First of all, I would like to thank Mardigrasmax for the pictures and description on his webpage, and for the threads where he describes pretty much the same as what I'm writing here. He was the first to do this, if I'm not mistaken.


Here are the steps involved in converting to a 70mm Pathfinder throttle body:

1. Make adapter plate. See the attached figures in my thread titled “Pathfinder throttle body installed” for dimensions.

2. When you first do a trial fitting of the adapter plate to the intake manifold, you will see that the 70mm opening is considerably larger than the bore of the intake manifold. I got my high speed drill (cordless drills are too slow) and a bag of coarse grit 2” sanding drums and started opening up the intake to match. First scribe or mark the 70mm diameter of the adapter plate bore onto the mating surface of the intake. Then start removing material. I did it with the intake manifold removed from the engine. If you do it on the engine, stuff several rags down the throat to keep aluminum dust out of the engine and then use a shop vac to suck all the dust up. It’s a good idea to have the shop vac running with the nozzle fixed in place at the grinding area so that the dust immediately gets sucked away. Note that the outer surface of the intake necks down several millimeters just beyond the mating surface. For that reason I was not comfortable increasing the bore all the way out to 70mm in that region, rather I tapered down to a 68mm bore to keep from breaking through the wall of the intake. I removed material for about 3-4 inches into the intake, and followed up with a nice polishing job with a Dremel. I wish I had a picture to show you, it was very pretty.

3. If you bought a TB that had the Pathfinder IAC and coolant passageway attached, you will have to remove them because there is not enough space beneath the TB for the IAC stuff.

4. You will have to make a plate that bolts to the bottom of the TB to seal it off, otherwise you will have a massive vacuum leak. See the attached jpg below. You can reuse the fancy o-ring gasket if your TB came with it, otherwise you will have to buy a new one from the dealer. I drilled a hole in the bottom of the plate and attached a hose nipple for the EGR control valve solenoid vacuum hose.

5. Some people have left the TPS as is, with the connectors pointing away from the intake manifold. This really stretches the TPS harness and in my case there was not enough slack in the harness to reach, so I took the TPS off and rotated it 180 degrees so that the connectors point backward to the intake manifold. The harness connectors can now easily reach the TPS.

6. After you remove the Maxima TB you will have to connect together the two coolant lines that connect to the TB, since you removed the coolant passageway and IAC from the Pathfinder TB. But you’ve always wanted to do the useless TB coolant bypass, now, haven’t you? Admit it.

7. At this time you can bolt the adapter plate to the intake manifold (if you haven’t already) and then bolt the TB to the adapter plate with a new gasket. The Pathfinder TB gasket is a fancy metal one, similar to our IAC gasket. You may have to connect the TPS to its harness as you are mounting the TB.

8. Attach the throttle and cruise control cables. My .75” thick adapter plate allowed me to attach the throttle cable without having to reposition the throttle cable adjustment bracket, but the cruise control cable was just a hair too short. I don’t care since my cruise control hasn’t worked since I did the tranny conversion anyway, but if you want cruise control you will have to do some repositioning of the bracket. I'll do it eventually since I don't like the looks of a loose cable.

9. Attach the intake pipe to the TB and you’re done. On my setup, the TB sticks out about .25” further than the Maxima TB did. The Pathfinder TB is shorter axially than the Maxima TB, which helped make up for the .75” thick adapter plate. The extra .25” or so was not enough to cause any problem with the intake pipe.

 

nice write up.....

wonder if nissan has a slightly lower TB.....

say around 65-68mm? Might just give you that larger airflow and a 4v WOT mix.....

like the exploded CAD pic tho....

 

Apparently the Pathfinder uses a different voltage range. You can adjust the TPS to give you 4V at WOT, but then the fully closed position gives a voltage that is too high, resulting in an idle speed of about 1200 rpm.

I'm going to play around with it tonight or tomorrow and see if I can get the Maxima TPS to fit. That would be the best situation.

 

what kinda mods do you need to benefit from this? 70mm seems a bit big. what about part throttle power?

 

Ahh, I see, you are using the TPS from the pathfinder. Someone with a FSM should be able to tell you at what voltage the ECU seems WOT. Is it 4 volts and above, or 3.9-4.1 or something?

 

I set up my pathfinder TB exactly like a maxima TB in the haynes manual. The manual calls for 500 ohms resistance closed, increasing gradually to 4000 ohms at WOT for the TPS. Mine is about 800 closed and 4200 WOT, which drives and idles perfectly. The WOT switch should show some continuity when the throttle is closed and none when it is open. How are you checking to get voltages? The resistance is what the manual shows to adjust.

 

I'm using an Apexi SAFC to monitor the TPS voltages using the sensor check feature. The FSM gives the range of voltages for closed and WOT.

 

I checked the FSM last night. Oddly enough, it says that the closed throttle voltage should be "about .5V" and the WOT voltage should be "about 4V". I was able to adjust the Pathfinder TPS to those values last night (actually I set it to 4V at WOT and the closed throttle voltage was a little less than .5V, but I don't remember the exact number), but that resulted in a high idle speed. I'm puzzled about that.

I also found out that the Maxima TPS is a direct drop in, and can be adjusted to give the right idle speed and 4V at WOT, so maybe that's the way to go.

 

Mods that allow for or produce more air into the engine, especially at high rpm. I don't think there's much benefit to this unless you're boosted or have the MEVI and JWT ecu with extended redline. The increased throttle response at low rpm is pretty neat, but it can also make stop and go driving in heavy traffic a bit more wearisome.

 

Hmm, "about" doesn't really help much. About could be 3.5v. Keep us updated if you decided to drop the Maxima TPS in.

 

I guess I wasn't clear. I installed the Maxima TPS last night. It works fine, and that's what I'm running now.

 

Oh I figure about 32.7 hp/23.4 tq


Honestly, I don't know. I'm doing this as part of an overall SC intake tract rework. When I'm done I'll dyno.

 

The best thing to do is follow the procedure in the haynes manual , you can get the same setting on the PTB as the maxima TB so dont worry. So get the manual and you need .3-mm feeler gauge and .4-mm feeler gauge .Page 6-9 adjustment , if you dont do it this way you cant possibly get it right ,its impossible.
And another thing ,do this with it rite off the car . Dont do it on the car it makes it 10x harder. This should be the first thing you do when you get the TB.
Dont forget to loctite the bolts when its set.

 

Depends how much you can get one for. I got one pretty cheap. You need one from a ~00-01 Pathfinder. It must be from the VQ35 with cable TB. I wouldn't bother getting one though unless you are CRAZY NA modded or boosted. They are getting rarer and will only get more expensive. I got mine for pretty cheap from h2kFrosty (he got 2 by accident), but I plan on turboing. It probably won't be going on until I am turboed or right before though.

Not really.

Bolt ons should never really increase fuel consumption unless you have a heavier right foot. In theory since you are removing a restriction you should get better if you drove exactly the same as before, which never happens.

70mm PF vs. 60mm A32

Thank you for bringing a 2 year old thread back to life....

 

ask stephen max for one. he'll have one for you readily. they are in mint conditions, too: adapted and converted to your choice of usim's, mevi's, and 00vi's. they run around 300-350 altogether. i liked mine very much.

 

q45tb's are too big for our vq's, not that it's not do-able, but it's not really necessary to use that big of a tb. Besides, how much bigger can you bore the manifold to match the throttle size? pathy tb's throttle is almost too big to fully match the 4th gen manifolds, mevi or usim. By the time you bored out to match, there's a thin line between the manifold's throttle throat and the outside. I wouldn't risk it.

Even for boosted cars, I dont' hear much needs to adapt a bigger tb than the pathy's.

 

cause this is an old assss thread and the links no longer exist.

installing the pathy tb is 4 bolts plus the adapter plates. pm stephen max.