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My 1996 3.4 liter (manual) T-100 loses power in all gears at 3000 rpm and unitl yesterday has been getting harder to start. If I put the truck in neutral and let the RPMs drop below 1000 I can re-engage the gears and continue on as long as I stay below 3000 rpm. I changed the fuel filter which made no difference, I began thinking it was then either the fuel pressure regulator or the fuel pump but my local mechanic checked out my fuel pressure system and didn't see any issues. I lost total power on the highway yesterday and couldn't re-start, had to be towed to Toyota service shop. Any ideas on what the issue may be?
 

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1997 Toyota T100
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My 1996 3.4 liter (manual) T-100 loses power in all gears at 3000 rpm and unitl yesterday has been getting harder to start. If I put the truck in neutral and let the RPMs drop below 1000 I can re-engage the gears and continue on as long as I stay below 3000 rpm. I changed the fuel filter which made no difference, I began thinking it was then either the fuel pressure regulator or the fuel pump but my local mechanic checked out my fuel pressure system and didn't see any issues. I lost total power on the highway yesterday and couldn't re-start, had to be towed to Toyota service shop. Any ideas on what the issue may be?
My guess is your plugs/wires have gone bad, or your injectors are shot. But it could also be the MAF, the throttle body, or O2 sensors. Is the CEL on?
 

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I replaced the plugs and wires in the spring. CEL is on and it indicates O2 sensor 1/port although the truck was running rough without the lights being on. It was interesting to me that the CEL remained illuminated after I removed the key at the service center. The mechanic was able to start it up and drive in to shop this morning.....? It seems like it gets starved for fuel. This will be the third time that it hasn't started right up after driving around but if given time will eventually start with no problem.
 

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1997 Toyota T100
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I replaced the plugs and wires in the spring. CEL is on and it indicates O2 sensor 1/port although the truck was running rough without the lights being on. It was interesting to me that the CEL remained illuminated after I removed the key at the service center. The mechanic was able to start it up and drive in to shop this morning.....? It seems like it gets starved for fuel. This will be the third time that it hasn't started right up after driving around but if given time will eventually start with no problem.
Looks like it's time to change those O2 sensors then. Make sure you get the right ones...there is a thread on here somwhere that indicated most brands don't play nice wth the T100s ECU. But if you are at the dealer they should be correct. I would have the injectors inspected as well, just to be sure. :thumbsup:
 

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1998 T100 SR5 2WD
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Pull all the codes from the ECU and post up what those codes are.

Put it on a diagnostics computer and look at all the readings. Something like AutoTap would work. Keeps you from pulling good parts and replacing them when it's not the problem. ;)

What were the numbers yer mechanic came up with fer the fuel pressure at idle and at RPMs above 3000? What were the numbers on the fuel pump?

How long have you been running it with the bad O2 sensor?
 

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Discussion Starter #7
Toyota said that they couldn't get their diagnostic equipment to give them any readings when they took it out for a test drive so they'll have to attempt diagnosing manual, (something I told them my local guy had already determined). Apparently the Toyota guys are going to run a pressure check on the fuels sytem and I'll let you know what kind of numbers they come up with. I'll be in the hole $180 just for the diagnosis assuming they can figure it out.......

Been running bad o2 (I think sensor 1, bank1) sensor for several months per that Clownmidget guys advice.

Hey Clownmidget...How's the land Cruiser? Still stuck and lifeless in AZ?
 

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Discussion Starter #8
After all that....It ended up being a loose ground wire:headbang:. Still having trouble with my ECU but the truck hasn't lost power since the ground was tightened down.
 

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1998 T100 SR5 2WD
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Which ground wire was it? I think this is the 2nd time that I've seen that the check engine light stays on if there's a weak/bad ground.
 

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I'm not sure how to identify the ground other than it is the one associated with the fuel injector system and is on the drivers side of the engine. The dealer indicated that their diagnostic equipment still was unable to recognize my ECU. Guess I'll start looking for a used one to change out for my old one.... I cannot for the life of me figure out how to the loose ground kept my vehicle from reacting poorly at such regular intervals (die at 3000 rpm and recooperate at 1000 rpm). Don't look a gift horse in the mouth they say....


Thanks to all for the help!
 

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1998 T100 SR5 2WD
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I think the oscillation/vibration of the engine/road was just enough to make a weak connection weaker at speed.

BTW...did you pull the ground off and clean the connector and the ground spot really well so they were both nice and shiny? Some dielectric grease will help keep the crud out of there, too. ;)

The other grounds are on the air plenum by the diagnosis port and near the back of the engine. There are a few other critical spots that depend on the body ground to be just right.
 

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T100 has same problems

My 96 T100 is an automatic and mine is doing the same thing, i think. when i drive and stop at a light it sometimes shuts off, and while im driving at a constant speed and hit the gas to accel a little bit my T100 looses power then it starts going again. you can hear from the exhaust that it looses power then goes and then looses power and goes again. im very tired and frustrated :headbang: with this, my dad owns a shop and his mechanics worked on it and took apart the exhaust manifold and replaced a sensor, but the truck still is acting up. iv also noticed it has been burning a lot more gas. Somebody Please Help
 

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1997 Toyota T100
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My 96 T100 is an automatic and mine is doing the same thing, i think. when i drive and stop at a light it sometimes shuts off, and while im driving at a constant speed and hit the gas to accel a little bit my T100 looses power then it starts going again. you can hear from the exhaust that it looses power then goes and then looses power and goes again. im very tired and frustrated :headbang: with this, my dad owns a shop and his mechanics worked on it and took apart the exhaust manifold and replaced a sensor, but the truck still is acting up. iv also noticed it has been burning a lot more gas. Somebody Please Help
Sounds like your 02 sensors are going maybe :confused:. You could also have bad injectors, bad/dirty spark plugs and wires, MAF, TPS, or IACV. Are you having trouble starting it? Could be a bad alternator too. Are you throwing any CEL codes? Have them read somewhere and that will likely tell you what's up. Let us know what codes (if any). There are quite a few gurus on here that will have a good idea of how to correct some of the codes.
 

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1998 Toyota T100 4WD
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My 96 T100 is an automatic and mine is doing the same thing, i think. when i drive and stop at a light it sometimes shuts off, and while im driving at a constant speed and hit the gas to accel a little bit my T100 looses power then it starts going again. you can hear from the exhaust that it looses power then goes and then looses power and goes again. im very tired and frustrated :headbang: with this, my dad owns a shop and his mechanics worked on it and took apart the exhaust manifold and replaced a sensor, but the truck still is acting up. iv also noticed it has been burning a lot more gas. Somebody Please Help
Try this out. http://www.toyotanation.com/forum/showthread.php?t=359324 My truck has been DRINKING gas like crazy since i've been having this problem and even a bit before. After I got the ultra-gauge I was actually able to see that my avg mpg is 14-16!!!! Follow that thread and I'll post up how it improves once I fix the problem.
 

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I'm having the same problem on my 95 toyota hilux 4x4 but at 2000rpms with no CEL. I've put a used maf and it temporarily fixed the problem but just today its a whole lot worse than before. Hopefully changing out the plugs/ wires and tps will do the trick.
 

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1998 T100 SR5 2WD
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Which engine do you have? I'm guessing the 3vze, 3.0L, V6? If that's the case, you won't be able to use an OBDII scanner on it to figure out the possible issues. I'm not one fer throwing parts at something and hoping it will solve the issue(s) since you really won't know what the cause was in the first place. ;)

Have you checked the exhaust flow at the exhaust pipe? Does it flow normally? It's possible you may have some exhaust issues like a partially clogged converter. You could unbolt it out as a test only procedure and see if you still have the same issues or not. Have you inspected the air filter fer any issues? How good is yer throttle body? Has it been cleaned lately? You could use a vacuum gauge on the engine and see if it shows any issues or not. Harbor Freight has one. I'm not sure if the auto parts stores have them fer rent or not. ;)
 
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