car revs go up and down on

hi my bmw e46 compact when stoped at traffic lights i noticed rev counter engine revs going up on theyer own to about 1 to 2ooo revs they drop back down would this be anything with the coils i replaced about two mounths ago or anything else you may know of.

Get hold of an OBDII scanner and tell us if there are codes.

ok ill try and see if i can get any codes ive read some posts would it be cleaning the idle control vaulve how do you clean this where is it

Originally Posted by darran

hi my bmw e46 compact when stoped at traffic lights i noticed rev counter engine revs going up on theyer own to about 1 to 2ooo revs they drop back down would this be anything with the coils i replaced about two mounths ago or anything else you may know of.

any misfiring?

Originally Posted by TrickTizzle

any misfiring?

no missfire can drives well just when its idle it goes up to 1500rpm then back down but performance feels normal just put full tank fuel in and some injection cleaner any advice

Originally Posted by darran

no missfire can drives well just when its idle it goes up to 1500rpm then back down but performance feels normal just put full tank fuel in and some injection cleaner any advice

Fuel filter was changed when? What are your miles? How about the air filter? Any maintenance done?

Originally Posted by Lanc3r

Fuel filter was changed when? What are your miles? How about the air filter? Any maintenance done?

air filter changed last year and fuel filter two years ago spark plugs oil change three months ago and new coils two months ago

driveing car home today engine light come on says in book exhaust emissions values have deteriorated car still drives well but idle revs up to 1500 and back down what do you think

fuel injector cleaner...go get sta-bil from your auto place...they'l try to sell you "sea-foam" dont buy that. buy sta-bil.

i placed fuel injector cleaner in last night did 100 miles today in it now light has come on took air box out checked filter no air leaks or cracked pipes i can see i did replace coils and plugs two months ago is it worth changing plugs and coils around i have two spare coils to change them also i can get it onto machine by next week ive read about icv but i dont know if it has one or is there anything else i can check

Use periods please...

hi soildjake what does use periods mean sorry

my car does the same thing when i park (back in) it rev up and down, i scanned it with Inpa Ediabas ( best investment) and nothing, it only happens when i reverse. maybe its not maybe its something..

Originally Posted by darran

hi soildjake what does use periods mean sorry

As in when you are done with a sentence put a period then make another sentence.

This is a period .

ok thanks .i got that.

Thanks

- Check for vacuum leak around the intake
- CPS ( cam position sensors )
- DISA valve leaking
- MAF ( mass air flow sensor)

can i check these without being pluged into diagnostic machine,any photos on how to check these things thanks

Originally Posted by darran

can i check these without being pluged into diagnostic machine,any photos on how to check these things thanks

You need to buddy up with a friend who knows a bit about car to work with.

ok thanks .ill have a code tomorrow ,putting diagnostic on it ,let you know tomorrow

Ah !! i had the same problem !!! and the fix was as simple as the fuel i was using !!! i was putting in 89 octane and sitting at a stop light the car was revving up and down and on occasion it would stall out on me !!
called the dealer and as soon as i told him what was going on he knew right away what the problem was !! he told me to always run ATLEAST 91 octane ! so ever since i run sunoco 94 in my 330ci and it never did it again !!

Change the Vanos seals yet? Fluctuating rpm is a symptom. Thought I'd throw it in cuz no one else has yet. Good Luck

it runs on 95 octaine.i havent done vanos seal yeat going to have it scaned today, hope to find out what it is today, keep you posted later

just scanned car ,code p1153 came up,and oxygen sensor3 bank1 ,whereis this allocated ,can it be cleaned, or is it a new part,also what is code p1153 thanks

i just found p1153 code,o2 sensor heather circuit high voltage bank2 sensor1, plus oxygen sensor3 bank1 showed on diagnostic,the guy whom diagnostic my car,cleared the codes,then done a search again but engine light did not come on ,so ive driven 50 miles so far,and light still havent come on,so i cant check it one more time,to check it 100% sure,what code it is but so far i think its pointing to,oxygen sensor now have to find out for sure,and which one it is,also is this just wear or is this because ive replaced coils and plugs 2 months ago??????