Tacoma running rich

So I did a compression check on my 96 4x4 2.7l auto Tacoma a week ago and when I pulled the plugs there was a lot of carbon built on the plugs. Clearly it’s running rich. And I don’t know what to do i have no engine check lights. I do have a po441 that pops up every 1k or more in miles. Is the maf sensor the problem?

 

any help here please?

 

P0441 is an evap leak, one possiblity that works with the rich and evap is the switching valve for the evap purge is allowing fuel vapour through when closed. This causes rich, and for the system to detect a leak.

Evap purge solenoid is something worth looking into.

 

what exactly does the solenoid look like? in the engine bay

 

Concur

 

i went to autozone and they said it was the VSV Vaccum switching valve? is it located under the manifold.

 

Usually carbon fouling of plugs is caused by oil getting into the cylinder (piston rings) and burning. If the plugs were in there for a while then some fouling is pretty normal, especially on a 24 yr old motor.

I wouldn't worry about rich or lean if you don't have any codes that state "too rich/too lean" (p0171/p0174)

For the trouble code Google or look up a evap purge valve for that year/size engine to get a picture of what it looks like. It should hold vacuum at all times on the port that goes to the intake manifold. If it leaks or sticks shut during a purge that code can be set.

 

well i do have a p0441 code and i have a rough idle that annoys me quite a bit.

 

Put a vacuum pump on the purge valve and see if it leaks down

 

In addition to Bishop84 diagnosis... when you fill the fuel tank to you keep adding fuel after the first time after the nozzle clicks off?

 

No. I did a compression test as well all cylinders were in the 180s all good. It’s clearing not getting enough air. Can the VSV valve cause a rough idle?

 

is this a stock engine or are there "power adders"?

the 4 cyls are notorious for a rough idle... how rough is too rough, that is a good question. There are rumors of a revised PCM that raises the idle speed but I cant confirm that even through my Toyota parts guy.
If you have a scan tool that can do live data look at the fuel trims... +- %5 is OK anything above or below that hints of an issue.

You are going to have to get back to basics on this... the compression test is a good start and I use that as a go-no go test. I would also do a cylinder leak down test... yes, a pain in the ass but this test gives you a good indication of is there is a mechanical problem, where it is. If she is ok mechanically then we are looking at an ignition issue or an injector issue. I would get the injectors flow tested just to eliminate that as a possibility.

The only thing that I can suggest right now is with a pair of needle nose pliers start to pinch off the vacuum lines one by one to see if the idle quality improves, don't forget the brake booster either.

an after thought... when was the last time the valves were adjusted?

 

The valves were adjusted by Toyota at 312 I’m at 325k. It’s idles around 640 is that to low? I have a ultra gauge as well

 

Where are the long term fuel trims?

 

Fuel trims?

 

LT FT %
ST FT%

 

How do I check that? I don’t know if the ultra gauge with show it

 

how many miles on engine ??

180 compression all cylinders aint bad

consistent type o driving makes a big difference ......................
running rich around town bump/grind commuter route ????

running rich hi way for several hundred miles ?????

all plugs carbon build up no doubt Ur intake tract could use a goooood cleaning

good luck

 

Sorry to thread jack but you're talking about the long term not short right? I thought long term fuel trims were okay up to +/- 10%

Would poor performing injectors cause excessive fuel trims? I hover around 7 to 9% but I know crappy injectors will cause a rough idle. I've got the 4 banger and I idle around 900 I swapped used injectors with slightly less used injectors and it fixed my initial rough idle lol