gcncsuhd Posted January 20, 2010 Share Posted January 20, 2010 My fiance has been having trouble with her 1997 Infinity Qx4 misfiring lately. The problem started about a month ago. Idle is fine, it seems to miss at part throttle while accelerating, but will cruise just fine until you try to accelerate slightly. At WOT it runs perfect. Also if she parks the car and comes back out a little while later it will start and idle fine, but stumble once it is put into gear. I checked codes and got a P300 Random Multiple Cylinder misfire. I have changed plugs, cap and rotor. I was going to change the wires also, but the new ones, Autolite, were about an inch too short on one cylinder so I returned them and have not gotten new ones yet, although the current wires seem to be in good condition. No arcing that I have found. Old plugs were in good shape and showed no sign of fouling/rich/lean conditions. I also cleaned the MAF sensor. I doubt it is a fuel pressure issue as I changed the fuel filter about 3 months ago, and it runs great at WOT. I have also run a bottle of Seafoam and injector cleaner through it as well. Any ideas? Thanks. Link to comment Share on other sites More sharing options...
180sx Posted January 20, 2010 Share Posted January 20, 2010 Timing comes to mind. How many miles? And have you chanegd the timing belt? Link to comment Share on other sites More sharing options...
gcncsuhd Posted January 20, 2010 Author Share Posted January 20, 2010 Timing comes to mind. How many miles? And have you chanegd the timing belt? 183,000 mi. Timing belt was last done around 120k I believe, by the previous owner. If it was timing, I would think the idle or WOT would be missing as well, it doesn't appear to have jumped timing. Link to comment Share on other sites More sharing options...
skulptr Posted January 20, 2010 Share Posted January 20, 2010 183,000 mi. Timing belt was last done around 120k I believe, by the previous owner. If it was timing, I would think the idle or WOT would be missing as well, it doesn't appear to have jumped timing. i'm havin a similar problem. out of gear it idles just fine, cruises fine, but sitting in gear at idle it runs rough. i havent pulled my codes yet, but i know my knock sensor is shot, might check on that as well Link to comment Share on other sites More sharing options...
Thunderbolt Posted January 21, 2010 Share Posted January 21, 2010 It's time for a tune up. Definitely sounds like plug wires and if you decide to replace the spark plugs go with the NGKS. They are the only ones that I would run in Japanese cars. Link to comment Share on other sites More sharing options...
fleurys Posted January 21, 2010 Share Posted January 21, 2010 (edited) If the problem seems to be sitting in traffic while in gear, wouldn't this be more pointing at the torque converter clutch selenoid ?? I<m thinking the TCC is trying to lock and causing the idle to almost die... Also it would fit with the symptoms you have 1) WOT ok = torque converter lock not on 2) cruise ok but not anymore when try to accelerate = on cruise the torque converter will lock, when you accelerate it will unlock (or at least try).. An easy test would be to unplug the TCC to see if the problem goes away...if it does , then you know what to change... just a thought.. Edited January 21, 2010 by fleurys Link to comment Share on other sites More sharing options...
gcncsuhd Posted January 21, 2010 Author Share Posted January 21, 2010 (edited) i'm havin a similar problem. out of gear it idles just fine, cruises fine, but sitting in gear at idle it runs rough. i havent pulled my codes yet, but i know my knock sensor is shot, might check on that as well The day before I changed out plugs/cap/rotor, I seafoamed the engine as well as ran some in the tank. That caused it to run somewhat rough for a short period of time, setting off a knock sensor code that has not come back. The only recurring code is P0300 Random multi cylinder misfire. It's time for a tune up. Definitely sounds like plug wires and if you decide to replace the spark plugs go with the NGKS. They are the only ones that I would run in Japanese cars. I did replace the plugs with NGK Platniums, (Pulled out Bosch Platniums that were still in good condition). The wires I bought (Autolite Professional) Did not fit on Cyl #1 as they were too short, so I have not yet had the time to get new ones and try them. I did run the engine in a dark room, and noticed no arcing, and the old wires were in very good condition. If the problem seems to be sitting in traffic while in gear, wouldn't this be more pointing at the torque converter clutch selenoid ?? I<m thinking the TCC is trying to lock and causing the idle to almost die... Also it would fit with the symptoms you have 1) WOT ok = torque converter lock not on 2) cruise ok but not anymore when try to accelerate = on cruise the torque converter will lock, when you accelerate it will unlock (or at least try).. An easy test would be to unplug the TCC to see if the problem goes away...if it does , then you know what to change... just a thought.. Doesn't do it sitting in traffic while in gear, only while easily accelerating. WOT is fine, and idle is fine in/out of gear EXCEPT sometimes right after starting, while still warm, it will stumble in gear for a couple seconds. Give it a bit of gas and let off and it smooths out. I will try unplugging the TCC. I'm assuming it's default would be to leave the TCC unlocked at all times when the solenoid is unplugged? Is the solenoid easily replaceable and where exactly is it located? I am currently 150mi at school, so it will be a couple weeks before I can actually get to her car to mess with it, but if it's a test as simple as disconnecting a solenoid I may be able to explain the process and location to her. (She is somewhat mechanically inclined ) Thanks for the help guys. Edited January 21, 2010 by gcncsuhd Link to comment Share on other sites More sharing options...
JUDGE Posted January 22, 2010 Share Posted January 22, 2010 Had a very similar situation with my car and it turn out to be a plug wire. After a very close inspection of the pulled wires, one of them had a cut in it that looked like it was done with a razor blade. The car ran perfect once the new wires were installed. HTH! Link to comment Share on other sites More sharing options...
fleurys Posted January 22, 2010 Share Posted January 22, 2010 i just looked, and it might be more difficult to disconnect the tcc solenoid than I thought... You actually need to flush the trans oil, and remove the transmission pan. Then you'll see 2 connectors (one for the oil temp, one for the tcc)... disconnect than reinstall pan, fill back the oil.... So maybe you're better off by re-looking your cables like judge said.....hope it works... S. Link to comment Share on other sites More sharing options...
Precise1 Posted July 1, 2010 Share Posted July 1, 2010 Damn, no reply as to the fix. I hate that... The wife's 1999 R50 is giving me a PO0301 misfire on cyl #1 code. Going through the forum via search first. I haven't checked anything yet because I worked 12 hours today and don't have it in me. Onward with the searching... B Link to comment Share on other sites More sharing options...
Tungsten Posted July 1, 2010 Share Posted July 1, 2010 i would guess its the injectors causing the random misfire one of them isn't injecting as much fuel as it needs to put some of that injector treatment in the tank my second guess would be something is funky with the ignition coil Link to comment Share on other sites More sharing options...
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