Mustang Rough Idle Low Rpm Misfire

I have an 87 Mustang GT, 5. It idles rough at stop lights and has a hard time getting up to speed. Anyways, the not so premium 91 octane gas cause build up on the valve heads, thus causing a rough idle. question = When i turn on my a/c and let it idle the rpm dips way below 1 and almost shuts off until i rev it up again but if i let it sit there it shuts off, it does the same thing when i turn on the heat, other than that the engine is fine, but only when the a/c and heat get turned on it starts to die, i just. Then it is back to just the rough idle. At Highway speeds it is fine, and it will rev fine too. The misfire is very intermittent. It failed the low idle portian of smog but was clean at the higher rpm portian. Now when driving while the car is still cold it will miss between 2. Engine Performance Troubleshooting Tree - ISX15 CM2250 This troubleshooting procedure should be followed for the following symptoms: • Engine Acceleration or Response Poor • Engine Difficult to Start or Will Not Start • Engine Power Output Low • Engine Runs Rough at Idle • Engine Runs Rough or Misfires • Engine Speed Surges at Low. Intermittent rough idle with no misfire codes stored. All of a sudden running rough misfires, knocks rough idle. 65 289 stumbles at lower rpm during accelleration. Not only that, but quite a few things can cause a misfire condition (or misfire trouble codes). 5T rough idle (feels almost like misfire) Page 2 of 3 < Prev 1 but my 97 was idling for an hour and no stalls or rough. In the case of a steady misfire, isolating the misfiring cylinder is the first step in diagnosing the problem. Every now and then I get an extremely rough idle. Ford Mustang V6 2005-2014: Why is My Check Engine Light Flashing? A flashing check engine light is a good reason to worry. Symptoms seem worse when engine is cold. If it doesn't stall immediately, it will instead develop no power - cannot accelerate much beyond walking speed. Car will shake. We were convinced the misfire was ignition related or rooted in weak compression. If the vehicle is equipped with On-Board Diagnostic (OBD), a MIL illumination may also have occurred due to Diagnostic Trouble Code (DTC) P0300 - Multiple Cylinder Misfire. 0L Rough Idle Low RPM, this is with the bank 2 sensor 1 unplugged (front of car, upstream o2 sensor before cat). I have 16,000 miles. no check engine light is on. My 1994 Town & Country (3. Motorcycle manufacturer recommendations vary, but most issues can be isolated using a. The truck still ran rough but somewhat better. Personally, my '16 Silverado had a slight rough idle when sitting at red lights while the transmission is in drive. Re: Misfire when started, NO IDLE Fuel Pressure is good, Throttle Body is clean, I found online that the IAC gets stuck from carbon buildup, so we cleaned it, it idles great, and starts good too, we also found that the cruise control cable was holding the throttle partially open. At idle the headlights will dim and the A/C quits blowing cold air. The new code is misfire in 1,3,5 cylinders with low current in 1,3,5 injectors. Update: Not the front o2 sensors. Tests performed/Action taken:-Choke is operating fine. It seems to stumble a little bit at low RPM. I've tried cleaning the throttle body, IAC, and EGR. 2004 Ford Escape XLT 3. I bought my truck to drive not idle so I am ignoring it. It is still idling very rough at low idle. The rough idle isn't as bad as the first time the rough idle occurred and is fine above 800 rpm in park. Tracking Misfires. Exterior; Chrome front and rear bumpers; Conventional lens halogen bulb headlights; Courtesy lights; Metallic paint , black paint , gloss paint; Rear platform step; Heating, Venti. As to why the system could not recognize the misfire, I have no idea. The plugs have been replaced three times. Top end/power is excellent, above 2000 RPM. How to Properly Set You Mustang's Idle. Ford Explorer | Intermittent misfire This is the tale of a 2002 Ford Explorer with an idle quality complaint. Well as my profile states I have a DSS 331. so i have a 2005 ford mustang v6 automatic transmission with 95k on it in florida, united states of america. Do have a code for catalyst bank 2 low efficiency. I can put it in park or neutral and RPM increases (as it should), but the idle quality is still less than desirable. Engine Performance Troubleshooting Tree - ISX15 CM2250 This troubleshooting procedure should be followed for the following symptoms: • Engine Acceleration or Response Poor • Engine Difficult to Start or Will Not Start • Engine Power Output Low • Engine Runs Rough at Idle • Engine Runs Rough or Misfires • Engine Speed Surges at Low. Got a weird idle and sounds like it wants to die if I am in Drive and just at a light for a period of time, Would I have to mess with the air/fuel screws, or is this the high idle and low idle i gotta mess with?? From what I have read, I do the high idle adjustment screw in Park or neutral and the low idle in Drive?. It will go from normal to a low idlenot a rough idle and it doesn't act like it's going to shut off but a definite low idleprob around 350-400 RPM. I bought my truck to drive not idle so I am ignoring it. At IDLE, there should not be any more than 5. I'm not getting any engine light, and I know it would turn on if there was a misfire, but since its been fixed, I'm still feeling the shakes and what I can only describe as a slight kick. RPMs hover in the 500-600 range in Drive and after shifting in N or P, its smooth. But the cause might be anything from a hard-to-find vacuum leak to dirty fuel injectors, low fuel pressure, a weak ignition coil, bad plug wires, or compression problems. Doug's original 289-2V had received only one valve job in its 42-year history. In my neighbor's Blazer, the PCM wasn't even registering a P0300, but it was obviously running very rough (at idle that is). It is idling at 650 RPM steady. When the engine idles, there will usually be a misfire that you can feel just from holding onto the steering wheel. This is because at idle the intake valves are only open 1/8th of an inch so any build up that occurs on the valves restricts airflow intake causeing the rough idle. But if the misfires get out of hand and occur too often, they can make the engine idle or run rough, stumble when accelerating, waste gas and fail an emissions test. i took it to a ford dealer and that was the fix. If there are misfire codes stored, you will also want to diagnose and repair those prior to diagnosing a P050D. Unstable idle speed. The main problem is, the car is refusing to run smooth at idle. Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4. Hello, this is my first post here but Ive seen some very helpful responses on these forums and thought I'd ask for some help. when i start the car, the idle bounces between 1500 and 2000rpm constantly. Unstable idle speed. P0300 (and P0301 & P0302?) Check. Once thats set the engine will be running more efficiently and you can turn down your idle speed and adjust the idle mixture screws to obtain a nice smooth low rpm idle. I do not have any drop in RPM when I am sitting there it just shakes a little harder then it should. Sometimes the engine will misfire on Idle also, and your engine sensors will get faulty values, and the air-fuel mixture will get messed up. Runs rough or - Chevrolet 2004 Malibu question. The Misfire Monitor constantly checks the rotational speed of the Crankshaft by counting the pulses of the Crankshaft Sensor. If the spring breaks somewhere in the middle it will affect both idle and power conditions. I have a 2005 EB Expedition. But when it warms up it has a noticeable misfire and only at idle. 8 automatic. Cleaned carb and replaced all inlet needles, new gaskets. Turns out it was a vacuum leak at the intake manifold plenum. It's been -15C to -20C all week and -30C here this morning. The rough idle & misfires are still present. The Mustang’s idle strategy relies on the idle air being supplied by the IAC. Managed to get the car to a garage 12. It idles rough, misses and lays down at upper rpms. Throttle body, mass air flow, fuel filter and plugs replaced with no change. If the frequency of misfire is high the Powertrain Control Module (PCM) may place the engine in "Limp-In" mode. Just keeps cycling. and when I think it's swithcing from OL to CL. Can someone please help with what I should check next, I have a 1998 Chevy K1500 5. Replaced fuel pump motor only, cleaned tank changed fuel filter and it ran great for about 60 miles. Misfire/Rough Idle. Several here have had ongoing issues with misfire codes. All of a sudden running rough misfires, knocks rough idle. Also, i know i have an exaust leak, because some starter sprayed into the leak will cause the engine to idle up, and coincendentally run smooth. Testing would prove us wrong on both theories. Recently started having a problem with - Ford 2006 Mustang question. Rough idle after startup once rpm's drop down. This is because at idle the intake valves are only open 1/8th of an inch so any build up that occurs on the valves restricts airflow intake causeing the rough idle. And a glowing exhaust. There also seems to be a very strong exhaust smell mixed with a slight fuel smell at low revs as if not all fuel is being burnt. It is sputtering and hesitating in low rpm's from 1k to 2k rpm's and is more evident under heavier acceleration. So suspect the injectors. ^lol My car doesnt idle low though. 050" lift, 114 LSA) with valve springs to match. The car runs well when NOT idling? When you start the car, and press the gas (to bring it above idle) what kind of RPM are you holding it at? Is it running rough at all? Was the carb adjusted?. Login with Facebook. Had a similar problem did all the same things 2, oddly it was a bad ground on the block to body the ignition system didn't operate good ( stumble, hesitation at low rpm and hard stat) also the charging system had week amps and volts at idle ( when the brake lamps came on the draw would pull from the engine harness causing a stall ) I hope you. 00 vacuum line. Car will shake. I can only notice it when its in gear and i am at a stop. Place it in gear and it shakes pretty good. If it does, a fuel pump with more capacity may be required. I look at the dash and see my RPMs fluctuating, check engine light comes on and starts flashing (misfire I presume from previous experience, as well as would explain the rough engine idle), “Reduced Performance” notification, as well as a slight smokey haze coming from the exhaust (smelling strongly of fuel). Any suggestions on what the rough idle could be. That is poor acceleration, slow to return to idle. When I accelerate, no matter if I just started the truck or if I have been driving for a while and am leaving a stop light, the truck studders, and then will accelerate dramatically. An engine that is idling too high may be caused by a faulty idle air control motor valve that has completely failed or that has simply become weak and is not functioning correctly. Any mustang guru's have some input? I'm absolutely stumped. Rubber was rotted at bottom causing a vacuum leak (, rough idle). On 1996 and newer vehicles that are OBD II compliant and have misfire detection, OBD II tracks and counts misfires. Vacuum at idle is 21 in/m. I bought my Jeep with a blown radiator, replaced that to find a very rough idle which goes away at 2000 rpm cold and 1500 rpm warm in neutral and it goes away almost instantly when driving. Remember also that a rough idle doesn’t always meet the criteria for storing a cylinder misfire code. But my main concern is that today I felt a misfire or skipping when i barely push the gas pedal at about 40-45 mph in overdrive. I just bought a 2006 F150 with the 5. Car is sluggish on idle. Well as my profile states I have a DSS 331. Testing would prove us wrong on both theories. Adjust the lifters first then set the idle mixture & speed and timing as well. Several here have had ongoing issues with misfire codes. My 1996 Ford Contour did this--I was driving it and the CEL came on, started flashing, and it was idling a little rough. By definition, as diesels are compression/ignition, they cannot misfire. The 1-6 in the powertrain codes, indicate which. Vibrations. Engine Misfire or Rough Idle on GM 4. The car started to idle rough and occasionally surge at a stop, it would drop below 500 rpm then shoot up to around 1200-1400 rpm but if I gave it a little throttle it would clear up. I have been chasing a rough idle on a 2002 Seville SLS. there was lack of power, and then to top it off the check engine light. It idles rough at stop lights and has a hard time getting up to speed. 2002 Ford Mustang 3. How to Properly Set You Mustang's Idle. If your car has a rough idle, it may be because your idle speed setting is incorrect. The Ford Mustang, with the 4. Intermittent rough idle with no misfire codes stored. Went to town to get some material. What Could Cause a 2000 mustang to shake at about 1400 RPM with New it will run with a. it seems to be problem with 3. This car has been on a smoke machine twice plus me doing a cigar test (old school check for vacuum leak test) and it still misfires. If it doesn't stall immediately, it will instead develop no power - cannot accelerate much beyond walking speed. Unless it's leaking but that would cause rough at low idle which is not a problem for me. A misfire in a 3. The idle speed control systems will not be able to hold a steady idle speed, so the idle will be rough and hunting, and often stall on deceleration. It idles rough. At IDLE, there should not be any more than 5. I recently dropped a new 260 long block into my 64. Do have a code for catalyst bank 2 low efficiency. Replaced fuel pump motor only, cleaned tank changed fuel filter and it ran great for about 60 miles. [FIXED] Aveo 2007 Rough Idle and Low Vacuum × Help us help you. the car runs better, problem solved but my engine still shakes a little when it idles. Try reading the plugs, and testing the cops, if it has a cel the code should point you in the right direction, but if it started out of the blue I would read the plugs and change the fuel filter. The most common symptoms of a vacuum leak are rough/high idle, misfires and a check engine light. Didn't want to start a new thread on this so I just revived this. Ford Explorer | Intermittent misfire This is the tale of a 2002 Ford Explorer with an idle quality complaint. Chances are that if you fix the misfire; you’ll also repair the rough idle at cold start. Some 2013-2016 Escape vehicles equipped with 2. It could be, a spark plug failure or an ignition coil has failed. Slight bogging when accelerating moderate to high. >"but upon acceleration at high rpm it misfires. However, when the engine RPM drops below the normal range of 750-800 RPM (for most cars), this may indicate a dirty or faulty idle air control valve. Check engine light and trouble code P0300 misfire. The short answer is an imbalance of fuel and air, improper spark, improper isolation or mechanical damage that has caused the engine to vibrate. When the car starts it idles fine at about 1000 RPM. Rough acceleration is a typical sign of that your engine is misfiring. Having a a major dilema with a rough idle / Multiple Cylinder Misfire on my 2001 Chevy S10. Didn't want to start a new thread on this so I just revived this. Either way, you should use mode $06 in combination with other scan tool data (DTCs, fuel trims, freeze frame data) to get a complete picture. Recently started having a problem with - Ford 2006 Mustang question. I have a 05 chevy silverado with the 4. Has anyone else experienced rough shifts up and down, rumble strip feeling on decel, shudder on tip in acceleration and slight shudder at low RPM regardless of speed or gear? Probably the worse AT I have experienced. Comp Cams 05-09 GT MuthaThumpr Cams- Very Rough Idle, Largest Cam that will work with Stock heads- BIG CAM , Helvetica" size="2">MUTHA' THUMPR - Very rough idle, biggest cam for stock heads. I'm thinking a clogged fuel injector as the common denominator from those codes. Replaced fuel pump motor only, cleaned tank changed fuel filter and it ran great for about 60 miles. 73 -pypes pype bombs -13k miles Oil is in good condition. Average failure mileage is 23,650 miles. P0300 Diagnostic Trouble Code Discussion for March 2011 Multiple Misfire Detected * Note: This is a professional automotive technician's resource. This occurred no matter what the temp was. I've tried cleaning the throttle body, IAC, and EGR. Rough idle and low power 10 Answers. The car is running rough, low rpm idle and shaking sometimes when accelerating. Such symptoms have to be checked out, determining which vehicle components might. 8 Mustang v-6. One of the most common problems is likely a rough running or poorly idling engine. Drove it for a few days and it would misfire at idle but accelerate with out hesitation then for a few days it cleared out, well I moved and didnt drive the car for about another 4 months, then when I came to move it I tried to turn it on and the motor would turn over start for about 2 seconds and die. Went to town to get some material. Yesterday checked compression and cleaned throttle body. It may or may not dip down low enough to be rough again, it varies, but in the last couple weeks it has done it for about half of the stops I. The Ford Mustang, with the 4. I just seen another post identical codes and Identical symptoms idle and low speed misfires go away about 3000rpm and WOTit was like reading a journalhowever HIS was the IMRC cracked issue yet mine has identical issues and codes with a TVSnothing he did resolved it. Lean misfire can also be caused by an EGR valve that is stuck open or is not closing fully. Search the history of over 376 billion web pages on the Internet. from as low as 450 rpm up to 650 rpm once it is warmed up. My 1994 Town & Country (3. It runs fine but I can't seem to get it to idle smoothly. It idles rough, misses and lays down at upper rpms. engine running rough and shaking at idle It felt like I was riding on cobblestone, as I slowed it was easy to notice that the vibration was coming from the engine. Hey guys, Im having a rough idle on my 99 Grand-AM (2. 2), one day they run normal, and the next day its runnin rough-fuel. I used to think it was worse when fuel was low. Any mustang guru's have some input? I'm absolutely stumped. The car started to idle rough and occasionally surge at a stop, it would drop below 500 rpm then shoot up to around 1200-1400 rpm but if I gave it a little throttle it would clear up. When I put the car in neutral the car runs way better and revs to about 1000 rpm, when I but it in gear it runs to about 750 rpm in idle and idles a really rough. Possible cylinder head or valve damage on the GM 2. old one ran good. low and rough idle and stalling at complete stops. The problem: rough/low idle (warm and cold engine) that appeared in the past 3 days and random misses from the engine…at stop lights, car acts like it is close to dying. If it doesn't stall immediately, it will instead develop no power - cannot accelerate much beyond walking speed. 2L I-6 Engine and Drivetrain > OEM Issues: 2004 GMC Envoy Misfire/Rough Idle, Replaced Coil w/Success, Misfiring w/ use of A/C. load on engine and if idle can't compensate then it would idle too low and set a code. Hence, after knowing the ways to troubleshoot rough idle when warm problem, anyone. At cruise, there was a definite surging around 1,400 RPM under a low load. Whether it is in gear or not has no bearing. Doug's original 289-2V had received only one valve job in its 42-year history. I have an 87 Mustang GT, 5. 7 at 1500rpm, dropped to 11. (should have said that sorry) its been into the mechanic but they couldnt get it to run rough in the test tank so hard to fault find unless on the water i guess (still charged $$$$$ so cant afford to continually put it in the shop). Essentially it just means turning the distributor till the engine reves the highest it can without pinging when pulling hills in a high gear. The check engine light flashes when the car is shaking as well. Symptoms Of A Misfire Condition? The basic symptom of a misfire is a light to severe rough idle that's felt when the engine is idling and a light to severe engine miss (hesitation) when the engine is under load (for example: your Ford vehicle moving from a stop). It may or may not dip down low enough to be rough again, it varies, but in the last couple weeks it has done it for about half of the stops I. Check the fuel vapor purge valve. I've gooten random EGR codes for a long time. Although generic, the specific repair steps may vary depending on. Hi All, I have a 2010 1. shut down while running 3500 rpm. At the end of the drive I ran the car's internal "Key On Engine Running" self test which didn't show any errors. Idle roughness improved slightly, but MIL returned, P0172 running rich. Misfires are probably one of the most common reasons when it comes to rough idle. It has 97k miles, I saw the car, drove it, and knowingly purchased it with the check engine light. Rough idle and light backfire. If however, I am driving fast (75 - 80 MPH), or have the transmission downshift while passing someone (high engine RPM), the car will occasionally be misfiring when I next stop at a light. Rough idle 3 Answers. Please try again later. I test drove it a little and it worked fine, then I put in a. Author: Topic: 2000 Miata- 50,000 miles, Check Engine Light, misfires, idle rough, won't run (Read 9087 times) 0 Members and 1 Guest are viewing this topic. Symptoms seem worse when engine is cold. At idle, it is very rough but it does not stall. It did with my 88 GT and it went to a steady 650 RPM. Replaced all plugs, coil pack, EGR and 2 injectors (3-4)which showed misfire on diagnostic. No code was set, but she ran terribly, with no power, major misfires, and an occasional backfire. Anyone have one of these, with a similar problem? Any sugguestions? ratherwhalering: posted 11-09-2001 01:03 PM ET (US). Rough idle indicates either a maintenance problem or a failed part. my truck does something similar. 1) Changing distributor fixed the original rough idle/misfire problems. Rough idle and random misfires when accelerating slowly from low rpm while driving. I bought my Jeep with a blown radiator, replaced that to find a very rough idle which goes away at 2000 rpm cold and 1500 rpm warm in neutral and it goes away almost instantly when driving. 0 450 whp / 352 wtq Intermittent hiccups or cold start rough idle makes me think misfire. It seems to stumble a little bit at low RPM. Technical Chevy 6 with misfire at low speeds. When driving up to a stop sign or light, clutch pressed in, the rpm's will dip very low and the car will run rough for a moment then the idle will automatically go up to around 1500 to correct itself. Rough idle and random misfires when accelerating slowly from low rpm while driving. The engine starts missing intermittently and will also stumble at low rpm. If the engine runs rough between 1200 and 2300 rpm, proceed to Check Valve. It didn't have any codes and had no mechanical issues. Author: Topic: 2000 Miata- 50,000 miles, Check Engine Light, misfires, idle rough, won't run (Read 9087 times) 0 Members and 1 Guest are viewing this topic. This can cause a very uneven idle which can jump up and down and the engine may also shut off on idle. and it isn't even 1/2 qt low in. 1990 Mustang 5. CEL self-corrects? Check. As soon as it warms up, it starts to idle rough, between 500 and 750 RPM. So it was not a clean misfire, other things went wrong at the same time. The sound goes away after the car warms up. Remember also that a rough idle doesn’t always meet the criteria for storing a cylinder misfire code. The first time I replaced them, the misfire was gone and the car performed. Intermittent hesitation when accel from stop. Throttle has no input or effect on the issue, I can kick it and it will get up to about 2k rpm then die. runs rough 2000 mustang 3. Mitsubishi Eclipse stall/idle. Ive done all the searching I can, as well as tons & mega-tons of diag work, and cant figure this one out. It will rerpeat this randomly. >"but upon acceleration at high rpm it misfires. Checked all the fluids and everything was perfect. Car will shake. When the idle is high or low, it could be caused by a malfunction of this system or any of the individual components that comprise the system. I drive a 1997 ford Mustang v6, when I'm in idle the rpm guage goes up and down between 1 and the half mark. Got a weird idle and sounds like it wants to die if I am in Drive and just at a light for a period of time, Would I have to mess with the air/fuel screws, or is this the high idle and low idle i gotta mess with?? From what I have read, I do the high idle adjustment screw in Park or neutral and the low idle in Drive?. Boat engines have the same operating principles as do land vehicle engines, but having trouble with your boat engine can leave you and your family in a precarious predicament. Now I can get it started but it's very rough, rev's high occasionally, and won't run for more than 30-45 seconds. now there is no smell, i have plenty of power, but at cruising it still jerks bad and runs rough, and only at low rpm. I read the codes, which got me absolutely nowhere since there were so many. RE: Very rough idle when stopped IP: Logged Message: "Detori, I'm on my third dakota, the rough idle just comes with age. RPM is 650 to 750 and I can feel a slight vibration. I have a rough idle and hesistation on acceleration I can't get rid of. The Misfire Monitor constantly checks the rotational speed of the Crankshaft by counting the pulses of the Crankshaft Sensor. Didn't want to start a new thread on this so I just revived this. It seems that the average idle RPM is fine, but it bounces around a little and when it's on the low end that's when it "feels" like it's going to go dead. Exhaust didn't seem to be an issue because high rpm power and performance was excellent. A misfire in a 3. what could be the problem. One of the most common problems is likely a rough running or poorly idling engine. at idle in N or P the 289 rough idling and rpm changing - Vintage Mustang Forums. I look at the dash and see my RPMs fluctuating, check engine light comes on and starts flashing (misfire I presume from previous experience, as well as would explain the rough engine idle), “Reduced Performance” notification, as well as a slight smokey haze coming from the exhaust (smelling strongly of fuel). Plugs have been gapped at. Yesterday checked compression and cleaned throttle body. Anyone know where I can find a diagram or other thoughts? Thanks. LTFT stayed at zero the whole time. Although generic, the specific repair steps may vary depending on. Rough Idle - Random Misfire - Erratic RPM. Hi, I purchased a 2008 Volkswagen GTI 2. Mustang Monthly Magazine shows you how to tune your vintage Ford Mustang for improved performance. Many systems and parts are used to keep the engine idling. i restarted it to see if it was any better, nope. I have an 04 Grand Am and it is running rough at idle so I hooked up the scanner in his reading PO 301 and PO 171 I just changed all of the spark plugs but still reads the same codes. 94-95 Gt Bad Misfire , Rough Idle ,Runs Rich But Up until a Few weeks ago i was Having a Problem With A Slight Misfire When It Was Only Warmed Up At Idle & Driving , On Cold Starts it Would Idle And Drive perfectly Fine Until it warmed Up & Than started Bucking(misfiring) Like crazy and a Very Rough And Hesitant Idle and Ran Very Rich. The truck still ran rough but somewhat better. Has anyone else experienced rough shifts up and down, rumble strip feeling on decel, shudder on tip in acceleration and slight shudder at low RPM regardless of speed or gear? Probably the worse AT I have experienced. Misfires are often caused by a bad spark or a faulty air-fuel mixture. It is sputtering and hesitating in low rpm's from 1k to 2k rpm's and is more evident under heavier acceleration. Any clue on possible cause?. Well it has just got a little worse I think. When it reached 1500 RPM it runs smooth and when I stopped on the stop light it idles rough. I've tried changing the spark plug wires, and plugs will come tommorow. The Ford Mustang, with the 4. OBIO3 Dodge Dakota JOIN HERE 1/12/2007 19:00:10: RE: Very rough idle when stopped IP. Replace them and it fixed the fuel trim issue i was having, but it still has the rough idles and misfire through mid range rpms. old one ran good. cleaner removes this varnish that is put there by the gas/additives so you should use a inj cleaner every now and then, 93 is not self cleaning. It doesn't seem to do it until the bike is warmed up. Engine 1994 mustang gt Rough idle, misfire under acceleration: Engine '93 running rough, especially at low rpm's and idle. no modifications. I scanned it for codes and it was a cylinder misfire. Engine Misfire Detected on Startup (First 1000 Revolutions) What does that mean? This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. The idle speed control systems will not be able to hold a steady idle speed, so the idle will be rough and hunting, and often stall on deceleration. 0L mustang 7 years ago, it has had an idle surging/hunting issue that is extremely annoying and worrisome to me, that I have not yet been able to find the problem to. Misfire at idle (2002 Mustang GT) problem. 8L Poor Idle Quality, Hesitation, Misfire Posted to Ford Driveability on 12/19/2007 3 Replies This mustang either cold or after a hot soak will extremely intermittently run rough miss and idle rough after cold soak or short hot soak. We changed plugs/ wires and a new coil - Answered by a verified Ford Mechanic. Stationary, the miss is tolerable. Maybe that was the cause.