Introduction and some problems with bucking/surging at 4k.

[sage]

Hello all. I recently purchased a 1990 325is and enjoyed the brief driving I have done with it. I've owned an e36 and currently own an e46, and I can understand why the e30 is sought after.

Here's what's going on. The day after I purchased it, it was exceptionally cold and wet. It wouldn't start in the cold; I had to park it in the sunlight a few hours and tried again succesfully. Later that day, it idled a bit rough and it would drive as if some kid were learning how to drive manual. It would buck and surge while in gear. Everytime it did this, the CEL would turn on and off. It seemed to improve as the engine warmed up, and I decided to go straight to my mechanic friend (who I trust). On the way there, it would only buck at around 3800 rpm. By the time I arrived (about a 10 minute drive) the CEL was always on. Mechanic said it was a bad cap and rotor. We also changed the plugs, fuel filter, and the oil. Started up right away, idled and drove smoother, except that it would exhibit the same symptoms a bit higher in the rpms, around 4500. The CEL is still on and the code is 1232, a throttle idle switch. My mechanic friend looked it over last night and says everthing seems fine but it the ECU that is malfunctioning.

Is the ECU malfunctioning common problem? Is the throttle idle switch the same as the TPS or ICV? The car seems drivable for the time being as long as I don't rev up too high, is this okay?

Oh, and another thing, when rev matching to downshift, sometimes there is little/no throttle response and so I have to hit it again.

I've searched through similar threads on the site, but none have had the CEL code 1232 issue.

Any input from you guys would be greatly appreciated.

Thanks.

[rede30]

could this be caused by the icv? I dont really know whats linked to cel 1232 other than somethign with the throttle. ECU's can go bad but its never a first guess from me.
ps. welcome to the forum and are you sage francis? lol

[jlevie]

Check the TPS and see if the idle switch opens when the throttle arm moves just a bit off the idle stop screw (the spec is that it should open with 0.020-0.040" of movement). If the switch is operating properly you'll need to check for shorted wires. If neither the switch nor the wires are at fault the DME is the cause. Fortunately they are pretty cheap with used ones running $50-75.

[sage]

The mechanic believed it was the ECU from checking the voltage at the components in question and at the ECU.

But now, for whatever reason, the car has magically fixed itself. And I've been redlining it all day long with no problems. What gives? It is very slightly warmer today than the past few days, if that makes a difference.