luvS2000

hi guys, i'm new to this forum.. i sold my miata to buy a s2000 so i bought a 2001 black s2000 and has 130k miles bone stock
1 month ago and had no problem driving until a weeks ago. im just gonna cut to the chase.. previous owner replaced iac and tp and, a new ecu
and o2s fuel pump checked compression 220 all cylinders then gave up , it doesn't run smooth as it should be h said.
i have this bluedrive obd so i hook it up and look what is wrong but with no code.

here's mysteries i can't understand.. first of all rpm drops on steady throttle regardless of rpm range in parked. but if i give a little more then it stays and also hear engine sound is going up and down.

2.( this only happened once)i found out the Map sensor and "timing adv" i think that's crank position sensor and calculated engine load were all fluctuating
and when i started it stopped fluctuating even after i shut it off.


3.Map reads sometimes 29.5 to 29.8 inhg when engine is off. if engine is on and warmed up it reads unsteady 7.4 - 8.9 inhg at idle. (but the owner said it should be at 10ish inhg? ) idk..
o2 b1s1 voltage goes up really slow somtimes, b1s2 goes up fast with key on.
tps is at 5.9%
map has some short of ziptie holder.
air and coolant sensor goes up or down sometimes like something is shorting out
so i unplugged most of sensors where i can reach from top,
then i found out tps was fluctuating 0-0.4% with unplugged
and map reads 52 inhg but no fluctuation. idk if that normal or not..
Next thing i did i gave a lilttle wiggle the tps connector wires to the back of engine it and it started to fluctuate more
but... i don't see any damaged harness and no signs of exposed wires

so i'm thinking it is wiring issue but i don't wanna crack the engine harness open because it looks perfectly intacted.
i wish ive bought a good condition s2000 but this is what i can afford since i'm kinda low on budget.
i'll try anything to fix my S2000 but i really need s2ki members help.
really appreciated.

Car Analogy

Ok, back up a little. What is actually wrong? It doesn't run smoothly? Rpm fluctuations is it?

And PO says it all ran perfectly fine until recently, so he did a bunch of stuff that didn't fix it, gave up and sold it to you? Is that right?

luvS2000

yes. he told me he reset ecu , also reset it by pulling fuse if drives sluggish..
rpm doesn't fluctuate if it is idling, feels like losing power time to time.

Halfassjack

Have you ever seen check engine light on.....with koeo or any other time?

luvS2000

no check engine light.
i fiddled around aftermarket alarm system and it stopped tps and calculated engine load from fluctuating and i don't see any damaged wiring..
does it have to do with aftermarket alarm system? it is a viper 5900
but when i start the warmed up engine map reading rises to 12 inhg then it stays at 10 inhg ( normal vacuum ?) for few second then it drops back to 8 inhg and stays at idle again like i mentioned above.
also noticed short term fuel trim drops to -10 to -15 at idle and rpm still drops at steady rpm.
i thought i solved it but it looks like it made it worse cuz i start smelling fuel

ive also noticed something buzzes in rear end under the car as i was fiddling the alarm system.

Halfassjack

Check engine light should come on and go off within a couple seconds of turning key to run position. Does it?

luvS2000

light does not come on when KOEO omg what does that mean

Halfassjack

If check engine light does not come on get factory service manual and start there.

Hfreak

Your CEL lamp may be burnt, not really fun to replace. You may as well test all the bulbs in the cluster while you have it out. Good luck.

Spartarus

double digit negative fuel trims at idle indicates sticking injector.