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I had a busy day outside of the garage but i was able to finish up the last items that I needed to do before putting the intake manifold on. This mostly consisted of getting all the power steering limes situated. The adapter i bought for the pump worked out, i had to shorten both low pressure lines for the new PS reservoir location.

The low pressure line that connects to the rack was not going to allow the hose to connect to the reservoir. I pulled this banjo fitting (left) off the spare e36 pump i had and am using it instead of the E30 line (right). It works much better and im happy with my hydraulic line situation, although i dont want to touch them ever again. Hate those things.

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The manifold is torqued down. I just have to connect the icv hose, evap hose, intake/maf, and coilpack ground straps and i will be ready to fire it up. I am at a christmas party now so i will have to finish it up tomorrow around 4p

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It started, its running.... poorly.

The positive: everything is connected properly, no leaks or strange noises that I can tell, lifters are much quieter than expected.

The negative: cylinders 2 and 4 seem to be dead.

Cylinders 2 and 4 have spark so I pulled out the compression tester 🤭 (horrible idea, I know) but to my relief they were both 190 psi. I removed and replaced the injector harness to ensure everything was clipped in correctly and ran it again with no improvement.

Possible issues:

-injectors are bad (they were cleaned and tested, but who knows)

-injector wiring harness is bad

-injector drivers (ECU) are bad

Overall, for all the screwing around involved with the engine swap, cam swap/timing, and obd1 conversion, im happy to at least see that it fires up and runs.

The next time I work on the car I will swap injectors around and see if the problem follows the injectors as well as checking continuity with the injector harness and ecu pins

I will win this

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Just now, jc43089 said:

You could use a screwdriver or stethoscope to see if those injectors are clicking like the others while running.  


I tried a screwdriver and also a piece of hose and I wasn't able to really hear any real contrast. 

 

12 hours ago, Daggerty said:

If you need a noid light tester let me know I'm off the next three days.

I'm a bit in the doghouse for wrenching so much this weekend (ha!), Is this a tool you'd be willing to let me borrow for a week while i find the right opportunity to get back into the garage?

 

I also wonder how much the mixture and old gas has to do with things. I dont have the O2 sensor connected because the exhaust isnt finished and the fuel in the tank is probably a year and a half old.

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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.

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I personally have never had issues with old gas, but I wouldn't rule it out. 

Is your ground coming out of the injector harness "box" good?
Easy enough to crack that case open and check the wiring at the injectors. 
Double check to make sure the plugs are all seated on the injectors, sometimes those can be a bit finicky. 

What spark plugs are you using? 


Glad it's running! I also like your throttle cable! :)

 

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48 minutes ago, GunMetalGrey said:

I personally have never had issues with old gas, but I wouldn't rule it out. 

Is your ground coming out of the injector harness "box" good?
Easy enough to crack that case open and check the wiring at the injectors. 
Double check to make sure the plugs are all seated on the injectors, sometimes those can be a bit finicky. 

What spark plugs are you using? 


Glad it's running! I also like your throttle cable! :)

 

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.

I did re-clip the injectors in because those clips are abominable, no improvement unfortunately, but yes, thanks for the idea of popping the cover off, should make electrical testing a bit faster and easier 

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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

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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.

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1 hour ago, 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. 

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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.

 

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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

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

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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.

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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!)

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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...

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