Poor gas mileage update.

Okay i think i found the issue with my low single digit gas mileage.
One of the previous owners capped off the Idle air valve on both sides.
What are the odds this is my issue, im thinking about 88% chance it is.

Also any potential problems with the fact that i have the pcv acting like a road draft tube as it was letting the motor ingest too much oil.

My o2s are okay and my maf is a good used oem one from a wrecking yard that i got for $40 as i could only find counterfeit ones new.
My tps is functioning and i am running out of ideas here.

Another thing, does this have anything to do with the fact that my fuel pump power wire broke somewhere in the harness and i didnt want to mess with it so i have the fuel pump ran to a toggle switch on the dash with an inline fuse 10Amp.

Want to know what you guys think i should look into first as i am running in circles right now with this.

-Thanks
Paul

 

The IAC has a vacuum line (Air Assist) as well as two coolant lines (Water Bypass):


People used to cap off the coolant lines as a "performance" modification to not heat up the air coming into the intake. This shouldn't hurt mpg at all. The idea is that the coolant in the IAC is heating the air in the intake manifold, but real world testing proved it didn't make ANY notable difference.

If you have a significant amount of oil returning to the intake via the PCV valve. First.. Replace it, along with the grommet and the vacuum line to make sure they are working properly. Another option is to install an oil catch can. These used to be hard to come by, but are now widely available on Amazon. Piping the PCV to the catch can will only prevent most of the oil, as there is another return line from the back of the drivers side valve cover to the intake tube. Less oil comes through there than the PCV, but don't expect to catch EVERYTHING because of that.

I don't know why you couldn't find a legit OEM or Denso MAF.. RockAuto has the part:

There is usually a TW discount code in the vendor section as well.

Speaking from experience, I really hope the wiring you spliced into your fuel pump circuit is the same gauge as the oem wiring. When I was young and dumb, I thought wiring a kill switch into that circuit was going to stop someone from stealing my truck, and used a larger gauge wire cause it was what I had available. Ultimately (after many years) that caused an issue with the harness under the drivers seat, and I got to spend some time rebuilding that harness.

But honestly, if you have your fuel pump wired to a dedicated toggle switch to avoid fixing things properly, your truck sounds like an electrical fire waiting to happen.

How about the simple things? Fuel filter, oil change, air filter? Those all good? Spark plugs, wires, coils? Injectors? fuel pressure regulator? Vacuum leaks? Exhaust leaks?

 

If you don't already have a scan/ultra gauge or ODBII Bluetooth adaptor & mobile app, you should get one so you can monitor things like the TPS, MAF, and more importantly fuel trims. That's going to be really helpful data to diagnose your engine and mpg issues.

 

No cats, glasspack, i regret this now but ebay shit injectors, new filters all around, new oem toyota plugs, rockauto coils and wires, new oil, no exhaust leaks after some copper rtv as my homeade exhaust reused an old cat flange so a stock gasket wouldent work, no vaccum leaks, and unknown fpr as when i redid my injectors my fuel rail broke when one of the pedestals broke when torquing the bolts and i didnt reuse my old fpr so there is a lead. i installed a used fuel rail.
My o2s are working the tps seems to read correct and my only codes are both knock sensors that trigger at more than half throttle under load.

 

also i dont know the real mileage on the engine as i did a bit more digging when installing my skar door speakers last weekend and it turns out this is a mutt truck built from random parts.

 

Another thing i failed to mention, when i let off the gas and apply the clutch the engine surges from 800 to 1200 rpm a few times before returning to "Idle".

 

How much did you pay for the ebay injectors?

 

Again i regret this alot but 50 bucks...

 

My understanding is the chance of those injectors working well is zero. Even known brand aftermarket ones that might or might not be ok, and refurb OEM ones, are 6x that price for a set.

 

Yeah i know that now, wish i had done some research beforehand.

 

https://motorwestperformance.com/

All you need^^^^^^^^^^

 

Also forgot to mention i didnt know that the intake bolts were torque to yield and broke all but 2 reusing them, so i used whatever bolts i had laying around and drilled out the broke bolts and retapped them so i dont want to get into that again.
Yes i did that for intake to head bolts too so i cant just get a different intake and be good.
This motor has also been severely overheated before as after the injectors were installed i drove it without realizing it had no coolant in it at all.
Drove until it started pinging and bogging then instead of stopping my dumbass drove it home.
It now burns alot of oil and idles rough.

This was 3 years ago and i was overconfident and inexperienced (More like fucking retarded) back then, i regret most of what i did when fixing shit.

I am much smarter and skilled now, and i have forums to help me.


Considering this and my own personal desires, does a tdi swap sound better than fixing this mess my past self made.
I want injection knock and some smoke for a cheap price.
Also decent mpg for daily driver use.
I have the tools and skills to do the swap and i can afford it if i can find a cheap bug as a donor and sell my v6 and part out the bug afterwards.
The bug will be paid for by parting out my squarebody i got for free from my cousin, i was going to fix it up as it is all original, but then found out it has no motor or trans and a bent frame from hitting a stump back in 93.

 

Your truck is a nightmare dude, and no one is going to buy your v6 after it's been wrecked.

Why TDI swap it? What is that going to gain you? Have you really looked into what that takes to still have a viable vehicle after that? ECU and down stream systems, etc?

You still sound young and inexperienced, latching on to wild ideas, SAS, TDI, buying parts vehicles... Your best course of action is to find a suitable rebuilt v6 and put a working motor in it. No ECU swaps or other systems to worry about.

Or drop your truck off at a scrap yard, get a decent used vehicle, and leave it the hell alone.

 

Here is an idea…. How about entering this truck into a smash’em up derby…. Just weld up a cheap cage and maybe a brush guard on the front and let her rip!!! Maybe you win some money and then you can buy a decent used truck?

 

As i have mentioned before I know what is wrong with this truck and if i get another one it will just have a whole different set of issues.
I am already invested in this truck past the point of no return.
My 2 issues are frame and engine, i have made the patches to fix the frame.
So one issue, bad engine.
Everything on the truck is in good shape except for the frame and engine.
To me this truck is still worth fixing.
I am going to do the tdi swap but for now i am limping along this motor.
I cant get another vehicle because my mother has decided that i made the frame rot out (She is legitimately crazy), so her decision is that since i destroyed the truck i am now going to be stuck with it.
I told her not to buy it and the bitch then decided to give the bastard selling the truck $9000 for it!!!

I am trying to make the best out of a really fucked up situation, and i came here for help, any help given is very appreciated.

 

This truck isn't worth the time of day. This is a parts vehicle if it has a good frame. If it doesn't, remove all the valuable parts like trim, ecu, and roll it into a scrap yard.

There are so numerous and severe issues that you'll never get a truck worth the money you put into it.

 

Really, bet, i have only $500 of my own money into it.
To you that aint much but for little ole unemployed me that is a shitton of cash.

 

The frame and the engine are arguably the most important parts of the vehicle other than maybe the brakes…. If the frame + engine are as fucked up as you claim then the truck is junk.

 

Do you live in a state with no emissions testing or vehicle inspection?? Because from the info you have provided you probably won’t be able to register this vehicle in the next year or two when you have to pass inspection…. I’m not sure what states don’t require inspections but your truck certainly will not pass if you have to pass an inspection before you can register the truck….