E30 M52

[B C]

jc43089 said:

Bad gas could be a significant problem.  Especially if it was not ethanol free.  I would disconnect a feed line and jumper the pump relay to pump it out into a jug.  Then hook the line back up and put fresh gas in and then run the pump with the jumper again for a minute to circulate it.  Then run it again.

o2 sensor isn't a problem for a cold start.

The only deal with the O2 is that I have a custom tune and it hasnt established any fuel trims, but otherwise yes you are right, it isnt a contributor otherwise

[jc43089]

I'm not sure what the learning procedure is for OBD2, for OBD1 I believe it runs on preset tables for cold start always, but I am not sure if it learns and adjusts after "seeing" the engine run at temperature.  You are probably right that with OBD2 it adjusts startup parameters based on warmed up characteristics.

[GunMetalGrey]

Snap said:

Thanks,  and yes, I havent bothered to figure out how the throttle cable attaches quite yet. At the moment it would appear to be too long but its an E34 cable and its supposed to work.

Ahh, you have an M52 Throttle body. 
I have no idea how to do that, or if it works with that cable. The e34 cable is a direct plug and play with the OBD1 throttle bodies. 
From looking at the throttle body it looks like some modifications will need to happen to the cable.

[Jdesign]

YAS!!! 

Coilpacks bad? I would try swapping those suckers around first. Did you ohm them out at all?

[B C]

Coil packs are brand new BMW/bremi units, switched them around, checked for spark, they are good

[Daggerty]

Yes you can borrow it, you know how too find me.

Mb your engine has too much compression.

[Daggerty]

As far as the car using set parameters for warmup that is not true for obd2 it still looks at the input of the sensors and will adjust. It just will do it if it goes out of the 1-6 range instead of the 3-4 range when it's warm. 

Numbers do not represent actual value of a sensor. 

I would at least shove the o2 sensor in whatever exhaust you have. But that isn't your problem.

[HipMF]

Did you remember to take the paper towels out before putting the intake manifold on? 

[B C]

HipMF said:

Did you remember to take the paper towels out before putting the intake manifold on? [emoji3]

You made me second guess myself for just a moment [emoji275]

[GunMetalGrey]

Snap said:

You made me second guess myself for just a moment

You'll realize it when you start shooting bits of paper out of the exhaust. 

Not that I would know....

[B C]

For Ben: Here’s the other throttle I have. It doesnt have a purge valve provision and it has a different cable connection. It does have the o-ring groove on the mating surface. I dont see a part# on it. The casting date stamp shows 96.

All of this 24v stuff is interchangable but different enough to matter

[B C]

Having tackled the mess under the intake manifold last week I am now tackling the mess above the intake

The injector harness checks out good. (Huge relief!) Continuity and resistance on all connectors check out normal, and I even flexed/wiggled the harness while testing in case theres an intermittent connection.

As I checked the ground wire at the end of the harness I noticed a crumbly rectangular block encasing one of the wires. It had electrical tape around it. I removed the tape and crumbly block hoping to find a broken wire and an obvious solution but only found a resistor soldered inline with the ground wire as pictured above.

The resistor tested good, i do find it very strange that a ground wire has a resistor though. Mike, any ideas why this might be?

This leaves me with injectors themselves being bad (who knows, perhaps some junk in the fuel lines/rail jammed them up right away on first start) OR the ECU being bad.

I didn’t see any burned components inside the ECU when i took a look and no broken solder joints on the injector drivers, but I should have another ECU to try out sometime soon (thanks Kaiser!)

[HipMF]

You really took the wind out of my sails by posting the resistor value... Memorizing the resistor color code is one of the few skills I picked up at my last job.

A resistor in series with the injectors would limit current through then circuit. It's a bit of a mystery to me why they would want to do that, but my guess is that the DC resistance of the injector when it's on might be too low for the driver circuit.

Electrically, an injector is an inductive load. Inductance resists a change in current flow through a circuit. So, if you want to turn the current on and off very rapidly, you need to keep the inductance low. In practice, inductance, resistance and magnetic force are all related. So my guess is that to get a high enough magnetic force to open the valve of the injector (which has fuel pressure pushing it closed), and get the injector to open and close very quickly (which means changing the current flow very quickly), they had to lower the inductance (and in turn, the resistance) to a point where, when the injector is fully "on", the DC resistance is too low for the driver circuit.

Kind of shooting from the hip here, but that's my best guess. Putting the resistor in the harness instead of the ECU means you can change the injectors after-the-fact without having to rev up the ECU, not to mention that it probably generates a fair amount of heat...

[B C]

[emoji16] I knew you would have the resistor color codes memorized.

[HipMF]

Yep, I used to program, run and maintain a Universal axial inserter.

She was a blast from the past. The computer that ran the thing was the size of a microwave oven and only slightly more powerful than a Commodore 64 (not even exaggerating). Crazy high-tech stuff by late 80s standards, but I left tech school in 2011...

[GunMetalGrey]

I'll have to double check the harness I have laying around, but I don't think I've ever seen a resistor in the injector wiring. 
In regard to your throttle bodies, I'm not sure how to connect the throttle cable to those, I believe those types used a ball end instead of the kind you are used to.

[B C]

GunMetalGrey said:

I'll have to double check the harness I have laying around, but I don't think I've ever seen a resistor in the injector wiring. 
In regard to your throttle bodies, I'm not sure how to connect the throttle cable to those, I believe those types used a ball end instead of the kind you are used to. 

The gray block in line with intake runner #3 is the resistor is. The gray encasement is some sort of clay or ceramic

[Jdesign]

HipMF said:

You really took the wind out of my sails by posting the resistor value... Memorizing the resistor color code is one of the few skills I picked up at my last job.

A resistor in series with the injectors would limit current through then circuit. It's a bit of a mystery to me why they would want to do that, but my guess is that the DC resistance of the injector when it's on might be too low for the driver circuit.

Electrically, an injector is an inductive load. Inductance resists a change in current flow through a circuit. So, if you want to turn the current on and off very rapidly, you need to keep the inductance low. In practice, inductance, resistance and magnetic force are all related. So my guess is that to get a high enough magnetic force to open the valve of the injector (which has fuel pressure pushing it closed), and get the injector to open and close very quickly (which means changing the current flow very quickly), they had to lower the inductance (and in turn, the resistance) to a point where, when the injector is fully "on", the DC resistance is too low for the driver circuit.

Kind of shooting from the hip here, but that's my best guess. Putting the resistor in the harness instead of the ECU means you can change the injectors after-the-fact without having to rev up the ECU, not to mention that it probably generates a fair amount of heat...

At that, if you said the harness tested alright, and you check the injectors, I would say the ECU. I ran into a similar scenario and it was bad capacitors inside the ecu. Old aged  potting material seeping or cracking out would cause super random injector feed issues. Sometimes only under load.

[B C]

“Why do I need a compruter? What does a compruter look like? What does a compruter even do?

I dunno

Who cares?!?

For your swap, ya dangus”

[Jdesign]

Snap said:

“Why do I need a compruter? What does a compruter look like? What does a compruter even do?

I dunno

Who cares?!?

For your swap, ya dangus”

That was almost more hardest to read that of my post above yurs.