Not sure what to try now

[a70droptop]

I know that there are a hundred threads on M20 miss and starting problems and I think I’ve read them all and tried many of the suggestions to solve my problem, but none have worked, so I’m asking for suggestions from all the knowledgeable folks on here. Around 3 months ago I was cruising down the highway in my 88 325ic and began to have an irregular ‘stumble’ or sputter every once in a while, I headed for home and by the time I got there; about 15 miles, it would barely run. Now it’s 3 months and nearly everything I can think of or find in the forum later and I’m not sure what else to try. Here’s a description of symptoms and what I have tried … sorry it’s so long.

Current symptoms: starts fine idles normal for a few seconds, then begins to miss or stumble (one time only) every few seconds but not in any regular time span. When it does this the econometer goes up (to the left) and pegs for a split second and the CEL flashes once. When I first turn on the key the CEL is lit before starting the engine and the stomp test doesn’t work. (btw … 173 ECU) Holding the revs at around 2K it seems fine at first then begins the irregular random stumble.

What has been done:

Replaced O2 sensor
Replaced ECU with known good (twice)
Replaced fuel pump, pressure regulator, and filter
Replaced CPS
Replaced AFM
Replaced main, fuel pump, and O2 relays
Cleaned and verified correct operation of ICV on another car
Smoke test, replaced intake boot, crankcase vent hose, ICV hose
Cleaned and tightened ECU and battery grounds
TPS checks out fine at the ECU pin test
New injectors a couple of years ago

I’m stumped! Anybody have any ideas? TPS? ICU? Temp sensor?

Thanks in advance! Phillip

[E30Gus]

Spark plugs
Cap/rotor
Wires
Loose injector connection

[StereoInstaller1]

I would check the connector under the intake manifold. They often get corroded.

[jlevie]

If the economizer drives towards zero in an event but the tach doesn't move, something is reducing fuel flow and the DME is trying to compensate. A common culprit is corrosion in C191 (under the intake). Even though you have replaced the fuel pump, FPR and filter, a check of fuel pressure while driving is indicated.

[KirkerBezerker]

My car is missing right now because of a faulty set of BAV Auto wires. You've already replaced a shit load of parts, might as well do the cap, wires, rotor, and plugs

[scrowner]

I would have first guessed TPS as I had a weird problem where the TPS at idle would change its resistance reading and cause crazy things to the idle. But that jlevie guy pointers are good to start with and if there is nothing obvious with the C191 connector nor the fuel pressure (this requires some purchases and some fuel line setup to get done), then I would replace the TPS. The TPS is cheap or was, and is fairly easy to do. Hell, just do this first before the fuel pressure check.

[a70droptop]

My car is missing right now because of a faulty set of BAV Auto wires. You've already replaced a shit load of parts, might as well do the cap, wires, rotor, and plugs

I started to reply that I had changed wires cap rotor plugs a year or so ago but I put BAV wires on mine too. Maybe they're the problem. I'm gonna check the C191 plug first though, I had trouble there several years ago, then the fuel pressure.

Thanks everyone for the great ideas ...

[KirkerBezerker]

Well I should've been a little more clear: one of my cars POs put a set of bav auto wires on but didn't take the caps off the spark plugs. So he forced the wires over the plugs and when I took them off they all felt apart to pieces. And because the wires were all bent up it would arc and misfire or pre ignite

[nando]

bavauto wires are crap. You wouldn't be the first person to report severe issues with them.

bremi wires are a good alternative, as good as OEM quality and look nice too.

[nando]

Well I should've been a little more clear: one of my cars POs put a set of bav auto wires on but didn't take the caps off the spark plugs. So he forced the wires over the plugs and when I took them off they all felt apart to pieces. And because the wires were all bent up it would arc and misfire or pre ignite

there are people who've had them arc over without being installed improperly. On my first set the plug ends fell apart before I could install them. Then one of the wires broke right at the end of the boot. Ended up hacking them apart and using them for another project.

given that there's absolutely no benefit at all to the + sized wires, stock or OE wires make the most sense. Much better quality.

[HR2L]

bavauto wires are crap. You wouldn't be the first person to report severe issues with them.

bremi wires are a good alternative, as good as OEM quality and look nice too.

Agreed. I just picked up some Bremi Wires for my ignition overhaul and was impressed with the quality of the wires. Looked exactly like OEM! Car felt like a new beast after replacing my Rotor, Cap, Plugs, Wires, Coil. :)