annoying idle (really need some help)

[liquidtension]

it's been like this since i bought the m3,
sometimes the m3 is just idling fine at 800rpm
then all of a sudden the rpm will jump to 1400+rpm
then after a bit itll go back down... then just randomly go back up

i always suspected the TPS, even though it does click right before the throttle is fully closed..

other times, if i give it some gas, the idle will go up to 1400+... if i tap on the gas again ... sometimes it goes down to 1000, if i tap again itll randomly go back up.. sometimes it takes alot of tapping to get it back down while waiting in the traffic

tonight, the idle went up to 1500 or so, and i tapped the gas pedal a million times and it wouldnt go back down so i parked and wanted to see what was up... i disconnected the TPS connector and the idle didnt change at all (it usually sounds the exact same when disconnected)

so then i suspected a loose connection ... so i started pulling on the TPS connector and the idle would go back down ...id let it go .. then it would go back up ... anyways but it doesnt make sense.. cuz sometimes the m3 will go up to 1200rpm and not as high as today ...so i was thinking if it was a bad connection it should always go up to the same value right ? (as if the TPS was disconnected) which made me think "ICV" .. i put a screw driver on it with the ignition on .. and i could feel it working.. so i guess it is still good ...

what do you think this could be ? TPS misadjusted ? loose connection ? could the ECU be fried cuz of a bad ICV in the past which is causing this random problem ? (btw i drive it sometimes with no idle issue at all..)

im sort of confused about how to fix it ... maybe cuz it was at night .. im going to try and fix it tomorrow.. so i thought i could use some ideas thanks

[liquidtension]

sorry for the long post... :/

btw i tried to adjust the TPS ... but the damn screws are so tight ... i used a couple screw drivers but i couldnt get them loose... not even one of them... and everytime i try the screw is getting messed up ..ill try spraying some wd-40 tomorrow maybe itll do it some good any ideas ?

[hardtailer]

have you tried this?
http://www.e30m3performance.com/inst...ips/clips1.htm

I would do that before you start fiddling with the tps. I mean the screws are tight and idle is ok quite often, so what could the tps do wrong?
Do you have an OBC? In that case drive in any gear with engine rpm higher than 1500rpm and then coast. At the same time reset your avg fuel consumption on the OBC. If it then reads 0.00l/100km or --mpg, your TPS idle setting is ok. At approx. 1200-1500rpm fuel injection should cut in again to prevent the engine from stalling.

[d2a4]

I think I have the same issue. The P/O told me that he replaced the ICV (can't verified that) but I suspect he did not recalibrate the TPS. I tried to serach for the TPS calibrate procedure but no luck. I will need to watch this thread closely.
Ryan

[project86]

The spark plug wires have been known to cause missing which causes the engine to hunt which is maybe what is happening here.

[Jim]

You can alos tried loading th eelectrical when the idle is stuck high. Turn the fan on high and see if this evens out the idle. Then it's a good chance the transitors in the ECU need replacing.
Jim

[liquidtension]

yesterday i could have sworn when i turned the headlights on the idle was dropping like 30rpm or so ... i could hear it sound a bit different ... dunno if i was imaginating or something ... ill have to take the ECU apart and get you some pictures

about driving above 1500rpm and coasting ... when u mean coasting do you mean keeping a steady rpm or completely removing my foot off the pedal ?

ive never reset the obc but i searched here and people are saying "press the code key and then the little button to the right corner"

anyways ill try some stuff today thanks alot

RYAN: here's a link to the adjustment of the TPS http://www.bmwe30.net/cgi-bin/datacg...066&Section=15

[WBSAK03]

I suspect the coolant temp sensor. The symptoms you are describing sound exactly like what my ///M was doing shortly after I bought it. I replaced the part and all was well. I am talking about the sensor on the coolant rail that gives everyone a problem sooner or later. The part I replaced was PN 13621709966 (about $30). The other sensor is PN 12621710512 (about $15).

HTH

[Darren M]

is it just when the engine is hot? or all the time?. I`ll hopefully start work on my car soon when I get it back and this is one problem I need to fix on it. When the engine is warming up it is fine but as soon as it reaches operating temp the idle searches (slowly rises from 800 to 1400rpm before suddenly dropping back to 800 and starting this all over again). I suspect it is the ICV (the previous owner gave me a brand new one as he suspected this also) and the ECU might of fried a resistor or two.I have a spare ECU so will replace the ICV and then switch the ECU`s around to test this.
If not, I too will try the other things mentioned in this thread.

[liquidtension]

i couldn't do any testing today i was busy cleaning the interior with my cousin.. removed the seats and door panels and cleaned the carpet very well... the trunk is so clean i didnt put the junk back in .. im gonna put something over it so it stays clean.. and hopefully source some good leather interior to install ... any 2-door e30 interior(front and rear panels and seats) will fit the m3 right ?

btw my spark plug wires suck... i touched one that had a little tear ... and i got zapped... but im low on cash right so i got to sell my vw to spend more $$ on the m3

[liquidtension]

the searching happens all the time even when it is cold ... sometimes it takes a blip of the throttle to get it to malfunction ... other times itll happen without even being in the car ..(so it is definitely not the throttle cable) ...it's so annoying ...and humiliating as well cuz it makes you look like an ass in traffic with the s14 at 1600rpm...it makes you look like it is your first time driving stick ...

[///Mflossin]

Originally posted by WBSAK03
I suspect the coolant temp sensor. The symptoms you are describing sound exactly like what my ///M was doing shortly after I bought it. I replaced the part and all was well. I am talking about the sensor on the coolant rail that gives everyone a problem sooner or later. The part I replaced was PN 13621709966 (about $30). The other sensor is PN 12621710512 (about $15).

HTH

Absolutely. VW's are notorious for the same symptoms when the CTS (Coolant Temp Sensor) goes haywire. It could be a loose connection at the CTS or the CTS itself. As mentioned here...the sensor is on the main rail.

[hardtailer]

coasting is your foot off the throttle pedal. resetting the avg fuel consumption etc. on the obc is done pressing the set-res(et) button on the obc.

[liquidtension]

yup the sensor is the one to the left (blue one) anyways i tried wiggling it a couple weeks ago and it didnt make a difference.. so i dont think it is a connection problem .. maybe the sensor is bad though... but how come giving a blip of throttle cures the problem right away sometimes ... other times it just wants to stay up ...ill look around and update tomorrow ..or whenever i find out something new ...
ill try the stuff you guys mentioned as well

[liquidtension]

it's been raining since i last posted ... but i was able to try a suggestion ...

i coasted and reset the consumption ... it stayed at 0.00 .. till i hit around 1500 rpm ... then it felt like the car isnt slowing down as much ..and the consumption went up and changed..
so does this mean i should leave the TPS adjustment alone and that it is adjusted right for sure ? thanks.. as soon as the weather clears up ill try the rest of the suggestions