'99 V6 1st Gen power loss/miss in low RPM ~Assistance Request

Hello everyone,

I just picked up a new to me 99 Tacoma 4x4 V6 5 spd 185K+. I'm seeing some issues when I take off from a stop that I'm hoping some of you could point me in the right direction.

First, when sitting at a stop it's very difficult to get into first gear (clutch has to be all the way down to floor). Think this might be clutch related (not sure it was ever changed )

When I accelerate quickly the engine feels like it's missing or stuttering and it feels like it has power loss (bogged down). Then when I get past 2K RMP it smooths out and the power feels like its back.

In the same scenario, if I accelerate more gradually (not stomp on it) the issue is not remotely as bad (almost gone) until I'm hitting past 3K RMP and it kind of stutters (almost like the clutch is slipping). I have a feeling that some of it is clutch related, but I'd love some input from ya'll.

Doing some searching around it sounds like it could be a couple of things like: Fuel filter, spark plugs, wires, MAF sensor dirty and or the throttle body gummed up.

I've not had time to dig into since getting the truck (my other mode of transportation for wife crapped out so I had to fix that).

My plan was to change/clean the following:

• new plugs
• Sea Foam via: Brake booster vacuum hose, oil pan and gas tank
• new wires
• new air filter (done)
• new fuel filter
• Oil and filter Change
• Change diff, tranny and transfer case fluids
• Clean throttle body
• Clean MAF sensor

Based on the above info and the list of things I'm planning to do, do you think this should solve the problem or should I look at something more or something else.

I'm also considering doing the oil catch can mod for the PCV valve.

Any input or insights is much appreciated.

 

Did I post this in the wrong section???

 

Update:
After a long weekend in the garage building stuff for some customers and then cleaning it all up. I was able to poke around the engine. I'm adding to the list replace ALL vacuum lines (that I can). Many of them are cracked at the connection point so I can only assume that's not helping.

I found that the air intake box was completely separated at the box just in front of the MAF sensor and being held on by duct tape (not what you would call the best seal possible. So no air was was/is going into the air intake in front of the sensor, but not filtered. I can only assume that the sensor is massively dirty because of this. I was able to tape it back together for now and took it for a drive, there was a massive improvement in throttle response and power in the low end. However, it's still missing and gets bogged down.

The engine has a little back fire when I rev it up every now and then when I'm parked and in neutral.

Instead of going with a factory cold air box (that's kind of what's in there now) I ordered up an S&B "Cold Air Intake" and I'm going to replace the filter with an AFE Pro S dry flow cone when I get it. The factory replacement would have been about $180 shipped this was $200...I know I'm not gaining much if anything with a CAI, but it will clean up the appearance of the engine bay a bit and I needed something anyways.

Next up, I'm going to beef up the grounds this week. On another forum, someone did a little write up on adding some grounds and (linking the body to battery, battery to frame, engine block to frame). Early reports are positive that this has helped out some other people.

I'll continue posting updates as I go and get some pictures in here when parts come in and work actually begins.

 

Update:
Changed the oil and checked/improved grounds (added a ground from engine to frame to battery and battery to body. No change in performance.

Parts are coming in and by next weekend should be able to do a major tune up.

Clutch issues continue. This morning was strange, I had the clutch smashed to the ground and I could not get it in 1st gear. I had to take off in 2nd gear and that was very difficult to get into that gear. After driving for about 15-20 min the clutch was back to normal and I was able to get it into 1st gear to take off from a stop.

 

So my Check engine light came on today...

 

What codes did it pop?

Something is definitely effed up with your trans/clutch.

 

Sounds like a clutch issue to me; slipping is the right word maybe.

 

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This, from what you describe as plans for truck (sea foam/cleaning MAF/etc) puts you on the right track but I think you'll find yourself going in circles unless you get a code reader, anymore for todays vehicles it really is a "must have" tool, it narrows all the issues down & gives you the places that need addressing...

 

I bought a code reader last week because it was on sale...man I'm glad I did lol.

Found the code was a P0446 (EVAP system). Seems pretty common. I cleared the code and replaced my gas cap. I think that was the problem for the CEL. The previous owner did the diff breather mod and located the breather a little too close to the cap and it was interfering when the cap was screwed on.

The issue with loss of power when it's warm or cold continues.

So far, I've beefed up the grounds, I've changed the oil and filter and replaced the gas cap. This weekend is the major tune up (might try and change fuel filter today).

The truck has not thrown an engine code yet...so something is off still. I did discover that the air box is cracked and separated from the air intake tube (being held on by duct tape right now), it also has a crack in the hose just on top of the throttle body. So there's a potential that un-mapped air is getting into the throttle.

Thankfully i have a new cold air intake to replace this worn out OE version. I know it won't do anything for me from a gains perspective, but it will replace the broke unit.

 

Update:
Replaced the fuel filter and that seemed to work for that evening...then it came back on my drive to work the next day.

When I listen closer to the engine it sounds like a backfire at high RMP and the stutter (seems the best way to describe it) is still there. Under load it's worse, I can't pull out into traffic and floor it because I don't have enough power to get to speed. I have to very gradually work up to my normal speed in street traffic.

 

Sounds like the same problem I was having. After replacing everything I could think of I realized it was the number four cylinder fuel injector. After I replaced that everything went back to normal and all is well. It's been three months and still running good. Hope this helps, good luck

 

It sounds like there are several problems...one is I think you have a dead cylinder, another is that your clutch hydraulics are probably bad.

Howard

 

Ok so the tune must have worked because the truck is running great right now.

Time and more driving will tell if it holds.