dicer

I was at first reading thinking it just shut off. Most of the time on some car makes a no fire is no timing or rpm signal, cam or crank sensors, and that should throw a code. There is an igniter test on youtube, but to have both sides down its not likely an igniter problem. So have you checked for the ecu signal to igniters? Sensors to ecu? Simple stuff grounds and the connections even connections at the fusible links they get pretty bad, good power to ecu?

gymguy79

Thanks Dicer. I have not done all of this so I am in the process of doing it. Shop manual details this. Do you know if I can force a signal to igniters to check for spark? Is an uplevel such as using a light bulb that limits current a good way or does it fire on downlevel to ground? Shop manual seems to suggest a current limited uplevel. Do you have the link to the youtube test?

dicer

I know there was a way to one shot it on you tube but it was the gen 1, I'll see if I can find it.

here ya go

gymguy79

Thanks Dicer. I will try the test to see if I need a pull up or pull down and then try to force it by probing the inputs. Looks like it is a pull up. It still seems that since both igniters get similar signals from the ECM that it must be defective since both cam sensors would have to be bad to prevent the ECM from signaling both igniters. The shop manual however requires both cam sensors and the crankshaft sensor to be tested before concluding that the ECM is bad. Seems also unlikely that both coils would be bad at the same time. I have taken the cover off the ECM. The inside appears pristine but I have not tested the electrolytic caps for value. The part number of the ECM is 89661-50142. I could swap the good ECM from my '93 to see if it works in the '94 but I'm reluctant because of possible damage to the good one. Please advise.

dicer

That is a Yamae question, I don't know enough about the differences between the 93's and 94's.

gymguy79

I don't either. I will continue to eliminate all issues that might be due to items external to the ECM. It sure looks like the ECM is the culprit however. Thanks for your help.

gymguy79

I forced a spark by pulling up the IGT inputs to 12V on both sides and got sparks. I also found 5V and 12V on the ECM was good but didn't look at ripple. I will now use an old analog (non storage type unfortunately) oscilloscope to look at the cam and crank sensors rather than test them with a multimeter to see if proper inputs are there while cranking. If those are good I will have to conclude that the ECM is bad. Don't know if new caps will fix it as an IC in the ECM may be bad. I may just go down to Autozone and pay a couple hundred just to get going. The remanufactured ECMs are guaranteed for a year and are flashed with the right code (supposed to be replacement for my factory part number). Advice is welcomed.

gymguy79

Unfortunately my old 150Mhz Tektronics scope is essentially dead (possibly due to bad caps as it is over 20 years old) or not calibrated as the trace will not display (although I see it go off scale when powering up). I may have found another way to measure ripple on the 5VDC. I measured the voltages on the unplugged connector to Igniter 1 and found that the IGF1 voltage was 5VDC but dropped to .55VDC when plugged in. This makes sense when looking at the schematic block diagram. My multimeter has a DC blocking cap inserted when set on AC scale and is sensitive down to 5 mv. It has one problem in that the frequency response is only accurate up to 10 Khz so higher frequency ripple with likely not show accurately. I measured 5-10mV on the AC scale. I really would like a scope to see the ripple before declaring the multimeter method a good solution. At least I know the 5VDC is good.

dicer

On my old Tek scopes its usually the pot for positioning is scratchy, takes a bit of fooling with to get it sometimes.
I've always liked them very quality item. I don't play with them as much as I should, gosh the 545 its been years.

gymguy79

I've got the 2445 repair manual but I'll put it off until priority items are done. News is I found the problem! An open crankshaft position sensor. Advanced auto had one in stock so I'm up and running! I did find some things that need repairing such as the shroud plastic mounts around the radiator had broken away all across the top so I'll have to fabricate something to secure the broken plastic My thanks to all who have helped. Hope I can return the favor.

dicer

I have a 2445 also. Hmmmm cool a cps, looks like I got another one. Glad you got it sorted.

gymguy79

There is a small amount of leakage from the main bearing that flows over the CPS. I wonder if that is the reason for failures in older models. Probably not since the sensor is sealed. Thanks again.