I didn't expect to remove and install the throttle body so many times, if so I would have a photo here of me flashing 2 fingers. <insert photo>
Remember, I had already removed everything once and rebuilt the entire throttle body. After installing and finding that the joint didn't hold air under pressure without a seal, I removed the piping and throttle body and lathered it with rtv. This fixed the leaking but then the next issue arose.
The idle was very high. I adjusted the idle screw until it was no longer touching the butterfly wheel. This is otherwise known as the absolute minimum it could be set. The idle was still very high.
I removed all the piping and throttle body for a third time to adjust the mechanical minimum idle of the butterfly. You can see the excess rtv.
I adjusted the butterfly position inside the shaft slot. It was in the correct orientation as observed from part 2, but it can be fine tuned by moving it around before clamping down on the mounting screws. It may not seem like much, but this greatly affects the fit in the bore when considering the operating fluid is air in this case.
Sand off old rtv from throttle body and plenum, install piping with maf, install throttle body, connect silicone, tighten clamps. Third time's a charm. Not really.
Test.
High idle was completely gone but the max tps reading was over 5 volts and maxed out the sensor at wide open throttle. First photo of the ecu controller is of the car at idle, second and third are of it at wot. Look closely at the second row, left column, the throttle position sensor. As in part 2, the tps can only be fine tuned once the shaft adapter and, and as I feared, turned all the way down it still maxed out and threw an error.
Simply put, if it can't read the position at the extremes it won't know how much fuel to send to the engine, not to mention while driving the car may go into a limp mode it if senses a sensor out of it's normal range and do even weirder things.
This begins pull 4.
This was getting exhausting. And irritating. Exhaustingly irritating.
I moved the adapter around the shaft in the direction it needed to move the range upward as compared to the actual throttle position. Essentially it had enough minimum but not enough maximum. It's like if you needed to measure from 0 to 5 and were measuring from -2 to 3.
I can't show this well as it's inside the adapter, but this orientation placed the set screw right next to the flat edge on the actual butterfly shaft, so I tightened it significantly since it no longer has a flat controlling it's position, only clamping force and friction.
I assembled the tps again, and this time used 2 washers between it and the ring. The adapter can be mounted at any position in/out relative to the shaft. I may have mounted it a bit more out this time when placing the set screw. Either way, the tps needed the extra room for the inner face, which you'll suspiciously see more of later.
With all the installing and un-installing of the tps, a piece broke off from the inside. I was sure I would need a new tps when this happened, but luckily the adapter input goes past this lead-in guide and turns a matching flat deeper inside the tps. It did make it more difficult to engage the tps flat to be sure. I had to spend a lot of time pulling it on and off to finally get it to engage. It reminded me of a transmission shaft that doesn't want to go through a clutch and into a pilot bearing.
You'll have to take my word for it, but I installed everything yet again, including sanding off the old rtv and applying yet another batch. At the very least I was getting very efficient at it all. On the bright side, each issue was going away very definitively after each test.
As you can see the throttle was much higher in it's range at idle after installation.
I adjusted it down.
And took a break.
At this point I took it for a test drive and slammed through the gears. Same lack of ability to even think about boosting. One more time it is.
At this point I was running out of ideas, but thought that the tps may have been mucked up from the constant trauma over the last 24 hours. I had to force it onto the adapter shaft a few times a bit harder than advised, and especially after the guide broke off it was increasingly more difficult to engage. Then again, the adapter may have rotated because the set screw wasn't seated on the flat on the butterfly shaft flat anymore.
Go.
Back inside the house, my main concern was to verify that the adapter wasn't interfering with the tps. I verified the adapter position and that it didn't rotate, but it may have actually popped out of the sensor's flat. With the adapter positioned a bit too far inboard and the tps on spacers to clear it's plastic clips and bottom protruding circle, considering it's new lightened weight sans-inner guides, it looked like the sensor may have not been engaged.
Without the washers to space it out the black plastic clips rested on the mounting ring causing it to pitch at an angle. The tps center circle also rested on the shaft adapter where it goes from male to female. I couldnt mount the adapter any further back without drilling/taping another hole to move the set screw, as the allen wrench was already flush against the side of the throttle body when installing. There wasn't that much room for the butterfly shaft to go inside the adapter before it bottomed out anyways, regardless of the set screw. It's like the adapter should have have more room for the outer tps features and a longer input shaft portion to engage more. Not to forget about the housing clips cocking the whole tps.
All of the previous issues needed to be addressed and required removal of the throttle body. Knowing what I know now about the reason for my lack of boost, this fifth removal and work may not have been required per say, but it was probably for the best to double check the tps functionality and mount it correctly, installing it how it should have been from the beginning.
I blended the tps circle and rear housing clips which fixed the need for washers to space it off the mounting ring because it was cocked and interfering between the tps circle and the adapter when installed flat.
I plugged the tps in and turned on the car to make sure everything was ok before installing yet again. The butterfly shaft adapter was in the right position and I adjusted the throttle to within its operating range. I don't have photos of wot position, but it's less than 5v.
Installed and rtv'ing (yes, thats a verb now) for the fifth time, I really just wanted to go to bed. All the recent throttle body and maf work took place one saturday and well into the night. There were more than several unsuccessful test drives and once when I even thought the tps disengaged completely and would have to tow the car back, somehow. This wasn't completely unnecessary, but definitely added to the long day.
To recap, I wrote it all out. See image.
This fixed many small issues, but the main solution still eluded me. If you go back to part 1 and look at the to do list however, you'll get a hint of the solution and it was even on the list before everything hit the fan. A few years ago I was running this motor in my 28o with what turned out to be a less than desirable fuel tank. I actually physically blew up a few maf's <blow thru>, and once this was fixed, a similar boost cut issue remained. It was not as violent as the one I was experiencing now, but at higher boosts it would sputter. I knew the maf was ok so I checked the fuel connections and lines, working my way back to the clogged fuel filter.
My 28o z tank rusted into the filter causing significant restriction.
I considered this enough in the probable realm of possibilities now to put it on the to do list, but did not take it seriously this time as the fuel pump and lines were all new, the tank cleaned and not rusty. I even replaced the fuel pickups and fittings around the tank previously in preparation of -an line upgrades. That entry was another multi-part-er actually.
In an effort to delay the solution as long as possible, I found out that the stock position for Nissan tps' is o.4o v at idle, so I adjusted mine to that assuming it had been set there during the tuning and maybe would be enough to affect the boost, but it wasn't. It didn't change the tune at all.
At this point I pulled the fuel filter and so much crap came out of it it was ridiculous.
Started the car again and checked the fuel pressure. +1o psi at idle. No maf issues, throttle body issues, tps issues, and finally, no fuel issues. Troubleshooting 1o1.
She's never ran better.
Remember, I had already removed everything once and rebuilt the entire throttle body. After installing and finding that the joint didn't hold air under pressure without a seal, I removed the piping and throttle body and lathered it with rtv. This fixed the leaking but then the next issue arose.
The idle was very high. I adjusted the idle screw until it was no longer touching the butterfly wheel. This is otherwise known as the absolute minimum it could be set. The idle was still very high.
I removed all the piping and throttle body for a third time to adjust the mechanical minimum idle of the butterfly. You can see the excess rtv.
I adjusted the butterfly position inside the shaft slot. It was in the correct orientation as observed from part 2, but it can be fine tuned by moving it around before clamping down on the mounting screws. It may not seem like much, but this greatly affects the fit in the bore when considering the operating fluid is air in this case.
Sand off old rtv from throttle body and plenum, install piping with maf, install throttle body, connect silicone, tighten clamps. Third time's a charm. Not really.
Test.
High idle was completely gone but the max tps reading was over 5 volts and maxed out the sensor at wide open throttle. First photo of the ecu controller is of the car at idle, second and third are of it at wot. Look closely at the second row, left column, the throttle position sensor. As in part 2, the tps can only be fine tuned once the shaft adapter and, and as I feared, turned all the way down it still maxed out and threw an error.
Simply put, if it can't read the position at the extremes it won't know how much fuel to send to the engine, not to mention while driving the car may go into a limp mode it if senses a sensor out of it's normal range and do even weirder things.
This begins pull 4.
This was getting exhausting. And irritating. Exhaustingly irritating.
I moved the adapter around the shaft in the direction it needed to move the range upward as compared to the actual throttle position. Essentially it had enough minimum but not enough maximum. It's like if you needed to measure from 0 to 5 and were measuring from -2 to 3.
I can't show this well as it's inside the adapter, but this orientation placed the set screw right next to the flat edge on the actual butterfly shaft, so I tightened it significantly since it no longer has a flat controlling it's position, only clamping force and friction.
I assembled the tps again, and this time used 2 washers between it and the ring. The adapter can be mounted at any position in/out relative to the shaft. I may have mounted it a bit more out this time when placing the set screw. Either way, the tps needed the extra room for the inner face, which you'll suspiciously see more of later.
With all the installing and un-installing of the tps, a piece broke off from the inside. I was sure I would need a new tps when this happened, but luckily the adapter input goes past this lead-in guide and turns a matching flat deeper inside the tps. It did make it more difficult to engage the tps flat to be sure. I had to spend a lot of time pulling it on and off to finally get it to engage. It reminded me of a transmission shaft that doesn't want to go through a clutch and into a pilot bearing.
You'll have to take my word for it, but I installed everything yet again, including sanding off the old rtv and applying yet another batch. At the very least I was getting very efficient at it all. On the bright side, each issue was going away very definitively after each test.
As you can see the throttle was much higher in it's range at idle after installation.
I adjusted it down.
And took a break.
At this point I took it for a test drive and slammed through the gears. Same lack of ability to even think about boosting. One more time it is.
At this point I was running out of ideas, but thought that the tps may have been mucked up from the constant trauma over the last 24 hours. I had to force it onto the adapter shaft a few times a bit harder than advised, and especially after the guide broke off it was increasingly more difficult to engage. Then again, the adapter may have rotated because the set screw wasn't seated on the flat on the butterfly shaft flat anymore.
Go.
Back inside the house, my main concern was to verify that the adapter wasn't interfering with the tps. I verified the adapter position and that it didn't rotate, but it may have actually popped out of the sensor's flat. With the adapter positioned a bit too far inboard and the tps on spacers to clear it's plastic clips and bottom protruding circle, considering it's new lightened weight sans-inner guides, it looked like the sensor may have not been engaged.
Without the washers to space it out the black plastic clips rested on the mounting ring causing it to pitch at an angle. The tps center circle also rested on the shaft adapter where it goes from male to female. I couldnt mount the adapter any further back without drilling/taping another hole to move the set screw, as the allen wrench was already flush against the side of the throttle body when installing. There wasn't that much room for the butterfly shaft to go inside the adapter before it bottomed out anyways, regardless of the set screw. It's like the adapter should have have more room for the outer tps features and a longer input shaft portion to engage more. Not to forget about the housing clips cocking the whole tps.
All of the previous issues needed to be addressed and required removal of the throttle body. Knowing what I know now about the reason for my lack of boost, this fifth removal and work may not have been required per say, but it was probably for the best to double check the tps functionality and mount it correctly, installing it how it should have been from the beginning.
I blended the tps circle and rear housing clips which fixed the need for washers to space it off the mounting ring because it was cocked and interfering between the tps circle and the adapter when installed flat.
I plugged the tps in and turned on the car to make sure everything was ok before installing yet again. The butterfly shaft adapter was in the right position and I adjusted the throttle to within its operating range. I don't have photos of wot position, but it's less than 5v.
Installed and rtv'ing (yes, thats a verb now) for the fifth time, I really just wanted to go to bed. All the recent throttle body and maf work took place one saturday and well into the night. There were more than several unsuccessful test drives and once when I even thought the tps disengaged completely and would have to tow the car back, somehow. This wasn't completely unnecessary, but definitely added to the long day.
To recap, I wrote it all out. See image.
This fixed many small issues, but the main solution still eluded me. If you go back to part 1 and look at the to do list however, you'll get a hint of the solution and it was even on the list before everything hit the fan. A few years ago I was running this motor in my 28o with what turned out to be a less than desirable fuel tank. I actually physically blew up a few maf's <blow thru>, and once this was fixed, a similar boost cut issue remained. It was not as violent as the one I was experiencing now, but at higher boosts it would sputter. I knew the maf was ok so I checked the fuel connections and lines, working my way back to the clogged fuel filter.
My 28o z tank rusted into the filter causing significant restriction.
I considered this enough in the probable realm of possibilities now to put it on the to do list, but did not take it seriously this time as the fuel pump and lines were all new, the tank cleaned and not rusty. I even replaced the fuel pickups and fittings around the tank previously in preparation of -an line upgrades. That entry was another multi-part-er actually.
In an effort to delay the solution as long as possible, I found out that the stock position for Nissan tps' is o.4o v at idle, so I adjusted mine to that assuming it had been set there during the tuning and maybe would be enough to affect the boost, but it wasn't. It didn't change the tune at all.
At this point I pulled the fuel filter and so much crap came out of it it was ridiculous.
Started the car again and checked the fuel pressure. +1o psi at idle. No maf issues, throttle body issues, tps issues, and finally, no fuel issues. Troubleshooting 1o1.
She's never ran better.
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