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Toyota Pickup
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198 Posts
Discussion Starter #1 (Edited)
Hi guys, I read the other post of Gas Mileage Frustration but it doesn't really apply to my situation I have a different case.

Toyota Pickup 1991 22RE Regular cab LONGBED (7ft) 240 000KM (Head gasket was replaced by previous owner about 40 000km ago)

Ever since I had this truck I get some pretty consistent 10mpg with it..sometimes a little more like 11 or 12 but its pretty much the best i'll get.

Here is what I've changed recently:

Spark plugs, Wires.
Oil (5W-30 High mileage Quaker state)

Here are some issues I noticed or know about that I would like to know if they could affect my gas mileage and if so which one should I address first?

The EGR is disconnected completely.
I have changed my stock air filter for a 'shortRAM' type air filter still using Stock assembly just changed the tip (MAF and original piping are untouched)
The Gas Tank has a minor leak when the tank is 'REALLY FULL' (Could this be reducing my gas quality as it evaporates through this hole?)
When my truck gets just a bit under 1/4 of gas, when I accelerate the truck BOGS down for a split second then resumes acceleration.
There is very often a high gas smell from the exhaust.
The sparkplug closest to me when I'm facing the engine is the only one with minor 'Rust' on its exterior could this mean anything?

SOMETIMES but very rarely, when it rains pretty hard out the engine will not rev over 2000Rpms it will just hesitate and shake the hole truck and at some moment it just unblocks and works fine.

I used to have an exhaust leak around the O2 sensor that I have welded at my mechanics but he told me 'sometimes when we weld around these we fuck them up'

So I checked my bearings, and brake drag, everything is really good, I've never changed transmission oil or Diff oil don't know if those are worth it..

Never changed the FUEL filter so don't know if that can also help

Thanks guys, I'M a bit lost and am a student so I don't really want to ruin myself but want to look at some of the major things that could be causing it to be so unefficient fuel wise...

Just one last thing, I go see my girlfriend that lives quite far away on the weekends..

I fill the tank DEAD Full, and get 270 miles out of my full tank..is this what you guys get with yours on the highway? Is my truck normal or are there some improvements that can be made?

I drive it pretty hard on the highway get about 120kmh in average sometimes faster and sometimes slower in construction areas.

Thanks alot
MAt
 

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Languishing in Virginia
1994 XtraCab 4x4 P/U
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2,026 Posts
1. Check for stored ECU codes.

2. Replace the O2 sensor if it has more than 100,000 km.

3. Check for vacuum leaks.

4. You have an electrical shortage somewhere if you have that happening when it rains.

5. Find & fix the fuel leak!
 

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Registered
Toyota Pickup
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198 Posts
Discussion Starter #4
1. Check for stored ECU codes.

2. Replace the O2 sensor if it has more than 100,000 km.

3. Check for vacuum leaks.

4. You have an electrical shortage somewhere if you have that happening when it rains.

5. Find & fix the fuel leak!

Spoke to my friend today has almost the same truck as me hadn't spoken about his truck to him for a while and he said he changed his 02 and got a VERY noticeable improve on gas mileage!

I tried patching the tank with different products but, no luck it just leaks anyway.

An electrical shortage being at what level? Fusebox level, engine electricals/sensors?

How can I find vacuum leaks easily?
 

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Languishing in Virginia
1994 XtraCab 4x4 P/U
Joined
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2,026 Posts
Electrical shorts are a [email protected] B!TCH to find. Just get a multimeter & start at the source.

Use a propane/MAPP gas torch (UNLIT!!!!) with the engine idling to find vacuum leaks. Anywhere there's a leak, the engine will idle up when you hold it there. Works like a charm!

But before you do anything, check for codes. It might point you in the right direction.

Also, x2 on the fuel filter replacement. I have 252k miles & have replaced mine twice now.
 

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Toyota Pickup
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198 Posts
Discussion Starter #6
Ok I've been looking up the O2 sensors on Ebay and there are quite a few part numbers... I'm not really sure WHICH fits, or if they all do...

There seems to be two with different prices in DENSO and NGK but I thought there was only one on my 22RE can anyone help?
 

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Newbbie
2004 Toyota Tacoma
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536 Posts
Well for starters, a disconnected EGR valve will cause driveability issues. The EGR valve helps to cool the cylinder temperatures and with it disconnected you run the risk of blowing a head gasket. Depending on where the hole is in the gas tank you could be getting water in the fuel tank when it is raining out or when driving on wet roads, this could be another reason. Pretty much you need to fix all the things that are wrong with it first, then start your diagnostics.
 

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Toyota Pickup
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198 Posts
Discussion Starter #8
Well for starters, a disconnected EGR valve will cause driveability issues. The EGR valve helps to cool the cylinder temperatures and with it disconnected you run the risk of blowing a head gasket. Depending on where the hole is in the gas tank you could be getting water in the fuel tank when it is raining out or when driving on wet roads, this could be another reason. Pretty much you need to fix all the things that are wrong with it first, then start your diagnostics.
I agree to the gas tank, but the EGR valve will not affect overall drivability as it does not compose a major part of cylinder cooling, because on these 22RE engines, the PAIR VALVE, which sucks in air using the exhaust vaccuum, has that job of cooling cylinder temperatures, and my engine runs rather cool, I'm not really worried for the head gasket issue.

Thanks for the pointers!
 

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YOTA Master
'93 2wd P/U
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2,434 Posts
really the egr is not likely to be a significant driveabilty issue at engine speeds much over idle.

The pair valve allows air into the exhaust under certain conditions and has no effect on the combustion process. However if the pair valve is allowing air into the exhaust when it is not supposed to (most of the time) then the O2 sensor will read lean and the ECM will start incorrectly adding more fuel.

Definitely fix the things you know to be wrong, then look closely at the secondary ignition components (misfires when wet are almost always to do with the secondary ignition) and the O2 sensor operation as this can also greatly effect fuel mileage. There is definitely something wrong if you can't get more mileage than that with a 22RE
 

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Discussion Starter #10
Well my PAIR valve works correctly, I used the shop manual to test it and verify all the other valves around are doing their jobs what you said about it giving a false reading of 'lean' does make sense, I'm just wondering if the whole PAIR valve assembly could just get cut off completely for the rest of the truck's life without any negative effects.

I also took the voltages from the DIAGNOSIS plug near the primary fusebox in the engine bay and diagnosed a faulty O2 sensor as of now.

Of course I am not expecting to obtain factory brand-new MPG but atleast pinpoint the biggest problems to get a bit more of it.

So I'll be receiving my new O2 sensor this week, need to find where the connection is located under the carpet...
 

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YOTA Master
'93 2wd P/U
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2,434 Posts
The O2 sensor harness connector should be on the transmission crossmember, not under the carpet
 

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HiluxSupraISF
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4,529 Posts
holy crap dude, your truck is missing alot of attention....

I drive mine hard (xcab auto) and I get 21mpg at the least.

Anyway, Spark Plugs, get some NGK's.
Intake, does it have a path for cool fresh air to reach it? You said you have a short ram intake, that's bad... why? hot air gets to it faster than anything else.
Is the cat clogged?


anyway, that's all i can say!
 

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Toyota Pickup
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198 Posts
Discussion Starter #13
It gets quite a lot of attention my short ram is quite far from the engine, it gets the fresh air from the front grill directly.

I change the oil very often, keep the air filter clean, always keep the engine clean in the hood its always very shiny all hoses seem in health, I change the coolant every year, the spark plugs too, the wires I've changed them but they seem to be quite 'cheap' I don't know if that has any effect even if they're less than a year old.

The truck's got a really clean interior, exterior look no rust and that's why I'm concerned about it because the engine has quite a lot of power, and runs smoothly burns no oil, does not smoke or any shit, starts VERY easy, I just find it a bit 'gas consuming' and since everything seems to be 'FINE' I am asking you guys who might know more about the truck what could be the problem?
 

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HiluxSupraISF
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4,529 Posts
hmmm, when is the last time you had injector cleaner?

I'm also hoping the cold start injector isn't wide open lol
 

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198 Posts
Discussion Starter #16
hmmm, when is the last time you had injector cleaner?

I'm also hoping the cold start injector isn't wide open lol

Haha hope so too, whats the best way to clean them I'm very skeptical with all these GAS TANK ADDITIVE CLEANERS what formula really works for injectors? and how can I know my Cold start is wide open?
 

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198 Posts
Discussion Starter #20
Basically, it depends how much gas i Put in because, I could still drive it on empty if it was operating normally put since it has a really fragile 'STUTTER' when the tank's under 1/4 full I get gas in it to be able to drive comfortably or else it always bogs down and resumes acceleration until I fill it up, so in my sense, I get betweeen 12-17mpg...
 
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