rough running

[RED IS 91]

OK , In my obsession to eliminate the rough idling and hesitation I have.
Today I replace gas filter which only had 5K  miles on it but couldn't rule it out. Didn't help .
Next checked the ICV ( voltage and ohms were good but can't check the mech aspect ) so change it out . didn't help
Next checked the TPS again ,everything was ok .
Next pulled plugs and they seemed wet .They too were relatively new but WTF change them out . Car seems to run alot better . Took it out for a quick spin and it pulled really well with no hesitation.
I don't get all Cocky cause It's teased me before .
I take it to town with my son and daughter to shop for mom' s gift .runs good but on the way back it starts to hesitate again . Half way home it snaps out of it and starts to run good again .Almost home and it hesitates some more .I've also check  the MAF and have new plug wires .It also has a new CO2 sensor.
It seems to be running rich so what is telling it to run rich ?


If it was a vacuum line wouldn't it run like shit all the time ?
I am going to remove the manifold and replace the vacuum lines tomorrow .
If that doesn't help then I don't know what's next .
MAF ?
Crank Pos. sensor ?
coolant temp sensor ?
I always said that I hate to keep changing parts but I will solve this mystery before spring or  go broke trying .
Sorry for the long post but want to get as many facts in as possible.
HELP!!!!!!!!!!!!!!!

[silverblades181]

I have a similar problem. If you had a bad crank sensor, then the car wouldn't start. It's easy to check the coolant sensor, get the engine to between 77Celcius and 83Celcius and it should give you between 300 and 360 Ohms. I checked mine and it was within specs. Does your engine shake a lot? Mine does so I think one of the cylinders is missing occasionaly...though when it's not at idle it's fine. I've been told bosch injectors get dirty easily so I'll try an injector cleaner, not the one you put in the tank but a real one thats directly into the injectors. Both 318is I've owned had the rough idle issue and the hesitation...it is puzzling.

[kowalski]

not true, the car starts with a bad crank sensor, it just depends HOW bad. Mine read 580 ohms, which is about half of what it should, and it drove around fine, just had a shitty idle and didn't pass air care. I also thought the crank sensor would stop it from running, so i replaced wires, coils, plugs, chip, 02 sensor, injectors, TPS... and then i checked the crank sensor and it was efff'd. do a quick ohm test, takes like less then 3 min. But that should really cause it to run rich unless you aren't getting any spark. get a spare plug and pull of each wire one by one and grown the plug to some thing and see if it sparks, run through each cylinder, let it crank a few times to see if its intermitent, or a constant thing. then check fuel if spark isn't your problem, perhaps an injector is stuck open or something to that effect? a 02 sensor could also cause this as it is reverting to running rich to stay on the safe side of things. just some things to check...

[RED IS 91]

not true, the car starts with a bad crank sensor, it just depends HOW bad. Mine read 580 ohms, which is about half of what it should, and it drove around fine, just had a shitty idle and didn't pass air care. I also thought the crank sensor would stop it from running, so i replaced wires, coils, plugs, chip, 02 sensor, injectors, TPS... and then i checked the crank sensor and it was efff'd. do a quick ohm test, takes like less then 3 min. But that should really cause it to run rich unless you aren't getting any spark. get a spare plug and pull of each wire one by one and grown the plug to some thing and see if it sparks, run through each cylinder, let it crank a few times to see if its intermitent, or a constant thing. then check fuel if spark isn't your problem, perhaps an injector is stuck open or something to that effect? a 02 sensor could also cause this as it is reverting to running rich to stay on the safe side of things. just some things to check...

I did  a crank pos sensor ohm test this morning and also had around 570 ohms(less than half required ).
I also checked the engine coolant temp sensor . I had at 40* F  4.93 K ohms and at operating temp had .25 K ohms. When I first started the motor and pulled the ECT plug the car raced up to 2K rpms.When the car was fully warmed up I pulled the plug and it didn't affect rpms .
I've ordered from Bav Auto numerous vacuum hoses and an engine coolant temp. sensor but now I'll also order  a crank pos. sensor .
I think the cps and ect are both suspect so they will be replaced in my quest for correct idle and smooth acceleration.

[kowalski]

ahh well it looks like you found A problem, hopefully it fixes your idle problem. Hopefully it fixes mine as well...

[318isle]

I did  a crank pos sensor ohm test this morning and also had around 570 ohms(less than half required ).
I also checked the engine coolant temp sensor . I had at 40* F  4.93 K ohms and at operating temp had .25 K ohms. When I first started the motor and pulled the ECT plug the car raced up to 2K rpms.When the car was fully warmed up I pulled the plug and it didn't affect rpms .
I've ordered from Bav Auto numerous vacuum hoses and an engine coolant temp. sensor but now I'll also order  a crank pos. sensor .
I think the cps and ect are both suspect so they will be replaced in my quest for correct idle and smooth acceleration.

Where is this crank sensor, and what is the required ohms you talk about?
My idle hasn't been smooth for some time now either. I'll be changing out the ICV only because it hasn't been done by the PO as far as I know.

[kowalski]

you don't need to change it out unless its broke, just give it a good clean. as for the crank sensor, its on the crank pulley, look at the cam sensor, and follow the wire that leads down to the crank and that will lead you to the crank sensor.

click here and scroll down until you see instructions. for the crank sensor

[RED IS 91]

good reading on icv here


http://www.esatclear.ie/~bpurcell/318isfaults.html#idlecontrolvalve

also

http://www.esatclear.ie/~bpurcell/318isfaults.html#inletmanifoldleaks

[RED IS 91]

I did  a crank pos sensor ohm test this morning and also had around 570 ohms(less than half required ).
I also checked the engine coolant temp sensor . I had at 40* F  4.93 K ohms and at operating temp had .25 K ohms. When I first started the motor and pulled the ECT plug the car raced up to 2K rpms.When the car was fully warmed up I pulled the plug and it didn't affect rpms .
I've ordered from Bav Auto numerous vacuum hoses and an engine coolant temp. sensor but now I'll also order  a crank pos. sensor .
I think the cps and ect are both suspect so they will be replaced in my quest for correct idle and smooth acceleration.

Update
Recieved new coolant temp sensor and hoses today. I removed the intake manifold and installed the hoses . noticed the fuel pressure regulator hose  was iffy so went to napa and they gave me a section of hose FREE (they must like me). Put everything back together and fired her up with fingers crossed . I still have shitty idle .( slight hesitation) :mad:
Well I am still waiting for the crank position sensor to come in on Friday . Hopefully that cures it as the readings weren't good . If it doesn't there will be some more diagnosis and more parts .
THE QUEST CONTINUES

[bmwman91]

I forget...have you tried swapping to a different AFM and resetting the ECU?

[RED IS 91]

I forget...have you tried swapping to a different AFM and resetting the ECU?

I don't have another one to swap but all my testing with the multimeter says it's OK .
Today when I pulled the upper manifold the lower manifold had some greasy oil film  in it . I should have taken a picture .I know it's running rich but can't seem to figure  out how or why .
 I know the CPS is not within specs from testing so it's next .
Damn AFM's are expensive but I don't believe that's the problem.

[kowalski]

buy one used off ebay or the wrecker. i got mine for $30

[RED IS 91]

buy one used off ebay or the wrecker. i got mine for $30

If the crank position switch doesn't do it then I'll look at doing that next.
Thanks

[RED IS 91]

While I am waiting for more parts I thought I'd check the Idle control valve again . I changed it out within the last couple of weeks with one I bought on ebay. It was used but looked like new . When I changed it out it didn't make any difference . When I checked it against the values in Bentley it was within specs (12volts) but Bentley also said that when the car is running you should hear a buzzing sound coming from the valve .I put a screwdriver on the valve and held it against my ear . I don't think I hear anything .I put the old one back in and couldn't hear anything from it either. Both check out with 12 volts to the valve .Could it be that the replacement ICV was no good.
Does anyone Hear buzzing from their valve when the engine is running ?
The Quest continues

Checked my TPS (throttle position switch) after doing a code check (1216) .At closed throttle I had 4K ohms and at full throttle I had 1K ohms .  Is this backwards Bentley says for from 1K -4K  .I have 4K - 1K

[bmwman91]

I have never heard the buzzing from either of my E30's ICV's.

IIRC the Bentley has the leads mixed up on the TPS test procedure.  It will read 4k - 1k if you follow its instructions.  Leave the probe on the middle terminal and switch the "outer" one, it will read properly.