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00 740i - rough idle

7321 Views 11 Replies 7 Participants Last post by  Inspector 7
I bought a used 740i three weeks ago which ran perfect when i bought it. Passed California smog with flying colors. After about 2 weeks i got a rough bumpy idle and it threw a p0011 code for cps bank 1. Replaced cps,plugs and valve cover gaskets to eliminate oil on plugs. Reset engine light and now have a p1344 code for coil cylinder 2 misfire, still has bumpy idle. Cleaned maf and throttle body and replaced coil for cylinder 2. Idles at 6-700 rpm, runs rough or perfectly smooth at will, cold or hot, maybe the idle control valve? Need advise on what to check next.
Thanks wmolter
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Throttle position sensor? Elec plug half out or a pin pushed in? Slowly check all connections for physical security and connectivity. Use switch cleaner and fit / defit the plugs several times to clean the contacts.
Thanks for the advise - I'll give it a try today !!!
2000 740i rough idle

I cleaned,inspected and sprayed connectors as suggested. Then the car ran really bad and the dash display coded engine fail safe program. After a few restarts it's back to just running rough at idle again. This car is tricky and i'm starting to think TPS or throttle body ?? The last code was p1344 misfire cylinder 2. (all new plugs and coil for cylinder 2 no change)

Vac leak

Already tried vac leak test with brake cleaner. No change in idle at all !!
I't strange that the engine acted like it did after cleaning the connectors though. Frustrating car !! If I raise the rpm as little as 200 rpm the roughness is almost gone. I'm thinking that spraying elect cleaner on the throttle switch contacts may have caused the increased rough running symptoms. Just don't know ???
Is the TPS correctly adjusted? The setting is in the w'shop manual. Basically a switch is in one state at idle and changes to the other as soon as the gas pedal is touched. Is the throttle cable too tight? Throttle body can be cleaned with carby cleaner and compressed air. Idle control valve may be worth a good look too..
A 00 is "drive by wire" there is no throttle cable or idle control valve (idle control is done with the TB by the ECU). Its all one unit on the TB. I dont believe the tps is adjustable either. You have to replace the whole unit. I think there about $80 from EAC. Do you get any TPS or throttle codes?
Where is the throttle position sensor?

War Machine
Check timing. How are the chain tensioners and guides?
i would not know, how do i check the tensioners and guides?
Wmolter (or others), i was wondering if you had any resolution to your rough idle problem. I have the same issue, but is sporadic (rough idle occurs 1-4 time per week) I have changed out the ccv and checked and replaced vac lines as needed, cleaned out the maf, changed plugs. In my case its cylinder 5 misfiring, i also swapped coils to see if one was the culprit with no avail (all ones that i swapped where good)
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