car acts weird at WOT under 2500RPM

[87300zx22]

so my 87 300ZX act really weird...i have to slowly feed throttle into it... if i go WOT under 2500RPM it stumbles and studders..no vac leaks, all is good but it stumbles, hard..but once its over 2500 it rockets away..


any idea wtf is wrong???

[evildky]

mas? you check the ecu for codes yet?

[87300zx22]

MAF works fine..i check codes and only get code 44 (no codes) even tho the 87 ECU is code 45...so i must have a 86 ecu..no difference that i know of between them tho..

[87300zx22]

well...what ever it was fixed itself...runs great, has a hard kick at 2800 RPM tho o.o like the car hits a wall, then gains 50WHP and rockets off..really weird..

[evildky]

moisture ina maf connector can do things liek that and when dried up, back to normal

[87300zx22]

ill put DEG on the connector and see if that fixes it for good..

[AZ-ZBum]

When was the last time you did a tune up or checked the timing?

[87300zx22]

sparkplugs were changed 3 days ago..very corroded..fixed alot of low rpm issues. installed a 240tb (i highly reccomend this mod to all Z31 drivers) yesterday and all low rpm issues are gone, car pulls extremely hard (for being n/a) compared to the stock TB..my TPS front connector broke off tho...so I only have the bottom connector hooked up. the wires were green in the front one, so I'm gonna grab a new TPS, and try to find a new harness connector..

car holds 15* timing..I set it there cause it was at 25 and had no power. I'm running 89 oct and can't hear any knocking, or pinging from the motor

[evildky]

a disconnected tps would have been good information to have, untill you fix what you know is broken we can't help you

be sure to dial in the tps as it does not bolt to the sx tb and even then needs to be clocked properly

the car should run on 87 octane with no knock or ping

[87300zx22]

my Z's tps fit perfectly on the sx TB. I have it set in the middle right now..no clue how to clock it tho..every time I tried running a diagnosis on it the ecu wouldn't like up for it..

what exactly does the TPS controlled anyway???

[87300zx22]

another issue my car has, if I leave from a dead stop slowly, my car has no power at all..feels like it has 80whp, but if I launch from a stop the car pulls hard..but around here I can't let the car pull hard all the time..this has been around since I got the car, any clue what it could be??? I've checked everything and can't find anything..also my car seems to dump fuel at idle, and be overly lean over 3k cause at 3,000-3,200 the power peaks and the car wont pull any harder, and actually starts slowing down slightly but 600-3,200 it pulls hard as hell..after 3,200 its nothing I hope the maf isn't going bad...don't wanna spent a ton of money for a new one...but when sitting at a light you smell a strong gas order, no gas is leaking any where I've looked for it and can't see any gas puddles on the motor/under the car

[evildky]

the z31 tps fits ont he 240sx tb shaft, but the bolt holes do nto line up, one uses a wider pattern I can't recall which off hand

on the z31 the tps basically lets the ecu (and trans on an automatic) know whan the car is at idle and when it is at full throttle, the 240 sx tb is a potentiometer

[87300zx22]

so..how do i clock it correctly??? no clue how to do that...but it'll have to wait until after i get a new harness connector to connect into the front of it...and possibly get my maf checked out..my car jumps in power (in steps) up to 3,000 RPM. then after 3k the power drops off

[evildky]

buy, borrow or download the fsm

unless you have a wideband hooked up you have no way of knowing if the car is rich or lean

if the exhaust smeels of fuel and the car has warmed up completely, it could be a bad cat, also an bad O2 can cause the car to run rich, and a bad or diconnected CHTS will cause the car to run extremely rich to the point of fuel fouling

[87300zx22]

buy, borrow or download the fsm

unless you have a wideband hooked up you have no way of knowing if the car is rich or lean

if the exhaust smeels of fuel and the car has warmed up completely, it could be a bad cat, also an bad O2 can cause the car to run rich, and a bad or diconnected CHTS will cause the car to run extremely rich to the point of fuel fouling

FSM is on my laptop
too poor for a wideband haha
car has no cat, Sensor light still works, and O2 looks new, car has no codes except the "no codes" code, and the car pulls hard, it just leans out too much above 3k it seems cause it has no power over that..i can try to get a video of the pulls if itll help..

1st gear pulls like a monster, 2nd pulls fairly ok, but 3-5 pulls crappily

[evildky]

FSM details how to dial int he TPS

you have no way of knowing if the car si lean or rich, unless you have a wideband you failed to mention?

if you have no cat your car will always smell like it's rich, thats kinda why we have cats, morons remove them to gain 2 whp

you said the car pulls good through first gear, but that it "leans out" over 3k, so it pulls hard in first up to 3K? is the issue rpm dependent or gear dependent? this an auto or manual?

[87300zx22]

ive followed the FSM on the stock setup and never got any reading from the TPS..

cat was clogged and my friend (the PO) didnt wanna spend 150 for a high flow cat..

and its both RPM, and gear dependent..

1st gear: hard pull to 3k
2nd gear: hard pull to 2500-ish
3rd medium pull to 2800-ish
4th gear ok pull
and 5th gear is just blah

[evildky]

mas would be suspect, might try swapping in a known good one

assuming the mas is ok, first thing I'd do is get an inline fuel pressure gauge and enough extra fuel line to loop it up under a wiper arm to hold the gauge in place while driving and see what the fuel pressure does when ti starts to cut out

[87300zx22]

it dosn't cut out, it just looses power


but i pulled out my maf, and cleaned it

she pulled hard to 5500 now!