Aftermarket Chip Question

[325iCabrio]

I did a quick search and didn't find anything, so I thought I'd ask. My car's had a rough idle for a long time, and I'm still not sure what the culprit is. It's rock steady at 700 rpm, but it vibrates the car, and it's not supposed to. I'm going to replace a few more vacuum hoses (I've replaced the major ones like the air intake boot), my distributor/rotor, and maybe my ICV. I've already replaced my FPR, and my fuel pump is fine.

But my big question is, would an aftermarket chip help? I read in another post that replacing the Motronic unit fixed their rough idle problem. Since the aftermarket chips adjust the fuel and air mixtures (among other things), I'm wondering, if those replacement parts don't fix the problem, whether that's something I should look into? Of course, it'd be a nice performance boost too. :)

[bimmer2288]

I'm no expert, but I know performance chips are not designed to fix problems with your idle and fuel mixture, they're made to enhance and increase them. I wouldn't suggest a chip until after the car is running the way it ought to. Look for another ECU - that may fix your problem or at least help it out. I had an idle issue where my car would cut out when shifting from 1st to 2nd (auto tranny). I rebuilt the engine with a new camshaft and other parts and somewhere along the way I replaced something that made my idle issue go away.

How long has it been since your last tune up?

[JGood]

Fix your problem first.

Check motor and trans mounts. You may have a bad vibration dampener. Replace plugs, cap, rotor, wires. Is the engine strong or does it feel like it's losing some power under WOT?

[325iCabrio]

That's what I was thinking. I thought maybe it might help, but I thought it might not.

The motor and tranny probably need new mounts, but I've (unfortunetly) got my steering rack to fix first. Here's what I've done to try and fix my idle problem:

Air intake boot
ICV to throttle body hose
Fuel pressure regulator
Cleaned ICV with Seafoam

The car had an Inspection II done at an Independent mechanic about 15,000 miles ago. So it has new spark plugs and the valves have been adjusted. I'm going to buy a new distributor, rotor, and another hose (from valve cover). It probably needs new ignition wires and O2 sensor, but I also need new tires and new steering rack. I can't afford all of it right now. The chip was more a theoretical question that anything.

The engine seems to be strong mid-range, but loses its steam over 5000 RPM, almost like it's missing. When I toe into the throttle while I'm stopped, the car hesitates for a second and then is fine. I've been trying to figure this problem out for a good year, and still haven't found the answer.