$1 gifted to whoever solves my problem. 325 bucks like a fuckin' horse.

[Savagefurai]

My 88 325 has recently undergone a bit of maintenance. When I got her back on the road, she was running great. About two weeks ago I noticed a minor stumble. This stumble progressively got worse until now, and its pretty much undriveable.
When I first noticed it, it seemed to start at around 3k rpm and would not be dependent on throttle position.
When it got worse in the following days, it became apparent that it was manageable when cold but got progressively worse as it came to temp, at which point it became horrible.
Then we come to today, where it is now doing this even at cold temps.

When it happens it feels like its coughing or stuttering at light throttle and a very jerky, hardcore stumble at wot. It will hunt at idle which is generally around 1k rpm.

I have recently replaced the following
Tps
Cps
Afm
Injector harness
Throttle body gasket
Fuel pump
Fuel filter
Fpr
All new relays
Cleaned and checked c101
Tested DME
Blower motor resistor
Evap canister thing behind tps under throttle body
Checked grounds and contacts @ battery

Another issue that may or may not be related is that my #10 and #20 fuse keeps blowing and I have no gauges, power mirrors or blower. Aux fan does work tho...

Any help would be very much appreciated as this is my main transportation and I'm stumped.

Whoever finds the problem gets $1 gifted to their paypal.

Thanks guys.

[bmwm42]

Shitty engine wiring harness......has a break somewhere is my guess

[Dphraner]

check and clean all the grounds. could be the issue.

[kylelauffer]

It sounds like you covered all fuel stuff. And air. I would try new spark plugs spark plug wires rotor and cap. When is last time those replaced? Any custom coputer chip? And when you replaced throttle position is it adjusted all right? All vacuume lines in good condition?

[Savagefurai]

check and clean all the grounds. could be the issue.

Grounds have all been removed, wire brushed and rechecked.

Shitty engine wiring harness......has a break somewhere is my guess

It a new harness. It better not be shitty for what I paid for it. :/

It sounds like you covered all fuel stuff. And air. I would try new spark plugs spark plug wires rotor and cap. When is last time those replaced? Any custom coputer chip? And when you replaced throttle position is it adjusted all right? All vacuume lines in good condition?

I forgot to mention that the entire dizzy cap and rotor assembly is new as well.

The plugs are fairly new and were double checked to be gapped correctly but they are about a year old so I will definitely go ahead and replace them.

Tps is working correctly and clicks at wot and closed.

No chip. Just stock. I even got an extra dme to check with.

As for the plug wires, I'm not sure. I replaced those about two years ago and they look to be in great condition.

I have gone over my vacuum lines multiple times and can't seem to find any cracks or breaks. All the hose clamps are tight as fuck.
Then again, it doesn't hurt to check again...

[arthb7]

Try changing the idle control valve module. Its behind the ECU on the passenger side has a green plug.

[bmwm42]

Move your harness around I had the same issue and came to be a faulty harness I stumbled upon it by accident

[Savagefurai]

Try changing the idle control valve module. Its behind the ECU on the passenger side has a green plug.

I think i do need to replace the icv. Unplugging it at any temp does nothing for my idle and even when it is plugged in, it doesn't hum at all. I still haven't tested its resistance; I can't seem to find a consistent number for telling if its good or bad.

But what else besides the icv does that module control and how do I test it?

[Savagefurai]

Move your harness around I had the same issue and came to be a faulty harness I stumbled upon it by accident

Beleive me, I have been all over that harness and nothing. Juggle this and wiggle that; the same problem.

[bmwm42]

If you had a working icv you would notice it right away just by unplugging it cause your idle would surge another thing to check its the cold start injector?

[Savagefurai]

If you had a working icv you would notice it right away just by unplugging it cause your idle would surge another thing to check its the cold start injector?

Yeah, I will be picking up a good icv to test with tomorrow but I suspect that will only solve part of the problem since it has drivability problems as well as a surging idle.

As far as the cold start injector goes, I haven't messed with that at all.
Doesn't it only engage until its up to temp?

[Savagefurai]

So here's my list so far...
I will change the icv and cold start injector (bmwm42),
Icv control module (arthb7), plugs and wires (kyleauffer), and my o2 sensor. You're all in the pot for a shiny, digital dollar. ;)

[Pdxseth]

It's not the cold start injector you can run it just fine without it. It will just take a little longer to start in the morning.


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[Savagefurai]

It's not the cold start injector you can run it just fine without it. It will just take a little longer to start in the morning.


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That's what I had thought too.
After a bit of research I get both answers tho.
Some say it won't start at all at cold with a bad cs injector but then some people say it will, just after ages of cranking.
May as well replace it anyway.

[Chuck C]

My money is on ignition. Have you checked primary and secondary connections at the coil and dist. cap? You said the cap/rotor are recent, but I would look at them, as well as spark plug boots. You're not going to get a running condition problem like yours from a cold start injector.