LQ4 280Z running TERRIBLE!!!
04-30-2009, 05:14 PM
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LQ4 280Z running TERRIBLE!!! I have had this problem for the past week or so and I am having trouble getting it fixed..
It started as a not REALLY bad problem, and progressed with time. It feels as if the coil packs could have gone bad, and now are misfiring VERY bad... I pulled all the plugs and checked them and they aren't brown, and they aren't white, but seem to be running a tad bit lean.. went ahead and replaced them all anyways.
Exhaust under throttle smokes black, and stinks like it is running way rich. The car has hardly any power, seems to run on 5-6 cylinders, and on the highway it will go from feeling like 4-5 cylinders worth of power and under moderate throttle, will just come out of it just a small amount and you can hear it start running on 6-7 cylinders.
I changed my coolant temp sensor, checked all my plugs and connections, checked all grounds, and still cannot shake this problem!!
Any suggestions?
It started as a not REALLY bad problem, and progressed with time. It feels as if the coil packs could have gone bad, and now are misfiring VERY bad... I pulled all the plugs and checked them and they aren't brown, and they aren't white, but seem to be running a tad bit lean.. went ahead and replaced them all anyways.
Exhaust under throttle smokes black, and stinks like it is running way rich. The car has hardly any power, seems to run on 5-6 cylinders, and on the highway it will go from feeling like 4-5 cylinders worth of power and under moderate throttle, will just come out of it just a small amount and you can hear it start running on 6-7 cylinders.
I changed my coolant temp sensor, checked all my plugs and connections, checked all grounds, and still cannot shake this problem!!
Any suggestions?
04-30-2009, 11:02 PM
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Checked for them and I had a malfunctioning coolant temp sensor, was reading -40*, I replaced it but do not know right now if that fixed the -40* issue.. it still runs like horse pewp.
I also have a DTC for something about an accessory? Cant remember exactly, but I didnt think it really had anything to do with my issue.
I also have a DTC for something about an accessory? Cant remember exactly, but I didnt think it really had anything to do with my issue.
05-01-2009, 03:17 PM
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Has anyone ever had coil packs go bad?
Driving it today, it seems like there is a variety of cylinders not firing at all under any kind of throttle, but there is a constant few cylinders that do fire.. I cannot tell which ones, and all primaries on the headers are hot, so i cant really determine which are and which aren't.
Put it this way, It hardly had enough power to pull itself up a long, very lightly sloped hill on the highway in 5th today..
Needing some help quick!
- Oh yeah, and if anyone could imagine a briggs n stratton 5 horse motor, thats exactly what it sounds like going down the highway
Driving it today, it seems like there is a variety of cylinders not firing at all under any kind of throttle, but there is a constant few cylinders that do fire.. I cannot tell which ones, and all primaries on the headers are hot, so i cant really determine which are and which aren't.
Put it this way, It hardly had enough power to pull itself up a long, very lightly sloped hill on the highway in 5th today..
Needing some help quick!
- Oh yeah, and if anyone could imagine a briggs n stratton 5 horse motor, thats exactly what it sounds like going down the highway
Last edited by Datsun350Z; 05-01-2009 at 03:37 PM.
05-01-2009, 09:01 PM
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All brand new plugs, old ones looked clean and somewhat lean. Not wet.
Computer was throwing a coolant temp sensor input code and was reading -40*F, so I replaced the sensor. Not sure if that has fixed it, haven't had a chance to throw my buddies scanner back on.
Wires are new.
Computer was throwing a coolant temp sensor input code and was reading -40*F, so I replaced the sensor. Not sure if that has fixed it, haven't had a chance to throw my buddies scanner back on.
Wires are new.
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05-02-2009, 01:16 PM
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Old plugs looked fine before and after the sensor change. After I changed the sensor is when I replaced all plugs. The plugs made no difference. Batt voltage is and always has been since I got the alternator issue figured out a long time ago, 14.xx volts under charge and 12.xx not charging.
05-02-2009, 02:24 PM
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This is a long shot, but I have had 2 local full size chevy trucks do this, the a/c condensate was dripping on the o2 wires and running down getting the inside of the plug wet, shorting it out I guess. They would run just as you described. If you unplugged the 02's it would run fine. I would have never thought the o2 circuit could have made it run that crappy, they would hardly pull themselves. You may check you wiring on the 02's, or just try unplugging them and see what it does. You may also want to check that your air intake temp sensor is reading right. That will make it pig rich too.
05-02-2009, 04:03 PM
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check the crank position sensor, located just above the starter. It could be bad, it should throw a code for it though. Worst case scenario is the reluctor wheel could be damaged. Unless you have had the crank out that is unlikely. The coil packs on these suckers are pretty good, I have never heard of one going bad.
Also check and make sure the starter positive wire from the battery hasnt welded itself to the headers/exhaust. I've had this happen and it ran but misfired randomly. When the headers cooled off, the wire sheilding would harden and create a barrier between the wire strands and header, but when the header got hot enough, it would melt again and arc like crazy.
Also check and make sure the starter positive wire from the battery hasnt welded itself to the headers/exhaust. I've had this happen and it ran but misfired randomly. When the headers cooled off, the wire sheilding would harden and create a barrier between the wire strands and header, but when the header got hot enough, it would melt again and arc like crazy.
05-02-2009, 07:43 PM
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If the PCM thinks the engine is running at -40F, it is going to go extreme rich. You need to check for DTC's again and check the wires going to the coolant temp. sensor. You should have a 5 volt reference key on.
05-03-2009, 05:34 PM
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I run speed density, so no 02's.
Just got the scan tool back and hooked up an in-car fuel pressure gauge.. ran 60psi all the way up to its coughing death of 5500rpm where it wont pull any farther.. and got pissed and held it longer and it even start revving down from 5500 at WOT!!! WTF!!
Coolant temp is perfect and the fuel pressure didnt move at all. Still running on multiple cylinders.
Just got the scan tool back and hooked up an in-car fuel pressure gauge.. ran 60psi all the way up to its coughing death of 5500rpm where it wont pull any farther.. and got pissed and held it longer and it even start revving down from 5500 at WOT!!! WTF!!
Coolant temp is perfect and the fuel pressure didnt move at all. Still running on multiple cylinders.
05-03-2009, 06:05 PM
#16
I run speed density, so no 02's.
Just got the scan tool back and hooked up an in-car fuel pressure gauge.. ran 60psi all the way up to its coughing death of 5500rpm where it wont pull any farther.. and got pissed and held it longer and it even start revving down from 5500 at WOT!!! WTF!!
Coolant temp is perfect and the fuel pressure didnt move at all. Still running on multiple cylinders.
Just got the scan tool back and hooked up an in-car fuel pressure gauge.. ran 60psi all the way up to its coughing death of 5500rpm where it wont pull any farther.. and got pissed and held it longer and it even start revving down from 5500 at WOT!!! WTF!!
Coolant temp is perfect and the fuel pressure didnt move at all. Still running on multiple cylinders.
If you yank the O2s, you're running open loop in which case your VE table better be tuned dead on. This requires a lot of dyno time with a wideband O2 monitoring your exhaust.
Who did your tuning?
05-03-2009, 06:07 PM
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ANOTHER UPDATE -
For some reason, I thought speed density was ran without a MAF or 02's
My car was tuned with the MAF plugged in?
I unplugged the MAF sensor and it started actually running a little bit better, but still had the repetitive miss and still starts choking out and stops pulling at 5500..
Chad at greenlight motorsports did my tuning.. he knew the MAF was on the car.. I honestly dont know much about tuning so I said - whatever - lol
The car did run great and the AF ratio was dead on when I had the wideband hooked up after the tune. The way the car misses, it sounds like an ignition - spark issue, not really in the tune. Its almost like the coil packs aren't getting enough power up top and they just aren't firing.
For some reason, I thought speed density was ran without a MAF or 02's
My car was tuned with the MAF plugged in?
I unplugged the MAF sensor and it started actually running a little bit better, but still had the repetitive miss and still starts choking out and stops pulling at 5500..
Chad at greenlight motorsports did my tuning.. he knew the MAF was on the car.. I honestly dont know much about tuning so I said - whatever - lol
The car did run great and the AF ratio was dead on when I had the wideband hooked up after the tune. The way the car misses, it sounds like an ignition - spark issue, not really in the tune. Its almost like the coil packs aren't getting enough power up top and they just aren't firing.