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Erratic idle audi

OK I HAVE A 98 AUDI A4 1.8T MANUAL THE ROBLEM IS THE ALTERNATOR WIRE GOING TO THE IGNITION SWITCH FRIED I REPLACED THE WHOLE WIRE CAR STARTED UP AND IDLED FINE. TOOK IT AROUND THE NEIGHBORHOOD IT WAS MISSING A LITTLE AND LITTLE HESITATION WHEN PUSHING ON THE GAS. SO DECIDED TO GO TO THE GAS STAION 2 MILES AWAY WAS OK FILLED UP WITH GAS IT STARTED TO IDLE ERRATICALLY AND WOULD STALL IF U LET OUT CLUTCH AROUND 2000 RPM YOU WOULD HAVE TO REV IT UP TO 3 SO IT WONT STALL. GOING DOWN THE ROAD I HAD TO KEEP IT IN SECOND GEAR GOING 40 IN 4000 RPM RANGE IF NOT IT WOULD BOG DOWN GOT IT TO MY HOUSE AND NOW WILL START BUT IDLE ERRATICALLY AND ONLY AROUUND 400 500 RPM FLUCATIING AND STALLS EVEN WHEN YOU GIVE GAS. I REPLACED SPARK PLUGS I KNOW ITS GETTING GAS I SMELL IT II THINK ITS JUST NOW GETTING SPARK. PLEASE HELP THANK YOUP

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  • Cars & Trucks Master
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See the diagram attached and proceed and fix it. God bless you
erratic idle audi - dea71140-af7c-491a-8097-25ebfefe9ded.jpg

Posted on Jul 10, 2013

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6ya6ya
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Posted on Jan 02, 2017

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emissionwiz
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SOURCE: car idles low, stalls after start

Common issue at the shop (i'm a ford technician), here is what I do to correct it.
Here is the most common cause of surges and stalls at stops and low erratic idle speed and rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Posted on Mar 11, 2009

  • 1 Answer

SOURCE: 2002 GMC Yukon, erratic idle(hi-low) when cold. 125K miles.

i now for a fact that it is the egr valve . carbon balls in side you have to take it of and clean them out

Posted on Apr 18, 2009

  • 1 Answer

SOURCE: idle problem

Try to disconnect the Air Flow Meter. It is the first plug just before the air filter/air intake box. If this improves your situation you will need to source a new or aftermarket Air Flow Meter.

Posted on Apr 28, 2009

mrhappyface
  • 205 Answers

SOURCE: idle problem

check the airflow meter it may be stuck and make sure the electrical connection to it is not loose and also check the hose leading to it are not loose or cracked they tend to crack at the bottom where you cannot see it unless you remove it and check

Posted on May 29, 2009

samtoler
  • 666 Answers

SOURCE: 1991 Chevy Caprice, V8 5.0L, throttle body

tune up is likely what you need from description

Posted on Jun 15, 2010

Testimonial: "thanks for replying, thats what I thought too, but I have another question, I just added more comments to the prior comments, please read. thanks again. "

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Engine diagram


When replacing wiring looms it is best to tag all wires first and un-plug and plug as you go. To have an auto electrician do it will be costly. Arm yourself with a workshop manual before you start as it will be the best help you will get.

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Jul 01, 2008 | 1992 Audi 80

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92 mercury topaz small 4 cyl. I hooked up jumper cables and engine started cranking, no key in ignition. I had installed a new starter, battery and solenoid relay on the fender well 2 months prior. About 2...


It sounds like the ignition switch again, thats the only source for the starter solenoid to power up. I'd disconnect the power to the starter solenoid (ignintion input small wires, not the battery cables). Jumper the battery again, check for power on the solenoid for the ignition feed, if it has power then yes the ignition switch is bypassed somehow. I've seen issues with the back side of the connector going to the ignition switch where the wires are bare from being flexed, the insulation breaks and wires touch each other. Carefully check the condition of the wires going to the ignition switch, if good replace ignition switch again.

Jan 31, 2011 | 1992 Mercury Topaz

2 Answers

Idle fluxuates up and down consistantly


Check the Idle Control System

Idle speed is controlled by the Idle Air Control Valve (IACV). The IACV changes the amount of air being bypassed to the intake manifold, in response to electric current controlled by the ECM. When the IACV is activated, the valve opens to maintain proper idle speed.

Symptom and Subsystems to Check:

1. Difficult to start engine, when cold--check Fast Idle Thermo Valve.

2. Fast idle out of spec, when cold:
a. Check Fast Idle Thermo Valve.
b. Check IACV.
c. Check idle adjusting screw (see Section C).

3. Rough idle:
a. Check hoses and connections.
b. Check IACV.

4. RPM too high, when warm:
a. Check IACV.
b. Check Fast Idle Thermo Valve.
c. Check hoses and connections, check Power Steering Pressure Switch Signal, and check idle adjusting screw.

5. RPM too low, when warm:
a. Idle speed is below specified rpm, with no load--check IACV and idle adjusting screw.
b. Idle speed doesn't increase after initial start up--check IACV.
c. Idle speed drops in gear (automatic transmission)--check automatic transaxle gear position switch signal.
d. Idle speed drops when AC is on--check air conditioning signal and IACV.
e. Idle speed drops when steering wheel is turned--check power steering pressure switch signal and IACV.
f. Idle speed fluctuates with electrical load--check hoses and connections, IACV, and Alternator FR Signal.

6. Frequent stalling, while warming up--check IACV and idle adjusting screw.

7. Frequent stalling, after warming up--check idle adjusting screw and IACV.

Additional Steps:

. Check Alternator FR Signal. Have alternator inspected, if idle speed fluctuates with electrical load. The FR signal communicates to the ECM how "hard" the alternator is working to meet the electrical demands of the car, including the battery and any loads which aren't monitored by the ELD. This square-wave signal varies in pulse width, according to the load on the alternator. The ECM places, approximately, 5 reference volts on the wire. The voltage regulator will drop this signal to approximately 1.2 volts, in proportion to alternator load. The ECM compares the electrical load (ELD) signal with the FR (Charging Rate) signal from the alternator and uses that information to set the idle speed and turn the alternator on and off. This helps fuel economy.

. Clean main ECM ground on thermostat housing.

. Reset ECM, by removing the 7.5 amp Back Up Fuse, in the under-hood fuse box, for 10 seconds.

. Replace PCV Valve, cleaning hose with brake cleaner spray.

. Substitute a known-good ECM. If symptom goes away, replace original ECM.

Check the ICM (Erratic RPM and PGM-FI System)

When the engine is cold, the air conditioner compressor is on, the transmission is in gear (automatic transmission only) or the alternator is charging, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. Here's an overview of how the PGM-FI System works.

Background:

Various inputs to the ECM are TDC/CKP/CYP Sensor, MAP Sensor, ECT Sensor, IAT Sensor, TP Sensor, HO2S, VSS, BARO Sensor, EGR Valve Lift Sensor, Starter Signal, Alternator FR Signal, Air Conditioning Signal, Automatic Transmission Shift Position Signal, Battery Voltage (Ignition 1) Brake Switch Signal, PSP Switch Signal, ELD, and VTEC Pressure Switch.

Inputs are received and processed by the ECM's Fuel Injector Timing and Duration, Electronic Idle Control, Other Control Functions, Ignition Timing Control, and ECM Back-up Functions. These are the primary functional areas within the ECM.

Outputs from the ECM control Fuel Injectors, PGM-FI Main Relay (Fuel Pump), MIL (Check Engine Light), Idle Air Control (IAC) Valve, A/C Compressor Clutch Relay, Ignition Control Module (ICM), EVAP Purge Control Solenoid Valve, HO2S Heater, EGR Control Solenoid Valve, Alternator, Lock-up Solenoid Valve A/B (A/T), VTEC Solenoid Valve, and Interlock Control Unit.

Idle RPM:

Once you understand how the PGM-FI system is configured, it's easy to see how the ECM, Idle Air Control Valve, and the Ignition Control Module affect idle rpm. If the ECM's Electronic Idle Control function is not working properly, then it cannot properly control the IAC Valve. Likewise, if the ECM's Ignition Timing Control function is not operating properly, it cannot properly control the ICM (igniter). Obviously, idle rpm will also be affected if there's a problem with the IAC Valve or the ICM. As stated above, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. This cannot happen if the IAC Valve is failing. The same situation exists if the ICM is failing. The ECM will tell the ICM to open and close the primary voltage circuit going to the coil and it won't respond properly. The result will be erratic spark plug firing and erratic rpm.

Conclusion:

If you are experiencing erratic idle rpm, try and isolate whether the problem is caused by the ICM (ignitor), IAC Valve, or the ECM. My experience has been that a failing ICM is usually responsible for the problem. Keep in mind that tachometers are connected directly to the ICM. Therefore, a fluctuating tachometer needle is often a dead giveaway. Heat and poor preventive maintenance (causing high secondary voltage to be discharge on internal distributor components) frequently causes the ICM (and coil) to fail. Besides performance, this is another reason why it's important to regularly replace spark plugs, spark plug wires, rotors, and distributor caps. Electricity will always follow the path of least resistance, even if it isn't the intended one. Our job is to ensure the intended path is the path of least resistance.

Ignitor (ICM) and Coil Replacement:

1. Disconnect negative battery cable.
2. Remove hex head machine screws, securing distributor cap to housing, using an 8 mm nut driver.
3. Move distributor cap and wires off to the side.
4. Remove machine screw securing rotor to shaft, using a #2 Phillips head screwdriver. It may be necessary to "hit" the starter once or twice, in order to rotate rotor for access to mounting screw.
5. Remove rotor and leak cover.
6. Unfasten ignitor wires, remove coil mounting screws, and set coil aside. Note: Removing coil first improves access to igniter.
7. Unfasten screws securing igniter to housing.
8. Remove ignitor from distributor and unfasten screws mounting ignitor to heat sink.
9. Coat back of new ignitor (or old igniter, if reusing) and male connectors with silicone grease. Silicone grease increases heat transfer to heat sink. Failure to apply silicone grease will cause the ignitor to quickly fail.
10. Mount ignitor to heat sink and reinstall ignitor, igniter terminal wires, coil, coil wires, leak cover, rotor, and distributor cap. Ensure female ignitor terminals fit snugly--crimp with pliers, if necessary.

AutoZone can test ICMs and coils for free. If you plan to keep the car, I would replace the ICM due the age of your Civic.

Sep 15, 2010 | 1991 Honda Civic

1 Answer

98 Ford Explorer erratic cold idle / SOHC engine / idle continuously jumps from 500 - 2500 rpms when cold / is fine when warm


98 ford explorer erratic idle from cold reves jump. ok when warm but still stalls at times.

Feb 01, 2010 | 1998 Ford Explorer

1 Answer

98 Audi Quattro keys don't srping back after starting the engine


You have a bad Ignition Switch they are known to go out on the 90's audi's.

The part is pretty inexpensive but the labor maybe quite high.

When you start it make sure the key gets back to the proper position otherwise you will burn up your starter and cause another expensive problem.

Oct 20, 2009 | 1998 Audi A4

1 Answer

Surges of 3 to 26 and failures of idle speed


If the Battery is GOOD, the Alternator should produce a near constant of 13 to 13.4 volts at the Battery at all engine speeds. Your fluctuations recorded [if the multimeter is good] would indicate an uncontrolled open circuit from the Alternator, due to Regulator Failure, and a JUNK Alternator. Confirm by taking it to a reputable Accessory Store, where they will Bench Test it for FREE.
Regards, DT

Aug 28, 2009 | 1995 Audi A6

1 Answer

Ground Wire fried...


Unfortunately there are only two ways to do this. 1. open up the harness and trace & replace burned wire. 2. cut both ends of the burned wire and leave burned section in place, then run a new wire BUT you need to know if there are any branch circuits coming off it and destinations, and, if the burned wire has crossed over into any other wire you will not see it. Third option is to replace entire harness with a good one. (time intensive and expensive, but actually the best option) Note: you also need to find the reason it burned or anything you do will likely fry again!

May 11, 2009 | 1992 Saturn SL1

1 Answer

98 Audi A6, Battery died overnight, when jumping smoke rises


Sounds like the alternator is badly damaged. The alternator will drain the battery if the regulutor or diode assembly goes out and/or the alternator is seized or locking up, which will cause the smoke (belt slippage) and drag on the engine (rough idle).

Apr 06, 2009 | 1998 Audi A6

2 Answers

Battery light comes on and goes off


CHECK ALL WIRES THAT GO TO ALTERNATOR.CHECK BATTERY BY TESTER( LOAD).CHECK WIRES FROM IGNITION SWITCH (YELOW) WITCH GO TO ALTERNATOR.AND CHECK GREEN RED WIRE WHITCH GO TO ALTERNATOR WITH IGNITION ON. IT SHOUD BE 12V AND WITH ENGINE RUNNING IT SHOUD SHOWS NOTHING.IF EVERY THINK OK - REPLACED ALTERNATOR.WITH EVERY THING OK VOLTAGE SUPOUS TO BE 13.8 - 14.5 V

Feb 18, 2009 | 1998 Lincoln Town Car

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