ejin4499 Posted April 30, 2011 Share Posted April 30, 2011 (edited) Ok so I rebuilt a vg33 and put it into my 95 pathfinder(first time rebuilding an engine). It ran a little rough at idle but as soon as it got some gas it flew. Also tach is a little goofy but the tach was goofy when I got it. So I get it to a smog station do the pre test and find out my nox, at 15 mph in second gear, is over 1500 ppm 5 times the limit but it recovers at 25mph to 61 ppm. Did a little research found a couple things on the forum to check out one of wich is the egr system. Looked up the different things that the egr and bpt valves are supposed to do and found out my truck isn't doing them. Namly supply vacuum to the egr valve to keep it open under certain conditions. At idle there is no vacuum going to the egr valve. ok fine there isn't supposed to be. When I get to cruising speed 55 mph still no vacuum. I checked the lines, all clear. I tested the silenoid all lines clear on that and it opens with 12 volts. Checked the valves those hold vacuum for 20 second no problem. I am getting 12 volts from the plug on the silenoid constantly. The only thing I can think of is that 1 I am not getting enough vacuum from the air intake in order to open the valve at low rpm. I am not getting any vacuum from this at all not matter how high I rev it. 2 the selinoid is never cutting out to allow the main vauum connection to open the egr valve. I am at a total loss any ideas on what I am missing or should I be looking at my cooling or fuel supply. Thanks Edited April 30, 2011 by ejin4499 Link to comment Share on other sites More sharing options...
thehuntersam Posted April 30, 2011 Share Posted April 30, 2011 I have the vg33 swap in my 90 and it's off about 5mph too, but I have 33 superswampers on it as well so that for sure doesn't help. I had no smog problems on mine. Did you reset your ecu? I did a few test on it once I got the engine in so you may want to check that. How old is your cat? Link to comment Share on other sites More sharing options...
ejin4499 Posted April 30, 2011 Author Share Posted April 30, 2011 (edited) I have the vg33 swap in my 90 and it's off about 5mph too, but I have 33 superswampers on it as well so that for sure doesn't help. I had no smog problems on mine. Did you reset your ecu? I did a few test on it once I got the engine in so you may want to check that. How old is your cat? Hey thanks for the reply but I'm not having any speedo problems. My problem relates to how much NOx I am making at 15 mph. How do I reset my ecu I haven't seen anything about doing that in any of the swap guides that I looked at? I think my cat is good cause my HC is waaaaaayyy low and at 25 mph my NOx drops to 21 ppm. Edited April 30, 2011 by ejin4499 Link to comment Share on other sites More sharing options...
Tungsten Posted April 30, 2011 Share Posted April 30, 2011 Does your truck make snapping noises on acceleration? It is probably the BPT valve. Mine has been doing that forever. Link to comment Share on other sites More sharing options...
ejin4499 Posted April 30, 2011 Author Share Posted April 30, 2011 Does your truck make snapping noises on acceleration? It is probably the BPT valve. Mine has been doing that forever. Na no snapping noises. Tried disconnecting that and using that connection for the vacuum gauge and still no vacuum. Link to comment Share on other sites More sharing options...
thehuntersam Posted April 30, 2011 Share Posted April 30, 2011 It's not really resetting it but run the diagnostic on it once. Like as if you were pulling a code, then put it back into the normal mode and see if that works. Link to comment Share on other sites More sharing options...
ejin4499 Posted May 1, 2011 Author Share Posted May 1, 2011 I have the vg33 swap in my 90 and it's off about 5mph too, but I have 33 superswampers on it as well so that for sure doesn't help. I had no smog problems on mine. Did you reset your ecu? I did a few test on it once I got the engine in so you may want to check that. How old is your cat? Hey did you have any idle issues when you put your vg33 in? Which injectors did you use? Link to comment Share on other sites More sharing options...
sewebster Posted May 1, 2011 Share Posted May 1, 2011 NOx can be caused by overadvanced ignition timing and lean fuel/air mixture in addition to EGR problems (plus bad cats or combustion chamber deposits). Link to comment Share on other sites More sharing options...
ejin4499 Posted May 1, 2011 Author Share Posted May 1, 2011 (edited) NOx can be caused by overadvanced ignition timing and lean fuel/air mixture in addition to EGR problems (plus bad cats or combustion chamber deposits). using a timing light I am at 15 degrees. I think. Started vacuum testing all the parts of the upper intake think I found a vacuum leak (which could cause lean running at low rpm) the poor beat up hose that goes to the fuel pressure regulator, wich may also explain my rough idle. Edited May 2, 2011 by ejin4499 Link to comment Share on other sites More sharing options...
thehuntersam Posted May 2, 2011 Share Posted May 2, 2011 (edited) Hey did you have any idle issues when you put your vg33 in? Which injectors did you use? I used the VG33 injectors, but every now and then it will idle high as it warms up. Other than that, never any problems with it. Be sure to do a full tune up on it. Once I had the engine in, I didn't have the chance to tune it up for 2 days, just drove it up the block and it ran like crap but once it was tuned nicely, no problems. Edited May 2, 2011 by thehuntersam Link to comment Share on other sites More sharing options...
Alkorahil Posted May 3, 2011 Share Posted May 3, 2011 (edited) using a timing light I am at 15 degrees. I think. If your vehicle is automatic, make sure you do the test light with the vehicle in neutral. (and parking brake on) Started vacuum testing all the parts of the upper intake think I found a vacuum leak (which could cause lean running at low rpm) the poor beat up hose that goes to the fuel pressure regulator, which may also explain my rough idle. Yes, that vaccum hose would definately cause the vehicle to be cranky at idle. Edited May 3, 2011 by Alkorahil Link to comment Share on other sites More sharing options...
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