Misfire and Car shakes at idle.

[ianxflo]

Hey everyone, I have a 1991 325i sedan with 140,600 miles. I tried to diagnose the problem myself but I just cant figure it out. My car's idle is constant, but it shakes the car when im fully stopped at a light. Ive checked all vacuum lines and replaced them, replaced my spark plugs and fuel filter, and cleaned up my MAF. I plan to change the O2 sensor sometime soon, because it looks like its the original part. My car runs fine, but I feel like the acceleration is a little slow, especially uphill. Could be that I have auto transmission, but I dont know.. Ive driven stick for so long I forgot how much power you lose when you switch to auto. Any thoughts on the idle shaking problem? Also I noticed my car gets hot when Im idling but cools down while im moving. Probably a bad fan clutch or coolant temp sensor I need to replace, but would this cause a shaking idle? or possibly a bad O2 sensor? I started to notice the problem 2 weeks ago and my mpg started to decline as well.

[Varinn]

Tried adjusting you ICV? I'm pretty sure it's got an adjustment screw to tweak idle setpoint

[davem]

Tried adjusting you ICV? I'm pretty sure it's got an adjustment screw to tweak idle setpoint

that's the throttle adjustment screw and you're not really supposed to touch that unless it's already been messed with (there's usually some paint on it if it hasn't been touched)

misfire and shake at idle could be many things... vacuum leaks, clogged injectors, coolant temp sensor, o2 sensor etc.

[Varinn]

that's the throttle adjustment screw and you're not really supposed to touch that unless it's already been messed with (there's usually some paint on it if it hasn't been touched)

misfire and shake at idle could be many things... vacuum leaks, clogged injectors, coolant temp sensor, o2 sensor etc.

I somehow didnt see the misfire part, so yes, likely not the ICV

[kikkoman]

My engine used to shake like that and wouldn't freely rev high. In addition to new plugs, fuel & air filter and some hose replacement I also did the valve adjustment which cleaned everything up. I did everything together so really can't say which maintenance was the actual fix but adding valve adjustment wouldn't hurt.

[JrCamacho]

+1 on valve adjustment.

[ianxflo]

My engine used to shake like that and wouldn't freely rev high. In addition to new plugs, fuel & air filter and some hose replacement I also did the valve adjustment which cleaned everything up. I did everything together so really can't say which maintenance was the actual fix but adding valve adjustment wouldn't hurt.

Yea I hear my rocker arms ticking so Ima take it in for a valve adjustment on friday and see if itll solve the problem. Thanks for the input guys.

[ROLLingKING]

hmmm. i know how u feel. my car overheated almost every time I drove it this summer. If i stopped it heated up. heres how i went about it.
If u push your ac button (and it turns blue) and your aux fan DOES NOT kick on, then u need a resistor. If after the resistor your aux fan still acts funny, then the auxilary fan temp sensor which plugs into the radiator needs to be replaced.

About the car shaking at idle, i would say check your motor and tranny mounts. no ones said that but any of those being messed up could make the car shake more. it made mine shake.
Other than that, does it idle at proper rpm?
Good luck tho!

[ianxflo]

hmmm. i know how u feel. my car overheated almost every time I drove it this summer. If i stopped it heated up. heres how i went about it.
If u push your ac button (and it turns blue) and your aux fan DOES NOT kick on, then u need a resistor. If after the resistor your aux fan still acts funny, then the auxilary fan temp sensor which plugs into the radiator needs to be replaced.

About the car shaking at idle, i would say check your motor and tranny mounts. no ones said that but any of those being messed up could make the car shake more. it made mine shake.
Other than that, does it idle at proper rpm?
Good luck tho!

Yea it idles at a steady and proper rpm, just shakes the car noticeably. Im taking it in to e30 motorwerks in huntington beach, Ive heard good things about their shop. Thanks for the input!

[JrCamacho]

now that i think about it, my transmission mounts are shot.. i should replace 'em

[ROLLingKING]

Yea it idles at a steady and proper rpm, just shakes the car noticeably. Im taking it in to e30 motorwerks in huntington beach, Ive heard good things about their shop. Thanks for the input!

well did u check your motor mounts and tranny mounts. If the car idles fine and pulls alright, then why would the car be shaking. it has to be the vibrations of the motor transmitting to the car. that sounds like mount issues to me. other wise u should be able to pop your hood and see the motor moving. it seems weird your idle shakes the car.if its idling fine theres nothing wrong with the motor causing this issue. its where the motor meets the car...right?

Yea I hear my rocker arms ticking so Ima take it in for a valve adjustment on friday and see if itll solve the problem. Thanks for the input guys.

I mean i havnt built engines or even replaced rocker arms before but a valve adjustment and rocker arms will not make your car shake. to me thats just common sense. im not saying u dont have common sense but before u dump a lot of money into a shop u may want to look at them mounts!lol im only trying to help. and good luck. im very interested as to what the actual problem is

now that i think about it, my transmission mounts are shot.. i should replace 'em

get E21 tranny mounts with the AKG aluminum caps!
peep my build thread to see how they fit. theyre 10x better, OEM, and cheap. bavauto has em for like $14 each. theyll tell u they have to be shipped from a different warehouse and may take a while cause its an old ass part, but it got to my house before my stuff did that was shipped from bavauto. go figure.

[ROLLingKING]

Hey everyone, I have a 1991 325i sedan with 140,600 miles. I tried to diagnose the problem myself but I just cant figure it out. My car's idle is constant, but it shakes the car when im fully stopped at a light. Ive checked all vacuum lines and replaced them, replaced my spark plugs and fuel filter, and cleaned up my MAF. I plan to change the O2 sensor sometime soon, because it looks like its the original part. My car runs fine, but I feel like the acceleration is a little slow, especially uphill. Could be that I have auto transmission, but I dont know.. Ive driven stick for so long I forgot how much power you lose when you switch to auto. Any thoughts on the idle shaking problem? Also I noticed my car gets hot when Im idling but cools down while im moving. Probably a bad fan clutch or coolant temp sensor I need to replace, but would this cause a shaking idle? or possibly a bad O2 sensor? I started to notice the problem 2 weeks ago and my mpg started to decline as well.

Sorry im posting so much but i just had another idea. i HAATE sending my car to a shop. especially after working on one. they just go to autozone for all their cheap parts and try the same tricks i do in my garage.

Well i re read this and try putting that lucas fuel injector stuff in the tank. also put half a can of seafoam in half a tank. CLEAN OUT THE LINES & THEM INJECTORS.

Other than that. i think we got your overheating solved. did u try any of the steps i mentioned. i had to do all of that and ive practically replaced aalll cooling components.haha okay thats my long shpeal

[ianxflo]

So it turns out, my motor mounts and tranny mounts needed to be replaced, as well as my flex disc lol the valve adjustment helped with the shaking a little bit, but I still need to replace the mounts. Also, 2 of my fuel injectors weren't working properly. Robert at e30 motorwerks pulled my spark plugs and showed me that two of them had barely any burn marks at the tip. Also did a compression test and cylinder 5 is pushing 85 while the rest are at a steady 150.

[ROLLingKING]

So it turns out, my motor mounts and tranny mounts needed to be replaced, as well as my flex disc lol the valve adjustment helped with the shaking a little bit, but I still need to replace the mounts. Also, 2 of my fuel injectors weren't working properly. Robert at e30 motorwerks pulled my spark plugs and showed me that two of them had barely any burn marks at the tip. Also did a compression test and cylinder 5 is pushing 85 while the rest are at a steady 150.

AHA! I kneeew it had to be something with motor mounts.lol The way u were describing it is what my car used to do. If I was stopped at a light it would almost be like having a little massage chair.
Are u replacing with OEM bushings all around?
I highly recommend some AKG motor mounts & some E21 tranny mounts W/ the AKG aluminum cups on top. I looove this set up in my whip.

Quick question tho, How do u test to see if all infectors are working properly? I havnt had a chance to get a valve adjustment or fuel injector test done yet but I want to. did u just take it to a shop...i really dont like doing that but i might have to for the injectors

good luck with the fixes. it will be another car once everything is bolted down good n' tight

[ianxflo]

AHA! I kneeew it had to be something with motor mounts.lol The way u were describing it is what my car used to do. If I was stopped at a light it would almost be like having a little massage chair.
Are u replacing with OEM bushings all around?
I highly recommend some AKG motor mounts & some E21 tranny mounts W/ the AKG aluminum cups on top. I looove this set up in my whip.

Quick question tho, How do u test to see if all infectors are working properly? I havnt had a chance to get a valve adjustment or fuel injector test done yet but I want to. did u just take it to a shop...i really dont like doing that but i might have to for the injectors

good luck with the fixes. it will be another car once everything is bolted down good n' tight

Thanks for the advice, Ill give that setup a try, Where did I buy it?

As for the injectors, I had it inspected at a shop. Im not sure of an easy way to check if they are working or not, unless you put new spark plugs in and drive for a week or so and take them out and see if there are visible burn marks on the white tip. If there is, then that means the combustion in the piston should be okay and the fuel injectors would be working. If not, then there is a problem with either the injector individually, or if its all of them, then something with the fuel lines or pump. Im still a noob at mechanic work and terms, so dont take my word for it. This is just what I picked up from the robert at e30 motorwerks in huntington.