Question about 2002 Ford F150 Regular Cab

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Engine surge during warm up.

On initial start up during warm up cycle, The engine will surge from 500-1200 in park and driving. No codes or check engine lights, After warm up no issues. Replaced air idle, throttle position, mass airflow sensors. slowed serge to 200-300 rpm. Did not find any vacum leaks. Throttle position and air idle sensors had carbon deposites.

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  • lawrence_fry Sep 27, 2009

    5.4L gas

  • RKmastertech May 11, 2010

    What engine do you have?



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  • 92 Answers

Try changing your PCV valve make sure the hose is clean and not full of oil. Also check the elbow end that goes to the intake they tend to collapse from oil saturation. Hope this helps.

Posted on Sep 29, 2009


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1 Answer

Surging idle when in neutral and park

Jimoh, RE POST your question with more detail.
Year, make, model, engine size,etc.,is the engine light on, are there any codes, was there any recent work done on vehicle.

press the helpful button

Feb 10, 2016 | Cars & Trucks

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95 sl500 check engine light reset and comes back on after it sits over night. any idea?

What code is it throwing ? Some codes are what are called two trip codes ! You clear the codes an start an drive the vehicle ,no check engine light . Park the vehicle over night an bam next time you start an drive the vehicle the check engine light comes back on .

??There are two types of DTC's, 1 trip DTC's and 2

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Feb 07, 2016 | Cars & Trucks

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Engine idle revs high when in park or nuetrol. When driving ckek engine light is on off intermittinlly, a loss of power.

Always check for trouble codes when the check engine light turns on during engine running. After repairs are made, a scanner can be used to erase the codes.

It sounds like a fuel problem, so you would need to have the fuel pressure tested. This will verify the fuel pump and fuel filter are not the problem if the pressure is correct.

Sep 15, 2015 | Cars & Trucks

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Buick Park Avenue hard to start and smell of gasoline at start

The sender the Expert is referring to is a temperature sensor that tells the computer your engine is cold. The control then enrichens the fuelmix, sets timing and goes into a run cycle after the engine is warmed up.

You instead may have a leaky fuel injector. This is bad because the gas that floods the engine can go into the oil pan and dilute the oil which eventually ruins the engine. A fuel line pressure reading is taken when the car is parked and then the fuel pressure is read later that day or the next morning.

If the pressure drops there is a problem. Some shops have machines which can benchtest the injectors when they are taken out. A single injector can be the whole cause or all may need cleaning or replacing.

There is a chemical that Dealers or Repair shops can insert into the fuel system by disconnecting your fuel source and inserting this can of chemicals. The engine is operated for a few minutes using only the cleaner as fuel. The car is suppose to sit for several hours or overnight for the chemical to finish working. This may be all you need if it works.

The reason I have made my comment is that you are getting a rich mix at startup. If all starts warm and cold are causing trouble it can be either my solution or the other Experts. The engine needs a warm signal to end the "cold start cycle" for later starts. But the difference is that the initial "cold" start ought to be fine if the "cold start" cycle was stuck ON. Leaking injectors would flood the engine between starts and on the initial "cold" start making my solution an accurate assessment of your problem.

I hope you find my idea useful and would like to know the outcome of your problem.

Aug 11, 2012 | 1995 Buick Park Avenue

1 Answer

I have a 1984 ford f150. The truck idles very high when in park but when you put in drive or reverse it goes down to normal. It has duel straight exhaust on it and I wonder if that could be the prob. Idk.

you didnt say if it was happening only during the initial warm up of the vehicle or all the time. if it is just during warm up this is not too unusual as long as the engine isnt racing. if it is just a "high idle", say arround 2,000 rpm's its normal. the idle would usually go down as the vehicle reaches operating temperature. when you put the vehicle in gear, you are actually loading the engine slightly, thats why the idle comes down then. when in park the engine has no load on it so it is free to rev a little higher at these times. if it a at a high idle constantly, then i would start looking for sticking throttle cable, binding throttle plates, ect and remedy the problem. this should not have anything to do with the dual exhaust.

Mar 13, 2011 | Ford F-150 Cars & Trucks

1 Answer

P1781 DTC

DTC P1781 - Engine Torque Signal Circuit

This code is set during engine start up when the ECM & TCM do not communicate properly during initial power up. It will only illuminate the service light if the condition occurs in 2 consecutive start cycles, but the DTC will be stored in the failure records after the first cycle.

Hope helps.

Jun 24, 2010 | 2004 Chevrolet Aveo

2 Answers

Car runs rough during initial startup!

Check the fuel filter,or just change it,it is more likely it is stopped up.

Jun 07, 2010 | 2004 BMW 3 Series

1 Answer

1994 taurus doesn't start like it used to ....I have to keep turning the ignition over and over; it eventually starts but during this process of attempting to get the engine to catch, the fuel gauge is...

Based on the information that you have provided me, my attention is now centered on the ECT Sensor (Engine Coolant Temperature). This sensor provides information to the ECM to richen the fuel mixture on start up and also to lean out the mixture as the engine warms up. Very similar to the old fashioned choke in operation. A cold engine requires additional fuel to start, while a warm one does not. This matches your situation of a cold start versus a re-start and also explains why you are having to cycle the start sequence several times to fire the engine. Those cycles are finally providing enough fuel for start up.

Check with a local auto parts outlet to see about having the ECM read for a memory code related to the ECT. Most of the stores will now do this testing for free.

Let me know if this helps you out or not. Thanks.

Apr 27, 2010 | 1994 Ford Taurus

1 Answer

Engine running -hot or cold- in park or drive the engine rpms go to aprox,500-400 and then stalls. cycle the kry and the engine will run for a while and then start the cycle again

Clean the temperature sensor wire connector.
Replace the temp sensor.
Check the condition of the sensor wire cut(s) or short onto the engine block.
Monitor the fan operation with the hood open during warm up (0-15 minutes.) It should ran after the engine coolant temp get above 195F +.

Jan 06, 2010 | 2000 Ford Focus

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