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VS 97 strange problem - heres a challenge for the smart ones on here!!

1997_equipe

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VS 1997 equipe v6 shitbox
ok i have a vs series 2 v6. was duel fuel (factory) but its all disconnected now. has a new motor that has 140,00k that came outta same model car. since day 1 of putting it in it has the following symptoms:

Idles rough as hell sort of hunts for revs u can hear it trying to idle right but it cant
When u cruise it at 60 or 80 or 100 whatever it shudders and misses and runs like crap
When u thrash it it drives awesome
Sometimes it drives better than others
The longer i drive it, or let it idle the worse it seems to get
Occasionally i get an intermittant engine light that comes and goes
Surges when accelerating kinda stumbles then kicks in sometimes

Ive done:

Plugs
Leads
Coil packs
Fuel filter
Intake manifold gaskets
Injectors
Injector cleaner (bout 6 bottles over time)
TPS sensor
Coolant temp sensor
MAF sensor
And ive played around with vacuum hoses and charcoal canister (which seems to make no difference at all whether they are connected or not, could be a possible clue...?)

Im absolutely stumped
I will worship anyone that can solve this for me
I will not only worship but pay anyone willing to fix it for me

Spoken to a few different mechanics and cluey friends about this and everyone just scratches thier head and replies... "i dunno"

Please help lol its driving me crazy
Thanks.
 

delcowizzid

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DFI module under coils or crank angle sensor
 

1997_equipe

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VS 1997 equipe v6 shitbox
i was thinking crank angle sensor... whats dfi module?
 

bandit10

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delcowizzid

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yeah ide do the cas first can cause **** idle and vibrations at cruise speeds but go good when on it and get hot when sitting idling and get worse the hotter they get
 

HamaTime™

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Definately check your DFI Module, they can be a real culprit for shitty engine performance and rough idling. They can cause backfires etc etc. First place to look. If not then try your Crank Angle Sensor.
 

Brett_jjj

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If changing the CAS and DFI module doesnt solve it. Then Id be checking all the wiring connections around the engine bay. If its been like it since the day the engine was re installed, then it might be a bad wiring connection somewhere. Carefully check the wiring connectors on all the engine sensors, and especially check the wiring connector that goes to the DFI module,the contacts inside this plug can get corroded and cause a bad connection,which can then cause it to run crook.Theres a small bolt that has to be removed from the connector before the DFI wiring connector can be unplugged from the DFI module.
 

immortality

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i'm gona go left field here and suggest that you also do the O2 sensors. if these are old and stuffed they will screw around with the tune. a vac leak in the climate control (aircon) system will also screw with the way the car drives
 

moff_man

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hows the gasket on the top of the inlet manifold the one on the top plate, is that sucking air. it sounds like its sucking air or the air flow meter is playing up.

also did you here the engine running before you put it in?
 

Siggers86

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I would have to suggest against the O2 sensor, you would notice a fuel consumption increase and alot of black smoke at times, also poor performance would be fairly consistent, or you would get fluctuations if faulty, the crank angle sensor seems to be the corporate here, as when a motor idles thats when the knock sensor if out can cause you problems, as your rev the motor and give it some stick, the 'knocks' get unnoticed (if small) from a steady vibration, however the dfi module could also be the problem, I would do the knock sensor first, even a second hand one from the wreckers will work to see if there is a problem, also check its plug and wiring, then look into the DFI module however the wiring and corosion on cabeling would be advisable to check as well straight away, but a replacement isn't necessary unless there is visual problems, the usually corrode or get damage from a combination of heat and water from the radiator getting onto/in to it.
Another thing would be to put some high grade fuel in it and some octane booster, this would also help the knock sensor...
 
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