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**ForcedFirebird** · 06-19-2020, 05:58 AM

Stock ECU? If it runs the same with the AFM unplugged in a stock ECU, then there is something major wrong. Typically the car will idle and stall as soon as any throttle input is suggested.

Check the c191 wiring if you have it, but depending what month the donor engine harness came from, you may not have that troublesome plug.

**Tinkerer007** · 06-19-2020, 10:16 AM

Originally posted by ForcedFirebird View Post

Stock ECU? If it runs the same with the AFM unplugged in a stock ECU, then there is something major wrong. Typically the car will idle and stall as soon as any throttle input is suggested.

Check the c191 wiring if you have it, but depending what month the donor engine harness came from, you may not have that troublesome plug.

The donor 325is car is pre 9/87. I think manufacture date is 12/86.
Do the early cars have the c191?

**ForcedFirebird** · 06-19-2020, 11:32 AM

Correct, the c191 came with the coolant system change, but also many parts have been swapped in these cars over the years, best to check manually.

Is the ECU stock, with only 19lb injectors being changed?

What are the specs on the motor? High compression? What camshaft?

All this will affect the ECU's ability to run the engine correctly. For example, if you just changed the injectors to 19lb from 14.5lb (without a matching chip), you are going to run very rich during warm up, even if that's how much fuel the engine needs during operation (and may even be lean at temp).

With all the swapping around, were all the connections checked? How did the 87 run? There's so many things changed at once, and the details are vague. It's already difficult to diagnose remotely, even harder when there's so much going on that's not original. ;)

**ForcedFirebird** · 06-19-2020, 11:34 AM

To add: I see you checked the injectors with a noid light. Unbolt the fuel rail, lift it up from the manifold and make sure they are actually spraying. The noid will only tell you if the ECU is sending an electrical signal, not if the fuel is physically spraying out. There's been a lot of threads here lately where members had injectors cleaned (or bought them cleaned/rebuilt) and they are getting stuck closed.

**Tinkerer007** · 06-19-2020, 12:42 PM

Originally posted by ForcedFirebird View Post

Correct, the c191 came with the coolant system change, but also many parts have been swapped in these cars over the years, best to check manually.

Is the ECU stock, with only 19lb injectors being changed?

What are the specs on the motor? High compression? What camshaft?

All this will affect the ECU's ability to run the engine correctly. For example, if you just changed the injectors to 19lb from 14.5lb (without a matching chip), you are going to run very rich during warm up, even if that's how much fuel the engine needs during operation (and may even be lean at temp).

With all the swapping around, were all the connections checked? How did the 87 run? There's so many things changed at once, and the details are vague. It's already difficult to diagnose remotely, even harder when there's so much going on that's not original. ;)

It is a stock ECU from the '87 325is.
The first time we started it the #6 injector was stuck, and didn't activate the Noid light. But, when it runs well, it is not missing on #6. It is smooth.

10:1 compression.
272 camshaft
The '87 ran well before being rear ended in stop and go traffic.
The '86 had an undiagnosed problem where the engine stopped running. It died at a stop light, I was able to restart, and it ran crappy, and died again at a stop light. So I towed it the few blocks home.
(I wonder if it could be the same issue...)

My mechanic was pretty thorough with the wiring and hoses. Although, there is an extra wire that we thought was for the AC, but the AC comes from the right front body. There are three wires that go across the front of the engine: Oil pressure, Crank sensor, ???

Thank you for the questions. I understand that it is difficult to troubleshoot over the internet. So, I really do appreciate your comments and questions.
I will check the spray pattern of the injectors. (But the fact that it can run smoothly at 80 MPH indicate that the injectors are not stuck closed?)

**ForcedFirebird** · 06-19-2020, 01:23 PM

Do a fuel volume test. The fuel pump needs to be able to put out about 1 liter/quart in about 15sec. Sometimes you can have adequate pressure, but not volume (indicating worn veins in the pump).

Also, the '87 (and 86) came with lifter low pressure (high volume) in-tank pumps, then an external high pressure pump to feed the engine. They both need to be checked.

Finally, check the EVAP system. If the fuel tank is becoming pressurized (or vacuumed out) due to a clogged vent line, it can cause weird issues as you describe (EVAP issues took us out of a 14hr race one year). There's several lines under the passenger rear fender well cover, going to the tank that easily get clogged - also a hard line that runs to the front of the car, then transfers to a soft line to the charcoal canister. Easy test - run the car with a fuel cap off so no pressure/vacuum can build.

Yeah, if the previous engine ran bad, very well could be related if there's a bad ground, fuel line, pump etc.

Honestly, if you still have the 87 stock injectors, I suggest put those back in until you are finished diagnosing. Just one less thing that's NOT stock to worry about.

EDIT: One more place to check is the fuel pump sock filter. These tanks are getting rusty as of late, and have seen many of them clog, also causing weird fuel issues.

**Tinkerer007** · 06-19-2020, 08:37 PM

Previously we did check the fuel flow into a milk jug. It filled the jug with about 3 cups in the short time that we had it on. It was our impression that it was plenty of fuel. (I think it was less than 15 seconds.)

I got to the mechanic this afternoon.
I checked the ground for G103 for each car, and the 325is harness had the ground moved to the shock tower (but there wasn't an attachment for that on the 325e so we bolted it to the battery tray).
I puttered around in the engine bay. Cleaned up some accessory fuses outside the fuse box. Took all the relays out and put them in different locations.
Removed the gas cap and went for a nice drive around the block.

Seemed fixed, so I replaced the gas cap and went for a longer drive around the block.
Then it started cutting out. So I removed the gas cap, but still had to limp back to the mechanics.

Here is a video with me holding the accelerator steady, but the RPM cuts out.

BMW E30 cutting out.

https://www.youtube.com/watch?v=1OYXn9344Kc&t=11

Revs are dropping.

We observed the behavior with the noid light on it and all the injectors were triggering. But they cut out when the engine did.
We pulled each plug wire and they all impacted the idle smoothness.

My mechanic did notice a sulphur smell from the exhaust when it is having the problem.

Tomorrow he will try an exhaust gas analyzer to see if it is rich or lean.

Is there a way to convince the ECU it is always cold by grounding the temp sensor? Or plugging in an extra one, but not into the coolant?

If I need to replace the plugs, what would be appropriate to replace it with?

**digger** · 06-19-2020, 11:04 PM

id say that dosnt seem like a fuel issue due to lack of splutter it's like a momentary loss of "electrical power" for lack of better term, the engine rpm arent changing with the tach which goes fairly nuts my guess is trigger issue or perhaps a global igntion issue but id check crank sensor first.

**ForcedFirebird** · 06-20-2020, 04:27 AM

Yeah, I agree with digger. The video makes things so much more clear, it appears electrical. Almost as if the coil lead was being dis/reconnected. The car ignition is staying on, or else the key would need a cycle when it dropped like that.

Check the CPS where the wire goes into the sensor. The wire gets stiff and often will break there, but not completely fail. They also like to scrape on the water pump pulley. There's supposed to be a plastic conduit there for the oil pressure light and CPS wires.

**Tinkerer007** · 06-20-2020, 10:29 AM

Thank you both for your comments.

I do still have the plastic cover over the front of the engine and we worked carefully to route the 3 wires through it.

I like the thought about the coil as that stayed with the the car. The CPS was from the running before crashed 325is. (Although the CPS is old.)
(And these are easier than removing the injectors...)

**ForcedFirebird** · 06-20-2020, 11:15 AM

The injectors don't have to be removed, just the four bolts that hold the rail to the manifold. Then pry up, the whole rail and injectors come up and expose the pintles.

**Tinkerer007** · 06-20-2020, 03:37 PM

BINGO! (I think)

I went and measured the resistance of the CPS on ECU pins 47, 48 and got 545 Ohms.

When I moved the car to the shade, it was in barely run mode.
I changed the coil to the one from the wreck.
And, went for a 35 mile highway drive and did not have any engine cutting out.

Earlier in the day, the mechanic used the exhaust gas analyzer and it is running rich.
RPM HC CO2
Idle 3000 130 - 300
3000 9.2 6.8 - 7.0

Looks like I will be changing to to the M50 injectors I had installed in the 325is.

Thank you so much for all advice.

**Tinkerer007** · 07-16-2020, 04:18 PM

I changed the injectors a week ago. It was not conclusive that it improved the running. Although after moving the wheel on the AFM, I don't need octane booster.

It passed smog today:
15MPH @1645RPM CO2=14.6 O2%=0.1 HC=13 CO%=.05 NOX=0
15MPH @1724RPM CO2=14.7 O2%=0.1 HC=11 CO%=.01 NOX=0

It still has a hesitation at 3800 RPM under load, and then power picks up again after 4100 RPM and pulls well past 5K RPM. This is not exhibited if revving in neutral.

On the gas analyzer, it is rich at idle, but then leans out at higher RPM. He adjusted the AFM to have 14.7 CO2 at higher RPM (and then idle is rich with CO@~1.23%)

Here is what was done to try to resolve hesitation:
Resistor to temp sensor. (To richen it up)
Added adjustable fuel pressure regulator. (To increase fuel pressure)
Tried another ECU.
Adjusted wiper on AFM.

What tools can I use to diagnose this?
Speculating that the crank sensor needs to be replaced.

Could this be seen with an oscilloscope on the CPS signal?

Is there a data logger that can see relevant info?

I still have the e tach installed. Could this be affecting it? Is this where the redline is on the ETA cars?

Any comment on Faucet CPS vs Genuine BMW? ($40 vs $160)
https://www.autohausaz.com/pn/101227...iABEgICMPD_BwE

Oh, and here are the specs for the motor:

2.9 Mahle motorsport stroker

10:1 Compression ratio

M52 Crank ( 84mm stroke)

85mm Bore

Super sport head with performance valve springs and 274 cam

S50 Connecting rods

ARP Rod bolts

ARP Main studs

ARP Head studs

Nuke adjustable cam gear

Pistons have two of the proprietary coatings for smooth operation

total seal rings

brand new pan

The head and the intake manifold have both been polished and ported

**digger** · 07-16-2020, 04:44 PM

what tune are you running?

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