Engine first runs good, but progressive chug/misfire.
The motor starts and runs well, but after several minutes begins to hesitate on acceleration with progressive chugging and misfire, loss of power, etc. Merely letting engine cool down a few hours is not enough to get clean engine start. It neeeds to sit over night I've done plugs, wires, rotor, distributer cap, ignition control module, Sea-foam internal wash with 2 follow-up oil changes, and catalytic converter. Still same problem. Check engine light works, but goes off upon starting engine and stays off indicating no apparent error codes being detected.
Re: engine first runs good, but progressive chug/misfire.
Is your engine a v-6 3.8 liter?i had similar problem with my ford,found it was pick-up coil in my distributor,nationally known auto repair told me it was 8 different devices with their $1300.00 analyzer. pure b.s.
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A plugged converter will cause a NO power situation where the vehicle is unable to expell exhaust gasses and cause poor acceleration. A flashing engine light is the result of a misfire. ( spark plug/coil/injector/wiring ). The engine should still be able to accelerate but will have a noticeable hesitation while doing so
THE BLINKING MEANS THERE IS A MULTIPLE CYLINDER MISFIRE CAUSING CONVERTER DAMAGE. NOT SURE KNOWING WHAT MOTOR YOU HAVE IF ITS THE 4.2 THERE IS A CAM SENSOR ON THE PASS SIDE FRONT OF THE HEAD THAT GM HAD SEVERAL PROBLEMS WITH. FIND A PLACE THAT WILL PULL THE DTC CODE FOR YOU. VERIFY ITS A MISFIRE AND/OR CAM SENSOR CODE, IF IT IS REPLACE THE CAM SENSOR. YOU HAVE TO REPOSITION THE POWER STEERING PUMP TO REMOVE AND INSTALL THE SENSOR
Misfire, From a cold engine you wont have the misfire. When you engine is cold fuel is in demand and it will run great. As it warms up the fuel strategy is to lean it out (proper balance is 14.1 to 1) . At normal operating temperature the spark plug required KV is 15kv. As you accelerate the sparkplug require more voltage from its coil reserve and it delivers and at the same time the engine demads are high in order to accelerate and the spark will seek the easiest path spark plug, now when you come to a stop the demands for spark decrease and it seek the easiest path where is that at ? out through the boot of the spark plug, The vehicle is equipt with what they call COP (coil on plug) along the boot path it deteriates and so does the coil it deteriates .170,000 mile of hard working COP. they are at their worn stage you can find the weak coil with a cop tool because it misfire on acceration your looking at a boot,probable water got in there shorting it out,if it misses at idle its either water in the boot or the boot itself or the cop.
An engine that
hesitates, stumbles or misfires when accelerating or when
it is under load is an engine that is either sucking too much air, not
getting enough fuel or misfiring. If the Check Engine Light comes on,
you may find any of the following codes:
• P0171, P0174 Lean
fuel condition codes • P0120 to P0124 Throttle position sensor codes •
P0222 to P0229 Throttle position sensor codes • P0400 to P0409 EGR
If there are no misfire codes, a common cause of
acceleration stumble is a bad throttle position sensor (TPS). The TPS
tells the computer how far the throttle is open. The computer uses this
information to determine how much fuel is needed to maintain the correct
air/fuel mixture and when extra fuel is needed if the throttle suddenly
Another common cause is dirty fuel injectors. If
varnish deposits have built up in the tips of the injectors, they won’t
spray as much fuel as they normally do, or will “dribble” fuel instead
of spraying a fine mist. This creates a lean fuel mixture and
conditions that are ripe for stumble and hesitation (also misfire). Look
at short term fuel trim (STFT) and long term fuel trim (LTFT) with your
If the numbers are high, it tells you the engine is running lean and
the injectors need cleaning. Treat mild cases with a high quality
fuel-injector cleaner additive. Severe cases require professional
Also you might need to run a test on your
starter/ fuel line for blockage. I suspect the fuel line blockage not
getting enough fuel to engine but we cannot rule out other things
around the engine transmission.
when my cars do this I check the fuel supply first.....should be a small filter near the throttle body somewhere that could be prob. then check electric/fuel related items. there are several different items with these symptons, nearly always related to fuel....go to a good websight like autozone repair guide for help....also a haynes or chilton manual available at parts houses will save you lots of bucks----i never take my cars to a garage...this is general info, but i hope it has helped...
There are several ways about this. Could be fuel filter, water in fuel, ignition part starting to fail(plug, wire, cap, rotor, coil) or possibly even oxygen sensor. The oxygen sensor will clear up if you accelerate heavily then when under normal load it will start chugging again. These are a couple of areas to check without getting into serious diagnostics.