alextnecc

I have a fresly rebuilt 3vze with rv2 cams and some head work. Downey ceramic coated headers with 2-1/2 free flow exhaust and cat. Weapon-r intake setup with cold air filter kit. I have a few questions and wanted to see what people have to say.... I am sorry if much of this has been covered.

1) my timing is currently set at 22degrees I do run only premium and I don't know but this sounds way extreme. I have plenty of power after 3200 rpm but not sure if it is wise to run this much advance. I don't have any knocking at all. I ran it at stock 10deg during break in and don't really notice a hell of a difference... Any ideas or thoughs.

2)Pair valve ? is it necessary, I have unplugged the solenoid that controls the valve because with the cold air intake (weapon-r) which I modified I get a ton of noise thru the filter connected to the pair valve when it actuates. I have read that it can cause premature cat failure but really not sure.....

3) Any good ideas for squeezing any more power out of this pig?

4)I am looking at a few options for chip/computer upgrades, anyone have any experience with 3vze automatic with v-force? venom ?

5)Manual says 18gal fuel tank is this true cause spectre aftermarket ones available are 15gal. It is a 1995 limited sr5 with factory 31 wheels... You can tell by the hole in the bumper that it came with 31"s

The truck kicks a$$ but hate the 340h trans with 31 tires. Jumping down a size to 30's help fuel at all? what about performance?

I drive the truck hard and am seeing city 14mpg up and down the maine hills. I think it seems good mpg but not sure. Yet to really run it hard on highway to see economy but it seems mixed drive gets me about 250miles to the tank.

abecedarian

1) your timing is not at 22 degrees. It might look like it, but it's not. Figure out the right way to check and set your timing and get back to us.

2) Pair valve... not particularly necessary but it helps the converter do its job. if you don't have it working properly, the converter will probably give up the ghost sooner than you'd expect.

3) More power from the Pig? Should've thought of that before you did the rebuild.... a 5VZE is the cure for that problem but since you'd dumped a couple G already, swallow that pill.

4) Chips? Overall useless. Yup. Useless.

5) Fuel tank depends on the options. I'd suggest draining it then filling it, then you'd know without question, how big the tank is.

14 MPG? sounds a bit poor. I'd expect at least 17 MPG with an out-of-tune v6 on oversized tires.

anything else... ?

alextnecc

The timing is definately at 22 deg . I've checked it quite a few times. I am way off the scale now and have to use a advance timing gun. I definately know what I am doing here. Just asking as a reference point to others....

I'm into the upgrades / replacements for $5500. not including my labor. This is just about everything in the engine compartment replaced performace except the ignition. I am however looking at those next.

I'm mostly looking for information about what point this thing should act up. That and what point the flexibility of the ECU won't allow any further tweaking.

As far as the pig thing... It is what it is and granted it's much much quicker now than it ever was. I just love to push the envelope and if I really wanted all the power I would have gone with a full v8 conversion. I wanted a stock/semi-stock 95 and once I hit that 3k rpm it goes like hell right up to redline. If I wanted a 5vze I would have bought a 96. I have an affinity for the 1st and 2nd gen 4runners hence my 95. When I say pig I mean underpowered stock esp with that 340h trans (the weak point). So what's the next hot upgrade as I have done a ton to this and want more. Is there a flat out trans swap for a 5spd auto avail ?

17mpg city with out of tune setup and 31 tires? this throws me cause it seems to me it would be much worse out of tune and with bigger tires especially since I am constantly pounding on it to keep it in that 3k rpm sweet zone...
As far as out of tune advancing the timing doesn't present a problem until knocking occurs (the point at which the the rapidly expanding air-fuel mixture can actually push against the piston still moving up). Optimally and Ideally the time that the mixture should be fully burnt is about 20 degrees ATDC. Maybe I am way off here as I come from a school of motorcycle mechanics but it should be advanced till knock and then backed off some. What point do you all see knocking occur on these trucks?

Yes I am anal, uptight, and compulsive hence every piece being replaced under the hood if I were to just done the motor, headers, exhaust, and cold air. I would be into this project for $3300.... Not bad cause a new 5vze would run me well over that.

Bumpin' Yota

I know exactly what you mean. I had mine at 17* BTDC post top end rebuild. These engines CAN take a LOT of timing advance IF there are no carbon buildups.

abecedarian

Okay... before I go any farther, I apologize for sounding snotty. That doesn't change what I meant though so....

Timing:
You're inserting a jumper, bridging the proper terminals in the diagnostic check plug and the idle is changing when you do so, correct? If not using the jumper and if the idle doesn't change, you're not doing it correctly... or the throttle position sensor needs attending to.

Pig and Transmission:
5 speed swaps are 'relatively' common place, i.e.: many people have done them and there is a lot of 411 here on yotatech regarding doing such a thing. I believe though that with an engine making good power at the right RPM's, swapping to a stick is a step backwards. You may want to look at regearing as opposed to swapping transmissions, just like many of the real muscle car guys did- particularly those with the heavy ones like the RoadRunners and such- light pony cars could recover from clutch/shift/gas quicker than their autos could but the heavier cars need the constant application of torque as they shift... and you have a heavy truck .

Mileage and timing:
Okay, maybe I was exaggerating a bit expecting 17 out of tune. But then again I was thinking that if it had oversized tires, it would've been regeared for those tires. Considering that, 14 MPG doesn't sound that far out. Now having said that, you will get the best mileage when the engine is putting out the most power with the least throttle, which typically means that your engine RPM's are on the rising side of the torque curve when at speed. If you're on the back side of the torque curve at highway speeds, you're having to hold the throttle open more than you should to maintain speed and needing any more power will require a downshift.

I am somewhat familiar with detonation, and deflagration, and how it impacts engine performance. Optimally, the pressure peak from combusting the fuel occurs just after the piston reaches TDC and is on its way down, thus transfering the force of the explosion in to the motion of the piston. This in no way, shape or form means that the fuel is completely combusted (burned). It's actually desireable for some fuel to remain uncombusted as the piston passes TDC so there is some additional force from fuel being burned to be applied as the piston moves down-stroke.

Additionally, the ideal time for the spark plug to initiate combustion is highly variable and depends on engine load, engine RPM, fuel quality / octane (RON / MON qualifications, etc.), compression ratio, inducted air temperature and density, oil vapor and residue within the combustion chamber (which lowers effective octane rating), spark plug gap / plasma temperature (depending primarily on discharge voltage), atomization of the incoming fuel / air mixture..... So there are far too many variables at play to say that 20 ATDC is where the fuel should be completely combusted. Top-fuel dragsters don't have fuel completely burned at even 180 ATDC. And we can go in to the nitro-methane fuel arguement if you'd like, but that fuel has an octane rating lower than pump gas.