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Engine, Trans, F/I & Tuning

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Community Member Credit: Gerson Flores

Highlights:

  • Tuned by AdminTuning
  • LS Hiram Manifold Adapter
  • 90MM Throttle Body
  • Total Power: 324 WHP / 261 TQ

Dyno Videos May 8th, 2021 (324 WHP / 261 TQ)

Community Member Credit: vbxmaxima

Well, if you’re here, you are probably experiencing some trouble because the TPS is not a regular maintenance item! Unfortunately, TPS failure seems rather common. It’s happened to me, and I see it in one to two other Maxima enthusiasts a year. Heck when Edmunds.com was evaluating the new 2K Max, they had problems with the TPS. And the car was brand-spanking new!

WHAT IS THE TPS?
The throttle position sensor is a potentiometer – a variable resistor. The ECU sends the TPS a 5V signal. Depending on the position of the throttle, the TPS will send back to the ECU a voltage proportional to how open the throttle is.

Here is a pic of the TPS.

This is the back. Notice the metal bracket that connects to the throttle body. This bracket is rotated by the throttle to change the TPS’s internal resistance.

Symptoms: The most obvious is if the TPS just up and dies. You’ll get a check engine light and the 0403 trouble code. (Trouble codes will be covered at a later date). However, if the TPS is still gasping its last few breaths, you won’t necessarily get the light. But you will get inexplicable, “spontaneous” drops in RPMs. It’s most pronounced when you are at idle or the engine is coasting to idle after disengaging the clutch. I have yet to see someone tell of problems when the car was moving/accelerating.

TROUBLESHOOTING:

Here is the TPS in the engine bay (red arrow).

You want to pull out the connector away from you (yellow arrow). Do this when the engine is OFF.

You will then expose the pins on the connector.

1. Connect the positive lead of your multimeter (voltage checker) to pin 1.

2. Then connect the negative lead to a ground in the engine bay.

3. Turn your key to the ON position (Do NOT start the car)

4. You should see about 5 volts on the multimeter, indicating the ECU is sending the proper signal.

5. Reconnect the harness to the TPS and start the car.

6. Warm up the car. (This is because heat affects resistance)

7. When warm, turn the engine off, and put the ignition switch to OFF.

8. Connect your meter to pins 2 & 3.

9. With the throttle completely closed (foot off the gas pedal), you should read about 500 ohms of resistance.

10. Start pushing on the gas pedal – resistance should rise. When the gas is fully depressed (wide open throttle), the resistance should be about 4000 ohms.

11. If you are slightly off, you can still adjust the TPS to compensate.

12. Notice that the holes that the screws go into on the TPS are slotted, giving you some clearance. Loosen the screws so that you can turn the TPS in place. If you can twist the TPS so that the values are correct for the different throttle positions, retighten the screws – you’re done.

13. Otherwise, you are out of luck. Time to pick up a new TPS.

A new TPS will cost about $60-$70. Just unscrew the two screws holding the old TPS and put the new one in and adjust until the resistances are right. Then, tighten down the screws. (Yes, the 2nd screw on the other side not shown in the pic is a pain to unscrew) (And yes, these are not the OEM screws. I galled the OEM screws unscrewing them out. These screws are bought from “Home Depot Motorsports” hehe.

Community Member Credit: Stephen Max

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

1. Make or purchase adapter plate,

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.

Community Member Credit: LatinMax

Why Needed? If you want to gain at least 1 more lb of boost.

Parts/Price:

  • K&N Filter  3.5″ Diameter Opening (#RU-1785) $52.00
  • Rubber 90 Degree 3″ Pipe $5.00
  • 3″ PVC 6-8 Feet
  • 3″ ProFlex Coupling (Brand FERNCO)
  • 3″ Silicone Hose

Remove the low-pressure SC pipe and cover the SC with some duck tape. (to keep shavings out of the SC) Also jack up the car and remove the passenger tire. Remove the wheel well cover and pull out the washer bottle. But first, pull out the fill neck. Just grab it and pull, it pops out (this has 2 10mm bolts that you will need to remove)

Take out the MAF and cut the 4 wires that go to the MAF. Make sure to cut all 4 wires staggered. (cut each wire 1″ than longer the next). Now cut 4 16-18 gauge wires that are 3 1/2-4 ft long. 3M Crimps connecters is what I used. Now when you get to the other end you will know that you are connecting the right wires. The stager from the MAF should match the stager of the new wire, plus your wire won’t be too thick to hide in the split loom. (do not plug in the MAF just yet)

You will have to modify your MAF some. Remove the 4 bolt (10mm wrench) and then you will need to grind the flange off. Make sure that you don’t grind out the screen. Cut the 3″ silicone hoses to fit over both ends of the MAF.

Before

After

Use the MAF to get an idea of how much bigger you will have to make the hole for the piping to go thru. You will also need to cut the bracket in the fender well for clearance. (clean out all the shavings i.e.: vacuum or blow it out)

Cut the PVC pipe to about 5 1/2″ (you may want to measure for your own fit. I had a custom front bumper that is deeper. So my PVC was closer to 9″) (a miter saw works well to cut PVC).

Assemble the PVC to the rubber elbow and then to the K&N filter (this way you can slide the PVC pipe up and down inside the filter to get it just right) (If you go too far into the filter take it out and cut again)

Trim the 3″ ProFlex coupling. Turn it inside out and trim it with a sharp (new) razor blade (I use a grinder or Dremel to grind off the lip in the middle).

Before

After

Remove the tape off of the SC and place 3″ ProFlex coupling on the SC and tighten it on there. Next, push the filter assembly thru the wheel well. Then route it so that you can place the washer bottle back in later.

Line it up with a 3″ ProFlex coupling that is attached to the SC. Mine did not go on really square (it seals just fine).

Tighten all the clamps up and place the washer bottle back in. You will only be able to get to the back bolt to the washer bottle and the filter will hold the rest in. Put your fill neck back in. Plug the MAF back in.

Start your car and feel for any leaks around your CAI.

Put the wheel well cover back on and your tire.

Test drive and see if you can feel the difference. Re-check your connections once again.

Happy Modding!

Community Member Credit: Eddy

I wanted to add a sequential shift light to my 2002 Nissan Maxima. After doing some research, I decided to go with the Ecliptech Shift-P2 Shift Light Light. Pretty simple and straightforward to install. I ordered it from the link below and these guys shipped it out super-fast. Would recommend ordering from them if you choose to go this route. It was super easy to install as well.

Order Link: https://www.flyinmiata.com/default/shift-p.html
Price: $219.00

Shift-P2 - Ecliptech

Benefits:

  • You get smooth and consistent anticipation of your shift point.
  • It reduces driver workload and fatigue, both in sprint races and endurance events.
  • It provides drivers with reference points for performance.
  • You can achieve consistent staging RPM for standing starts & launches – so no more watching the tacho on the start line!
  • In enduro events, you can manage your fuel by short-shifting at an indicated point below the peak RPM.
    You can improve your lap time consistency and get up to speed at new tracks and with new suspension setups faster.
  • Eliminate unnecessary engine/transmission wear by keeping the RPM within the range you want, without bouncing off the limiter.
  • A good progressive RPM display can give you what you don’t have… a gauge in your peripheral vision showing the range of RPM you’re interested in! It gives you a reference for improving performance and building on skills. For example, maintaining staging RPM while concentrating on race start, smooth anticipated shift points and maintaining corner entry pace.

Installation:

  • RPM (Blue) –> PIN 34 on ECU (Green/White Wire)
  • Switched 12V (Red)
  • Ground (Black)

ECU Pinout:

Demo Video:

Product Feature & Walkthrough from Manufacturer

Community Member Credit: ATTappman

Recently I had to remove my UIM to tighten the hose clamps on the coolant hoses connected to the backside of the UIM. Here’s a description of the job with some photos. The car is a 1997 GLE Fed spec.

Part 1:

First, you have to remove the air intake. Start by popping off the four clips that secure the top of the air filter box:

Disconnect the MAF sensor electrical connector:

Disconnect the two large vacuum hoses and one small hose from the resonator:

Note that I unhooked the IACV end of the second large hose, to keep the hose attached to the resonator.

Part 2:

Loosen the hose clamp on the throttle body, wiggle the air duct off of the throttle body, and lift the whole air intake assembly out of the engine bay:

Disconnect the two electrical connectors from the throttle position sensor:

Disconnect the four electrical connectors from the IACV/fast idle solenoids/EGR temp sensor:

Part 3:

Unhook the cruise control and accelerator cables from the throttle lever. Note that the accelerator cable runs underneath the little tab on top of the throttle lever:

Remove the three 10mm bolts that secure the cable brackets to the UIM. Move the whole assembly to the back of the engine bay:

Disconnect the electrical connector on the EVAP purge volume control valve:

Part 4:

Disconnect the electrical connectors to the ignition coils and the front O2 sensor:

Unhook the wiring harness. It’s secured by plastic clips. With a pair of needle-nose pliers, compress the two “wings” on the bottom of the clip while simultaneously lifting up from the top. Move the wiring harness to the passenger side of the engine bay:

Remove the two 10mm and two 12mm bolts/nuts securing the EVAP purge control valve and the EVAP purge volume control valve to the UIM:

Part 5:

Remove the 10mm bolt holding the EGR temperature sensor bracket onto the IACV. This bolt is hard to see – you can locate it by feel. You’ll need a 3″ extension or a deep socket. The EGR temp sensor wire is in the way – make sure to move it aside to keep from pinching it with the socket. (No pics for this – it’s too hard to see).

Remove the three 12mm bolts holding the IACV to the throttle body. You need an extension for the bottom bolt (my camera battery went dead here and I switched to my cell phone camera – the pics are blurry, sorry):

Lift off the IACV, being careful not to lose the gasket in the engine bay:

Move the EVAP valves back toward the driver’s side of the engine bay. Most of the hoses will still be attached:

Part 6:

Remove the clamps on both ends of the PCV hose assembly, remove the 10mm bolts holding it to the UIM, and remove it:

Unscrew the two screws holding each ignition coil, and pull out the ignition coils. (No pics).

Unhook the vacuum hose from the UIM to the brake booster:

Now comes the hard part. The UIM is bolted onto the rear cylinder head with two support brackets. The EGR guide tube is also bolted to the UIM with two bolts. All of these are 12mm. The best way to locate the support bracket bolts is to feel with your hand along the firewall side of the UIM. Here’s what it looks like with a socket and ratchet on one of the bracket bolts:

You can see one of the EGR tube bolts, but you have to locate the other one by feel. It’s difficult to get a socket on the right UIM bracket bolt. You need a pretty shallow socket and a low-profile flex head ratchet (this is one job where Snap-on tools pay off). If you can’t use a ratchet, try a 12mm offset wrench. Once you loosen the bolts, use a socket to spin them off. Be careful not to drop them.

Taking off the left EGR tube bolt:

Part 7:

At this point, I was soaked with sweat and had a backache, so I stopped taking pictures.

The only remaining bolts are the four 12mm bolts on the front of the UIM. There’s a pattern for tightening these bolts, so I loosened them in the opposite order. If you’re looking down at the UIM from the front of the engine bay, the tightening order is 4-1-2-3 from left to right, so take them off in the reverse order.

Now the only thing holding the UIM on is two coolant hoses in the very back. If the UIM won’t separate from the lower intake manifold, take a thin putty knife and gently pry between the UIM and the gasket, being careful not to gouge the UIM.

Next, get an assistant (I used my wife – she’s a good scout) to hold the UIM as far up in the air as they can. This will reveal the two coolant hoses on the back of the UIM. It’s an extreme PITA to loosen the hose clamps and pull off these hoses. When you pull on them, you just pull the UIM and your assistant toward you. It took me a lot of patience and a lot of swearing to get them off. Getting them back on is no fun either. Maybe somebody can share a trick for this.

With the coolant hoses off, you can lift the UIM out of the engine bay. Here’s what it looks like with the UIM removed:

You can see the two support brackets and the top of the EGR guide tube. Here’s what my EGR guide tube looked like the first time I took the UIM off:

Reinstallation, as they say, is simply the reverse of removal.

Be careful not to knock the EGR tube gasket off into the engine bay. If you put in a new EGR tube gasket before reinstalling the UIM, it helps to tie two loops of fine dental floss through the EGR tube bolt holes and the gasket. This will secure the gasket to the EGR tube and keep it from falling off when you’re putting the UIM back on.

When reinstalling the UIM bracket bolts, get your assistant to move the UIM up and down slightly so that you can align the bolt holes on the UIM with the bolt holes on the cylinder head.

As you may have noticed, I rethreaded most of the bolts into their holes to keep from losing them. The ones you can’t do this with are the IACV/EGR temp sensor bracket bolts, the UIM support bracket bolts, EGR tube bolts, and UIM bolts themselves. I made post-its for each set and put the bolts on the post-its.

I used Permatex gasket adhesive to hold the UIM gasket and the IACV gasket in place during reinstallation. It was mildly successful.

That’s about it. Hope this helps somebody.