Need Help with this one!
#1
Rough Idle; Loss of Power
Here's the deal. I have a 2000 Tacoma 3.4 with the 5vz-se engine. I had a couple of codes thrown from the ECU. I replaced the the Mass Air Flow sensor, The Throttle Position sensor, bought a new gas cap, plug wires, plugs, fuel filter. The truck runs an idle at around 1000 RPM but idles so rough it seems as if though it's running on just two cyclinders. The truck also tries to stall if your foot is not left on the gas pedal. I checked the truck for compression and all cyclinders were within 5 lbs. of each other. They registered at 185-190 sq.in.lbs. I can also smell raw fuel that is being dumped into the cyclinders. What would be causing this problem? The codes that were thrown were PO171,PO120,and PO450.
Last edited by ravencrew; 01-23-2009 at 03:19 AM.
#2
PO171 - System too lean
You probably either have leak in the fuel system or a blocked injector
PO120 - TPS malfunction
Replace TPS sensor
PO450 - Evaporative emission control malfunction
You probably either have leak in the fuel system or a blocked injector
PO120 - TPS malfunction
Replace TPS sensor
PO450 - Evaporative emission control malfunction
#3
Yeah I replaced the TPS and MAF plus the gas cap. This truck does not have any power whats so ever. I just can't seem to get the truck to have a normal idle. I also unbolted the cat to see if I may have had alot of back pressure it didn't make a difference.
#4
You might be able to smell unburnt fuel from a lean misfire (p0171) - the first thing to check would be fuel pressure, which could also cause your lack of power. If fuel pressure is low, replace the filter and recheck. If it's still low you probably have a bad fuel pump - FYI if the pressure is low and you decide to replace the pump first for some reason, replace the filter also - a clogged or restricted filter can kill a pump
#5
You might be able to smell unburnt fuel from a lean misfire (p0171) - the first thing to check would be fuel pressure, which could also cause your lack of power. If fuel pressure is low, replace the filter and recheck. If it's still low you probably have a bad fuel pump - FYI if the pressure is low and you decide to replace the pump first for some reason, replace the filter also - a clogged or restricted filter can kill a pump
#6
Contributing Member
Check for vacuum leaks. Easy but not exactly the safe way to tell is to spray brake clean or ether around vacuum hoses. If the idle goes up then you've found the leak.
#7
If the evap purge valve was stuck open,there could be your raw fuel smell...Also would raise idle speed ..technically its an unmetered vacuum leak...Pinch off that hose comming to the manifold from the canister...and see what happens..
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#9
Registered User
#10
Problem Solved!!
Here is what happened. We tried everything under the rainbow and everthing finally came down to the timing belt. The water pump had leaked coolant through the weep hole and coated the timing belt causing it to slip. Both cams were way off. The timing marks were off by one tooth. We noticed that the coolant had formed into a hard surface behind the belt and the belt was soaked with coolant. After we replaced the timing belt with a new one, lined everthing up and put the thing back together. We started it up and it purrrrs like a kitten. Thanks for everyones advice in the troubleshooting. We found the gremlin and put a hammer to em!
Here is what happened. We tried everything under the rainbow and everthing finally came down to the timing belt. The water pump had leaked coolant through the weep hole and coated the timing belt causing it to slip. Both cams were way off. The timing marks were off by one tooth. We noticed that the coolant had formed into a hard surface behind the belt and the belt was soaked with coolant. After we replaced the timing belt with a new one, lined everthing up and put the thing back together. We started it up and it purrrrs like a kitten. Thanks for everyones advice in the troubleshooting. We found the gremlin and put a hammer to em!
#14
The culprit:
Last edited by ravencrew; 12-22-2008 at 04:56 AM.
#15
#17
Contributing Member
:thread hijack: Yeah but it helps me find exactly where the leak is coming from LOL. Find the pink crusty stuff and I know where coolant is coming from.