BimmerFest BMW Forum banner

1985 635 csi rough ideling. help

12K views 22 replies 5 participants last post by  Limarxy 
#1 ·
i rebuild the motor.
here is new parts
fuel filter
temp coolent sensor
fuel regulator
spark plugs
distributor cap
wires
ignition coil
new refrance sensor
new cam sensor
thouse are the some important parts
now car starts and idles at 1100 rpm step on the gas and rew up to 5000 drop it it drops slowly to 1100 and then goes to 550 and 500 rpm. now the plugs are wet soked in gas and catolic convertor gets red hot. cat is new but o2sensor is old.
can it be thermo time sensor or cold valve injector.
 
#2 ·
more things to test

Did you check the AFM? Do a resistance check as you manually sweep it across its range.
I replaced the main and fuel pump relay and that fixed a stumble I had - but your issue sounds different.
Is your idle control valve clean? Is the idle control module OK? Easy enough to replace.
Is the cat plugged/broken? Remove it and see how it goes - that might be your problem. It will sound a lot better too!!

The cold start valve will make it run rich - and it will run like crap unless the revs are like 5,000 - so that does not sound like it is your problem.

If the plugs are wet it sounds like its rich - is the coil working OK - you are getting spark but is it weak?

Chris
83 533i (RIP)
85 M635CSi
89 M3 - don't ask about the S50
97 328i
 
#3 ·
thanks cdunlap. yeah my coil is new. some guy told me that it needs to be driven around for 20 miles so the computer learns the path and maps all the new sensors etc. i just ordered the TPS. see what it does. if i fix the problem i will let you guys know what was it. so next guy will have an easy way of find in out.
 
#4 ·
Help - response

No - the good old cars work better right away with new parts. There's no learning on the car's part. The AFM can be tested with an ohm check across the pins as you sweep the flap door through its range.

But - it might be bad right where you drive it. Crank it up to 6,000 and if it runs fine, it might be bad.

It's a pain to track down problems like this! I've had my fair share of them too!

Let me know if I can help with any factory manual stuff (I have one).
 
#5 ·
TPS testing

Oh yeah - TPS - at closed throttle two pins are at 0 ohms - at full throttle the other two pins are at 0 ohms. it's like the top and middle pins for one condition then the bottom and middle pins for the other condition. Easy test! it takes two minutes to do!
 
#6 ·
thanks. i am installing new TPS tomorrow and i will check the air flow meter you right the car works realy good at over 1200 rpm and revs good as soon as you let go of the throttle the car slowly drops from 1100 to 550 and then by it self shoots up to 2500 rpms then goes down to 1100 holds there then goes down to 550 rpm but it does bot die i am having fun and frustration to figure it out. soon after i am done with engine ill start on interior and body later. thanks
 
#8 ·
hi. i instaled the new TPS the car seems to work better. but it still wont hold the desirable 750 rpm. it holds 1100 rpm nicely by adjusting a throtle cable. the air control valve is clean and ohms checked good on it. whats the air control module is that the same thing? today i am wraping the car in dynomat and working on the stereo putting new speakers and dvd/nav system. cleaning a carpet etc. next week short shifter shipps in from BMP DESIGN. and new reupholstered sport seats are come in in about 2 weeks. i am exited. i installed a new cat and 3 inch single pipe to the magnaflow 18x6 muffler way too loud i hate it. i have to install a resonator now because it sounds like a v8 hemi. so far i am in love with this project. exept hardest thing is to find a ideling problems and the rest is easy. i will post the results if i find any solution to the problem. thanks to cdunlup for his imput. it helps.
 
#9 ·
today i did alot. wraped the inside car with dynomat and wired car for speakers and dvd/nav. and amps. i started it the car today it started right away then died. and i could not start it again checked the plugs they are dry. so i figured out its fuel low or pump went souht. opened the gas cap closed it the started the car with no problems. what ever makes it do that is some kinda little issue do next sat ill start checking on fuel pump and ill take my AFM to be rebuilded. if that not gona work ill do the idle conrol valve. and last would be injectors to rebuild. another $700 probably hate it but have to.
 
#11 ·
I would start with checking all your vaccum lines, then idle air sensor, mafs go bad but not to often .....not saying they dont just not often. Also I would check you evap system over good, could have cracks in line. May also put a timing light on it , your advance timing may be off causing high idle. Just some ideas.

Sent from my PC36100 using Bimmer App
 
#12 ·
my m635csi lost power need help!

Good day everyone,
I'm new member in this forum,,,,
I need advice to anybody that can help me regarding my problem to my m6.

I just bougt this car a month ago here in our place(1985 m635csi)it's been stock in the garage for almost 7 years without starting the engine.when I get it it's not starting then I fixed it myself...now the car is working i change a lot of things in the car

cam sensors,crank sensor,etc...sensors,high pressure fuel pump,new ECU,air mass,clean injector,but still the car not getting the full power.

I'm planning also to cancel air mass.

If anybody incounter the same problem I had?can you givesome advice on this matter?

Thanks a lot ....hope I can read more ideas or suggestion in this post.
 
#13 ·
check your valves they should be not too tight i think its 0.09. when i rebuilded the engine i changed alot of things and car was idling wrong so i purchased a compleate 635motor for $200 and took all the sensors off and put them on my engine now it works great. this motor has all this tempereature sensors and idle sensors and some of them you cant buy new any more. i will advise to change the fuel pressure regulator and rebuild your injectors. and buy specialty spark plugs for the bimmer from the dealer they are $20 to $16 each its realy important i tryed many spark plugs and best ones from your bmw dealer. right now my car is idling right but its seems like something holding it back from full power. so ill wait untill the engine broken in before full throutle. let us know how u fix it. join us at bigcoupe.com its a bmw e24 forums
 
#16 ·
If you dont have a charcoal canister and you plugged the hose, it will drop at idle. You need to vent the crank case. Dont plug the hose. But you say the cat is red hot. It may be plugged, broken. Remove it. Straight pipe it. If you block the exhaust it will run like crap too.

Sent from my PH44100 using Bimmer App
 
#17 ·
Thank you very much for the quick reply,Actually all the valves are working properly.The problem is seems I lost 50% power of the car.

Parts installed:
1.new ECU
2.new injector
3.spark plugs
4.ignition wire set
5.delco
6.crankshaft sensor,timing sensor...etc sensor
7.new air mass
8.clean engine.
 
#18 ·
greetings to evryone.......

I hope somebody read my post last time.....
Need advice on what I can do the regain the lost power for my 1985 bmw m635csi.

parts installed:

new ecu
air mass
injector
fuel pump
cam sensor
crank sensor
thermostat
fan clucth
spark plug
ingition wire
delco
 
#19 ·
Do a compression test, and a leak-down test. Those two will tell you if it needs a rebuilt. Lost power across the board even after replacing your extensive list of parts usually points to worn rings and/or burnt valve(s)
 
#22 ·
Agreed I tried to post that this morning but my net was screwed up. My geuss would be low compression or the cats clogged. He mention something earlier about eliminating the MAF, I didn't know this was possiable? We had had them come into our shop before and the maf was burnt up and wouldn't run or ran like crap.
 
#23 ·
i fixed my idling problem
#1. guy was selling used engine for $200. so i paid $200 but took only all sensors. air mass thing. and changed to my car. and now its idling normal. my cat is new and its magnaflow cat back exhaust. too loud sounds like the american v8. where are you located? find the parts car on craigslist and take the parts off that car and swap em. and try again. if not then its possible your compression too low and will need a bottom end rebuild. its not that complicated. Land vehicle Vehicle Car Personal luxury car Coupé
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top