911 3.2 to 3.4 conversion; engine not running

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I thought I post a brief summary of my rebuild. Also I have hope for assistance to get this engine to actually do what is was supposed to do - at least that was the plan
It all started long long time ago - some time I don't even remember anymore. What I do remember the engine was actually running. So my rebuild thread could also state: "How to turn a 3.2 running engine into a 3.4 non-running engine
So to summarize:
1. old engine



2. dropped engine



3. Coming apart




4. Then got side tracked with some other projects



Will continue

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...




Notice all those hammers in the photo below - I thought that was interesting. One of my favorite tools


and the maestro in action




....

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5. Back to the basics





6. Again get side tracked. My 2 Cyl Boxer daily ride needs a new clutch


7. Back to the engine. Again observe my collection of my favorite tool on the bench.

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Some beer milestone is reached

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Getting there:

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It almost looks like an engine again

[billybek]

Wow, you have done a lot of work to make that engine not run!
Is it back in the car yet?

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Well. It is time.









Dog in the way

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And voila:





The only problem is ... it won't run

So now come the diagnostics part. I filled the engine with sufficient oil. I disconnected the fuel pump relay and cranked the engine a few times to build up oil pressure. Then connected the fuel relay and the engine cranks nicely but won't start. However it makes some nice loud detonations. Every 4-5 cranks. Had to go slowly for a while cause neighbors may call the cops on me because of shooting going on in my garage

I performed the following tests:
1. Compression. All cylinders showed identical 175 psi





2. Check for fuel pressure: 38 psi

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Today I checked the fuel delivery volume. I found that the volume was 2 qt. in 30 seconds. Which is much more then mentioned in the Bentley manual: page 240-8 it states only 0.9 qt in 30 seconds



Another thing I did was to remove all the spark plugs. All the plugs looked pretty identical (blackish)




with exception of the two plugs (top and bottom - I have twin plugged) with both looked still white and shiny like brand new:



So I need to diagnose further. I also checked for spark. All plugs have nice spark. I checked the timing, made sure the distributor is aligned correctly timing wise and all the plugs are connected correctly 1-2-3-4-5-6 going to the right terminals on the the distributor caps.
So I have spark and fuel pressure. Now the next suspects are the injectors. Also I did the test where I remove the airbox and open the AFM to see/hear if the injectors are running and they did not.
So how can I check the injectors? Is there a voltage test?
I also need to check the AFM. I did some stupid mistake opening up the connector when I took the engine apart.





I am afraid I broke this connector and there may not be a valid signal to the Mototronic unit.

More troubleshooting ahead.

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A) Fuel injector testing results:
1. Resistance: all at 2.6 Ohm
2. Voltage: all have proper 12V DC against ground

B) On to Volume Air Flow Sensor
1. Voltage of Terminal 3 against Ground: 0V

OK. So seems like I will be spending some fun time with this device. I, in my stupidity messing with it, may have managed to break it. So I need to figure out how to repair it now. Is there any good place to send this to to get it repaired and checked?

[johnman001]

Apart from the air flow sensor that now appears broken or damaged, I would have checked a couple simple things before going further.

1. I would have checked with the key on that there was power to the idle stabilizer (the yellow zinc plated can that bypasses the throttle valve. It will vibrate slightly with the key on and will indicate that the DME relay and the DME is sending power to the components.

2. I would swap the two leads to the flywheel sensors. I don't know how many engines I have put in where those two leads are swapped. Swap the leads and the engine fires almost instantly.

Good luck with it. Looks like a nice engine.

[efhughes3]

Injectors should not sit more than a month or two, they will stick. I'd send yours out for cleaning. You'll have them back within a week.

I let freshly cleaned injectors sit for 10 weeks, and only two would fire initially.

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Thanks very much for the feedback.
John, I have checked power to the idle stabilizer. It is humming nicely 8)
I will try swapping the leads. Thanks for that tip!

Where is the best place to send the fuel injectors and the air flow sensor for overhaul/testing?

I will order a set of new injector seals from our host. Although the ones that i have look brand new and they sit tight and are sealing fine. I took the injectors out and put them back in and all is well. But I see almost everyone seems to suggest to change the entire set. So I will do that.

[efhughes3]

Witchhunter.com

They provide the new seals as part of the cleaning.

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OK. Injectors are on the way to Witchhunter for cleaning and testing. I hope they all will be back by Friday and all in good working condition.
In the meantime I fixed all the connectors in the air flow sensor. When I removed the main connector - not a good idea!!! - the contacts got bend and when I put the connector back the connections were not in proper condition. So now I think I got all the connectors back in place and in good contact - I hope.





And the test data looks within range. 1.7 kOhms between terminals 1 and 4 at about 83 degrees F



and continuous resistance across the flapper range:







Sealing it and then will put it all together again. Then waiting for the injectors and keeping my fingers crossed.

[awharmse]

When I did 2 rebuild2 some time ago and I had the same type of problem on both occasions:
1. No spark. The one sensor at the fly wheel was faulty. On my DME (1985) it needs signal from both to fire the plugs.
2. The head temp sensor. I cut the wire and didnt reconnect it correctly. 2 wires 50:50 chance. After I did all the things that you did, one day I decided to try that and the engine fire instanly.

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I think too it's an electrical problem at this point. None of the sensors seem be be reversible in terms of wiring. I just connected them as they are so I don't think I can swap the wires anyhow. I am wondering if my O2 Sensor is the culprit. I have it not hooked up yet. It appears the car had an old one wire sensor and I have put in the correct 3 wire sensor. How would I connect this? Maybe that's the culprit? How can I wire the sensor up to the DME?

Here you see the old brown one-wire sensor and to the left the wires for the new sensor. Do I just cut the two-wire connector on the new sensor and connect one to the old wire and other to ground? Could that be why the engine does not start?

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I checked all the sensors, cables and measurements against spec. (Reference Sensor, Speed Sensor, Head Temp Sensor). Also my AFM connector has the correct 5V. So all the tests check out ok. However I think my problem is the injectors not running. I did various tests trying to crank the engine and also engaging the fuel pump and opening the throttle body flapper. However it seems the injectors never run. Neither do I hear the injector whistle nor do they slightly vibrate as they should I think. So somehow I don't get signal/power to all the injectors. I know they are all good because they just came back from Witchhunter and they all checked out ok. Nice flow diagram they included as well - testing before and after. Nice job. So I think all the parts are good. Now what

It appears the injector wire harness goes through this connector in the back on the firewall



Is there a way to test the power or anything else or where do I go from here