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

[BonnschE30]

The c191 is the round plug below the manifold on late models (88+??) that connects the fuel injector, engine coolant temperature, temperature gauge to the main wiring harness. The general consensus seems to be that moisture and other elements seep in over time and cause a bad connection. The result is erratic engine behavior presumably caused by the coolant temperature sensor, which controls timing, fuel, and other essential ingredients in producing smooth, reliable running conditions.

I haven't yet pulled back the rubber on the harness to plug connections, honestly I hadn't even thought of that. I just examined the pins and they do have that light green copper look to then. Originally I scuffed them with sandpaper and used dilectic grease, but my issues are still present. They are random at best (sometimes my car runs perfectly) but when they do pop up...my car dies instantly abs I'm stuck pushing it through traffic to the side of the road. I'm thinking a hardwire will be in the near future...

I like the process of elimination idea, but unfortunately I don't have a disposable income to use troubleshooting parts.

To answer the question above...I'm using m50 green top 17# injectors, not s50. Supposedly the spray pattern is the only difference (4 pintle vs. 1??) which is said to possibly increase engine efficiency.

[BonnschE30]

So I completed the aforementioned repairs (new O2 sensor, valve cover gasket, m50 injectors, fuel injection harness, resealed intake) and once the car got fuel pressure it fired right up! Idle still reads low on the tach, but was steady. No more code 1223 for coolant temperature sensor. After letting it run, I could see there is definitely a misfire. Sounds okay at idle, but under load it has a major lack of power and sounds a bit like a Subaru. Shut it off for awhile, started it again only to have it fire right up and then pull the old wandering idle trick again...

I'm pretty sure the misfire has to be related to the injectors. I put a screwdriver to them and listened for clicking and although it was audible on all, some sounded a lot clearer than others. Pulled plug wires while running, all of them put a drag on the engine and made it seem to want to die. Removed the plugs and nothing looks seriously off. 5 and 6 look kinda lean, but I'm at a loss for now....

No more time to work today, next chance will be Wednesday. Any ideas on where to look next? Thanks!!!!

[jlevie]

Let me see if I have this right. The engine had problems which you still haven't fixed, so you changed to M50 injectors. If anything that will just aggravate the problem that was there.

Go back to the stock injectors and find a place that can run a smoke test. While there can be other causes of what the engine is doing it is pointless to investigate those until there is no possibility of intake leaks.

Once the engine is running correctly you can get a chip for those injectors and install them. I assume they are used, which means that you need to have the professionally cleaned and flow tested before installation.

[BonnschE30]

To clarify, the engine had problems that I attempted to fix which were stated in parentheses in my last post. The addition of the m50 injectors was more of an experiment than anything else.

However I did take jlevie's advice and swapped back to the m20 injectors and the car is starting, idling, and driving really nice for the time being. Hoping things stay this way and I do intend to perform a smoke test on Saturday just to be sure there aren't any vacuum leaks in the system. Plus I'm going to have the AC inspected for leakage before summer heats up too much.

To summarize, I'm almost positive my poor (and sometimes unreliable) running conditions were caused by a faulty c191 connection in conjunction with bad valve cover gasket. The connection had been exposed to coolant when I had a mystery leak from the throttle body heater gasket being bad and dripping on and into the c191. I'm assuming the glycol advanced any corrosion already present.

A used injector harness from an e34 removed the 1223 fault code and for now seems to have the coolant temp sensor functioning correctly and an new oxygen sensor seems to have helped as well. Aside from checking relays, CPS, and fuel pressre, the c191 on these cars is probably a safe bet to look into. I'd also recommend replacing the o2 on any car, much less e30, that doesn't have documented mileage on the part. Its easy to cheap out on this part and I'm guilty of doing this on several cars in the past as well.

There will always be lots of maintenance and troubleshooting, but that's just part of owning and loving these cars. Never-ending list of little things that keep it fun (or annoying as hell) now includes having m50 injectors cleaned and flowed and a chip to run them too. But I'll need to read up on that as well...