Running rich

is there a way to test the EGR?

 

interesting that they indicate that line the same as they do all other vacuum lines on the diagram under the hood

 

oh forgot.....when i plugged this line, i got no change in the fuel trims

 

wondering if a plugged/bad catalytic converter would cause these problems?

 

Sorry, I am currently out of new ideas. I don't think a plugged cat behaves this way.

 

Sorry been supper busy. There should be some info some where on the site. Search may bring it up. Try driving i with the vacuum line off the egr and also you can remove egr and check for carbon holding it open. Also could have an evap system causing richness. Post a pick of you vacuum diagram and i'll show you which line to plug and test drive.

 

been very busy myself. so what i did was pulled the vacuum line off of the EGR and applied vacuum (by mouth) and could hear the valve opening and closing.

here is a pic of the diagram:

 

bump for still suffering on this.... any other ideas out there??

 

anyone?

 

Sorry man I'll bump for you. I haven't forgotten you, just out of ideas, and hoping someone else can.

 

Have you inspected your manifold really good? The 3rz manifolds are bad about cracking. That would make your o2 sensor go nuts.

 

exhaust manifold? it's in good shape, no exhaust leaks anywhere

 

To rule out a vacuum leak. Pull each vacuum hose and plug it. Then check your fuel trim. When it changes, you found the leak. I would start with the big ones, like the brake booster line, IAC line, etc.

 

Not to burst anyones bubbles but probably badly clogged injectors, they are an easy explanation for this and always fixed by removal and professional cleaning and rebuild everyone thinks gas additives work,lmfao. 100.00 R/C injector cleaning torrance (builds injectors for the fastest supra) worked for me was around 5 mpg with the 3.4l. Its a fuel issue so a cheap fuel filter and a new fuel pump too and she'll come back. Vaccum leak I believe is out by his testing, the vac leak would be huge if the trim went that far positive.

 

clogged injectors and/or dirty fuel filter and/or weak fuel pump ...... any or all of these things would cause it to run pig rich? mind you it is pig rich all while throwing a PO171 (lean code)

 

Yes it seems baas awkwards but fuel issues need to be looked at as suspect aswell, 20+ year old truck... vac checked out sooo??? fuel then spark then timing.

 

Have you pulled the spark plugs and compared them? Are the all black sooted? You replaced O2 sensors awhile back, what brand did you use? What does coolant temp show on your scanner? does you scanner have a graph feature for the O2 sensors?

 

changed the plugs to NGK iridium. all 4 old plugs were very black. both sensors were replaced with Denso brand. coolant temps show what i would expect to see as the engine warms up.

i am new to the scanner and have played with many features but have not seen a "graph feature" for the O2 sensors

 

Help me understand something:

the LTFT being stuck at 39.8 is telling the system to add fuel correct? i would expect that to be the case if i did indeed have a vacuum leak and/or had "false air" or even "real air" entering the system.

But, once that extra fuel is applied wouldn't the Bank 1 sensor "sense" the extra richness (hence that value climbing to 4.991 and staying there once warm) and send a signal to back off the fuel delivery?

 

You sure the value is 4.991? "The higher the concentration of unburned oxygen in the exhaust, the lower the differential across the sensor tip and the lower the sensor's voltage output. The sensor's output ranges from 0.1 volts (lean) to 0.9 volts (rich). A perfectly balanced (stoichiometric) fuel mixture of 14.7:1, gives a reading of around 0.5 volts."

Edit: That's for the older o2 sensors and generic OBDII software converts it.
The new wideband is actually an Air Fuel sensor. Around 2 volts is rich around 4 volts is lean.