I've searched a bit for this kind of thing but my situation seems a bit unique.
Whenever I get in the car and start it, middle of winter or middle of summer, the rpms start bouncing and bouncing all over the place from 500 - 2000 then when I give it gas a few seconds later it will stop. Occasionally it will just die. It almost seems like misfires. I was thinking it could be plugs but it drives fine after the first 2 seconds I start the car.. My SES light is also on.. But I think that's due to me removing my MAF sensor for my CAI
The SES light tells you the ECU has detected a problem with your car.
Let it tell you what is wrong!!!
Get the stored codes read to start your troubleshooting.
Most Auto Parts stores will read the codes for you.
Have you checked sparks plugs or coils? I had the same problem, replaced all spark plugs and coils and problem was fixed.
Could also be an intake leak from cracks in the boots
I think the CAI was messing with the MAF because when I had the sensor installed the car would stall when I turn it on. It wouldn't last more then a few seconds before dying. So I had to unplug it
That my friend means your maf needs a changing. Remember not to buy anything but an oem one. You'll regret it if you ignore my caution. Thats only but the start of your problem now.
And dont rule out your plugs. If you recently had to deal with a valve cover gasket leaking, or have a leaking gasket,oil has fouled the plugs causing misfires
I'm also getting 16.8 average mpg. And I barley ever push my car.
I shift around 3k always. And I always use premium. I should be getting way better gas mileage.
Id also reset that mpg on the obc to get more of a current live reading to make sure if I was you. Mpgs could be a lot of reasons, the plugs being one of them. Check air filter,tire pressure, if you got over 100k on it then the o2s should be in the planning stage to eventually get it swapped out if you are keeping the car. My car gets 19-22 with mixed highway city, 14 with only city, and 25-26 with all highway. This was all done after running through a full tank under those conditions
Ill do the plugs for sure. Any recommendation on which brand/where to buy? I've got 135k on the dash. O2 sensors i wanna do in the future. I have a weird kinda strange bad smell coming from under the car after driving hard. So I assume my o2 sensors are part of this problem. O2 sensors and plugs ill do. MAF I have to wait on considering its expensive
since the public eye is on me I must robotically tell you "oem all the way. Yay" with enthusiasm. I've read what others have used and my conclusion is what people have done makes sense. The cheaper plugs you buy,the sooner you have to change them. A guy even installed cheap $1 plugs but did admit he swapped them out after every oil change. Its up to you.
What kind of weird smell? Plus with o2s, don't buy genuine bmw. That could mean at least over $150 each. Get the Bosch ones by searching for the o2s not by your car but by the Bosch manufacturer part number. I forgot what they were but they work as good as dealership. Good part is they should only cost right around$50 each. If tight budget, at least get pre cat o2s done first.
Be careful of sellers like on ebay who wilk sell cheap counterfeit o2s. My first time I got from ebay I noticed they didn't even come with any original bosch packaging, Missing anti seize on threads, heat insulation around wire didnt cover all of it. I called them up and called them out on this. Got my money back and bought from another seller on ebay. I made sure he sent me it with original packaging or else I guaranteed hes going to hear from me and insured I'd get a refund and make him pay return shipping.
I bought mine online. Oem ones originally for our cars was the ngk platinum quadruple spark nodes thingy. Forgot its technical name but google that. Its easy to spot them since they have 4 spark tips. Ive also bought the current oem ones they now use on bmws which are ngk ones as well but only have 1 spark tip thing. Couldn't tell the difference. People say the single tip could last around 100k miles before changing
Just got the codes read. 02 sensors! I also bought a set of NGK laser platinum plugs which ill do tomorrow. Turns out my dads Saab had been misfiring cyl 1 + 2 due to bad plugs for the last year and a half. Hahahaha he's been running on 2 cylinders and had no idea
Your Dad is an artist. No problem with that, but he's not a mechanic. First get a code reader, such as PASoft, it will help you figure out exactly what's wrong. Second, get rid of the CAI, it's not helping. Go back to stock. BMW produced a performance car, no need for performance add-ons. If you want more hp, do an engine swap for an S54 or a Chevy LSx.
Don't replace the O2 sensors just because you get an O2 sensor code. If you clear the code, and it keeps coming back imediatly, then you can replace them. I had an issue that threw O2 codes, but it turned out to be something else.
The fact that I'm getting such poor gas mileage and having the code kinda makes me skeptical. I think I'm gonna do plugs first tomorrow then see if the SES goes away. Ill put the stock air filter back on and see what happens
Surprisingly MAF wasn't a code I was getting even though its completely removed. I just got o2 sensors and some a/c circuit board thing. Plugs I'm doing just for fun. Haha
CAI dont always throw error. I made mine going off a DIY somewhere on this forum. piped tubing from maf all the way down by left fog light. no issues for a year now.
im really surprised you arent getting a light for maf. thats so odd. now if you dont have maf on, them how does your system run efficiently without knowing how much air is entering? I know that when maf is disabled, the dme runs off preset mappings, but that should severely impact mpgs and performance. the dme can no longer make adjustments to the car seeing as it is like being blind.
now Im also suspecting now that maybe its related to your o2s error. I always thought the pre cat o2s measure how well the engine is burning up its mixture, informing the dme so that it could make adjustments. if the o2s are working but try and report that the car isnt being efficient, all its doing is reporting to deaf ears.
when my maf started acting up, it didn't throw a maf code either. it told me my o2s were shot, but at that time I was having other issues as well butt yeah, I never got maf errors
I'll put my new plugs in tomorrow and replace the MAF to see what happens. I haven't noticed any change in performance or mileage with the MAF on or off. Except a super rough idle at start with the maf on
aside from the rough idle, see if that o2 error shows its ugly face. if not blame the maf. then with a new maf, perhaps you can see the benefits of the maf
You need to actually post the DTC/CEL codes you are reading along with any Freeze Frame data if the tool you are using supports Freeze Frame data, not some general mention of a sensor mentioned in the DTC. Just because a sensor is mentioned in the DTC does not mean the sensor is bad or faulty. More often than not the sensors are not actually the problem, buy even seasoned mechanics knee jerk and jump on a sensor replacement party.
As for your mileage issue and cold start issue, the very first thing you should do is confirm your engine coolant temperature is correct. You cannot do this with the dash temp gauge, you need use the Hidden OBC Menu and/or a scan tool that reads real time data.
Also suggest you read the 1st & 3rd links below in my signature.
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