Another high idle thread

[87'moneypit]

First I want to thank the community, I have been on here for a few weeks while working on my car and by searching I have found most of the info I needed. I recently bought an 87 325is, build 7/87. I am having some strange idle/bogging issues. I have just replaced the following:
New timing belt
water pump
rotor
cap
spark plugs
throttle body gasket
intake manifold gasket
valve cover gasket
some water hoses
oil pan gasket
did a valve adjustment with new eccentrics
deleted the power steering
deleted the clutch fan and added a electric fan wired in with a relay
added new 19lb injectors
ebay chip

The car starts fine, and actually idles good when cold. When it warms up it idles 1000-1200rpms. The car drives great all the way to red line...most of the time. sometimes it will cut out while accelerating, then it drives with no problems for the rest of the drive. Today it was bogging and I had to pull over, car was barely idling, I shut it down, restarted it and it drove fine for another 30minutes. while idling if I unplug the ICV there is no change in the idle? I have read a ton about vaccum leaks, but Im unsure if that is my problem since the car idles fine when it is cold, seems to get worse when it gets warm. Im going to order some more maintainence stuff soon, just wondering if you all could suggest anything else to pick up. I appreciate all your help.

Update: 7/12/12
Found what appears to be a small vaccum leak on one of the injectors, seated it a little better and appeared to take care of that vaccum leak. I readjusted the valves since the car ticks like crazy, seemed to help a little, but its still loud. I took the car for a 30 mile drive to pick up our dog. 15 miles almost all highway 65mph and the car ran great... still had the high idle, but no boggin or anything. Picked up our dog and started the drive home. A couple minutes later the car starts bogging, but really bad this time, no response at all from the gas pedal, and then the car dies... I cycle the key while im still rolling and it fires back up no problem, bogs a couple more times on the way home....? Any thoughts

And since eveyone loves pictures, here is the car

[5Toes]

If there is no change, then check your tps.

My car does the same shit. ugh

[dnguyen1963]

Small vacuum leak is more pronounced at warmer temp (things expand when they get hot). I would drive your car for about 30 min then perform a smoke test.

[7pilot]

sounds like :
1, A weak fuel pump that cannot deliver sufficient fuel vol/pressure for the engine under load.
Cold idle is good...so the engine likes the mixture it is getting.
Warm idle is too fast...It likes the small leak or the idle speed is incorrectly set.
Stumbling under load....Mixture is
1, maybe too lean. or
2, perhaps static engine timing is retarded.

I'd do a smoke test, a fuel vol/pressure test, check static timing, Check/set base idle, check O2 sensor function.
Looks like weak pump and air leak issues to me.

m

[87'moneypit]

sounds like :
1, A weak fuel pump that cannot deliver sufficient fuel vol/pressure for the engine under load.
Cold idle is good...so the engine likes the mixture it is getting.
Warm idle is too fast...It likes the small leak or the idle speed is incorrectly set.
Stumbling under load....Mixture is
1, maybe too lean. or
2, perhaps static engine timing is retarded.

I'd do a smoke test, a fuel vol/pressure test, check static timing, Check/set base idle, check O2 sensor function.
Looks like weak pump and air leak issues to me.

m

Now that I think about it the fuel pump is pretty loud, going to put one on order, and replace the filter and lines as well. Any good write ups on checking and setting the base idle and O2 function? Dont have a bentley yet as I have been finding most of the info I need online. Thanks for all the replies.

[87'moneypit]

update added, see first post.

[dnguyen1963]

Do a smoke test to find vacuum leak again. Driving it for 30 min probably create more leaks that you did not find before. Yes, this is a pain, but it is a 20+ yrs old car.

[CarsSuck]

My car ('89 325is) has a similar idle problem that yours does. Its okay when cold, but idles right around 1000 rpms and is a bit lumpy when warm. I can't seem to find the problem, but I can pretty much promise you it isn't the fuel pump. I really think that the idle and bogging issues are separate. Bogging is usually a fuel pressure issue, so you really need to have a gauge hooked up and visible while your driving.

Also, there is nothing to adjust for engine running parameters. Idle speed and timing are set by the Motronic Unit.

I would buy a new bosch o2 sensor and splice on the old connector. Then I would check the resistance on the coolant temp sensor and the CPS. Then I would start doing fuel system diagnostics.

Has your AFM been opened/tampered with?

[Scutt]

I had been chasing a similar problem for almost a year now.....I did have a 6 month engine rebuild in there but I just solved the issue.

My idle was much more pronounced...up to 3k at times and when you got on the throttle it would cut out and die. I wouldnt be able to restart it for about an hour after that. I had already replaced the fuel pumps so I was stumped. Long story short I found a check engine light for the coolant temp sensor.

I'd definitely check your CTS, CPS, TPS and go through fuel pump diagnostics. Your main relay or fuel pump relay could also be on the fritz but if you have a multimeter check everything first before you drop 300 on new pumps and another 500 on all those sensors. Thankfully the coolant temp sensor is only $15.00 from Autozone or O'reilly's etc.

Not only was my check engine light an indicator but also I noticed my idling and stumbling issues would start when the aux fan kicked in. The coolant temp sensor was telling the DME the wrong temp and it was dumping fuel in.