Question about Geo Prizm
Replaced all spark plugs, and since then the car chugs/jerks when accelerating. Once I'm past 50mph it's fine, but at lower speeds it has a hard time accelerating. It stalled out on me twice when stopping at a stop sign, could it be the fuel pump?
You have a bad spark plug wire. Just, because it's new doesn't mean it's good
Posted on Apr 12, 2014
Could be lots of things, its EFI.
what you mech, does, is use tools and gauges. to gather evidence.
he also has a scan tool , to see what EFI is doing.
That jerking is called Misfire (not arguing names, ,but using the right name allows better google searches or getting help)
this can be (lost spark or lost fuel or too much fuel)
the prism has distributor, and if the car has and old cap, rotor and wires. then they are no good. finish the 60,000 mile tune up.
if its misfiring, it might be:
1: bad spark.
2: bad fueling.
bad spark ? tune it up fully this time.
bad fueling, is complex.
sure fuel pump, but why does the pump magically work on over 50 demand which is more demand?
my guess is lean misfire. at cruise.
when you go over 50mph the ECU can drop using the oxy sensor.
this is normal and goes rich.
so maybe the 02 front sensor is bad or an exhaust leak near it.
a scan tool can find this in a jiffy , a $50 tool)
you see the oxy sensor ,reading wrong or dead at low speed cruise.
ok stop sign stalls. (in order of most common 1st)
1: EGR main sticks open (clean it)
2: running rich and it misfires so bad, it stalls.
fuel pump reg bad? and fuel pressure way too high.
3: fuel starvation.
what a tech does, is make car fail, and look at the sensors to
see what is going wrong. Evidence, is first. guessing at parts never.
lets see the op guide shows the 60k as....
new cap,rotor wires.sparks. (they dont last 100k, sorry)
new fuel and air filter.
Posted on May 18, 2013
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Posted on Jan 02, 2017
The throttle speed control valve must be cleaned. The valve is located near the throttle body throat. It has an oval flange with two bolts. Unplug it, take it off and clean it out with throttle body cleaner. You will notice a big difference. This is a common issue with this engine.
Please remember to rate this fix.
Posted on Feb 16, 2009
Look for an IAC sensor (motor) Idle Air Control.
Usually located on side & front of throttle body. Not 100% sure which type you'll have but if you have pintle type (pointed end) Remove it, spray it well with throttle body cleaner as well as port it came from, and retry. If it cures it temporarily & starts to do it again, replace it.
Posted on Aug 21, 2009
There are a few other things taht could be causing fuel starvation. First of all, did you pull the injectors and clean out the individual filters? There are small, conical screens inside the top of each injector, and they could be clogged. Second, There could be some carbon build-up on the intake valves, which would act like a sponge for the fuel after initial start-up. A can of BG44K fuel system cleaner from NAPA will get rid of that. If it is neither of these, the fuel pressure regulator could be leaking. Other than this, the car would need to be diagnosed by a shop before action is taken. I hope this helps you!
Posted on Dec 04, 2009
Testimonial: "I ended up taking the car to a local shop for diagnosis. It turns out that the fuel pump is week and not supplying enough pressure to the motor. "
for that cost you could have taken it to a mechanic and had the compretion tested, that is what needs to be done. at least 90psi and all cyliders sould be within 15% to that.
Posted on Mar 16, 2010
Determine whether the jerking is engine or transmission related. One way to determine if it is the transmission lock up converter is acting erratically is to down shift out of OD. And see if jerking persist. If it goes away suspect transmission to have problems with torque converter or TCC solenoid . If it doesn't go away determine whether or not the engine sounds to be misfiring. If so vehicle may require a tune up. Many vehicles can be diagnosed for free at your local Auto Zone.
Posted on Jul 19, 2010
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