hello guys i am there today cuz i got real problems about one car

i am professional tech i own my self garage /

i register this forum to know if some one can help me about this hyunai
i am french canadien so if some word are not properly i be sorry !

ETA |:

hyundai accent 2005 //

first step in my story
i got 2 month ago job to install 2.0l elentra inside this accent
job done all go well i set up performance clutch header performance down pipe and cata t-belt kit all seal and gasket plug wire ect.. / /
car run properly and perfectly

but engine come from local scrap yard and month later see this engine burn internal oils
smoke really bit but 1 liter in month for about 700km
then whe ask for other engine from scrap yard
on warenty

i swap all t-belt kit and buy new seal for crank front and back and cams seal
i swap engine agains all go well and start back new engine but bit rought idle so i make breakcleaner test and find intake manifold gasket leak
i remplace and start back engin run real better me bit rought is not running like new engine but any way i send it to my customer after i make few road test and put this car up tu 180km/h in the 4 speed
engine have torqu and good performance

my customer get is car and have to make 45km to get is home so by the way get gaz from local big gaz station and half way to is home car stop to get performance... what happen ? nothing wrong with the driver .// get back car here and try to get high speed with nothing go engine can't make is tire spin on wet street and can't get 140 km/h with
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now test on
genesis scanner
no code
see all is spec from
t-belt ok
timing chain ok after remplace it it whas loose then where come
my rought idle
02 sensor up ok
02 sensor dwn ok after remplace it he was stuk 0.45v
gaz pressur ok 55lbs
gaz qty ok about 1 gallon / minute
tps ok 0.3v close 0% and 80% full trottle and! full trottle
swich on
engine compression 150lbs on 4 cyl
i whas tinking about Cams sensor is fructuat but go up to 6.5-7 volt
not supose to
map sensor tell me 11 in.hg but if i remove from intake and i set up my
gage is telling me 17 in.hg // idle
i remplace it but same
i try coils pak fuel rails and still have no change i look back timing mark on crank and set rod on piston to see if is really tdc / ok
check ground on engine /// bad

bad ***
fix ground but still have high resistance
clean it from battery to body battery to engine starter bolt tower to intake manifold add 1 from firewall to intake manifold and left tower to front of head
i think is have power crossing some where engine off 0.1 ohm
engine on 35-55 ohm
then test ecm
battery voltage ignition voltage and all ground look like bad ground here too but only when engine runnig
and after make some test i find sensor ground problems (i think) and
5v problems (i think)
white wire from ecm pin #33 to map have 2.5 v ( should be 5 not ?? )
voltage should be from the ecm
i try 2 other ecm and still have same problem by volt and performance

i have no more idea where i should look at and my head will blow out
i have car here from 5 day .. try and look and try and look // can some
one have idea if some electric positive jump across ground in engine can make this but i did not find where is from //
car stop to get performance in road
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ty for your patience to read if you can help me as well ty anyway else !!!
if you need more information about anything i can get you all info about anything

car can't get 140 kmh