Engine test stand

[Dave WM]

switch hooked up, wiring cleaned up some (still have the pump on its own circuit, but I do hear the pump relay clicking so may just go ahead and hook that up as well).

Hooked up the water temp sensor, it will just barely idle, but if you throttle it, you can hear it misfire and then catch and sound good, but if I throttle back it will start missing again.

5 and 6 were totally carbon fouled so I put in new, still running too rich on those 4 looked perfect as did a couple others. I am beginning to think my injectors are not great at least on 5&6, may swap them around with some others and see if this improves.

I reused the manifold gasket, maybe that was a mistake. I have a exhaust leak that is working right past the gasket. It did not look to bad when I installed it.

geez, I just realized I had the idle screw all the way in I forgot to even try to adjust it.

 

[Dave WM]

replaced with new plugs, now they are ALL carbon fouled. I may have done that by trying to keep it running by opening the AFM valve manually, thinking it was too lean to start. I will give it a go again tomorrow with a cold engine and see what happens. argh...

[Zed Head]

Have you given it some wide open time?  Get the fuel flowing through those old crusty injectors, with the pintles banging open and shut.  Probably help clean up the plugs too.

[Dave WM]

1 hour ago, Zed Head said:

Have you given it some wide open time?  Get the fuel flowing through those old crusty injectors, with the pintles banging open and shut.  Probably help clean up the plugs too.

I was doing that some during the video, it will misfire badly then as I advance the throttle, suddenly all will all fire and smooth out. I finally got a halfway decent idle after doing that for a while. This was with the cold water keeping the engine at about 70f, and the best run was with the temp switch disconnected (it was about 1.6k IIRC at pin 13 when connected with the cold water). I was hoping with the rad and the controlled temp it would idle better, but I struggled to get it to idle at all today. Again it would sputter and then catch on and run well (with lots of throttle), but never got settled down with any kind of reliable idle. This was all before I realized I had the idle screw completely closed off. I just could not find the sweet spot today.

I did find the AAR was completely blocked off, will not open even after sitting for hours. I replaced it with the good one and will try again tomorrow. Will give it another go tomorrow and this time will resist the urge to mess with the AFM while its running. The plugs were caked with soft cabon deposits, brand new plugs in just a few minutes of attempting to run.

The water temp sensor was down into the low 100's this time with the 180f t stat (tested at pin 13 and ground).

I confirmed no leaks at the CSV. will double check the FPR vacuum line, but it was ok on the bench. Pressures all seem normal.

Edited April 25, 2019 by Dave WM

[Dave WM]

oh forgot to mention I did NOT use the same dist cap and wires as the prior running video (ones from my car). So will also put that back on to be sure I don't have spark issue.

[Dave WM]

another almost but no start deal. I tried the known good cap. I tried fooling with the AFM flap. Finally I pulled the fuel rail, all injectors seem to be spritzing just fine. I did have one that has developed a leak (reminder to all FI guys, look at the injectors now and then for leaks) I could smell it. Not sure if its a hose or a problem with the injector body will deal with that before going on.

I am starting to wonder if my spark is not strong enough. I will get some heavier primary wire. Right now I have lamp cord (x2) going from the coil to the ign switch and same for the neg from the coil to the module and the module to the ground. BUT I also may have gone to light on the main battery to ign switch. Think I will pull a plug on my 75 and compare the spark.

[Dave WM]

another try, same deal I can get it to run if I disconnect the WTS, it will idle but not very well, if I connect it I can get it to run as long as I throttle up, transition is not that good. I think CO is right there must be something I am missing. I tried a different ECU. I have to monkey with the distributor to smooth things out between idle and throttle up. I did hook up the ported vacuum to the distributer (the servo works and will hold vacuum). Measured resistance at 180f 270 ohms on WTS.

This is fighting me way too much. starting is not as is should takes way too much cranking. I even resorted to firing the CSV continuously during the cold start and idle (until I unplugged the WTS).

Something def not right. I am pretty sure I don't have any unmetered air. Perhaps is as ZH says just need to run it for a while with the high speed to help clean stuff up. I double checked all the EFI stuff I could think of (air temp/water temp/start enrichment voltage, fuel pressure, static and running with vacuum) all seems to be normal. This is what in the TV repair biz would be called a tough dog.

oh and I did compare the spark to my normal running car, the spark as about as energetic as my car so I don't think its a weak spark. I may break out the color tune spark plug  just to see the flame color on combustion.

Edited April 25, 2019 by Dave WM

[Zed Head]

I did something somewhat weird when I had my EFI system hooked up on my garage engine.  I connected the blue tach wire through the resistor and to ground.  Because in the past I had found that my car would not start with the tach disconnected.  I had even had my car not start while I was out tooling around one day when the resistor fell out after I had messed with it.  I saw the resistor on my passenger floor board, put it back in and the engine started.

Since then, with a GM HEI module in place of the stock ignition module, I've found that it will start with the resistor out.  But back when everything was stock t would not.  So maybe the stock system is finely tuned to all of the other parts.  My garage engine with standalone EFI like yours fired right up as long as I had the idle screw cranked open.  Needs that air when it's cold.

Anyway, worth a shot, easy to do.  Just find that blue coil (-) wire branch and run it through the resistor to ground.

Edited April 25, 2019 by Zed Head
Errorama

[siteunseen]

4 hours ago, Dave WM said:

another try, same deal I can get it to run if I disconnect the WTS, it will idle but not very well, if I connect it I can get it to run as long as I throttle up, transition is not that good. I think CO is right there must be something I am missing. I tried a different ECU. I have to monkey with the distributor to smooth things out between idle and throttle up. I did hook up the ported vacuum to the distributer (the servo works and will hold vacuum). Measured resistance at 180f 270 ohms on WTS.

This is fighting me way too much. starting is not as is should takes way too much cranking. I even resorted to firing the CSV continuously during the cold start and idle (until I unplugged the WTS).

Something def not right. I am pretty sure I don't have any unmetered air. Perhaps is as ZH says just need to run it for a while with the high speed to help clean stuff up. I double checked all the EFI stuff I could think of (air temp/water temp/start enrichment voltage, fuel pressure, static and running with vacuum) all seems to be normal. This is what in the TV repair biz would be called a tough dog.

oh and I did compare the spark to my normal running car, the spark as about as energetic as my car so I don't think its a weak spark. I may break out the color tune spark plug  just to see the flame color on combustion.

 

[Dave WM]

3 hours ago, Zed Head said:

I did something somewhat weird when I had my EFI system hooked up on my garage engine.  I connected the blue tach wire through the resistor and to ground.  Because in the past I had found that my car would not start with the tach disconnected.  I had even had my car not start while I was out tooling around one day when the resistor fell out after I had messed with it.  I saw the resistor on my passenger floor board, put it back in and the engine started.

Since then, with a GM HEI module in place of the stock ignition module, I've found that it will start with the resistor out.  But back when everything was stock t would not.  So maybe the stock system is finely tuned to all of the other parts.  My garage engine with standalone EFI like yours fired right up as long as I had the idle screw cranked open.  Needs that air when it's cold.

Anyway, worth a shot, easy to do.  Just find that blue coil (-) wire branch and run it through the resistor to ground.

will look for it in the FSM, so its just a resistor from the  - coil side same circuit that goes to the pin 1 of the EFI?.

With the new AAR it started better and ran a LOT faster, getting more air, all with the WTS disconnected. Its odd it like the richness to run but the 4 for the plugs look pig rich. 2 looked fine.

As soon as I reconnected the WTS it would die a idle (270 ohms 180f engine temp). odd super rich but leaning out kills it. Its still running with the carbon fouled plugs but I doubt for long before the build up shorts them out.

Ran out of gas, looked up and saw 10psi then stopped. oh well out the wawa for some more pure gas. I don't think the low pressure was for very long (which would account for the needed richness on the EFI) but I will reset everything for some more testing this weekend.

When it was running I had it on the orig distributer cap so I will not have to steal from Dat Boi (my car) to test.

Edited April 26, 2019 by Dave WM

[Zed Head]

1 hour ago, Dave WM said:

will look for it in the FSM, so its just a resistor from the  - coil side same circuit that goes to the pin 1 of the EFI?.

Its odd it like the richness to run but the 4 for the plugs look pig rich. 2 looked fine.

Not sure how exactly it would explain your problem but if I recall correctly, power is supplied in banks of 2 and 4 and grounded in banks of 3.  Although the diagram numbers imply 4 and 2 for grounding also, at least by the wire numbers.   Can't remember for sure, CO knows.  If the problem is electrical it might follow the plugs.  Maybe switch a "fine" one for a rich one and see if it stays or follows.

I used the funky looking factory resistor, with the two bullet connectors.  I think it's 2.4 kOhms.  

[Dave WM]

I need to be more detailed to track exactly which plugs are fouling (beyond 4 of the 6, more like exactly which 4) so will do that to better follow the plugs.

I know that resistor, I can measure it on my car, its the one that is located in the passenger side under dash correct?

Something I noticed, the bad exhaust leak at the #6 (looks like a chuck of the gasket must have blown out). I reused an older gasket, I wonder if I have over leaks including intake or even leaks from the exhaust to the intake...

Before I get too deep I am going to put a new gasket in there.

will recap the issue

good compression on all cylinders (160-165)

all injectors firing what seems to be about the same (visual inspection with rail pulled and cranking engine to observe).

new plugs that will quickly foul (4 of 6 that is) soft black carbon fully coating the entire plug  after minutes of running

all plugs sparking spark looks normal compared to normal operating engine

fuel pressure 38 no vac 30 at about 18inHg (observed when car idle is managed)

throttle position sensor tested at 36 pin (on at idle, off until about 1/2 then on  again to full throttle)

timing unsure but moving dist within range of adjustment helps depending on RPM (idle or throttle up).

Seems to require very rich to start (often will only start after CSV fire even when warm)

when it starts is missing badly like only running on 3

much throttling and messing with the AFM flay and it will suddenly "catch" like at least 5 or maybe all 6 will light off, from there you can throttle down and idles smoother, not perfect but much better.

all this is with the water temp sensor disconnected. connected and it will not idle but will run throttle up just fine

WTS tested at the 36 pin connector pin 13 and ground tracks resistance to temp in spec with the FSM.

all unused vac ports are sealed (brake/carbon canister).

all test for voltage and resistance of ECU done at 36 pin connector in spec per FSM

AFM known good unit and tested again( 100 ohm and 180 ohm tested, air temp resistance tested, voltage divider circuit tested with 9v battery and analog meter, no breaks normal looking sweep)

ECU known good unit.

All this leads me to a air leak issue of unmetered air, and the only place I can think of is that junction of the manifold to the head.

What really baffles me is the super rich running condition per the plugs yet leaning (water temp sensor plugged back in) will kill the idle. I was focusing on the water temp sensor and the throttle position sensor but they test fine.

one more observation, I don't notice any extreme black smoke while running, that's very subjective as to what it should be but you would think it would be very noticeable.