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93v6 3vz-fe spits and bogs when cold...

Old 12-17-2006, 02:39 PM
Junior Member
Thread Starter
Join Date: Dec 2006
Posts: 12
Default 93v6 3vz-fe spits and bogs when cold...

i'm about at wits end with this cold running problem.
1. it starts great and idles great, hot or cold
2. it runs perfectly hot, no complaints at all
3. the first 2 minutes of drivingis terrible:bogging down, backfiring through the breather (or coughing or spitting or whatever the techinical term is), the rpms drop badly out of 1st gear and i have to either: [/align] a. feather the throttle to continue to move slowlyor [/align] b. floor the throttle (at least press it past about 75* angle) to go fast until the temp needle starts to climb. the more it climbs away from C, the better until its gets to normal temp then it's great!

I've replaced:
-plugs (ngk platinum)
-disto cap
-disto rotor
-cold start injector switch (old one showed 75 ohms hot or cold)
-air intake, big black 4" hose
-'fuel up' VSV (old one showed open)
-fuel filter

I've verified these parts are working:
-cold start injector (although the injector fires when i apply 12 v to its terminals, i don't know if the ecu is firing it when i'm starting/driving or not - (the manual says it should come on both when cranking and after starting for a bit, if its cold))
-coolant temp sensor, ohms out good, hot and cold
-air intake sensor in the maf (ohms out correctly closed/open/hot or cold)
-o2 sensor (at least the one i can get to on the front - i pulled a vacuum with the wire disconnected to see if made it go lean .1v and it did, also revving it made it go rich .9v)
-timing appears to be correct as i can see the mark on the flywheel with the 2 pins jumpered at the testing terminal block
-there's no fuel leaking into the vacuum portion of the fuel regulator
-pulling the vacuum tube off of the fuel regulator makes it idle up
-pinching the return hose makes the pressure increase (you can hear the fuel pump pumping harder)
-pulling a vacuum on the EGR makes the engine idle like crap
-cleaned the intake
-checked the egr valve, but it wasn't gunked up
-cleaned the IAC, and it's not sticking
-clear air filter
-ran seafoam through it: half through the brake booster and smoked up the neighborhood and the other half in the tank of premium gas.[/align]-transmission isn't the problem - i don't think - because the engine is still weak when i shift into neutral, then it starts to pickup without being under a load, so i don't think it's the torque converter.

What I haven't done:
-checked out the distributor pickup coils for proper resistances. but it's dry with no oil/water inside.
-put a fuel pressure indicator on it to verify actual fuel pressure psi's
-had the injectors professionally cleaned, either on or off car.
-replaced or checked main computer/ecu/ecm
-checked the igniter[/align]
what should i do next?
Old 08-13-2009, 02:57 AM
Junior Member
Join Date: Aug 2009
Posts: 4

mine does the same thing....replaced ECT, cap, rotor, cat converter, timing belt, fuel filter.....other forums suggest that there is un-metered air getting into the engine via cracks in the intake hose or faulty MAF.....some reccomend drilling out the idle air bypass screw cover and turning it 2 to 3 turns counter clockwise, havent tried that yet....i started mine cold and at an idle sprayed carb cleaner all over the intake hose to check for air leaks (looking for an idle rise) and nothing,.....then i took the hose off and opened up the throtle plate and my whole intake was coated in black gunk...not just carbon, but a thick greasy deposit.....check yours....i'm gonna buy a gasket kit, take off the intake, do the back plugs while i'm in there, and clean out my intake and see if that makes a difference.

good luck.
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