Hey Guys,
I have a '86 325e, recently the cars rpm needle started to jump up and down abit, but the car idled fine, tried check for any vacumn leaks, couldn't find any, check all the plugs, they were fine, can't really think of anything at this moment what would be the cause, I'm abit stumped, its my wife's car and I'm trying to hopefully get to start running, any ideas or suggestions would be greatly appreciated, here's my number #222-6456/Joe

Mahalo

Is it just the guage, or the idle?

Is this when you are coasting?
Do the rpms slowly go up, then drop, and repeat?

Try and clean your IACV/TB.

Is this when you are coasting?
Do the rpms slowly go up, then drop, and repeat?

Try and clean your IACV/TB.
Well what I got from my wife is when it is in gear, so basically while driving, now while driving it started to idle really rough, she said it felt like it was going to die out, when I started it this morning, it idled fine for me, but I notice the RPM needle started to jump up and down. I read some where it might be one of the relay sensors, but I don't know which one? thanks for the replies - keep it coming

Mahalo,
Joe C.

Well what I got from my wife is when it is in gear, so basically while driving, now while driving it started to idle really rough, she said it felt like it was going to die out, when I started it this morning, it idled fine for me, but I notice the RPM needle started to jump up and down. I read some where it might be one of the relay sensors, but I don't know which one? thanks for the replies - keep it coming

Mahalo,
Joe C.


Give the ICV throttle body clean a try, and maybe the AFM flap too for good luck.

Thanks for the replies guys, I took the car out for a spin around my neighborhood several times late yesterday afternoon and it drove fine, no eradic idling, I added some injector cleaner, thinking maybe it was some bad gas, I don't know if that did the trick, but I will check and clean the throttlebody and AFM for good measures - thanks guys

Mahalo,
Joe C.

Thanks for the replies guys, I took the car out for a spin around my neighborhood several times late yesterday afternoon and it drove fine, no eradic idling, I added some injector cleaner, thinking maybe it was some bad gas, I don't know if that did the trick, but I will check and clean the throttlebody and AFM for good measures - thanks guys

Mahalo,
Joe C.


Joe I had the same issue and it ended up being a vacuum hose had a hole in it. The car would randomly act that way. If it starts back up check each individual vacuum hose to ensure they have no holes.

Wouldn't the tach's signal source be suspect too?

Does BMW use the alternator to count pulses like the rest of the world, or do they pull it off of another rotating part?

I'd suspect one of the alt wires may have a corroding fitting or broken strands.

Wouldn't the tach's signal source be suspect too?



+1 my first thought also




Brendan is yur wife's boss car up for sale yit? *snickers*

not anytime soon... we looked at that piece of crap today, and count get shit out of it... no spark or anything...

Wouldn't the tach's signal source be suspect too?

Does BMW use the alternator to count pulses like the rest of the world, or do they pull it off of another rotating part?

I'd suspect one of the alt wires may have a corroding fitting or broken strands.

E30? I think the DME drives the tach signal.

It would most likey be the cluster board if it was only the gauge acting up.

Brendan is yur wife's boss car up for sale yit? *snickers*


:nono:nono I will let you know once I pull up next to you:alright

Ok Guys,
Update, car still acts up abit as far as the idling goes, the tach gauge still spikes up and down and the idling fluctuates as well, I check the coil and distributor plugs to check for any loose wires, they seem all ok, check the computer for any corrosion, cause all the heavy rains we've had in the past, thinking maybe some moisture got in, but all the contact point appeared to be fine, maybe I'm just not looking at it correctly?

Check the AFM flap, throttle body and the ICV. Clean them!

Check the air boot from the AFM the the throttle body for cracks. If there is a crack or it's not clamped on good, you'll get a wild idle.

Your best bet would to be to do a search on the E30 forums. I'm sure this has been addressed there before.
If you clean you ICV, be sure you can hear a rattle, if not than it's clogged. However, if the idle is okay, but the needle is jumping it could be the tach itself. Sorry, but I can't add any more than this.
Searching the E30 forum will be your best bet at this point...imho.

Your best bet would to be to do a search on the E30 forums. I'm sure this has been addressed there before.
If you clean you ICV, be sure you can hear a rattle, if not than it's clogged. However, if the idle is okay, but the needle is jumping it could be the tach itself. Sorry, but I can't add any more than this.
Searching the E30 forum will be your best bet at this point...imho.
I have clean the AFM & throttlebody only, the ICV that would be the Idle Control Valve, correct? Sorry I know more about the parts on my GN, than the parts on the beamer, so that would be located on the passenger-side bolted on the intake correct? I'm pretty sure I know which part it is, just double check, you mention about hearing a rattle sound, I can see how it can affect the idle, but will it also create the tach gauge to spike sporadically up and down? thanks for the replies guys, much appreciated.

Mahalo,
Joe C.

I have clean the AFM & throttlebody only, the ICV that would be the Idle Control Valve, correct? Sorry I know more about the parts on my GN, than the parts on the beamer, so that would be located on the passenger-side bolted on the intake correct? I'm pretty sure I know which part it is, just double check, you mention about hearing a rattle sound, I can see how it can affect the idle, but will it also create the tach gauge to spike sporadically up and down? thanks for the replies guys, much appreciated.

Mahalo,
Joe C.
ICV = Idle Control Valve, you are correct.
Not sure of it's location on a 325e, but you may be correct here too.

I don't think this is your problem if the car idles okay, but the rpm needle jumps. The needle and idle should be in sync with each other. I.e. idle goes up, needle goes up, idle goes down, needle goes down.
Search the forums and let us know what you come up with.

UPDATE!!
Ok guys, I've checked all the wires, checked for any vac leaks, changed the fuel filter, thinking it might also have something to do with the idling, also I think its called idle ignition module?(located under the glove compartment) changed that as well, am I missing anything else, I will propably go ahead and change the alternator wires, I took a look at them and they looked abit frayed, would that also hinder the idling? Thanks in advance guys, if I can't get her up and running, can anyone of you recommend a reputable BMW mechanic w/ reasonable pricing, much appreciated.

Mahalo,
Joe C.

UPDATE!!
Ok guys, I've checked all the wires, checked for any vac leaks, changed the fuel filter, thinking it might also have something to do with the idling, also I think its called idle ignition module?(located under the glove compartment) changed that as well, am I missing anything else, I will propably go ahead and change the alternator wires, I took a look at them and they looked abit frayed, would that also hinder the idling? Thanks in advance guys, if I can't get her up and running, can anyone of you recommend a reputable BMW mechanic w/ reasonable pricing, much appreciated.

Mahalo,
Joe C.
A & A Motor Werkes, LLC.
Contact Info:
Main Line - 739-1599
Albert - 753-6139 BMW Master Tech.
Tony - 386-8649 BMW Master Tech.

Albert and Tony were the only 2 Master Techs at BMW of Honolulu when they left last year some time. They are prpbably the only two techs that can actually tear down any M car and put it back together.
Their prices are reasonable and they are very up and up...will tell you what you need and don't need.
Give them a call and tell them you got the info from bf.c