neutral and turn the wheel about 15 degrees and get a bump UP 50 to 100 rpms. if its goin down maybe ur AICV isnt adjusting like it should. does your ride have evap could be a evap leak. misfire at low rpms that improves with rpm increase. runnin out of ideas here man, get er fixed lol. pat Edited April 2, 2014 by fixinto Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 2, 2014 Author Share Posted April 2, 2014 I didn't think to check the evap can. I did find the top rear passenger side exhaust stud in my hand two nights ago..... the top half anyway. Not my doing, I just heard something loose and metallic over the crap bearing whine and loose power steering belt. I did order an IACV which showed up today but I'll have to wait until the weekend to install it as I'm going to be doing the fuel regulator and confirming that -all- of the fuel injectors are good. March has been a busy month: truck issues, apartment issues, ex-fiancee issues, money issues.... I'm needin a vacation! sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 21, 2014 Author Share Posted April 21, 2014 I thought I would make a short video with the engine running and see if I could get a diagnostic from the hive mind here.... since I'm not a real mechanic... https://db.tt/v4ynsDoy Link to comment Share on other sites More sharing options...
PeteyPathy Posted April 24, 2014 Share Posted April 24, 2014 Double check that you haven't accidentally crossed up plug wires. Sounds to me like a timing issue. Sounds like at least 1 maybe 2 cyl are firing on wrong stroke. This will be less noticeable at higher RPM. Remember KISS! If last thing you did before it acted up was plugs and wires, 90% chance that's where problem lays. Or a wire you bumped/jiggled while doing plugs. Link to comment Share on other sites More sharing options...
Slartibartfast Posted April 25, 2014 Share Posted April 25, 2014 Hmm. A stumble at idle suggests a vac leak to me... if not a line, maybe a gasket or an injector O-ring. One cylinder runs lean at idle, the rest are fine, and you wouldn't notice under load (less vacuum to show off the issue). Another place air can leak in is through the rubber intake tube. If it has cracks in it (probably down below where you can't see them), it could suck air in and cause a stumble. I've read about this being an issue under load (when the engine twists around) rather than at idle, but you say this happened after a little wheeling and a bit of engine brake deceleration... long shot but maybe you've got a motor mount on its way out, and the engine rocked enough to open up a crack in the tube? Link to comment Share on other sites More sharing options...
PeteyPathy Posted April 25, 2014 Share Posted April 25, 2014 After some more thought on this one look for, any intake piping that are not seated correctly. Run your hand over or better yet separate and reconnect every junction. You may be suffering from whats called "unmetered air" make sure all clamps are tight and any hard plastic tubing is not cracked or split. Air entering intake system behind the MAF creates a lean running condition, basically not enough fuel for amount of air going in. ECU only provides fuel for air passing MAF. Any leaks computer can't account for. I have seen many cars drive owner crazy because of this simple problem. Good luck. Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 26, 2014 Author Share Posted April 26, 2014 Hmmm...unmetered air leak after the MAF...that could be a torn gasket then after I pulled the plenum or a hole in the intake tube.... it's cold today and looks like it's going to snow again this weekend (seriouly... it's f@$#ing late April!!) So I'm going to have to wait until it warms up to tear into it again. I'll keep posting up progress reports until I fix it or die trying!! Thanks for the pointers gents! sent from under Ernest the Pathfinder Link to comment Share on other sites More sharing options...
Precise1 Posted April 28, 2014 Share Posted April 28, 2014 Snow? It's supposed to be 90+ Tuesday, Wednesday and Thorsday After some more thought on this one look for, any intake piping that are not seated correctly. Run your hand over or better yet separate and reconnect every junction. You may be suffering from whats called "unmetered air" make sure all clamps are tight and any hard plastic tubing is not cracked or split. Air entering intake system behind the MAF creates a lean running condition, basically not enough fuel for amount of air going in. ECU only provides fuel for air passing MAF. Any leaks computer can't account for.I have seen many cars drive owner crazy because of this simple problem.Good luck. I find the best way to find an intake leak, after a visual/manual inspection of course, is to test specific lines/areas with a flammable aerosol (WD-40, carb cleaner, etc). If your idle surges when you spray, you have found a leak... B Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 28, 2014 Author Share Posted April 28, 2014 Yep... snow....last night at 3-ish when I was up there were flakes floating around! Would intake cleaner not be recommended? I have some sensor cleaner that lights up quite nicely ( :-)) but I also like the cleaning power of the intake clean. Link to comment Share on other sites More sharing options...
Precise1 Posted April 28, 2014 Share Posted April 28, 2014 That should work. I prefer something that either evaporates quickly or is quite benign like WD-40. Last thing you want is something oily that leaves a residue and maybe even negatively aggects the rubber lines. Stay warm Bud! B Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 30, 2014 Author Share Posted April 30, 2014 Found it! Secondary air tube that leads up and back towards the firewall had a split above the clamp. I chopped off a bit and pulled it down, set the old clamp in a new position and bingo! waaayy less "crap vehicle" sound.... waayy more "tuff truck" sound!!! Again, thank you gentle-folk for the help....beers on me when we meet! sent from under Ernest the Pathfinder 1 Link to comment Share on other sites More sharing options...
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