shaggy Posted September 10, 2015 Share Posted September 10, 2015 Hi guys, I'm hoping for some suggestions for my old Pathy. My vehicle has 210,000 miles and ran reliably till now. This problem started out of the blue two weeks ago: After sitting overnight or through the day, with a short run (4-5 miles) the vehicle runs perfectly. If run during the middle of the day, esp. in high heat, or when driven for long enough to get to fully warmed up (it's not overheating AFAICT) she starts faltering right at or just before 2500 rpm--a bad farting misfire on several cyls--and she just won't rev any higher. BUT if I ease off on the throttle, she'll cruise around town at around 2000-2200 rpm just fine.Since this began, I've changed the plugs, the dist. cap (was toast) and rotor, fuel filter (was dirty),air filter, oil/oil filter. Have new plug wires and a new O2 sensor on the way. Cleaned the MAF sensor and checked electrical connections and vacuum hoses. All look good. There is a rattle in the vicinity of the AC pump, which seems to go away after awhile. I had a new muffler put on two weeks ago. Once when the miss was occurring I smelt bad sulphur, but not again since that time.ECU fault code mode III reads a consistent 34 = 'detonation sensor', but the engine check lightdoes not come on. Mode I is green/red both lit, mode II is green only. This seems to indicate the computer thinks the fule mixture is OK (I think). When the miss is happening, putting foot to floor does not improve anything. On the other hand (once revs are lowered) there's no sense that the engine is going to completely die on me. (That's the only good thing about this--the fact that I can still drive it around while attempting a diagnosis(!)Someone has suggested the fuel tank strainer. I am skeptical of that, but who knows. I've read so many posts like this where hundreds of dollars worth of parts could not fix the problem--and I can't afford to throw too many more parts at it in any case.That's all I can think of right now. Any new input would be very much appreciated. I'm getting desperate, as this vehicle is my work truck, and I am near broke(!) Update: actual rpm of trouble seems to vary somewhat lately. Also seems more hesitant to start when warm--even failed to start once, until I waited and tried repeatedly. For what it's worth, pulling 02 sensor connector when problem is happening does not cure the misfiring. Thanks for any suggestions!Shaggy Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 cts ? Coolant temp sensor for ECU ? Fuel Pump ? Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 cts ? Coolant temp sensor for ECU ? Fuel Pump ? Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 (edited) cts ? Coolant temp sensor for ECU ? Fuel Pump ? Hi BendRed--Thanks for your input! What's the egr? I'll check the temp sensor. I did consider the fuel pump, though I wonder why it would be a problem only when engine is fully warmed up... Is there an access hatch, or do I need to drop the fuel tank? Could it be the EGR, or associated bits? Could it be the MAF (even though I sprayed the electrodes clean?) I'm thinking fuel starvation, as I never smelt gas so far. Injector system? Hope not. I keep going back to why only when it's warmed up...? Thanks again Dave Edited September 10, 2015 by shaggy Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 (edited) Hi BendRed--Thanks for your input! PS -- Me (quote): "What's the egr?" (duh!) ...sorry-EGR, yep. Could be. Will have to clean and check it. Thanks Dave Edited September 10, 2015 by shaggy Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 Update: ECU mode III now gives code 21: 'ignition signal missing in primary coil'. This is after yesterday's failure to start. Could this be the ignition coil switching transistor? Or crank position indicator? thanks Dave Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 EGR - exhaust gas re circulation valve. All the components were talking about are monitored by the ECU so logic would dictate if there was a fault in them , even once warm (meaning the car has gone thru a run cycle and all sensors have kicked in and CTS has told the ecu to lien out the mixture due to the fact that coolant temps are at operating specs ) that there should be fault codes. If none exist then its a non monitored item ..... like a fuel pump. Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 Crank position sensor has its own code ... but crank position failure can make a no start issue since it sends the pulse to the ecu that the motor is turning and the fuel pump needs to send the motor some gas Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 You need to perform a fuel pressure test and rule out the fuel pump. Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 EGR - exhaust gas re circulation valve. All the components were talking about are monitored by the ECU so logic would dictate if there was a fault in them , even once warm (meaning the car has gone thru a run cycle and all sensors have kicked in and CTS has told the ecu to lien out the mixture due to the fact that coolant temps are at operating specs ) that there should be fault codes. If none exist then its a non monitored item ..... like a fuel pump. Thanks Red--did you see now I have code 21 'ignition signal missing in primary coil' --bad switching transistor, maybe? I know what you said about the ECU, this should have been indicated before...but(?) Still hoping for a simple fix... thanks Dave Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 You need to perform a fuel pressure test and rule out the fuel pump. OK--thanks, will do. Dave Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 Crank position sensor has its own code ... but crank position failure can make a no start issue since it sends the pulse to the ecu that the motor is turning and the fuel pump needs to send the motor some gas Thanks. She's starting OK again if not out in extreme heat. One thing I notice is, sitting and revving motor, then taking foot off gas pedal-- it seems slow to settle back to idle. What I'd like, next time it starts to misfire, is to be able to monitor things while driving. Maybe an LED ignition timing indicator--then I could see right away if it was spark-related or not. Will have to drive somewhere to borrow a fuel pressure gauge, that's the only issue with that... Dave Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 possible distributor issue ..... Link to comment Share on other sites More sharing options...
BendRed Posted September 10, 2015 Share Posted September 10, 2015 Dont know if you have a Harbor freight there but you can buy a fuel pressure set there for $30 or less. Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 possible distributor issue ..... Only thing no replaced there is the crank sensor electronics, or maybe a dirty disk(?) Worth a look? Link to comment Share on other sites More sharing options...
shaggy Posted September 10, 2015 Author Share Posted September 10, 2015 Dont know if you have a Harbor freight there but you can buy a fuel pressure set there for $30 or less. ~20 miles away, both of them 8>/ Dave Link to comment Share on other sites More sharing options...
shaggy Posted September 11, 2015 Author Share Posted September 11, 2015 possible distributor issue ..... Update: Looking the engine over this afternoon, found a loose ground lead, fixed it--don't think it was the problem. Checked again for bad connections and cracked hoses--found nothing obvious. Tried plugging/unplugging a few connectors with the engine running, just to see what happened. Took it for a spin and it seemed to be just the same, a little better...maybe. Then....came out an hour later, turned the key, and she belched and farted and misfired so bad I thought the timing belt must have slipped 8>/ The vehicle's undriveable now. What the heck happened? Seems like something finally gave up the ghost. 8>/ Hate to suggest this, but maybe 200,000+ miles is just too near the end of the road. On the other hand, maybe the fuel pump just quit... I really dunno anymore! I'll have a fresh look in the morning... Dave Link to comment Share on other sites More sharing options...
BendRed Posted September 11, 2015 Share Posted September 11, 2015 just do a fuel pressure test and be done with that theory . then move on ........ Link to comment Share on other sites More sharing options...
shaggy Posted September 11, 2015 Author Share Posted September 11, 2015 just do a fuel pressure test and be done with that theory . then move on ........ Yeah, thanks. Will check it when I can, but getting hold of a fuel pressure gauge ain't possible right now. Fuel seemed to be getting through OK yesterday when I checked, anyhow. After sleeping on it, I think... from the suddenness and craziness of the new misfiring -- like the timing went nuts on all cyls-- I'm thinking crank position sensor. Will report back later... I gotta get to a lift to work! 8>/ Dave Link to comment Share on other sites More sharing options...
richardcox4 Posted September 11, 2015 Share Posted September 11, 2015 What I'd like to do is offer you $500 for your vehicle and then once you hand me the keys and the title take the two minutes it's gonna take to make this fix for you and then drive it home but that's not gonna happen because you sound kind of determined to get this thing fixed so here's what you need to do. Go to the positive battery terminal where all those plastic connections are right by the positive cable you'll notice that one of the connections that has a thick gauge wire (not as big as the battery cable) I don't know it's a thick wire but not too thick that wire is going to be crusty and crunchy inside it's plastic housing. what's happening to your vehicle is that your engineControl unit is not getting 12v power so clean those connections really really good and then your pathfinder will be right back in business. Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
shaggy Posted September 11, 2015 Author Share Posted September 11, 2015 (edited) What I'd like to do is offer you $500 for your vehicle and then once you hand me the keys and the title take the two minutes it's gonna take to make this fix for you and then drive it home but that's not gonna happen because you sound kind of determined to get this thing fixed so here's what you need to do. Go to the positive battery terminal where all those plastic connections are right by the positive cable you'll notice that one of the connections that has a thick gauge wire (not as big as the battery cable) I don't know it's a thick wire but not too thick that wire is going to be crusty and crunchy inside it's plastic housing. what's happening to your vehicle is that your engineControl unit is not getting 12v power so clean those connections really really good and then your pathfinder will be right back in business. Sent from my iPad using Tapatalk Ha-ha! I probly would have taken your $500 last night I was that peed off! Unfortunately I've already checked and sprayed all those connectors with contact cleaner to no avail 8>/ None of them looked particularly cruddy, either. The ECU is still spitting out code 34 (detonation sensor) in fault mode III. To cap it off, she started and ran fine just now after sitting all night. No sign of the crazy missing today. So it's truly an intermittent PITA. One thing, there was a lot of banging and flapping around the driver's side of the engine bay--under the EGR and such. I know for sure I've got a few loose or stripped exhaust manifold studs that never got fixed, so maybe they've gotten to the point of causing a problem(?) You're right about one thing though--I'm determined to try and fix this. There's at least another 100K in this baby! 8>] Thanks for you time so far, and any other suggestions... Dave Edited September 11, 2015 by shaggy Link to comment Share on other sites More sharing options...
shaggy Posted September 11, 2015 Author Share Posted September 11, 2015 (edited) Ha-ha! I probly would have taken your $500 last night I was that peed off! Unfortunately I've already checked and sprayed all those connectors with contact cleaner to no avail 8>/ None of them looked particularly cruddy, either. The ECU is still spitting out code 34 (detonation sensor) in fault mode III. To cap it off, she started and ran fine just now after sitting all night. No sign of the crazy missing today. So it's truly an intermittent PITA. One thing, there was a lot of banging and flapping around the driver's side of the engine bay--under the EGR and such. I know for sure I've got a few loose or stripped exhaust manifold studs that never got fixed, so maybe they've gotten to the point of causing a problem(?) You're right about one thing though--I'm determined to try and fix this. There's at least another 100K in this baby! 8>] Thanks for you time so far, and any other suggestions... Dave The new set of plug wires (Beck-Arnley, US-made) just arrived, so I put 'em in not expecting a miracle, but she seemed to run much better...at least for a few times around the block. Clean thru 4-5000 rpm, no missing, but then it started again, just faintly at first, but it's the same miss, starting around 2500 rpm If she's driveable tonight and I make it home I'll go by the parts store in the morning and use their fuel pressure gauge. thanks guys--have a good weekend Dave Edited September 11, 2015 by shaggy Link to comment Share on other sites More sharing options...
Slartibartfast Posted September 12, 2015 Share Posted September 12, 2015 If something in the driver's side of the engine bay is loose enough to bang around, even if it's not causing the problem on its own, it could be setting off your knock sensor. It's just a little piezo deal under the intake manifold that sends a signal when the engine vibrates, so if something's banging around against the outside of the motor, the knock sensor could well be picking that up instead. Good luck! Link to comment Share on other sites More sharing options...
shaggy Posted September 15, 2015 Author Share Posted September 15, 2015 (edited) If something in the driver's side of the engine bay is loose enough to bang around, even if it's not causing the problem on its own, it could be setting off your knock sensor. It's just a little piezo deal under the intake manifold that sends a signal when the engine vibrates, so if something's banging around against the outside of the motor, the knock sensor could well be picking that up instead. Good luck! Thanks, I'm confident I'll track it down, but it might take some time. I'm on a job right now so won't be able to spend as much time as I'd like working on the truck. It's still driveable for the 3-4 miles to work. If I'm easy on the gas, it only barley starts to misfire. Meanwhile, I'd like some advice... I thought I might get myself a decent OBDI/II scanner (I believe I need OBDI for a '95 Pathy, right?). Any recommendations? (Preferably under $150). Also, with all the misfiring I've been having, does anyone think it odd that the engine check light has never come on? Thanks Dave Edited September 15, 2015 by shaggy Link to comment Share on other sites More sharing options...
BendRed Posted September 15, 2015 Share Posted September 15, 2015 If ist not a metered item (sensor) then no. Link to comment Share on other sites More sharing options...
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