Recently got my 1993 300zx started after sitting for a year and a half!
The problem now is that when driving in gears, first gear is just so god damn weak. I know the difference in power and I can somewhat even notice it in the other gears as well but not to the point where it could effect speed capabilities (given, it is harder to reach speeds with this problem). It seems like RPMS are slower below 2000 rpms in first gear and afterwards, it’s completely fine. Rev response in neutral on the other hand is completely fine and in fact, is what I’m looking for in each gear.
I’m suspecting IACV valve needs to be cleaned but other than that, I have no idea where to start.
All advice appreciated!!!
Loss of power in first gear
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JohnathanSins
- Posts: 5
- Joined: Mon Jun 26, 2023 2:25 am
- Car: 1991 Nissan 300ZX
Re: Loss of power in first gear
Same engine in 93 J30 , I believe , and mine and many others have experienced a weird condition like yours - weak power up to about 2900 rpm then after 3k rpm seems to " fill out " with enough normal power , feeling ok all the the way up to 5k & 6k rpms ? I had that , not really sure if ONE specific or multiple combo (symbiotic contribution from MORE than one problem ) .
My endeavor to STOP THE BOGG !!!!!!!!
MAF
Timing.......check OR try 1 - 1 1/2 deg MORE BTDC .............watch the pinging in this heat tho
PCV valves ( they clean up fine - metal , feel free to replace too ) very goofy & tight working tho
Grounds on and near engine on frame etc. Wire brush , may use " NO-Al-Ox "paste (Electrical prep for wire conn. ) as an anti corrosion inhibitor/protectant
Knock Sensor * UNDER INTAKE MANIFOLD !! You CAN bolt a new OEM KS to one of the threaded bosses that the 5" x14" eng cover bolts to AND this location works for me .....I GOT the POWER !!!!! ......Just re-plug harness to the 'new'.
Spark Plugs ( ya , gotta do a little work to check ) Plugs at rear of both banks usually the ones get 'burnt' .chk 'em
I have got a hold of TWO good OEM MAF's , I alternate when cleaning MAF and filter change's .ENDS "MAF Ok mystery" .
Also good practice to keep heat-sink thermo conducting grease on your IGNITER In THISJULY HEAT ( the 2" x 2" & 6 transistor device that fires your plugs @ back/top of eng) .) Be careful of brittle SZHITT around it ......like wiring and clips etc.
When these areas have been fine - no more hesitation/weakness . Some say timing belt or the ign sensor on the drvr's exh cam .............never been problems tho on mine , and I had Baaaaaaaaad hesitation.
Mysteriously gone , I really don't know the specific cause / causes ?????
p.s. Generally , the idle system (IAC etc. ) is out of the picture and this / my problem IS into the power aspect of the performance. or past the idle's job. NOW IF you CAN adj base idle like 550 rpm , AND the car ups idle for A/C to like 850-900 rpm , AND whith A/C OFF idle around 750-825 rpm is right ?? ...DO NOT MESS W/IDLE componants early on in your troubleshooting , for I've kinda stated pretty much ALL the idle system's job's MUST properly operate , and probly OK ??
My endeavor to STOP THE BOGG !!!!!!!!
MAF
Timing.......check OR try 1 - 1 1/2 deg MORE BTDC .............watch the pinging in this heat tho
PCV valves ( they clean up fine - metal , feel free to replace too ) very goofy & tight working tho
Grounds on and near engine on frame etc. Wire brush , may use " NO-Al-Ox "paste (Electrical prep for wire conn. ) as an anti corrosion inhibitor/protectant
Knock Sensor * UNDER INTAKE MANIFOLD !! You CAN bolt a new OEM KS to one of the threaded bosses that the 5" x14" eng cover bolts to AND this location works for me .....I GOT the POWER !!!!! ......Just re-plug harness to the 'new'.
Spark Plugs ( ya , gotta do a little work to check ) Plugs at rear of both banks usually the ones get 'burnt' .chk 'em
I have got a hold of TWO good OEM MAF's , I alternate when cleaning MAF and filter change's .ENDS "MAF Ok mystery" .
Also good practice to keep heat-sink thermo conducting grease on your IGNITER In THISJULY HEAT ( the 2" x 2" & 6 transistor device that fires your plugs @ back/top of eng) .) Be careful of brittle SZHITT around it ......like wiring and clips etc.
When these areas have been fine - no more hesitation/weakness . Some say timing belt or the ign sensor on the drvr's exh cam .............never been problems tho on mine , and I had Baaaaaaaaad hesitation.
Mysteriously gone , I really don't know the specific cause / causes ?????
p.s. Generally , the idle system (IAC etc. ) is out of the picture and this / my problem IS into the power aspect of the performance. or past the idle's job. NOW IF you CAN adj base idle like 550 rpm , AND the car ups idle for A/C to like 850-900 rpm , AND whith A/C OFF idle around 750-825 rpm is right ?? ...DO NOT MESS W/IDLE componants early on in your troubleshooting , for I've kinda stated pretty much ALL the idle system's job's MUST properly operate , and probly OK ??