Problems w/ Backfiring & blinking CEL
05-18-2003, 11:27 AM
#1
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Problems w/ Backfiring & blinking CEL
I just past 30k on my car and ever since I started to modd it alot It would back fired. Though recently that's all it does! yeah people think it sounds great but when I say back fire this thing pop so loud it kinda scares me when it happens.(yea that loud) the check engine light use to blink when I mash the throttle. Yes, I do have a Utec so I figured it was knocking so I hooked the laptop to the car and it was KNOCK FREE. Now ill just be accelerating normally and the CEL will blink. The car has also gotten sluggish. IM thinking its the spark plugs all fouled out anyone disagree? any help is needed.
The car was dyno tuned and was running GREAT. Though it has been popping a lot lately and the CEL has been blinking left and right. I forgot to mention so far twice the brake light has came on while I was mashing the throttle. I don't see why it would, it also started to come on when I pressed the brakes real hard (without using E-brake) which never made it come on in the past. The car has been acting real strange lately and I don't no what's up. Tonight on my way home I MIGHT have the answer for why its bugging out. I'M thinking the BOV, maybe it become to loose and causing her run richer then it should. Another reason why I think its the bov is b. c last week the bov was spitting a black oily residue on my I. c pipes which never happened b4. I know it sounds like the car is falling apart on me = [ but hopefully I can get her running A++ with some advice from you guys
Well, just adjusted with my bov to see if that's the reason why she's running bad and nothing changed. I also replace my fuel filter and nothing. I took the I C pipe that connects the throttle body and there was a coating of oil all inside the pipe. now my old greddy fmic had that too but as much as I have now. The CEL keeps blinking when IM just driving normally. Any adivce would be great thanks.
can anyone help me with some input on the problem?
-melo
The car was dyno tuned and was running GREAT. Though it has been popping a lot lately and the CEL has been blinking left and right. I forgot to mention so far twice the brake light has came on while I was mashing the throttle. I don't see why it would, it also started to come on when I pressed the brakes real hard (without using E-brake) which never made it come on in the past. The car has been acting real strange lately and I don't no what's up. Tonight on my way home I MIGHT have the answer for why its bugging out. I'M thinking the BOV, maybe it become to loose and causing her run richer then it should. Another reason why I think its the bov is b. c last week the bov was spitting a black oily residue on my I. c pipes which never happened b4. I know it sounds like the car is falling apart on me = [ but hopefully I can get her running A++ with some advice from you guys
Well, just adjusted with my bov to see if that's the reason why she's running bad and nothing changed. I also replace my fuel filter and nothing. I took the I C pipe that connects the throttle body and there was a coating of oil all inside the pipe. now my old greddy fmic had that too but as much as I have now. The CEL keeps blinking when IM just driving normally. Any adivce would be great thanks.
can anyone help me with some input on the problem?
-melo
05-18-2003, 11:37 AM
#2
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did you change anything on the car since your last session on the dyno? i'm not talking about things like bodywork or wheels, but any changes under the hood. if you have, i'd set up another appointment on the dyno to get things remapped.
before you hit the dyno, there are a couple of things you might try. pull the spark plugs and check those. the ceramic tops should be a nice mocha/latte color. if they're black and crusty with oily looking junk, then you're running way too rich. also look to make sure that the plugs aren't loosing material from metal points where the spark arcs from, it's usually a sign of detonation.
i think you're also on the right track looking into problems with the BOV. getting hard onto the brakes after being hard on the throttle is when the BOV is working the hardest, and if you're backfiring then it means that the BOV is dumping too much fuel into the motor causing a rich condition. you're probably running catless too aren't you?
before you hit the dyno, there are a couple of things you might try. pull the spark plugs and check those. the ceramic tops should be a nice mocha/latte color. if they're black and crusty with oily looking junk, then you're running way too rich. also look to make sure that the plugs aren't loosing material from metal points where the spark arcs from, it's usually a sign of detonation.
i think you're also on the right track looking into problems with the BOV. getting hard onto the brakes after being hard on the throttle is when the BOV is working the hardest, and if you're backfiring then it means that the BOV is dumping too much fuel into the motor causing a rich condition. you're probably running catless too aren't you?
05-18-2003, 11:45 AM
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i don't think that plugs would make it run the way that you described, they're just a symptom of the problem.
you could also try replacing the BOV with the stocker, which would probably solve the problem of backfires under hard braking, but wouldn't help with the problem under hard throttle.
i don't suppose that the UTEC has a datalogging function, does it?
you could also try replacing the BOV with the stocker, which would probably solve the problem of backfires under hard braking, but wouldn't help with the problem under hard throttle.
i don't suppose that the UTEC has a datalogging function, does it?
05-18-2003, 12:06 PM
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will your laptop let you do more than check for detonation? if it'll let you look at fuel curves/maps you might be able to figure out where it's running so rich. that said, if you aren't comfortable with that, take it to a professional tuner. it's too easy to make a real mess of things unless you know what you're doing with air/fuel mixtures.
as for why the car started doing this all of a sudden, i couldn't tell you. things don't usually break on their own, there is something that causes it. has the weather recently gotten really warm where you live? hot air contains less O2 per cubic foot, which could make you run rich if the UTEC was tuned to the ragged edge for maximum possible power under the conditions of the dyno run. it seems kinda unlikely to me that something like that would cause it, so i'd look hard at the car, and the underhood mods to see if i could find the problem.
as for why the car started doing this all of a sudden, i couldn't tell you. things don't usually break on their own, there is something that causes it. has the weather recently gotten really warm where you live? hot air contains less O2 per cubic foot, which could make you run rich if the UTEC was tuned to the ragged edge for maximum possible power under the conditions of the dyno run. it seems kinda unlikely to me that something like that would cause it, so i'd look hard at the car, and the underhood mods to see if i could find the problem.
05-18-2003, 12:15 PM
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what i'm getting at is that if the tuners made your air/fuel curve work really well on the dyno, then something changed so that it wasn't working so well. i can't imagine that a tuner would give a street given car a map so sensative that it would have problems with climate changes.
does the UTEC allow you to store multiple air/fuel/ignition maps? if that's the case, how are they switched? is it possible that the UTEC might have been switched to another map? i know that some of the other aftermarket ECUs have this capability.
does the UTEC allow you to store multiple air/fuel/ignition maps? if that's the case, how are they switched? is it possible that the UTEC might have been switched to another map? i know that some of the other aftermarket ECUs have this capability.
05-18-2003, 02:11 PM
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cold air wouldn't cause this, cold air contains more oxygen per cubic foot than warm air.
the reason the engine looses power when the CEL comes on (at least this is my understanding) is that the ECU retards the timing by a few degrees to prevent detonation. less aggressive timing means less power when you're hard on the gas.
you might try hooking up the laptop to the UTEC and going for a drive with a buddy holding the laptop in the passenger seat. when the CEL comes on, see what shows up in the data logger.
the reason the engine looses power when the CEL comes on (at least this is my understanding) is that the ECU retards the timing by a few degrees to prevent detonation. less aggressive timing means less power when you're hard on the gas.
you might try hooking up the laptop to the UTEC and going for a drive with a buddy holding the laptop in the passenger seat. when the CEL comes on, see what shows up in the data logger.
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