davem1111 2,030 #1 Posted April 24, 2023 Since I know there are a lot of people here who work on things other than tractors, I thought it was worth a try to see if anyone has any ideas with this problem. I have a 2007 Nissan Quest minivan with a transverse 3.5L V6. It started throwing codes for the #1 cylinder misfiring and running rough. For those who know these or similar engines, #1 (& #3 and #5) is in the back toward the firewall. To get to these to change the coil packs or spark plugs, you have to remove a bunch of stuff then remove the intake manifold = major pain in the rear. But I had done these before so I wasn't afraid of it. It took me about 2-1/2 hours to get to the point where I could swap the coils out. Unfortunately the last time I was in there, I just took all the ones that had tested "good" from the front and moved them to the back, since singles of these were about $75. I did replace all the spark plugs then though. In the meantime, I had found a deal on a six pack of coils for around $125 so I bought them and had them on hand, just in case. I replaced all 3 coil packs in the back and put almost everything back together (intake back on, all wires and hoses reconnected), so I could test run the engine before putting the rest back together. Now the engine starts and seems to run as expected above 2-3K RPMs, but dies on idle. Oddly it does not throw any codes. I double-checked that I reconnected everything properly, and everything looks good, but it's possible that I either missed something where I can't see it well or knocked something loose while getting the intake back on. [Probably unrelated but possibly: I had replaced the fuel pump a few months ago because the fuel level indicator wasn't working right. Then last week it started throwing codes for the fuel temperature gauge. When I tested the temp sensor it tested bad, so I replaced that sensor with the one from the old pump that I still had. Everything was fine after that, until it started with the P0301 code for cylinder #1] Is there something that needs to be done to reset the ECU after something like this? Battery was disconnected during this work. What is likely to be malfunctioning to cause the engine to run like this? It feels like it's firing on all 6 at higher RPMs, but feels like a lot of misfires at lower RPMs and won't idle. Maybe I should have tested the new coils on one of the front cylinders before going into the back, but it's too late for that now. I fear that if I pull it all apart again and put the OLD coils back in the back cylinders (except for #1 - no point in putting that one back in when it was throwing codes, but I may have another old "known good" spare, or could use one of the known good front ones...) then put it all back together, which takes a few hours, I'll be in the same boat I'm in now. I know this thing is old but it's only got about 180K miles, doesn't burn oil, and I've done a lot of other work on it too. My son has been driving it to school since February and I drove it for a few years before that. I'd like to get a few more years out of it, if possible. Any ideas? Share this post Link to post Share on other sites
ri702bill 8,316 #2 Posted April 24, 2023 7 hours ago, davem1111 said: and put almost everything back together Did you reinstall AND hook up the Mass Airflow Sensor......??? 2 Share this post Link to post Share on other sites
Pullstart 62,840 #3 Posted April 24, 2023 when you had it apart this time did you check your plugs? One or more could be cracked as well. They misfire at idle, but seem to bump right along at higher rrrrrs. 2 Share this post Link to post Share on other sites
ri702bill 8,316 #4 Posted April 24, 2023 (edited) Kevin brings up an excellent point - you were 98% of the way there to pull the plugs..... if they had a lot of miles on them, time to give them the quick toss.... Oh, how it burns my butt to go have to revisit an issue when I was that close to fixing it the first time ........ Edited April 24, 2023 by ri702bill 1 1 Share this post Link to post Share on other sites
davem1111 2,030 #5 Posted April 24, 2023 5 hours ago, ri702bill said: Did you reinstall AND hook up the Mass Airflow Sensor......??? I don't think I touched the MAF because I think it is to the right of the intake inlet, but I'll check. As I said, I'm pretty sure I put everything back where it was... 1 Share this post Link to post Share on other sites
davem1111 2,030 #6 Posted April 24, 2023 4 hours ago, Pullstart said: when you had it apart this time did you check your plugs? One or more could be cracked as well. They misfire at idle, but seem to bump right along at higher rrrrrs. I had replaced all the plugs the last time I was in there, several years ago. Guess I should check those again too, and for the cost, it makes sense to just throw new ones in there while it's open. 2 Share this post Link to post Share on other sites
ri702bill 8,316 #7 Posted April 24, 2023 1 hour ago, davem1111 said: I had replaced all the plugs the last time I was in there, several years ago. And double check the gap prior to installing.... As Willie sang..... "On the road again, can't wait till I'm on the road again".... 1 Share this post Link to post Share on other sites
davem1111 2,030 #8 Posted April 24, 2023 2 hours ago, ri702bill said: And double check the gap prior to installing.... As Willie sang..... "On the road again, can't wait till I'm on the road again".... Yeah, that reminded me that I did actually have to gap some of those, even though what I was reading told me that the Iridium plugs came "pre-gapped". Duh. And I need to get a new feeler gauge... 1 Share this post Link to post Share on other sites
squonk 41,079 #9 Posted April 24, 2023 A misfire can come from more places than just an ignition system. Bad injector or a vacuum leak at one cylinder. Back in the day, Oldsombile V-8's were known for a ruptured vacuum hose that supplied vacuum to the cruise control. The port was on 1 intake runner so that cylinder was too lean and it would skip at idle. Driving down the road you never felt it except the cruise didn't work. 3 Share this post Link to post Share on other sites
davem1111 2,030 #10 Posted May 1, 2023 Update: Bottom line, the car is running fine again. I ended up buying another set of 6 coil packs (ENA brand) and 6 NGK iridium spark plugs. Took the intake plenum off again and replaced all 3 plugs and coils in the back, put in a new plenum gasket and put it back together, and also replaced the vacuum lines. WTH? The plenum was leaking, making a very high pitched whistle. Maybe I torqued the bolts wrong or too much, or it was just a crappy gasket. Took it apart and put the OLD gasket back on. No more loud whistle and the car ran well, but there was a whistle toward the back now. Turned out I had loosened the bolts on the back of the plenum to the metal section that feeds in from the MAF, thinking I would need to take that off but didn't, and forgot to re-tighten those bolts. Tightened them up and everything is fine. I didn't change out the front 3 coils or plugs, because they weren't in there more than a couple years and are still working, and it only takes about 5 minutes to swap those out. I think I've gotten very good at removing and re-installing the intake plenum on a 3.5L Nissan V6 now. But hope I never need to do it again. Share this post Link to post Share on other sites
