1989 325i surging idle w/ video

[DinoSZ]

I have a 1989 325i that has a surging idle that I cannot fix. I've changed the 02 sensor, coolant temp sensor, icv, intake boot, misc. hoses...to no avail. In the video, I have not touched the throttle at all. I have sprayed starting fluid around anything that can create a vacuum leak...nothing, everything looks good. When the engine is cold, it does the same thing, but, it is more pronounced when warm as seen in the video. HELP! I don't know what else to check. I want to add that I did check the TPS and it checked good. Any suggestions? Thanks!

http://www.youtube.com/watch?v=EJKLOJJcgs8

[jlevie]

Have a smoke test run on the intake. I'll bet on there being intake leaks that you can't find with carb cleaner.

[DinoSZ]

Can a bad TPS cause this problem?

[jlevie]

A bad or misadjusted TPS can cause an unstable idle, as can serveral other things. But intake leaks are the most common cause. There are a number of possible leaks that can't be detected visually or with carb cleaner, but they will be found in a smoke test. Until it is proven that there are no intake leaks it is pretty fruitless to try to solve the problem by working the other possibilities.

[DinoSZ]

A bad or misadjusted TPS can cause an unstable idle, as can serveral other things. But intake leaks are the most common cause. There are a number of possible leaks that can't be detected visually or with carb cleaner, but they will be found in a smoke test. Until it is proven that there are no intake leaks it is pretty fruitless to try to solve the problem by working the other possibilities.

Thank you very much for taking the time to respond. I guess I will have to find a place to get a smoke test done. Would any garage be able to perform this or would I have to find a BMW specific garage to do the work?

[jlevie]

The test is appropriate for any make of car with EFI. So it is mostly a matter of finding a shop with the equipment rather that needing a BMW shop.

[DinoSZ]

Smoke test indicated a throttle body gasket leak. When I removed the throttle body, the bottom half of the gasket was missing. While I was in there I changed out the TPS. Hoping that fixed my problem, I started the car up and still the same. I was able to do the stomp test since I put in a new TPS and I got the code 1223 which is the coolant temp sensor, which I have changed already...HELP! What can I check as far as the wiring and such.

[325e10]

Have you checked the afm?

[DinoSZ]

Well, after replacing half a dozen components, I've finally fixed it! While chasing the wires from the CTS to the C191 connector, I noticed that there was a broken wire in the connector. Had to replace 3 of the wires in there! Anyways, thanks for everyone's help! Just wanted to report in just in case someone has a similar problem.

[rcfanatic]

Well, after replacing half a dozen components, I've finally fixed it! While chasing the wires from the CTS to the C191 connector, I noticed that there was a broken wire in the connector. Had to replace 3 of the wires in there! Anyways, thanks for everyone's help! Just wanted to report in just in case someone has a similar problem.

Where exactly was the broken wire?

[DinoSZ]

Where exactly was the broken wire?

The broken wires were in the connector itself, the ones with the female ends on the harness from the c191 to the ecu. I spliced in new wires with new female pins in the cannon plug.

[Cloudbase]

I have an '89 with the exact same idle problem. I've replaced almost every vacuum hose, throttle body gasket, ICV, TPS, clean the AFM wiper, and ECU. My CTS has a jerry rigged connector. I pulled two original connectors from the junkyard and got my new CTS's today (ECU one and Gauge one). Keeping my fingers crossed!