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Old 04-25-2011, 20:40   #1 (permalink)
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Unstable idling on startup and from park to drive

Hello all,

First off, i've made a tuneup less than a year ago, which include, sparkplugs, rotor, distributor cap, air filter, fuel filter.

I am having the 2.3 liter, 4 cylinder engine, automatic transmision. 1993

The issu:

When i turn the key ( engine crank a sec or two and fire right up) at first, for a sec, the engine go to about 800rpm than drop down to 300 or less (close to stalling), than bounce back up for a sec to 800-900 than goes back to 450 than goes back up to about 850 than stick to normal idling, about 700. ( it correct itself faster if i press the gas pedal just a little bit)

It idle well after but i could feel just little 'hicups' or 'hiss' , like if there is some missed but it's really minor.

The engine onced it started, will perform well. Accelerate okay with normal power.

Usually when the engine is real warmed, it will start okay and will idle okay right away.

Sometimes when i start the engine half warm, the engine start okay and idle fine right up but when i put it in drive, the rpm drop real low(about 300), again, real close to a stall. And alot of time, (when warmed) it will go from park to drive and will keep the rpm in the normal range right away when the engine is already warmed. But pretty sure it will do it if the engine is cold and especially when the engine is so what warm. ( start the engine and drove it 5 mins and shut it off than after 5 minutes, start it back up) -rpm will go crazy again for 4-5 secs. Couple of months ago, i've changed the iacv with no difference. I could see that i have oil leak under the valve cover. Could a leak under the valve cover cause this type of issu ?

another thing i've seen, not sure if it's linked:

Often, when i let the car in drive and brakes are applied, the steering wheel will shake (all car will vibrate) . If i put the feet on the gas pedal at the same time i'm having the feet still on the break, the rpm will get about 1000 and the shakes will disappear. Sometimes, the engine will turn with no vibration when in drive and brakes applied , but that's rare. About 2 years ago, the engine mounts and trans mount has been changed.

With this info, do you have any idea of what can cause this.

Thanks for reading and i'll be waiting for your respond.

Danny
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Old 04-26-2011, 09:57   #2 (permalink)
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Re: Unstable idling on startup and from park to drive

Try this and see what it shows. Ford Fuel Injection How To Run a Self-Test
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Old 04-26-2011, 21:31   #3 (permalink)
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Re: Unstable idling on startup and from park to drive

Hey Bert.

Thanks for the info. I've done it and here my results:

Key On engine Off:

Code 327

Key On Engine Running:

Code 116, 327,538,521

after some searching over the web:

======================================================
Code #327 - EGR Valve Position (EVP) sensor, Pressure Feedback EGR (PFE) sensor or EGR Pressure Transducer (EPT) signal voltage too low.
==================================================

About 3 years ago, the 'check engine light' was coming on. After diagnostic, there was an electronic part which was responsible, the egr pressure regulator sensor or some sort. Anyways, that was changed and the 'check engine light' was out for some months... Other than that part, what can cause that code ?

===============================================
Code 116 :coolant temp was higher/lower than expected
=============================================

Well, i just started the car and it was like 0 degree celcius out, is that code considered normal ?

======================================================
code #327 (EGR valve position circuit below minimum voltage)
#538 code (Insufficient RPM change during KOER dynamic response test)?
======================================================

327, same code the engine wasn't running...
code 538, during the test, i guess i needed to press the gas pedal ? Didn't knew that, anyways, let's forget that code too..

==================================================
Code #521 - Power Steering Pressure Switch (PSPS) - open connection circuit failure.
=================================================

I didn't move the steering wheel during the test, is that okay ? Because i didn't move the steering wheel, does it explain that code ?


Thanks for your time

Danny
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Old 04-27-2011, 11:34   #4 (permalink)
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Re: Unstable idling on startup and from park to drive

The DPFEs usually have problems and need to be replaced. As for the idle, it could be the temp sensor. Run the test when warm and see what comes up. Check the ECT sensor. Light green/red wire. Here are the specs.
Temperature °F Voltage
+50°F 3.52 V
+70°F 3.01 V
+100°F 2.26 V
+130°F 1.56 V
+160°F 1.01 V
+190°F 0.65 V
+220°F 0.42 V
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Old 04-28-2011, 17:09   #5 (permalink)
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Re: Unstable idling on startup and from park to drive

Thanks alot again Bert for your help with this. I've warm up the engine and than i did the test again, engine off and running and here the results:

Engine off: 327

Engine running: 411, 538, 521 and 327.

Code 116 didn't pop up this time, a good thing i guess. So the temp sensor is good afterall...

But code 411 is new... here what i come up after a search on the web...


411 Cannot control RPM during KOER low RPM check

Okay, i kinda knew that but the cause ? :)

I search on another website (Diagnostic Trouble Codes list (OBDI/II + Airbags)) and the 538 code get me little worried. Here what came up
----------------------------------------------------------------------
538 Insufficient RPM change during KOER dynamic response test
538 Invalid cylinder balance test due to throttle movement during test
(SFI only)

538 Invalid cylinder balance test due to CID circuit failure
----------------------------------------------------------------------

There is 3 different explaination for the same code. Because i didn't press on the gas pedal during the testing, i think the code which is related with my car is

'' Insufficient RPM change during KOER dynamic response test''

what do you think?


327 EGR (EGRP/EVP/PFE/DPFE) circuit below minimum voltage


Do you have any idea of what could be the cause ?

Do you think i should test the temp sensor even if the code is not present anymore when the engine is warm ?

While i was waiting for the engine to come warmer, i used my infrared temp gun and point it just below the thermostat and the fan started just when the coolant was getting 220 F.

Tell me what you think.

Thanks

Danny
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Old 04-28-2011, 19:09   #6 (permalink)
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Re: Unstable idling on startup and from park to drive

Here's what the brown/light green wire for the EGR sensor should have, Key-On-Engine-Off 0.40 Volts., at aprox. 55 cruise 1.3-2.0 Volts.

411 is that the enhine speed was out of the range ruring the test. Other problems can cause codes to show that aren't really a problem.

If the temp sensor is off, the PCM will just think the ambient temp is higher prower than it is an compensate for it. It won't set a code. Bhevk that and the EGR before worrying about the others. They may go away when those are fixed.
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Old 04-29-2011, 21:22   #7 (permalink)
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Re: Unstable idling on startup and from park to drive

Hey again Bert,

When you said check the voltage to the egr sensor, you mean that piece of electronic right? Standard EGR Valve Position Sensor (#VP-4) for Ford Tempo / Taurus 86-92 (Sensors)



i don't understand (sorry) what you mean by:

'' at aprox. 55 cruise 1.3-2.0 Volts. ''.

Do you mean when the car is cruising at 55 mph, voltage should be between 1.3 to 2 volts ?

I'll check the engine cooling temperature sensor as you described earlier and see what that do.

How do you check the voltage of a wire ? You poke the shield until you hit the wire than check voltage than after you put electric tape where you made a whole ?

I guess i need to make the engine run in order to check the voltage ? Not just key on engine off right ?

Danny
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Old 04-29-2011, 21:32   #8 (permalink)
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Re: Unstable idling on startup and from park to drive

You can check it with the first set with the engine off. The cruise reading is for the engine running at about the speed it'd be at. You do have to pierce the wire to check it but make sure to seal it back up with something. At least silicon. Did you check the ECT sensor?
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Old 05-04-2011, 07:08   #9 (permalink)
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Re: Unstable idling on startup and from park to drive

Sorry for the waiting. Okay so in order to test the engine cooling sensor, i need to poke the wire ( Light green/red) with the positive end of my multimeter and connect the negative end of my multimeter to the negative post of the battery and see what voltage comes up ?

Sorry, i'm kinda newbish when it comes to diagnostic of sensors, but really willing to learn !

i should come with the reading you added earlier,

+50°F 3.52 V
+70°F 3.01 V
+100°F 2.26 V
+130°F 1.56 V
+160°F 1.01 V
+190°F 0.65 V
+220°F 0.42 V

Also i've read that there is a coolant sending unit also, which also looks like the engine coolant sensor but that sensor is there only to show the temp of the engine in your dashboard, that sensor has only one wire in the connector. I need to look for the two wire unit, that one give information about the engine temperature to the engine computer...

I've read also that you can test the ohm or resistance between the two connector of the sensor itself which should change when temperature change ? But you seem to like better the voltage test. I will try that soon, when i will have confirmation that i'm doing it well, first.

Thanks again,

Danny
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Old 05-04-2011, 17:10   #10 (permalink)
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Re: Unstable idling on startup and from park to drive

Ok so if the idea of checking the voltage of that wire with the positive side of the multimeter and using the negative side of the car battery connected to the negative side of the multimeter is the correct way...here my results:

140F = 0.22V
160F = 0.21V
206F = 0.20V
212F = 0.18V

If i've done it right, the coolant temperature sensor is toast and my car's computer is thinking that it's always overheating....

Just for the heck of it, i've just disconnected the electronic connector of the sensor and started the car and guess what...the exact same symptoms as the usual problem but worst...

so it's looking like it's the ECT..

Danny
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