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Discussion Starter · #1 · (Edited)
Hey guys , havent posted in a while.
Let me tell you the story about fixing my 2000rpm hesitation.

2005 350z base 175,000 running strong with oil consumption since 40,000 miles(too bad i never knew about the new engine they couldve gave me back then)
Fully bolted , pulleys, ignition system etc.
All motor.

2 years ago i noticed a hesitation where the car would feel like the turbo spooled and kicked in. But i dont have a turbo. I saw this happened at 2,000rpm in 1st gear. Then any other gear at the same rpms it would sometimes just buck or jerk until i passed the rpms or gave it more throttle.

No check engine light, no pending codes.
Tried stock ecu and different flash to no avail.
I finally put it in AEM UEGO that i had from my RB that i ran in my S14 into my Z.

I noticed at the troubled rpms it would lean out to 17-18AFR when it should stay anywhere from 14-15.4 (depending on throttle). Thats when i tried a extra fuel pump i had and it did the same thing. My fuel tank was extremely clean for 175000miles. Might be do to running only 91, 93 (in Los angeles at a Private club for exotic cars )and 100 octane at 76 gas station. Or the returnless fuel system as well.

I tried a brand new MAF from the dealer, New spark plugs from the dealer new coilpacks and none of it fixed the issue.checked for vacuum leaks.

So after i took out my tuning software and timing was fine. I added more fuel to those rpms and nothing. So i kept adding way more fuel until it would stop hesitating, and it worked. But i was pushing the injectors way to far past their strenght in order to solve this and 2000rpms are cruising speeds in the Z so i was doing about 11AFar at light throttle.

So i knew gas was the issue again.

I couldnt find much info other than the fuel damper going bad but they make loud clicking noises and no one would mention hesitation or bucking. None of mine were making noises. So i decided to buy the passanger one from the dealer first. I changed it and nothing, but i did notice i now added a SECOND hesitation point...now at 4,000rpms, so i knew something was up with the fuel dampers. I ordered the driver fuel damper and that fixed the issue. No more bucking no more hesitation on light throttle and my UEGO read 14.7-15.4 at those rpms compared to 17-18. Not even then smallest hint of hesitation anymore at any rpms.

I just hope this helps ppl with hesitation issues that i keep seeing but no one ever says its resolved or i missed it.

Also i was having issues with my knock sensor harness and i had no check engine light. Replaced the harness and knock sensor and that helped my timing at WOT which was being retarded and extra fuel was being added(thanks to the UEGO and cipher for this catch)
My oem knock sensor was fine according to the resistance check i did and was not cracked. The new sensor put out the same resistance. So i know the harness was bad.

Well i wish to see people with hesitation issues to try the new dampers and post here with good results. BTW the new dampers have new part numbers and get them from nissan not anywhere else.




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Check out our website JB Performance Nissan / Honda parts and more
 

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Registered
Joined
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1 Posts
Hey guys , havent posted in a while.
Let me tell you the story about fixing my 2000rpm hesitation.

2005 350z base 175,000 running strong with oil consumption since 40,000 miles(too bad i never knew about the new engine they couldve gave me back then)
Fully bolted , pulleys, ignition system etc.
All motor.

2 years ago i noticed a hesitation where the car would feel like the turbo spooled and kicked in. But i dont have a turbo. I saw this happened at 2,000rpm in 1st gear. Then any other gear at the same rpms it would sometimes just buck or jerk until i passed the rpms or gave it more throttle.

No check engine light, no pending codes.
Tried stock ecu and different flash to no avail.
I finally put it in AEM UEGO that i had from my RB that i ran in my S14 into my Z.

I noticed at the troubled rpms it would lean out to 17-18AFR when it should stay anywhere from 14-15.4 (depending on throttle). Thats when i tried a extra fuel pump i had and it did the same thing. My fuel tank was extremely clean for 175000miles. Might be do to running only 91, 93 (in Los angeles at a Private club for exotic cars )and 100 octane at 76 gas station. Or the returnless fuel system as well.

I tried a brand new MAF from the dealer, New spark plugs from the dealer new coilpacks and none of it fixed the issue.checked for vacuum leaks.

So after i took out my tuning software and timing was fine. I added more fuel to those rpms and nothing. So i kept adding way more fuel until it would stop hesitating, and it worked. But i was pushing the injectors way to far past their strenght in order to solve this and 2000rpms are cruising speeds in the Z so i was doing about 11AFar at light throttle.

So i knew gas was the issue again.

I couldnt find much info other than the fuel damper going bad but they make loud clicking noises and no one would mention hesitation or bucking. None of mine were making noises. So i decided to buy the passanger one from the dealer first. I changed it and nothing, but i did notice i now added a SECOND hesitation point...now at 4,000rpms, so i knew something was up with the fuel dampers. I ordered the driver fuel damper and that fixed the issue. No more bucking no more hesitation on light throttle and my UEGO read 14.7-15.4 at those rpms compared to 17-18. Not even then smallest hint of hesitation anymore at any rpms.

I just hope this helps ppl with hesitation issues that i keep seeing but no one ever says its resolved or i missed it.

Also i was having issues with my knock sensor harness and i had no check engine light. Replaced the harness and knock sensor and that helped my timing at WOT which was being retarded and extra fuel was being added(thanks to the UEGO and cipher for this catch)
My oem knock sensor was fine according to the resistance check i did and was not cracked. The new sensor put out the same resistance. So i know the harness was bad.

Well i wish to see people with hesitation issues to try the new dampers and post here with good results. BTW the new dampers have new part numbers and get them from nissan not anywhere else.




____
Check out our website JB Performance Nissan / Honda parts and more
Sorry I know this is almost 10 years old but I guess it’s worth a shot. When you say bucking do you mean bucking at low Rpms like the car jerking back and forth when slowing down or when barely tapping the gas the rev hangs?
 
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