Question about 1999 Toyota Sienna

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1999 Toyota Sienna is randomly misfiring but no code is showing

Several weeks ago our van started almost stalling out while driving and after checking it out, we saw the spark plug wires were shot; we replaced the plugs and wires. Things were going great for a while, but then the van started misfiring and it quickly got worse. It generally only happens when it's idling and does it worse when the van is in reverse and drive than when it is in park. There is no check engine light and no code showing. While checking the wires again we saw that 2 were bad and there was an issue with 2 of the coils so we again replaced the wires and replaced the coils, but it's still doing the same thing. My van is now at the mechanics and they are doing a diagnostic test, but they are stumped because NOTHING is showing. We thought maybe it's something with the injectors or maybe the egr, but since no one can seem to find anything we don't know what to do anymore. Any suggestions or ideas will help at this point! Thanks!

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  • Toyota Master
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IN all causes for codes there is a constant ECM result While you have no codes, non of the codes record a direct ECM problem as such as the ECM will not record it's own fault. It has no sensors that record a fault in itself. I would be inclined to find a serviceable control unit and see if there is an improvement in your problems or see if your unit can be checked out for internal faults.

Posted on Feb 15, 2014


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SOURCE: 1999 toyota camry

Take it to autozone and have them to pull a code on it.It sounds like O-2 sincer

Posted on Dec 07, 2008

Big Poppa Ma
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SOURCE: Check engine light on

There are three kinds of gasoline engine misfire scenarios, first there is the "under load" misfire and there is the "at engine idle" misfire, and finally there is misfire continuously. All engine misfires exist because one of three things has occurred. First, a cylinder has lost compression, a cylinder needs a certain amount of compression to operate correctly. Second, the ignition system has failed or is failing intermittently, spark is needed at the time of compression to ignite the fuel air mixture. Third, the fuel air mixture is incorrect, proper mixture is needed for the ignition system to ignite fuel properly. If any of these conditions occur in the engine, the engine will misfire.
1. Low or no compression can be caused by

a. burned or leaking intake or exhaust valves
b. worn or broken piston or piston rings
c. worn out camshaft
d. wrong weight motor oil was installed holding the cam followers from adjusting
e. broken valve spring
f. failed head gasket.
2. Ignition system has failed or is failing
a. spark plug has fouled or is worn out
b. ignition coil
has failed
c. spark plug wires have shorted
e. engine control module coil driver has failed
3. Fuel/Air Mixture is incorrect
a. vacuum leak at the intake manifold
b. fuel injector has failed
c. EGR valve is stuck open
d. mass air flow sensor has failed
e. oxygen sensor has failed
f. air intake boot is cracked

common problems:
1. fuel injector has failed or is failing
2. spark plug wire has shorted
3. spark plug is worn out or is cracked
4. ignition coil has failed is failing

Testing a coil on the car is pretty easy. No special tools are required. Just remember to be careful, the amount of electricity generated by your ignition system can be dangerous. If your coil is already off the car, or if you would like a more specific data-driven test, you can bench test your coil. To set up the test, remove one spark plug wire from its plug, then remove the spark plug using a spark plug socket. Next put the spark plug back into the spark plug wire. Be careful not to let anything drop into the empty spark plug hole -- very bad.

Posted on Dec 07, 2008

  • 1 Answer

SOURCE: Toyota Corolla 98 Cylinder #1 and #4 misfire

I have power at the coils , have good compression , have you ever seen a crank pickup cause this problem?

Posted on May 09, 2009

  • 6 Answers

SOURCE: 2000 toyota 4runner pulling a random misfire in

try a new crankshaft sensor not hard to change 2 bolts and a wire

Posted on Jul 30, 2009

  • 775 Answers

SOURCE: check engine light on-code says egr valve is bad

the egr system consists of control circuits as well as the egr valve itself. troubleshooting will have to be performed in order to pinpoint the fault. the valve may just need cleaning. there may be damage in the long run since the egr system introduces exhaust gas to the air intake to reduce combustion temperatures.

Posted on Apr 21, 2010

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