Running rich, power loss, crappy mileage

[flesheatingvirus]

My 96 Tacoma 2.4L AT. has a lack of power that makes it difficult to maintain over 60 without riding in 3rd gear. The tailpipe is also very sooty, leading me to believe it is running rich. So far I have or have had checked:

-vacuum (good)
-timing (good)
-fuel pressure (high end of normal)
-exhaust (no obstructions)
-MAF sensor (cleaned)
-tire pressures (good)
-cylinder compression (good)

I have replaced:

-air filter
-fuel filter
-PCV valve
-spark plugs (properly gapped)
-plug wires
-both O2 sensors
-fuel pressure regulator
-transmission (rebuilt)

Fuel injector cleaner has also been tried to no avail. I did find a crack just below the exhaust manifold. I'm going to get that fixed soon. I'm running out of ideas for this thing.

I also always run it with a ScanguageII plugged in. I have never gotten any codes.

I just figured out that the dealership put in the wrong spark plugs. They put in the single electrode plugs. A sticker under the hood calls for dual electrode plugs only. I just replaced them the other day with no change resulting as of yet.

I also noticed that when I cover the exhaust with my hand it comes away wet, as well as black. So I held my hand slightly off the end of the pipe, and I could see small flecks of sooty water hitting my hand. I look under the exhaust pipe and see what looks like a sooty water drip trail on the underside. Upon looking inside the tailpipe, I can see water droplets coating the inside. Here are some pics of the underside of the pipe and the bumper behind it that is getting splattered.

[dually]

Have you run some seafoam through that beast? Reset your ECU???

[flesheatingvirus]

After I changed the plugs, I let the battery sit unplugged for about an hour. The Scangauge is still at "Not Ready", so I'll be waiting on that. I just put some Seafoam in the gas tank today. Should I get another can and put it somewhere in the intake? This is the first time I've used this product.

[dually]

Run seafoam through the vaccum line.

[dually]

I honestly dont see why you are running rich... are you throwing a CEL?? Have you scanned the ECU for any codes? O2 sensors should have cured any incorrect F/A ratio..

[flesheatingvirus]

I'm not getting any codes. I always drive with the ScangaugeII plugged in. The O2 sensors are less than 4 months old. I pulled them today to check on them; all black, of course. Which vacuum line is best for Seafoam; the brake booster? I can't figure out the rich part either. I've been dealing with this for months. Even my mechanics are stumped.

[dually]

Here ya go!: http://www.customtacos.com/forum/sho...hlight=seafoam

When i pulled the vaccum line, my truck studdered and ran shitty until i poured the seafoam in or put the line back on the Charcoal box.

[flesheatingvirus]

Thanks! I'll give it a try tomorrow.

[BrunesDoesTRD]

Yeah...Seafoam helped out my scion a decent bit...it's a bit smoother idling and it's got a cleaner throttle up.

[chris4x4]

Sounds like you have a bad cat.

[flesheatingvirus]

The cat is less than 6 months old. The original was stolen off the truck at the dealer lot before I bought it, and he had it replaced.

[BeefTaco]

-fuel pressure (high end of normal)

I would check a couple of things recheck your fuel pressure readings maybe a problem with your fuel pressure regulator. Also do some pin resistance checks of your MAF for problems with outside air temp readings.

[flesheatingvirus]

I just replaced the fuel pressure regulator. No change. I did notice that, when I bought the truck, somebody had rerouted the vacuum hose on the regulator to a T-split on the vacuum hoses for the power steering pump. Since there is stronger vacuum there than at the chamber where it should be connected, I figured that they were trying to hide/compensate for a failing regulator. I guess that wasn't the case.

I checked the voltage on the MAF sensor according to the Haynes manual. It just states that the voltage should fluctuate when air passes over the wires. How else can I check to see if the MAF is faulty? I also have a spare used MAF sensor that I tried. No change.

[BeefTaco]

Here is a link to some online Toyota service manual's
there are few other things to check on the maf sensor.
If the other maf you have is not brand new factory and
or a known good part I would not trust it.



http://www.ncttora.com/fsm/index.html

[-TRDMAN-]

Head gasket????

[flesheatingvirus]

Originally Posted by -TRDMAN-

Head gasket????

If that were the case, wouldn't it have failed the compression test? All 4 cylinders were between 160-180.

[-TRDMAN-]

Originally Posted by flesheatingvirus

If that were the case, wouldn't it have failed the compression test? All 4 cylinders were between 160-180.

I DON'T KNOW PROBLY NOT THE CASE IF THE COMP. IS CORRECT.... NOR WOULD IT BE THE RINGS..... HMMM.... IM STUMPED ON THIS ONE... I WILL SEE WAT THE OLD MAN THINKS(I COME FROM A LONG LINE OF PEOPLE WHO KNOW THEIR SHIT WHEN IT COMES TO VEHICLES...)

[flesheatingvirus]

I appreciate it. This has been stumping me for months. I'm getting tired of spending time and money on it. I keep coming back to the MAF sensor. I hesitate on spending $300 on a new one when it MIGHT be the issue. I've heard of them going out and not throwing codes.