Stumbling/hesitating, running out of options (2 Viewers)
- Thread starter arcteryx
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arcteryx
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- Thread starter
- #22
Well, I pulled the plugs and wires again. #3 shows no signs of combustion and had a small amount of oil on it. These have maybe 50 miles on them. #3 is the bottom one. You can see how white the tip is compared to the carbon on #4. I confirmed with my spark plug tester that there is spark. Closer but still unsolved..... I am thinking it's the injector, will test that in the next day or two.
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Is spark plug #3 cracked? Maybe move to another location and try again to see if it follows the plug or if it is cylinder specific. Will help isolate condition.
No Check Engine light?
I had a similar issue. Had a fuel injector that was not atomizing properly. Had my injectors serviced, and no more issue.
I had a similar issue. Had a fuel injector that was not atomizing properly. Had my injectors serviced, and no more issue.
oem plug wires? or aftermarket? if aftermarket i would check resistance on that #3 wire if not already done. if oem i wouldnt sweat it.
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Ok rotor and cap, check them, even try different ones, they can have a dead spot, also the plug/wire sending signal to injector #3
If you think its specific to one cylinder try disconnecting one spark plug wire at a time while the engine is running (at the cap & rotor). The one that doesn't make a change when disconnected is where the issue is (fuel, spark, compression, bad valve, etc...).
I still think its in the injector wiring by the EGR. I did all the same things you are doing (new plugs, air filter, fuel filter, plug wires, ran a bunch of injector cleaner through) and none of those solved the problem. On the plus side once I repaired the wiring I had a fresh tuneup already complete and it ran smoothly.
I still think its in the injector wiring by the EGR. I did all the same things you are doing (new plugs, air filter, fuel filter, plug wires, ran a bunch of injector cleaner through) and none of those solved the problem. On the plus side once I repaired the wiring I had a fresh tuneup already complete and it ran smoothly.
I had an intermittent hesitation under load which turned out to be my upstream fuel/air mixture oxygen sensor. The bad sensor tested fine and within specs on the FSM inspection for resistance. The problem mystified me for over a year and I could not get the problem to recreate itself while with the mechanic. One day I replaced the sensor during lunch and since then the truck has run beautifully.
My conclusion is the oxygen sensors are wear items which should be replaced at this point if original. I don't like to throw parts at problems, and in this case I was replacing a sensor which was testing fine. However, doing so solved my problem and cost me $45 and 30 minutes.
These trucks are old and sometimes ferreting out the problem is difficult. I hope your post and mine help some other Mudders, and that you solve your problem soon.
Good luck.
My conclusion is the oxygen sensors are wear items which should be replaced at this point if original. I don't like to throw parts at problems, and in this case I was replacing a sensor which was testing fine. However, doing so solved my problem and cost me $45 and 30 minutes.
These trucks are old and sometimes ferreting out the problem is difficult. I hope your post and mine help some other Mudders, and that you solve your problem soon.
Good luck.
I think listening to the injectors is a good idea. If you can get it to misfire with the hood open. Then pull one plug wire at a time on the distributor and see which wire is pulled that doesn't change the misfire-thats then you suspect cylinder. Careful, you may get shocked if you don't use plug wire pliers.
I've had similar issues with a yota mini truck that sat for years. Rust in tank, lines, filter, injectors. But it sounds like youve gone through that stuff and it's been running for years already
Update?
I would do a leak down test.
I am having a similar problem with my 95.
details:
Stock rig, lifted with 35's
EGR removed the mostly toyota way (no resistor mod, so I had a CEL on for that code)
Exhaust reworked, with both 02 sensors intact and a magnaflow cat as a replacement)
Plugs wires cap rotor replaced about a year ago
vac lines good, air intake tube good
Ran perfectly no issues for about 4 years since the above mods (except the CEL for the EGR) - ran good going to work 30 miles from home. Coming home from work Wed about 15 min into the trip, it felt like it had no power. Got to the gravel road and at 2k it has a stumble when you are in drive giving gas, seems like it has zero power. If you hit it WOT it will take off and move like it should.
So I suspected fuel Filter as I never replaced it - Replaced that and did the resistor mod for the EGR since It was in the shop.
Went to clear the code for the EGR and I had a PO133 and P0133 which I never had before (play with the scangauge quite a bit in it). Possibly this triggered from the stumbling ect?
I suspected the Front 02 sensor might be on its death bed, but I cleared all the codes out and went for about an hour ride (disconnected the battery). No codes, running it with the scanner plugged in, 02 sensors appear to be working like they should.
If I sit in the rig with it in park or neutral and rev it, it goes to 4k, with no hesitation. Hit the throttle and it rev's up and idles down like it should. Put it in drive and it stumbles at 2K.
Next step is the NSS to pull that apart and check that and the TPS and the fuel pump relay. I don't suspect the wiring harness by the EGR as if it had bad wires, that should of came up already as the EGR has been gone for 4 years
If that doesn't fix it, I suspect it is the sock in the fuel tank. I had a 93 that did Almost the same exact thing as this years ago that had a chevy 350 conversion. Would run great at idle, and rev to the moon, once under power it would not want to rev and felt like it was trying to pull a loaded car trailer behind it. Ended up the Sock was Plugged in the fuel tank. After I replaced it, it was good to go.
My bet is on the fuel pump sock or fuel pump as my rig has 307K on it and I bet its the original pump and sock. Won't try that until I order a new one, if the NSS TPS and relay don't take care of it.
When you did the new fuel pump/sock did you use a Denso or a different brand?
I guess if it isn't the sock/fuel pump, my next guess is the upstream o2 sensor, but you think the codes would come back if it was bad?
Anyways, hope this helps and I'll post what ended up fixing it.
details:
Stock rig, lifted with 35's
EGR removed the mostly toyota way (no resistor mod, so I had a CEL on for that code)
Exhaust reworked, with both 02 sensors intact and a magnaflow cat as a replacement)
Plugs wires cap rotor replaced about a year ago
vac lines good, air intake tube good
Ran perfectly no issues for about 4 years since the above mods (except the CEL for the EGR) - ran good going to work 30 miles from home. Coming home from work Wed about 15 min into the trip, it felt like it had no power. Got to the gravel road and at 2k it has a stumble when you are in drive giving gas, seems like it has zero power. If you hit it WOT it will take off and move like it should.
So I suspected fuel Filter as I never replaced it - Replaced that and did the resistor mod for the EGR since It was in the shop.
Went to clear the code for the EGR and I had a PO133 and P0133 which I never had before (play with the scangauge quite a bit in it). Possibly this triggered from the stumbling ect?
I suspected the Front 02 sensor might be on its death bed, but I cleared all the codes out and went for about an hour ride (disconnected the battery). No codes, running it with the scanner plugged in, 02 sensors appear to be working like they should.
If I sit in the rig with it in park or neutral and rev it, it goes to 4k, with no hesitation. Hit the throttle and it rev's up and idles down like it should. Put it in drive and it stumbles at 2K.
Next step is the NSS to pull that apart and check that and the TPS and the fuel pump relay. I don't suspect the wiring harness by the EGR as if it had bad wires, that should of came up already as the EGR has been gone for 4 years
If that doesn't fix it, I suspect it is the sock in the fuel tank. I had a 93 that did Almost the same exact thing as this years ago that had a chevy 350 conversion. Would run great at idle, and rev to the moon, once under power it would not want to rev and felt like it was trying to pull a loaded car trailer behind it. Ended up the Sock was Plugged in the fuel tank. After I replaced it, it was good to go.
My bet is on the fuel pump sock or fuel pump as my rig has 307K on it and I bet its the original pump and sock. Won't try that until I order a new one, if the NSS TPS and relay don't take care of it.
When you did the new fuel pump/sock did you use a Denso or a different brand?
I guess if it isn't the sock/fuel pump, my next guess is the upstream o2 sensor, but you think the codes would come back if it was bad?
Anyways, hope this helps and I'll post what ended up fixing it.
arcteryx
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- Thread starter
- #39
I went back a couple of steps. I was able to get a code in Test mode, DTC 51. I went ahead and replaced the NSS but it didn't help. I inspected the wiring more and while the plastic sheath is off on O2 #2 going to the DS harness, I did not see any ground issues with the wiring. #1 looked good coming up the PS as well.
I may replace injector #3 in case it s clogged.
I may replace injector #3 in case it s clogged.
Hi, Have you run a vacuum and compression test ? Mike
