need help from the pros who know there cars!
05-17-2010, 07:54 PM
#1
Staging Lane
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need help from the pros who know there cars! So I've got a great stumper for you guys. First Id like to say I am a proud owner of a 02 ws6 lightly modified exhaust,lid,cutout with 38k miles. Ok let's begin, I get incredibly **** gas mileage let's say 42miles to a quarter of a tank shifting at 2k rpms with my m6 
also I notice a slight missfire popping. So, I decided to change my plugs went with the ngk tr55s gapped them at .050. guess what still **** gas mileage and missfire popping. Now let me remind you that before I did the plug swap I hooked up to a slp tuner which read I was getting consistant random cylinder missfires 1-5-3-8-2-1 etc. Then decided to hook up to a hp tuner and it read nothing at all. Now with that all being said my car never threw any codes on the dash at any given time. I would like to believe my 02 sensor is bad because if so it wouldnt read a bad plug=no code and there goes my gas mileage, but if that was the case a code would throw for the bad 02 sensor..... Anyways I decided to buy lucas fuel injector cleaning $5 ehh why not. Also jumped under the car took a peek at the fuel filter and it looks to be in good shape.
also I notice a slight missfire popping. So, I decided to change my plugs went with the ngk tr55s gapped them at .050. guess what still **** gas mileage and missfire popping. Now let me remind you that before I did the plug swap I hooked up to a slp tuner which read I was getting consistant random cylinder missfires 1-5-3-8-2-1 etc. Then decided to hook up to a hp tuner and it read nothing at all. Now with that all being said my car never threw any codes on the dash at any given time. I would like to believe my 02 sensor is bad because if so it wouldnt read a bad plug=no code and there goes my gas mileage, but if that was the case a code would throw for the bad 02 sensor..... Anyways I decided to buy lucas fuel injector cleaning $5 ehh why not. Also jumped under the car took a peek at the fuel filter and it looks to be in good shape. 
05-17-2010, 10:59 PM
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I am not familar with the "SLP tuner", or how it reports misfires. On my scanner, I can observe random misfire counts or cylinder specific misfires. Are you saying that it showed cylinder specific misfires on several cylinders? If so, how many per read cycle per cylinder? 1 or 2 misfire reports per cycle is normal, once in a while (shouldn't happen often on a stock motor though).
Here are some questions/thoughts that I have:
- Have you used a scanner to check for any stored DTCs (codes)? If so, please list.
- What do you know about the previous owner? Is it possibile that the car has received custom tuning at some point? (I ask because, certain codes may have been turned off)
- You mentioned exhaust as a mod, how much exhaust work do you have? (meaning, do you have headers as well, or just a simple catback?)
- Does the car have a K&N filter? If so, have you inspected the MAF for filter-oil build up?
- You mentioned that you can hear a popping through the exhaust.... when do you hear it (idle, accel, decel, WOT, high rpms, low rpms, etc)?
Here are some questions/thoughts that I have:
- Have you used a scanner to check for any stored DTCs (codes)? If so, please list.
- What do you know about the previous owner? Is it possibile that the car has received custom tuning at some point? (I ask because, certain codes may have been turned off)
- You mentioned exhaust as a mod, how much exhaust work do you have? (meaning, do you have headers as well, or just a simple catback?)
- Does the car have a K&N filter? If so, have you inspected the MAF for filter-oil build up?
- You mentioned that you can hear a popping through the exhaust.... when do you hear it (idle, accel, decel, WOT, high rpms, low rpms, etc)?
05-18-2010, 05:19 PM
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I am not familar with the "SLP tuner", or how it reports misfires. On my scanner, I can observe random misfire counts or cylinder specific misfires. Are you saying that it showed cylinder specific misfires on several cylinders? If so, how many per read cycle per cylinder? 1 or 2 misfire reports per cycle is normal, once in a while (shouldn't happen often on a stock motor though).
Here are some questions/thoughts that I have:
- Have you used a scanner to check for any stored DTCs (codes)? If so, please list.
- What do you know about the previous owner? Is it possibile that the car has received custom tuning at some point? (I ask because, certain codes may have been turned off)
- You mentioned exhaust as a mod, how much exhaust work do you have? (meaning, do you have headers as well, or just a simple catback?)
- Does the car have a K&N filter? If so, have you inspected the MAF for filter-oil build up?
- You mentioned that you can hear a popping through the exhaust.... when do you hear it (idle, accel, decel, WOT, high rpms, low rpms, etc)?
Here are some questions/thoughts that I have:
- Have you used a scanner to check for any stored DTCs (codes)? If so, please list.
- What do you know about the previous owner? Is it possibile that the car has received custom tuning at some point? (I ask because, certain codes may have been turned off)
- You mentioned exhaust as a mod, how much exhaust work do you have? (meaning, do you have headers as well, or just a simple catback?)
- Does the car have a K&N filter? If so, have you inspected the MAF for filter-oil build up?
- You mentioned that you can hear a popping through the exhaust.... when do you hear it (idle, accel, decel, WOT, high rpms, low rpms, etc)?
The previous owner was a old gentlemen as far as I'm told. The car was bone stock when purchased although there is always a change it was modded then demodded for sale purprose and was once tuned when modded. How could I figure this out? As far as exhaust goes just a slp y, slpcatback and a qtp cutout. Yes ive got a K&N filter and I cleaned the maf about a month ago. Ive got a Mti clear lid and as far as I can still see the maf looks spotless. The popping you can actually hear at just an idle, its a very slight slight pop though but a trained ear can notice it, I also notice that the car seems to get little surges when the car door is open you can easily see from time to time it will move awkardly during these ''surges'' also when I give a lil petal to the metal then let off it then pops here and there ever so slightly.
Above all though I've always noticed it to have a bad gas mileage problem ever since I left the car lot in it. Yes i understand these get low gas mileage to begin with but 42miles per quarter tank with no racing involved is beyond me.
p.s there was no DTC's stored. was empty.
Last edited by torqls1; 05-18-2010 at 05:29 PM.
05-18-2010, 07:17 PM
#5
I am not certain but I know for a fact my car was getting bad back fires, and shitty gas mileage, but I ran my codes and it said dirty fuel filter, 10 min of work, 10 filter from autozone allll better, and majority of the backfires went away and mileage is wayyyy better!
Worth a shot, and cheap
Worth a shot, and cheap
05-18-2010, 11:03 PM
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Staging Lane
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I am not certain but I know for a fact my car was getting bad back fires, and shitty gas mileage, but I ran my codes and it said dirty fuel filter, 10 min of work, 10 filter from autozone allll better, and majority of the backfires went away and mileage is wayyyy better!
Worth a shot, and cheap
Worth a shot, and cheap
05-19-2010, 01:12 PM
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I would change it to to be able to rule it out as a possible problem. That and check to see if your MAF sensor is black and clean it as mentioned above. Those two things will KILL your gas mileage and have your car running like crap. GL
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05-19-2010, 07:11 PM
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Staging Lane
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what do u guys clean ur maf with alcohol and a cotton swap?
05-19-2010, 08:45 PM
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I actually swapped out my fuel filter yesterday. Today I cut open the fuel filter just to see how bad it was. Here's a pic of mine.
As you can see it's pretty dirty. Cleared up a hesitation I had around 1800 to 3000 rpms and I believe my gas mileage has improved. I've only put around 20 miles on it since I swapped it, but it feels better all around. Maybe it's because that's what I was hoping would happen, but I can't deny the hesitation is gone.
Before I swapped my fuel filter, I cleaned my MAF with a can of MAF cleaner spray from AutoZone. Sixteen bucks total for fuel filter and MAF cleaner and it's running a heck of a lot better. Now I just need to do plugs and wires and run some fuel system cleaner just to be sure.
As you can see it's pretty dirty. Cleared up a hesitation I had around 1800 to 3000 rpms and I believe my gas mileage has improved. I've only put around 20 miles on it since I swapped it, but it feels better all around. Maybe it's because that's what I was hoping would happen, but I can't deny the hesitation is gone.
Before I swapped my fuel filter, I cleaned my MAF with a can of MAF cleaner spray from AutoZone. Sixteen bucks total for fuel filter and MAF cleaner and it's running a heck of a lot better. Now I just need to do plugs and wires and run some fuel system cleaner just to be sure.
05-19-2010, 11:11 PM
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That's what I do. I feel it gets it cleaner than the sprays do alone, especially if there's a bunch of gunk built up from over-oiled K&N-type filters.
You mentioned some misfires showing up on the scanner; this could be the result of poor fueling OR spark. I know you mentioned that the plugs were new, are you sure the wires are good? There could also be an injector issue. I'd get the fuel filter changed out, just because it's a good idea and super simple. You mentioned runing a bottle of Lucas through the system.... I've never used that one, I like Red Line SI-1 the best, I've had great results with it. At 38k miles I doubt the injectors need to be rebuilt or replaced, but they may need a good cleaning if deposits have formed on the tips.
You mentioned some misfires showing up on the scanner; this could be the result of poor fueling OR spark. I know you mentioned that the plugs were new, are you sure the wires are good? There could also be an injector issue. I'd get the fuel filter changed out, just because it's a good idea and super simple. You mentioned runing a bottle of Lucas through the system.... I've never used that one, I like Red Line SI-1 the best, I've had great results with it. At 38k miles I doubt the injectors need to be rebuilt or replaced, but they may need a good cleaning if deposits have formed on the tips.
05-20-2010, 08:13 AM
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That's what I do. I feel it gets it cleaner than the sprays do alone, especially if there's a bunch of gunk built up from over-oiled K&N-type filters.
You mentioned some misfires showing up on the scanner; this could be the result of poor fueling OR spark. I know you mentioned that the plugs were new, are you sure the wires are good? There could also be an injector issue. I'd get the fuel filter changed out, just because it's a good idea and super simple. You mentioned runing a bottle of Lucas through the system.... I've never used that one, I like Red Line SI-1 the best, I've had great results with it. At 38k miles I doubt the injectors need to be rebuilt or replaced, but they may need a good cleaning if deposits have formed on the tips.
You mentioned some misfires showing up on the scanner; this could be the result of poor fueling OR spark. I know you mentioned that the plugs were new, are you sure the wires are good? There could also be an injector issue. I'd get the fuel filter changed out, just because it's a good idea and super simple. You mentioned runing a bottle of Lucas through the system.... I've never used that one, I like Red Line SI-1 the best, I've had great results with it. At 38k miles I doubt the injectors need to be rebuilt or replaced, but they may need a good cleaning if deposits have formed on the tips.
05-20-2010, 11:18 AM
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Also, if the Lucas stuff didn't work for you, give the Red Line stuff a try just for the hell of it. I've cleared up several fuel issues using that product (long cranking, rough idles, minor knock, etc.).
You are obviously getting both fuel and spark because the engine runs and drives, it's just that one of those elements is less than ideal. Again, are you sure the plug wires are good? What wires are you using?
05-20-2010, 03:13 PM
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This is off topic but I just wanted to say thank you to all on here. I heard on another forum we won't mention that everyone on here were a bunch of ******. That just isn't the case. Thank you all again for taking the time to respond to us. I myself have asked a lot of dumb questions on here and 99% of the time, I get a quick and knowledgable response. Now for another one. My car has this same problem kind of. I only get about 200 miles out of a full tank of gas. That's driving it normal. It is cammed with 3.73 gears, lid, UD pulley, ported polished maf ends, descreened(I know, stupid. Didn't know at the time.) LS6 intake, AC Delco iridium plugs, MSD wires and I think thats it. It is an A4 though it will be M6 in about a month. My car studders really bad at idle. Its like a misfire. But I can't figure it out. No codes. Even checked for soft codes but there are none. Cleaned the MAF to sparkling new condition. No change. Fuel filter changed about 10k miles ago.Should I go ahead and change it again? Air filter is a Fram air hog. Clean. Really don't know what the problem could be. It is tuned but it was doing this before the cam and tune. Thanks again everyone! Especially RPM WS6. You always answer!
05-20-2010, 05:42 PM
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My car has this same problem kind of. I only get about 200 miles out of a full tank of gas. That's driving it normal. It is cammed with 3.73 gears, lid, UD pulley, ported polished maf ends, descreened(I know, stupid. Didn't know at the time.) LS6 intake, AC Delco iridium plugs, MSD wires and I think thats it. It is an A4 though
My car studders really bad at idle. Its like a misfire. But I can't figure it out. No codes. Even checked for soft codes but there are none. Cleaned the MAF to sparkling new condition. No change. Fuel filter changed about 10k miles ago.Should I go ahead and change it again? Air filter is a Fram air hog. Clean. Really don't know what the problem could be. It is tuned but it was doing this before the cam and tune.
Looks like you've covered some of the basic tune-up stuff, but what about plugs and wires? Also, how many miles on your injectors? And have you checked fuel pressure? And does the car still have EGR? If you can toss a vacuum gage on there, those readings might give some indications as well.
05-20-2010, 06:32 PM
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Hey RPM, kind of off topic, but I stopped at autozone today to pick up a tail light and decided to try and grab some of the Red Line cleaner you talk about and they didn't have it 
would you happen to remember where you picked it up at?
would you happen to remember where you picked it up at?
05-20-2010, 06:43 PM
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It really is a good product, I've seen great results in several cases.
05-20-2010, 09:05 PM
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That mileage actually isn't too bad considering the mods and trans type. I'm guessing when you say 200 miles/tank you don't actually mean a full 15-16 gallons (most people don't run the tank dry every time).
Yep. About 12 gallons at fill-up. My gauge indicates it's empty at that point. Hate to push it you know!
But this part is definitely a problem. Is the studdering/misfire only happening when the engine is sitting there idling, or do you feel some sort of hesitation when accelerating from a stop in gear? And if you just leave it in neutral and hold the rpms higher than idle will it smooth out? And how well does the engine fire up (both hot and cold)?
Its basically at idle. If you sit at the back of the car and listen to the exhaust, you can hear what sounds like air pushing out the back. Not exhaust air either. Like just a fan blowing. Its cold. Hard to explain. And when it does this, the whole car shakes. Like it doesn't fire everytime. But its not rhythmic. Its very erratic. Idle is steady. If you raise rpms in neutral it smooths out some. But you can still occasionally feel it not fire. Starting is not a problem hot or cold as long as you hold it long enough to get it to fire the first time. Usually about 2 to 3 seconds. If it doesn't crank on first try and you try immediately to start it back its like it won't idle right and it tries to die.
Looks like you've covered some of the basic tune-up stuff, but what about plugs and wires? Also, how many miles on your injectors? And have you checked fuel pressure? And does the car still have EGR? If you can toss a vacuum gage on there, those readings might give some indications as well.
Plugs are AC Delco iridium plugs about 8k miles ago. MSD wires about 2k miles ago. No EGR. I assume the injectors are factory so that would mean they have about 105k on them. Vacuum gauge indicates no vacuum leaks or timing off. I don't remember the numbers but I remember it says on the gauge like timing retarded or vacuum leak or normal. It indicated normal.
Yep. About 12 gallons at fill-up. My gauge indicates it's empty at that point. Hate to push it you know!
But this part is definitely a problem. Is the studdering/misfire only happening when the engine is sitting there idling, or do you feel some sort of hesitation when accelerating from a stop in gear? And if you just leave it in neutral and hold the rpms higher than idle will it smooth out? And how well does the engine fire up (both hot and cold)?
Its basically at idle. If you sit at the back of the car and listen to the exhaust, you can hear what sounds like air pushing out the back. Not exhaust air either. Like just a fan blowing. Its cold. Hard to explain. And when it does this, the whole car shakes. Like it doesn't fire everytime. But its not rhythmic. Its very erratic. Idle is steady. If you raise rpms in neutral it smooths out some. But you can still occasionally feel it not fire. Starting is not a problem hot or cold as long as you hold it long enough to get it to fire the first time. Usually about 2 to 3 seconds. If it doesn't crank on first try and you try immediately to start it back its like it won't idle right and it tries to die.
Looks like you've covered some of the basic tune-up stuff, but what about plugs and wires? Also, how many miles on your injectors? And have you checked fuel pressure? And does the car still have EGR? If you can toss a vacuum gage on there, those readings might give some indications as well.
Plugs are AC Delco iridium plugs about 8k miles ago. MSD wires about 2k miles ago. No EGR. I assume the injectors are factory so that would mean they have about 105k on them. Vacuum gauge indicates no vacuum leaks or timing off. I don't remember the numbers but I remember it says on the gauge like timing retarded or vacuum leak or normal. It indicated normal.
05-20-2010, 10:39 PM
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Well, if you're getting 200 miles per 12 gallons, that's over 16mpg. I'd call that pretty good mileage for a cammed A4 with 3.73s. So whatever your issue is, it's not effecting fueling or spark much beyond idle.
One simple thing to check....you mentioned MSD wires. Did you put the factory metal heat shields from the stock wires onto the MSD boots when you changed them? If so, you should take those off. The MSD boots were not designed to work with the metal shields, and many people that have tried to use them have reported arcing issues. So if you're using those shields, remove them.
Since the injectors have 105k, they may just need a good cleaning. Looks like you've covered all the other basic tune-up areas and checks. Only other thing you could look at is fuel pressure, but in my experiance when the pump starts to go bad, cold starts are usually the first thing to deteriorate. Also, you'll hear more noise from the pump than usual when it gets hot.
You mentioned having a tune. Any chance that your tuner shut off some codes that shouldn't have been? This might explain why you're not getting a DTC for whatever is wrong. This is a slim possibility, but might be more likely if your tuner was inexperianced.
One more thing.... do you have access to a scanner that will show cylinder specific misfires? This would be helpful to watch when the conditiond is occuring, maybe you can isolate it to one cylinder.
One simple thing to check....you mentioned MSD wires. Did you put the factory metal heat shields from the stock wires onto the MSD boots when you changed them? If so, you should take those off. The MSD boots were not designed to work with the metal shields, and many people that have tried to use them have reported arcing issues. So if you're using those shields, remove them.
Since the injectors have 105k, they may just need a good cleaning. Looks like you've covered all the other basic tune-up areas and checks. Only other thing you could look at is fuel pressure, but in my experiance when the pump starts to go bad, cold starts are usually the first thing to deteriorate. Also, you'll hear more noise from the pump than usual when it gets hot.
You mentioned having a tune. Any chance that your tuner shut off some codes that shouldn't have been? This might explain why you're not getting a DTC for whatever is wrong. This is a slim possibility, but might be more likely if your tuner was inexperianced.
One more thing.... do you have access to a scanner that will show cylinder specific misfires? This would be helpful to watch when the conditiond is occuring, maybe you can isolate it to one cylinder.
Last edited by RPM WS6; 05-20-2010 at 10:48 PM.