Another Bogging down issue

[completelyrevlimited]

Sound alike an AFM issue. On a bone stock e30, if you unplug the AFM, it will start and idle fine, but die immediately with any throttle response, irregardless if the TPS is even connected.

Easy test. Unplug AFM and see if anything changes. If not, do a sweep test on the AFM. Key on, you should see a voltage sweep as you open/close the barn door. I'm out and about, so can't give you pin numbers from memory.

No worries, I doubt it's that as I do get readings to the DME, and have ran it unplugged with no change. I did have the MAF conversion installed before hand with the same issue though.

Edit: it actually idles roughly.

[ForcedFirebird]

Post # 3

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/alternative-tuning-w-a-r-megasquirt-etc/346553-how-to-wire-gm-iat-to-e30-afm-plug

There's 4 pins active. This looks correct. Disconnect the AFM plug, turn key on. Check volts between pin 4 and 2 on the engine harness.

[hasa]

I am not sure, it dies out after that, I don't believe I've ever seen the battery light and light, etc stay on whenever I've started it in the past. If I try to rev it it dies out instantly.

I'm running in circles here, nothing seems to give me info. Someone said it's possible that the FPR could be giving it too much pressure causing flooding?

I'm at crossroads trying to figure it out. I'm thinking ignition coil could be the issue? Not a strong spark? I've read multiple reports of the ignition coil tests jumping around. I believe my current one reads 2.6k ohms, and so does my original backup one, one is Bosch and the other is NGK iirc. .03-06 on primary.

I'm sorry my answer may sound rude and does not match the Californian polite culture present here, but I truly want to help.... You should do the debugging more systematic.

There are 2 alternative tactics you can follow:

1) Revert all the changes back to the last known and proved working engine setup. Change one part at time towards your preferable setup and see where it fails to work. Don't do any multiple changes to the setup at one time.

2) Test all your relevant engine components one at time. If you see any particular component fails to work, like alternator that does not charge. Repair it / change it to working part. Don't do any multiple changes at same time. Repeat until all parts are working as per OEM specs.

[completelyrevlimited]

I'm sorry my answer may sound rude and does not match the Californian polite culture present here, but I truly want to help.... You should do the debugging more systematic.

There are 2 alternative tactics you can follow:

1) Revert all the changes back to the last known and proved working engine setup. Change one part at time towards your preferable setup and see where it fails to work. Don't do any multiple changes to the setup at one time.

2) Test all your relevant engine components one at time. If you see any particular component fails to work, like alternator that does not charge. Repair it / change it to working part. Don't do any multiple changes at same time. Repeat until all parts are working as per OEM specs.

Not rude at all! I completely agree. I believe I'm doing all the tests sequentially, however, I can not tell if multiple things are going out at once, or if its one big problem all together, that I just can't map out.

Current state of the car is now flooded, which is strange, as now that's the complete opposite of the initial problem. I'll need to check for vacuum leaks again, and ignition coil readings. I've tried number 1 methodology, everything is stock again currently, which was working a while back when I first got the car.

I guess I should ask now, are tests conclusive? As in, my CPS is in spec according to Bentley, however, is it broken still? I'd expect the answer to be no, but I'm also assuming the answer is going to be "it depends" as most things are, and perhaps that's where Im debating if logic, mechanics, and engineering are combating each other, and I should take a less logical approach? "For Example: I assume its logical to assume if the alternator isn't charging, and just running off battery, that ignition can be a weaker spark / missed spark?"

Other questions that I've thought of:
1. Is it true the car does not charge on startup, that I would indeed have to rev it? Is it a sign on a soon to fail part, or is it normal?
2. I've thought about it being the OBC, which I assume could not be the culprit as I have not used that feature in quite some time, and I assume I also have a good OBC, as it has responsive normal like functionality, and the part of me is saying it couldn't possibly "un-wire? un-fuse?" itself to cause that?

[ForcedFirebird]

Alternator needing 1000rpm is completely normal, it's on every car, every make, but modern cars automatically do this for you. I have owned an independent BMW shop for 15yr, and have built/drove hundreds of e30's. I can tell you 100% if you take a stock e30, put a voltmeter on the battery, reach in the window and start the car, your alternator will NOT charge the battery. I have done this very test thousands of times myself, and if you ever drove an e30 race car with a voltmeter on the dash, you see it every time you push the start button.

The only thing OBC does to the engine, is late models have a CODE. You can immobilize the car via OBC, but it's a very simple system where the green ignition coil wire runs through the OBC relay. If that green wire is interrupted, the car will have no spark, as in ZERO. It's an on/off system.

Your fuel regulator is not likely the culprit. It's a very simple device. There's a rubber diaphragm inside that blocks fuel returning to the tank. The vacuum fitting on the top applies more/less pressure based on engine vacuum. Again, this is a part that has either completely failed, or works. Simple test, pull the vacuum line off the regulator and smell it. If it smells like fuel, or have evidence of fuel in the port then the diaphragm is broken.You can unplug the vacuum line from the regulator, cap the manifold side, and the carengine will run normally.

If you go back to post # 54, follow the troubleshooting guide step by step, and report back, it would be very easy to diagnose!

Do you have voltage on your AFM connector at the engine harness?

[completelyrevlimited]

Alternator needing 1000rpm is completely normal, it's on every car, every make, but modern cars automatically do this for you. I have owned an independent BMW shop for 15yr, and have built/drove hundreds of e30's. I can tell you 100% if you take a stock e30, put a voltmeter on the battery, reach in the window and start the car, your alternator will NOT charge the battery. I have done this very test thousands of times myself, and if you ever drove an e30 race car with a voltmeter on the dash, you see it every time you push the start button.

The only thing OBC does to the engine, is late models have a CODE. You can immobilize the car via OBC, but it's a very simple system where the green ignition coil wire runs through the OBC relay. If that green wire is interrupted, the car will have no spark, as in ZERO. It's an on/off system.

Your fuel regulator is not likely the culprit. It's a very simple device. There's a rubber diaphragm inside that blocks fuel returning to the tank. The vacuum fitting on the top applies more/less pressure based on engine vacuum. Again, this is a part that has either completely failed, or works. Simple test, pull the vacuum line off the regulator and smell it. If it smells like fuel, or have evidence of fuel in the port then the diaphragm is broken.You can unplug the vacuum line from the regulator, cap the manifold side, and the carengine will run normally.

If you go back to post # 54, follow the troubleshooting guide step by step, and report back, it would be very easy to diagnose!

Do you have voltage on your AFM connector at the engine harness?

Just got time to do the tests again, and everything is normal. Car still won't fully start again. Runs roughly after starting for the first time in a while, then when I give it gas it dies out. Won't start like it's flooded.

[completelyrevlimited]

Alternator needing 1000rpm is completely normal, it's on every car, every make, but modern cars automatically do this for you. I have owned an independent BMW shop for 15yr, and have built/drove hundreds of e30's. I can tell you 100% if you take a stock e30, put a voltmeter on the battery, reach in the window and start the car, your alternator will NOT charge the battery. I have done this very test thousands of times myself, and if you ever drove an e30 race car with a voltmeter on the dash, you see it every time you push the start button.

The only thing OBC does to the engine, is late models have a CODE. You can immobilize the car via OBC, but it's a very simple system where the green ignition coil wire runs through the OBC relay. If that green wire is interrupted, the car will have no spark, as in ZERO. It's an on/off system.

Your fuel regulator is not likely the culprit. It's a very simple device. There's a rubber diaphragm inside that blocks fuel returning to the tank. The vacuum fitting on the top applies more/less pressure based on engine vacuum. Again, this is a part that has either completely failed, or works. Simple test, pull the vacuum line off the regulator and smell it. If it smells like fuel, or have evidence of fuel in the port then the diaphragm is broken.You can unplug the vacuum line from the regulator, cap the manifold side, and the carengine will run normally.

If you go back to post # 54, follow the troubleshooting guide step by step, and report back, it would be very easy to diagnose!

Do you have voltage on your AFM connector at the engine harness?

Also, according to Jim I should have 13.5v on idle. https://www.r3vlimited.com/board/for...=3#post6384144

[ForcedFirebird]

After the alternator is excited, sure. Here's a video I took at work morning of me starting an e30 with a voltmeter attached. As you can see, the car runs off battery voltage until the engine is revved, what you are experiencing is 100% normal as far as charging: https://www.youtube.com/watch?v=PcvryW5eDus

Did you have voltage at the AFM connector? If so, how much?

Does it act the same if the AFM is unplugged?

[completelyrevlimited]

After the alternator is excited, sure. Here's a video I took at work morning of me starting an e30 with a voltmeter attached. As you can see, the car runs off battery voltage until the engine is revved, what you are experiencing is 100% normal as far as charging: https://www.youtube.com/watch?v=PcvryW5eDus

Did you have voltage at the AFM connector? If so, how much?

Does it act the same if the AFM is unplugged?

Still is very hard to start, no change with AFM unplugged. Still flooding a lot.

Checked 4 / 2, I spent quite a while looking for the AFM page to find it was on this page.

I get .8 volts between the two. And get a ohm value of 39.8 between 4 / 22

[ForcedFirebird]

With AFM unplugged, key on. Red wire to brown wire on engine harness should be battery voltage.

The 5 pin Bosch connector has a rubber boot on the back. Carefully peel that away and you expose the crimp side of the factory pins. Often times, you will see a green blue cheese like corrosion.

[completelyrevlimited]

With AFM unplugged, key on. Red wire to brown wire on engine harness should be battery voltage.

The 5 pin Bosch connector has a rubber boot on the back. Carefully peel that away and you expose the crimp side of the factory pins. Often times, you will see a green blue cheese like corrosion.

I'm confused by the asking? That would be pin 18 on the harness right? I have voltage on there from battery. Do you know the names of the pins from the layout? I'm assuming you meant that pin. But not sure what the brown wire would be?

No corrosion seen on any cables, car has been in good condition from when I bought it, besides a few spliced rubber sleeves which nothing a little liquid tape fixed :)

[completelyrevlimited]

I did also redo a compression test, 120 on two cylinders. Assumed that a dead battery could cause the minimum compression on it (starter wasn't spinning fast enough), also read it didn't need exactly high compression to start.

I'm assuming a flooded engine could of leaked down the cylinder walls. I use Zr1 oil from Valvoline.

[ForcedFirebird]

120 is fairly low. Put a few drops of oil in the low ones, if the compression comes up, then the rings are washed, if not then could be leaky valves and/or fire ring in the head gasket.

Good read on how the AFM works: http://e28-535i.com/technical/AFM%20Repair.pdf

Reason for testing the voltage at the wire harness, if there's too much resistance, input voltage will be wrong resulting in wrong output values to DME.

Your symptoms sound like the AFM signal is bad/missing, the DME cannot run the engine without it. It's further suspect since the results are the same if it's unplugged.

The Motronic is quite simple and will run/rev with only a two sensors |(three if you count the IAT inside the AFM). Crank sensor and AFM is all the inputs "needed" to start and free-rev an m20 on Motronic. The absence of blue coolant sensor will skew the fueling, o2 unplugged keep it in open loop, TPS unplugged just puts the DME in the "part throttle" map, brown coolant sensor goes to the gauge cluster, the # 6 cly identifier doesn't affect running at all (we leave them off the race cars), all of them can be unplugged and the engine should start and rev fine.