random high idle + stalling/(no start) = unreliablilty

[BonnschE30]

I have an 89 325ix. Stock m20 with new gaskets, waterpump, relays, filters. etc. Basically the same mechanical repairs we all do to keep our e30s alive and kicking.

When I first put my car on the road last spring ran great! Little by little I've been battling a stall/no start issue and its been driving me bonkers. It started last summer with bogging, no throttle response, dying and then failure to restart. Noticed a crack in my CTS wiring, soldered it, taped it, ran alright.

More issues so I cleaned the crappy intake manifold connector c10-something. Still don't completely resolve my problem. Within the last month my idle has started surging at weird times, usually in traffic, up to about 2500 rpm and even to 4000 once. After this high idle, the car typically dies and refuses to start. Sometimes for hours at a time.

I have a new CTS, new CPS. A different ICV didn't solve my problem. It may also be worth mentioning.g that the car has random hard starts and an unstable idle at start up at times. Other times it fires and idles perfectly.

I'm going to check fuel issues over the weekend. Cranking and idle pressure, FPR, and injector pulse. Then resistance for CTS, ATM, ICV, TPS.

Where else should I be looking? I'm beginning to believe my DME is bad? Although it may be difficult to source a known working IX unit due to ABS issues. Would I be able to swap a 173 without much complication? I have one in the garage.

Just wanted to open up my issue to the community in hopes of eliminating my unreliability issue. I hate being scared to drive my car. Thanks guys!

[dnguyen1963]

Random surges, hard start, or unstable idle are often the result of a major vacuum leak. Time for smoke test.

[jlevie]

Yep, the first actions should be a smoke test and a fuel pressure check.

[BonnschE30]

Going to test the fuel pressure and FPR after work today, assuming it starts up and gets me home. I also assumed a smoke test suggestion would pop up early...is this something most local shops are able to do?? I live in a pretty small town, but will call a few places to see if I can get an appointment.

[BonnschE30]

Fired up on the first crank....wandering idle and backfiring/popping sound with the smell of fuel. Idling at 800 a bit rough. Let's see if it makes it home...

[noE30]

I have the exact same issues as of lately.
All new gaskets, cleaned icv, new fuel filter and pump, coolant temp sensor etc. Let me know what you find out.
I think I'm going to try get the car in to my families mechanic and see if he can run a smoke test on it.

[BonnschE30]

Thinking it is still CTS related. Throwing code 1223....I wiggled the wiring where it had been soldered and the problem seemingly went away. Weird start up and wandering idle is still an issue, which seems indicative of a vacuum as well.

I know the contact on the solder is good and the coolant temperature sensor is new, but I did use a female plug from the fuel injector of a scrap harness. Think this would be an issue? My money is still on the intake manifold plug (c103??) and I'm considering hard-wiring this to bypass the connection as I've cleaned it up to the best of my ability.

[BonnschE30]

A couple other issues worth mentioning:

-Idle seems to be pretty low (gauge is reading 250rpm)
-Disconnecting ICV doesn't change anything whatsoever
-Unplugging any plug wire while running bogs and then kills the engine

[UserError]

The motor won't hold an idle at 250 RPM. Crank position sensors tend to go out on our cars, Might want to swap in a known good one, and see if the issue goes away.

[BonnschE30]

Yeah that's what the gauge reads, but surely it would be higher. Crank Position Senso is 8 months old, but I suppose that means nothing.

[chappys4life]

Any luck getting this straight? Think I'm experiencing some similar issues.

[BonnschE30]

In the process of replacing my injection harness, new O2 sensor, and installing m50 green tops. Looks like a slight oil leak at the dipstick which may indicate a vacuum leak.

I'm in the middle of a front axle re-boot and wheel bearing job on the IX, so I'll probably work more on getting it to run flawlessly once those issues are corrected.

[BMWManiac]

Good luck on this and I will be following this thread. Seems like this "issue" is consistent with the M20 E30s. I have a similar issue with mine to the point where over the course of a month, the driveability got worse and now it won't even run right.

I've replaced CPS, main relay, fuel pump, fuel filter, plugs, cleaned ICV.

Next up, replacing ignition coil, ignition wires, air filter, AFM, intake gaskets, all vac lines, clean the C101 connector, m50 fuel injectors.

As I replace one, I'll see if that corrects the problem and will post it as well. I also will do a valve adjustment.

[tim88325is]

Did you pull the boots off the C-191 (under intake) connector? The corrosion might be under the rubber boot on the "backside" of the pins (where the wire and pin join), not what you see when you separate the connector.

Hardwiring this connector solved a LOT of problems for me.

Before moving onto bigger/expensive items like the DME, I would rule out the intake leaks and wiring corrosion issues. My problems always seemed to be a "small" issue, not a major DME failure, fuel pump failure, ect. I actually have a brand new fuel pump sitting on the shelf because I thought that was the cause of hard starting/stalls but fixing the C191 was it for my car.

[chappys4life]

Where is the c191 and what is it. why are s50 injectors being used instead of the stock m20?