Ghc80

I've got a 95 sr5 4x4. Just rebuilt the motor I mean a total rebuild bored new heads pretty much a new engine. The engine runs smooth starts great transmission seems to shift fine. My problem is I have no power and pitiful fuel mileage. I'm talking to he floor on level road its all it has to make 65mph and I'm only getting around 8 to 10 mpg. I am all out of ideas as to what the problem could be. If anyone has any suggestions or ideas I'd be glad to hear them. I know 3.0 isn't a power house nor is it the greatest on fuel but, surely a basically brand new motor should do better than this. It is a a40h auto transmission.

ksti

How many miles are on your rig?
Have you checked to see if there are any codes stored.
It's possible o2 sensor needs changing.

BMcEL

Start by pulling codes and go from there.

Ghc80

It has 235,000. The rebuilt engine has only been in a few weeks. I don't have a check engine light on. Will there still be a code stored? I am sorry for the lack of knowledge I am new to owning a Toyota and so far this 3vze is turning my stomach. I can't find any vaccum leaks. I will check the codes and check the O2 sensor wires. Could the timing cause this?

ksti

Yes, codes can be stored even if no check engine light is lit.
3vze's are not as bad as you think, just a little more attention is needed IMHO.

Checking the wires on the o2 sensor is ok but it can still be bad especially with 235,000 miles. A bad o2 sensor doesn't always set off a check engine light.

Also is your gas mileage based on city driving only or freeway and city?
The 3vze is known for not that good of gas mileage.

Start with checking for codes and see what you get if any. Good luck

RJR

As far as expectations of performance goes, you should be doing better. With an auto tranny, people typically get 13-17 mpg, manuals more like 16-19, depending on driving styles. Doing 70-75 on the freeway should not be a problem with a good engine well-tuned.

Go after the power problem first. The mileage is just a symptom of an engine not running at good thermodynamic efficiency. When you fix the power, the gas mileage will likely take care of itself.

If the engine is running smoothly but just has no power, retarded timing is the first thing I would investigate.
Check for codes first. If the ECU isn't detecting the presenced of the knock sensor, it will retard timing and performance will suffer. There should be a code 52 if that is the case. Then check timing of the distributor.

Checking the O2 sensor would be next. There is a procedure to do that with a DVM and the diagnostic port, but I don't know how off the top of my head. The FSM will tell you. I'm sure a search of this site will also uncover how to do it.

Finally, do a compression check. Pay attention to the plugs as you pull them out and note if any are wet from unburned fuel or black with soot from misfiring. Compression problems seem less likely to me, because they would likely be confined to one cylinder, causing rough operation.

Good luck.

Ghc80

Ok thanks for all the good info. I will start checking all this out. I'll keep posting as I make progress. Again thanks .

Ghc80

I drive a straight flat 55mph road to work. I usually try to maintain 60mph. But its hard to with the lack of power.

Punchy

If you blew the HG on the last engine the O2 sensor could be bad, It does not like Antifreeze what so ever.
Also check that the vacuum lines are hooked up correctly, Sometimes small mistakes are made and the EGR is hooked up wrong.

Gevo

Misery loves company, 3vze loves misery... read through my own issues at this link.. maybe something there would be helpful. I'm still troubleshooting similar problems on my rebuilt engine.

https://www.yotatech.com/forums/f116...g-fail-277715/

Gamefreakgc

You're just gonna have to check components one by one.

• If you've never replaced the O2 sensor in the last 90k miles, just replace anyway. Runs about $90.
• Check your timing with a timing light. $20 at harbor freight. Severly retarded timing would cause utter power loss.
• Do a compression test. Low compression could cause loss of power
• Check for vacuum leaks with a can of carb cleaner or UNLIT torch on every seal, gasket, and hose with a COLD engine idling
• Check sensors, including TPS, ECT, VAFM: http://personal.utulsa.edu/~nathan-b...sm/engine.html

That's just a start. Is is most likely a combination of issues giving you this problem. My truck with an original engine with 285k miles holds 70 mph easy, with maybe 1/5 of throttle. I get 17 mpg mixed driving.

scope103

Absolutely. Check the basic stuff first, especially before you start replacing parts on the blind.

As gamefreakgc says, a timing light is a basic $20 tool you should get at the same time you're first buying wrenches. Shop at HarborFreight, and you can also get the multimeter for only $6.

RSR

Yes, replace O2 sensor. Buy a Denso aftermarket one for your truck w/ the gasket installed. Costs ~$60. Good to do regardless of codes, etc.

With advancing timing, be careful if you don't know what you're doing. Seafeam, Amsoil, Fuel Injector Cleaner, etc, your engine first. You want to get carbon build up off pistons else, you risk hot spots and holes in pistons if you run too lean...

Ghc80

Ok ...sorry.. its been a few days. I have ordered a denso o2 sensor from eBay waiting on it now. No codes.....in the mean time my oil light came on the other night only when I slowed down or stopped it would kind flicker dim to bright then stay on. I immediately pulled over checked my oil....it was good. When I started back home light went off. Came back on as I slowed down to turn in my drive way. Next day I started it let it idle til warm and no like light. Any ideas on this.

Gevo

Ghc80,

I may have solved my own similar power and poor gas mileage issue and thought I'd share. It seems it was my TPS adjustment that was causing my overly rich condition (poor gas mileage) and power loss issues. I had adjusted it per FSM, but after that I had adjusted the throttle body and pushed the TPS from it's idle position to the non idle position when it should have been idling, and as such I had set the timing with this position. Basically, check all the items gamefreak mentioned.

Punchy

The wire for the oil sensor runs down behind the distributor and the alternator.
About half way down there is a splice connector on some models, Check this wire and see if there are any spots that may have worn through from vibration or burned.

Ghc80

Ok its been a few but, I'm back with my findings. Swapped O2 made no difference in power. So I checked for codes again.....got a flashing o/d light throwing a 64 code (torque converter lock up selinoid wire severed or short circuit). So new question...Could this wire be internal? I'm going to check the wire from trans to ECU tomorrow and see if maybe something got cut or pulled loose during the motor swap. By the way the oil light problem was the wire its all fixed now. Thanks for all the great info...Any transmission info. Will be welcomed

destrux

It could be internal, but if you just had the motor out it's likely the external part of the harness was damaged then. Grab a wiring diagram and find it where it leaves the computer and then test from there to the plug at the trans while someone wiggles the harness. If it's bad you could look for damage, or you could run a new wire from point to point.

No TC lockup would cause bad fuel economy and lack of power for sure.