Running lean at idle. (loosen) Also: turn the screws with your fingers. May 8, 2012 · If it is falling flat on its face at W. I had a friend who has autotap and my iac counts and readings were 0 the whole time. Aug 3, 2016 · But idle mixture adjustment will make hard restarting. I also am replacing the fuel filter and another O2 sensor. Jun 14, 2021 · Rough Running and Stalling. - Hopefully I can get some advice as to what to look for, or pointers from those of you who have had or seen similar problems. Jun 8, 2009 · ive been playing around with my 350 sbc now for about a year and have not had any luck getting it tuned in well, just on normal drives the car runs lean enough to pull a plug out and have it be like new white. Running at full throttle right away causes the pistons to expand thermally. You can run a little leaner on the needle circuit, and fatter on the main jet or. You can then use a screwdriver to adjust both screws ¼ turn at a time until your engine purrs smoothly. 28 g/cyl inclusive (HPT > Engine > Spark Control > Spark Advance > Idle Spark Advance (in Apr 20, 2014 · I have been trying to figure out why my car is running so lean. No power loss, no knock, no missing cylinders. Jun 10, 2016 · The bigger your idle spark/coast spark disparity, the larger the number will be. May 6, 2012 · Hi guys, I just recently started my car back up after it sitting for 7 months while I've been gone. Idle is right around 14. 44:1, TFS 190 56cc 11R heads, Victor 5. gonna change the gauge to a different not so cheap one to see if its any different. I've been trying to read and learn all I can but this is kinda stumping me and I'd like to get the tune close at least so I can drive the car. Please note that a lean fuel mixture causes the engine RPMs to go high, raising the maximum engine temperature. Removing vac line from FPR causes O2 sensor to cycle normally. Jun 5, 2012 · Re: How to tell if running lean, or rich? Eric, Running lean will cause heat and can cause damage. i dont have an accordion hose i have a hard pipe. Oct 6, 2011 · Cams over 15º overlap, idle 950-1100 all cells across the board, add 3-4 g/sec to idle airflow across the board both in P/N and in gear (HPT > Engine > Idle > Idle Airflow > Base Running Airflow), add 6º of idle timing 1200 rpm and under and 0. It is running very lean at idle, reading a LTFT of 15%. 6L Triton V8, 4x4, automatic Story: Up until last Wednesday my truck Apr 30, 2010 · Set the idle first. Gonna go buy a 99 cent cigar and give the car a smoke test. I rebuilt the carb myself and is working great in the engine, the idle is good with 18" of vacuum at 550 RPM but I've the feeling that is running lean at idle because If I hit the throttle the engine will start misfiring a while once is back on idle rpms Mar 20, 2007 · Either way, what would be the most probable and simple cause of it running lean at idle? Also the car is sometimes hard to start, I have to give it a bit of gas to start. I can start the car and let it idle for a long time (an hour even) and it'll never miss. Im getting codes 1171,1174 lean on bolth banks,a bad hesitation off idle and it boogs when you try to take off when its first started. Mar 13, 2014 · I have a completely stock 2002 WRX with 103K. Both banks read about +10-15% at idle and light load. not sure about the details yet, but the tech told me my car was running lean at idle and car was dumping fuel on wot to compensate for lean condition. A vacuum leak allows air to enter the combustion chamber unmetered, which increases the air in the air/fuel mixture. Apr 14, 2019 · Rough, erratic idle that drifts toward higher RPMs than expected based on the setting of the curb idle screw. 19 and Bank 2 STFT is 0. The vehicle may even stall if the mixture is lean enough. 8. It was recently running about 14. Poor Acceleration: An engine running lean will have a sluggish response to acceleration. Jul 10, 2021 · The OBDII trouble code P0171 - System Too Lean (Bank 1) means that the engine air-fuel mixture is too lean, or there is too much air and too little fuel. Jan 12, 2023 · Intermittent surging at idle only after warming up. Check boost/vac leaks-None May 12, 2016 · Car (2014 3. May 23, 2012 · It will learn idle if you let it run long enough to go into closed loop unless you have an aftermarket chip with open loop idle. 9:1 - 15. I repin the maf plug to work on mk4 tt maf-idle and runs just like the VVTI one. Alongside running with a rough idle, a motorcycle running lean will also act a little sluggish when you take it out for a ride. 4) Clogged Air Filter Aug 11, 2013 · Its been running lean with code P0171 and my idle is really rough in park and at redlights, and in stop n go traffic it really jerks when in 1st,, tryin to rule out the easy things since the dealer sucks and im now waiting on week 3 for the blown strut. In that log i'm holding the throttle open. This issue has been going on the past two yrs though. The engine can run too rich or too lean. Search for threads covering enlarging the fuel return orifice (I usually do 2 mm) and checking to see if the return line is clogged. I HAVE NO LEAKS FROM MY AIR FILTER TO MY MUFFLER. My guess is that after fitting the downpipe, the O2 sensor is going crazy reading the exhaust gases and gi When fully tightened, it prevents fuel from entering the carb. I run the code it says it is an O2 sensor and so I replaced the sensor and it is still showing the same thing. In comparison, an engine that is running at a rich fuel mixture drops its RPMs considerably. My dad does not think it is a vacuum leak and told me to clean the intake and clean the filter. My example below is going from 8 to 22 degrees spark and while there is a slight RPM jump, it is vastly improved over before when it was just shifting at the full 22 degrees spark. May 9, 2019 · I’m still stuck here. The engine may rev up or down, or even stall when idling, causing a rough and shaky feeling. An engine running lean can also lead to a ‘soft seize. Im currently running stage 1 remap from bluefin, with some supportive mods like airtec stage 2 intercooler, ITG induction kit and a downpipe. 7 is max power -- depending on boost level that may burn (melt) a piston/ring Sep 13, 2020 · Still running lean at idle with +10. my fuel pressure is just a hair under stock, regulated with an aromotive regulator, walbro 255 pump running 12v full time, jtube Oct 23, 2015 · And the last thing that happens sometimes is it starts to idle sort of normally but then when it goes down to a low idle after a cold start, it bobs up and down from about 250 rpms to about 750rpms, when a regular idle sits around 1,250 or so. The acceleration seemed to be better. 034 primary idle feed restriction and . Turn the screws inward to lean it out. On the initial start up it seems to be fine, but after a couple minutes, the rpms drop a little, surges slightly, and it runs lean. Dec 26, 2023 · When an Engine is Running Lean, there is an imbalance in the air-fuel mixture, which can lead to a rough or shaky idle. i have a wideband but dont trust it all that much when its telling my i have a 12. Jun 24, 2016 · 1. Restarts immediately. A too-lean mixture will cause a rough idle. Jul 7, 2013 · Also, to add to the initial problem, the rough idle only starts when the engine has been run. I already replaced the PCV Any suggestions where to look at, or what parts might be causing it Mods: Injen cold air intake Turbo muffler delete IE stage 1 tune Oct 17, 2023 · A BMW fault code P0171 or P0174 means that your engine is getting more air than fuel, also known as running "lean". The IAC steps would not go down from 225 and the AFR just read 14. If the oxygen level is too low, the vehicle is running rich (too much fuel), while if the oxygen level is too high, the vehicle is running lean (not enough fuel). Some performance engines, especially those with idle vacuum levels of 10 “Hg or lower may not allow the engine to idle in gear and may require a much richer mixture. Make sure you check for air leaks at the manifold to head joints as well as the throttle body to manifold, and don't forget to make sure the rubber cap is still installed on the vacuum tube on top of the throttle body. May 27, 2024 · Rough Idling: When an engine is running lean, the idle speed may become erratic or unstable. It’s giving me misfire codes P0300 and P0304. Identifying Idle Problems in Kawasaki Mules. Once you have matched both carburetors you will need to set the idle to the desired idle speed setting. The car is running Lean and surges RPMs at idle. 78. Jul 22, 2004 · Modular V8 (4. Jul 10, 2021 · The OBDII trouble code P0171 - System Too Lean (Bank 1) means that the engine air-fuel mixture is too lean, or there is too much air and too little fuel. The motor may not idle correctly, however. Disconnect safc fully and run on stock ecu still lean at idle. While driving around its fine, but if I shift into neutral to come to a stop, it idles rough and is lean again. Jul 12, 2004. A too rich condition increases fuel consumption, while too lean cause the engine to idle rough. (tighten) Outward richens it up. ” Your engine running lean is always a symptom of another problem - it could be a dirty MAF sensor, a damaged oxygen sensor, or damaged fuel injectors. 3. This occurs when more air than fuel is in the combustion chamber, causing the engine to run hotter and potentially leading to engine damage if not See full list on rxmechanic. Oct 18, 2020 · Recently My engine has started to run lean and I am seeing the idle extremely low. Make one last check of lean best (smoothest running position) idle on all mixture screws one last time. A super lean running engine will often idle rough. Mar 11, 2020 · I was at an autocross on Saturday, long story short at the end of my second run I came into the paddock and had a really rough Idle, jumping up to 1000rpm and then down to 400. Running lean will cause the engine to run hotter. 08 – 0. May 24, 2011 · Erratic idle - faulty injectors / running lean Jump to Latest 13K views 20 replies 12 participants last post by HappyMint Feb 10, 2012 Aug 19, 2008 · car is at dealer right now. The car's computer will adjust the air-fuel mixture based on the oxygen sensor to keep the engine running optimally. Your BMW engine is equipped with oxygen sensors - small probes that extend into the exhaust system (usually near the catalytic converter) that measure the amount of oxygen left after combustion. Aug 27, 2024 · If you have an intake air leak, it makes the bike run lean. You'll know it has gone into closed loop when the O2 numbers start bouncing around and the decimal point stops blinking and is on solid. It goes from 1000 RPMs down to maybe 400 RPMs then surges back up to 1000 RPMs and starts loading up and I give it gas and all kinds of extra fuel is burning out of the exhaust. Play with the idle MPH and idle adaptive delay until you like how the car is stopping. my cheapo autometer hooked my narrowband is showing lean off the charts at idle. Jun 28, 2024 · Can Running Lean Damage the Engine? Yes, an engine running lean can certainly end up damaging itself. I had the same exact problem only to find out one of the hoses popped off the steering pump vacuum line on my MKIV. I hate to see it that lean. 6 Running lean - I have a 96 Merc 4 door. 0 to 14. i currently am running a 750 DP by Pro The vehicle's oxygen sensor measures the exhaust's oxygen levels. . 039 secondary idle air bleed. The truck is driveable, but when going up a hill the truck will surge. Trying to balance figuring out whats wrong and running a brand new engine at a 19:1 AFR. Fixed carb jets can get clogged and cause this condition. At idle my fuel trims at times will read a even negative number and other times read positive. If I let off the lean condition only gets worse. Blip the throttle, let the bike return to an idle, wait say ten seconds. Feb 26, 2001 · I have the bull**** Autometer A/F, i know its a lightshow, Just took notice-At the time the cars acts up, The gauge is pegged on LEAN and will not do the rainbow dance, at that point- The symptoms are as follws-The car goes from idling and acting normal to, car shakes, stumbles and wants to stall, But doesnt-it maintains a real crappy idle of Nov 25, 2020 · The fuel trims on my truck are reading very lean. Anyway, If idle mixture is too lean this means there's not enough fuel vapor trapped in crankcase from shutdown to make an easy warm restart Mar 12, 2024 · I have a 1996 mustang Gt 4. 6L, 5. Whatever the problem is, recognizing when your engine is running lean is important for maintaining the health Nov 23, 2011 · Now very slowly, open the fuel screw till the idle is smooth. Bank 1 STFT is 1. Jul 25, 2021 · Hi! My fiesta has thrown this DTC code recently. In boost, the short term is often negative. Apr 25, 2016 · Ok , raised sub frame so i could look inside carb with engine running , when idle hangs , i can bring it back down by pushing down on slide , throttle wheel is resting on idle screw , there is a little up and down mouvement off slide ( less than 1 mm ) when engine dead , even if throttle wheel is stoped , no problem with low idle . When an engine operates with lesser gas than it requires, it creates higher friction on the engine’s moving parts. com Apr 29, 2023 · The biggest difference in symptoms between rich and lean is that a car running lean will always run poorly, whereas a car running rich tends to only run poorly during idle. If it is just a huge bog, then you may be too large on the main. Sometimes a lean condition will cause a “hanging” idle that is slow to settle down to set idle speed. Mar 17, 2023 · Low/High/Jumping Idle; Hard Starting Condition; The engine may die when driving; How serious is the P0171 Code? Moderate – In most cases, the lean mixture is significant, and you will not notice any difference in the engine’s performance. Sep 23, 2012 · Do it while it's running and see how it affects the idle. Idling After Start-Up: I would always recommend running a chainsaw at idle for some time before going full throttle. Vehicle: 2004 Ford F-150 Heritage (97 - 03 body style) Specs: 4. Mar 19, 2019 · The truck would run, but it would idle up then almost die, and repeat. Drives the same 2. Running rich is usually not an issue. Apr 28, 2018 · It can become covered with carbon deposits or simply wear out. The piston and the cylinder get warmed up properly as a result. Apr 29, 2023 · The biggest difference in symptoms between rich and lean is that a car running lean will always run poorly, whereas a car running rich tends to only run poorly during idle. ’ Aug 5, 2013 · 12s would be pretty lean on pump fuel(91/93 octane), for E85 it would be acceptable. As long as the engine stays running idle speed is not important at this point. But after I start driving it, about 10-15 minutes later it starts to rough idle and the SES light comes on. The O2s are supposed to jump around during closed loop operation. However when this happens, if I even tap the gas, it revs up and falls at a normal idle perfectly. Meaning 10 is very rich, and 13 is very lean, well at least for a car under hard load, and one that is not direct injected. 040 secondary idle feed restriction 70/76 jetting Holley 670 vacuum secondary street avenger. Turning the screws in a clockwise direction will make it richer, while turning it counterclockwise will make it leaner. 6 I have replaced the MAF, ambient air sensor, new plugs, new coil packs, new wires. I figured it was because a leak I had in the throttle body so this weekend I swapped it out and also replaced my diaphragm on my Greddy Type S Start the engine, the engine will run very slowly more like a tractor. O. Sep 4, 2013 · A family friend replaced both sensors on bank 1 and the code went away and the car was running normal, (no rough idle). Start the engine and adjust the angled screw for tick-over, slowly a bit at a time. It's more complicated than that, with lots of other sensors having input into the calculations, The gist is that the ECU sets the fuel to inject based on the amount of air reported by the MAF, then adjusts fuel May 8, 2010 · do you know that its running lean? are you running a wideband? the exhaust leak could throw off the O2 sensor. Are you saying revert the open loop eq back to the stock shape and then try to tune the VE table with those Nov 1, 2021 · My Audi A4 is running lean at idle, I’m not sure how to trouble shoot it. The lower the air to fuel ratio, the richer it is. Release I have a 6. 4b. This is because the lean air-fuel mixture doesn’t provide the An idle run ensures that the engine temperature gets normalized. 8. The primary symptoms include: Mar 15, 2023 · The most common reason why an engine is running lean is due to a clogged fuel filter, vacuum leak, failing fuel pump, or clogged fuel injectors. 4L) - 4. The engine isn’t receiving enough fuel to make the motorcycle run efficiently. as far as the adjusting screws i set my idle screw high when i was first tunning my carb on my 4stroke tank scoot so it wouldnt die if i had the mixture off. 5:1 A/F almost all around. Fuel pressure at rail is 38 psi at idle and 48 psi when vac line removed. Light acceleration is pushing 15-16 Deceleration jumps to 18-20 at times Under 15-50% throttle, Knock Retard will pull as much a 3degrees of timing May 9, 2007 · MS CAI, MS CBE, Yellow Racing Coilovers, Hotchkis fonrt and rear sways, Enki RP01 17" with Hoosier R6 (track), AutoPower Race roll bar, GeForce 6 point harness, Cobb mild tune, 278 whp, 310 wtq on a Dyno Dynamics (heart breaker) dyno, Autometer Cobalt boost, oil pressure and oil temp gages. 9, but if I'm driving steady it goes to the 14 - 15 range and 12s for wot. When it does, the sensor will transmit incorrect data to the engine control unit, causing it to run too lean or too rich. could it be the stock fuel regulator not working right? it has pressure through two ports and one Mar 8, 2023 · If the idle is unacceptable, return the idle mixture screws to the highest vacuum setting, but in most cases this slight lean setting will still support quality idle performance. but i was riding it around too and would stop to adjust the fuel screw 1hr at a Oct 2, 2021 · The ECU thinks that the engine is running lean based on the air input data from the MAF, and the O2 sensor readings in the exhaust. The biggest question I have is the warmup idle. Any ideas? Jul 27, 2015 · Engines with big cams tend to want more fuel so you should run a richer mixture for a good idle. In some instances, engine damage might be the root cause of idling issues. 7. Checked my hoses and didn't find any that were loose. Apr 28, 2022 · Turbo Teal 95 GT 5 speed, Creb Engineering 331 10. Running lean at idle My car idles around 1100, and is smooth not jumpy. Backfiring ; Sluggish …hesitates when the throttle is opened, then recovers (often accompanied by a slight backfire) Aug 29, 2019 · If an oxygen sensor goes bad, it can make your Terrain run too lean (or rich). Question; 2G Running very lean, high idle & not Aug 24, 2020 · My car is running lean and rich. i am not concerned with that. 92tsifwd; Jul 11, 2004; Newbie Forum; Replies 8 Views 884. tried new o2 sensor-makes no difference. When an engine is running lean, there is an inappropriate air-fuel mixture, mostly on 2-stroke engines. Under extreme conditions, this can cause the piston to melt down or seize. 4:1 at idle which was lean but not horrible. Data: My O2 is reading 0 volts even after warming up. Starts up kind of rough but no loss of power and idles higher Apr 3, 2010 · when adjusting carb screws think of the screw as a clock and adjust 1 hour at a time small amounts i believe are best and im sure the other dawgs will agree. You’ll also notice that if an engine is running lean, the engine and exhaust pipes will become very hot, even hotter than normal. Confirm it is the same smooth idle. When I get it into boost, the LTFT drops to around 7%. Feb 7, 2024 · Failure to address a lean running engine can lead to unrepairable engine damage and cost you a fortune! But what exactly does a mechanic mean when they tell you that your engine is running lean, and what can you do about it? Keep reading, and we’ll break it all down for you. To adjust your idle speed, find the idle mixture screw that limits the flow of fuel at idle. Other times your car engine may actually run so lean that your engine parts are in danger on high load. Vacuum Leak. 4. The idle mixture screws are located outside the carburetor and can be turned with a Phillips-head screwdriver. 078 primary idle air bleed and . Idle mixture must be final adjusted in water for perfection of course. Checked the fuel pressure Jan 3, 2011 · 15-19 afr at idle is normal, google it. A few hours after I got rid of code 2195, code 401 pops up (egr insufficient flow) and the rough idle comes back. Start it up and go from there. The truck seems to run fine anything off idle. Please help. Jul 2, 2013 · Engine management light came on, had it scanned at a local Audi specialist Saturday, came back as running too lean. BTW - the idle mixture setting will never cause a motor damage. and it leans out at WOT just as much. Mar 17, 2024 · Then, start your car and let it warm up. It is in the 20 afr range on my wideband from ambient temp to 200, then it goes to whatever the tune suggests. 0:1 although an engine targeting economy may well, in my experience, be able to run as lean as 15:1. 7. There are 2 ways to approach jetting, and both are correct. The guy suggested it was one of two things, either a change of fuel (shell v-power to a regular unleaded) or a throttle body fault. Just go finger tight. 5. Oxygen sensor Nov 23, 2022 · You can adjust the idle mixture screws if your engine is running too rich or too lean. When it's at running temperature, find the 2 screws on your carburetor that adjust the air and fuel mixture. Usually factory spec idle mixture screw position is very close to perfect. 048 secondary idle air bleed Jul 18, 2011 · 1997 - 2003 F150 - Idle problem, running lean. Happens cold and warm, no change. When it's cold, the engine runs greatno misses. Engine stalling during halts. Vacuum leak-related engine performance problems are usually the most obvious at idle. I changed it and it stayed the same. Apr 23, 2018 · My Buick 455 stage 1 came with a quadrajet from a 78 chevy (according to carb number) when I bought it, pretty sure is a small block carb. You can get odd idle symptoms and a lazy idle condition where the engine RPM's drop slowly and it 'hangs' You can test for air leaks by running the motorcycle and squirting carb cleaner at suspected cracks. Got under the car with it running and put my hand over the exhaust joints - didn't feel any exhaust hitting my hand. Jan 2, 2019 · If you've ever tuned a seriously modified performance car, or even just fiddled with a carburetor, you've probably heard an old bit of advice: Running lean will make your engine overheat. When tightening all the way down don't over tighten with a screwdriver. checked my fuel pump and everything is ok according to them. 0 Iron block, built nearly identical to an LS2, but with bigger cam It's running lean all the way from startup. Sometimes it stalls at idle. Driving a car with the code P0171 can cause more damage to the engine over time, as when the engine runs lean, the combustion temperature is higher. Even if it is only at idle. As a result, the engine will run rough and misfire. Under heavier loads the fuel trims easily go above 20%. Running lean causes lousy idle and running hot, among other things. The first thing to do is not set up the idle speed, but to set the idle mixture screw to lean best idle setting. A too-rich mixture will result in poor fuel economy. well with 750cc injectors i dont see how your running lean at idle unless you messed something up with your SAFC, on the other hand that 190 walbro wont cut it for those injectors depending on where you have boost set at, and what kind of rpm's you intend to run, do you have an Dec 18, 2014 · . This will be done by adjusting both carbs up or down the same amount and re checking for synchronization. Lean condition fixes itself almost immediately upon accelerating the car, almost certain it is a vacuum leak. they pulled some data that points to the 02 sensor and are going to change that. If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet. 92tsifwd. 034 primary idle feed restrictor . Local mechanic shops are charging me $100 just for a smoke test, so I am just gonna save me some cash and go with the cigar route. 0 intake, F-cam, Siemens 80s, HP hotside, custom coldside, Moates QH T4M2 custom tune by me, 91 octane 560WHP 602WTQ Feb 2, 2024 · Vacuum leaks make the engine run lean, contributing to idling problems. Apr 27, 2021 · I want to mention, that the last time I ran the tune process on this truck, I had the idle at 700 rpm, and thorough out the full tune it was running very lean at idle. Several signs might point to idling issues in a Kawasaki Mule, such as: Engine idling at unusually high or low speeds. Continue until the engine has warmed-up. at wot tune for little lower than 12, 12. 5-14. Jun 26, 2024 · What Is Worse Running Rich or Lean? Neither is ideal, but in the long run, running lean is generally worse because it can do more damage. Apr 17, 2012 · Car ran better while it was still learning, once it learned idle was crappy again. AFRs going super lean at 20+ and boost vacuum is only hitting -6psi ish. 2%. 070 idle air bleed primary . It acts as if there is a massive vacuum leak, blocking off incoming air smooth out the rough idle and revs the motor up. Everyone wants their engine to run as efficiently as possible. Thus, causing the engine to run lean. Lastly, the two ground wires from the Z32 maf is soldered into one wire and grounded to chasis. he was behind me when i drove in to the dealer and noticed the black smoke. An engine that uses a stoichiometric mixture will produce less power when fed a lean mixture compared to its figure when it was running a stoichiometric or rich mixture. Oct 8, 2011 · my lean idle is the result running a lex afm with the adjustment screw all the way out. Feb 24, 2017 · Because your engine is running on less fuel than it should, it is running “lean. However 9 times out of 10 when idling the wb is showing around 16. My car has catless headers, ported gt350 intake manifold with IMRC lockouts, gt350 TB, and 47 lb injectors. I bought the car a year and a half ago and didn't know if the fuel filter had ever been changed. The idle drops for a few secs after I come to a stop. You may notice vibrations in the car and a distinct change in the idle sound. Jan 24, 2011 · Car running lean and Wont idle. Jan 10, 2014 · This will seem very counterintuitive, but excessively high idle fuel pressure will result in a lean run condition. T, then it could be lean, and needs a bigger main jet. I have replaced plugs,wires,fuel filter,and one o2 sensor which was showing a code. Jun 18, 2019 · To continue our series of carb tuning escapades, we thought it time to reveal a few tuning secrets for the Edelbrock line of carburetors. Mar 16, 2023 · The oxygen sensor may fail because of excessive temperatures and other factors. Most engines fall into the spectrum of 13. Leaving a petcock vacuum line off can create a lean condition on 1 cylinder but normal on the rest. The idle screw works as it should. It acts like it's not quite getting enough fuel, but then it finds the lost fuel and gets a surge of power. then 2 turns out. RUNNING LEAN Mar 17, 2010 · At idle you have just enough airflow to keep the car running and that is why it is running lean. Aug 21, 2018 · Idle issues and running lean at idle I'll go ahead and say I'm new to tuning. It can also be a faulty sensor like a bad O2 sensor or MAF sensor sending the wrong information to the ECU. Most high impedance injectors lose flow at idle pulsewidths when they are run at 4+ bar pressure. When this happens, it sends incorrect information to the engine computer. No change just wanted to try to see if the maf was bad. A vacuum leak can lean out the engine’s air-fuel mixture to the point that proper combustion can no longer take place. This occurs when more air than fuel is in the combustion chamber, causing the engine to run hotter and potentially leading to engine damage if not Engine running lean has more to do than using gas efficiently. 0 TFSI) has been running rough at idle and lean under any throttle with a small number of random misfires every drive I've replaced the spark plugs, ignition coils and fuel pump & filter (and tested for vacuum leaks) but had no effect on the misfires Jul 9, 2012 · idle stop switch has been set, still idle surge and super lean ive also driven it and it runs great when in gear but not when idling. The idle mixture screws do make a noticeable difference when adjusting them. 040 secondary idle feed restrictor Proform 650 vacuum secondary. lucysfnyynyrhmpiedpsgshucumrcjgcbtunqwubnbqcenhg