'91 Super coupe will not start..

tbirdtony

Registered User
have somebody grab a handful of wires at the dis module and shake them *while you try to crank the engine most likely have a loose wire or short. mine did that.
 

351tt

Registered User
""tbirdtony .. have somebody grab a handful of wires at the dis module and shake them ""

This was all suggested way back but agreed , have seen this before in another members car that was giving issues , but do it ** gently** , these are old cars with old wires .
 

Mranalla07

Registered User
I took a break for awhile. Car had 114 and 116 code and plugs were soaked again. Ohm'd sensors thay were new. Checked wiring. Replaced EEC with the new one. Codes no longer there with a KOEO test. Co-worker let me use his scanner. All data looked fine tps changes when pressed. Engine temps all normal. Bringd us to tonight. Go out and try it and boom fires up. Black soot out the tail pipe and rotten egg smell. Let it run for a couple minutes 3 times. Runs decent for what I know. Need to change the fuel soaked oil. With the spot and egg smell I am thinking rich fuel condition. Do we have a plugged exhaust or something. Plan is to change the oil and this week do a back pressure test maybe pull o2 sensors. Something Is not right it would not start after newer EEC was installed for 2 days. Now it starts out of no were..
 

351tt

Registered User
Plugged exhaust would likely not be intermittent , doubt that is your issue,although the blowing black smoke is super rich so there will be raw fuel in the exhaust or in the cylinders burning off when it does fire .
Again you are back to why is there raw fuel in it , either the spark is intermittent or the cylinder is getting overwhelmed with fuel or both , have you checked the fuel pressure regulator for a pin hole , fuel can run up the vacuum line into the air intake system .
But it would seem you changing the eec multiple times has resulted in something changing , so again could be a ground or wiring/s in the main connector etc .
I think Tbirdtony's advice is good and even better now that it runs .. once it fires up start moving wires/harnesses around in ""once section"" at a time .
it will tell you where the issue is .
 

DOUG H

SCCoA Member
You said all engine temp data looks good( air & coolant) So you've had it up to operating temp enough to go into closed loop ?
Until you get fresh oil in it, the O2 sensor readings & fuel trim may be misleading as fuel vapours are drawn into p.c.v. system & computer tries to compensate for undesired rich conditions.
 

Mranalla07

Registered User
Have not had much time too look at the car with my work schedule. car currently does NOT run. When i did get it running, I ran it for 6 to 7 days in a row, In my garage for an hour to 2 hours. Couple times it would idle a little weird like the iac was bad. One day it would not start. When it did run, my fuel trims were -33 indicating a heavy rich condition and eec pulling fuel. I figured with all the black soot out of the tail pipe (literally) that the O2 sensors were probably just as bad. A good test drive would burn some stuff up. never test drove it though just idle in garage. Scanner showed closed loop and ait, ect, tps, timing all that data looked accurate while idling. Ran the KOER test a few times. most recent codes were
173: EGO no switch Rich Bank 1
137: No EGO sw Rich Bank 2
which are to be expected with it being so flooded. So i changed the oil and it continued to run for 6 days then would not start. I have tried to wiggle harness check wiring and KOEO codes. nothing seems to work. Fuel is soaked in oil now again. So i pull plugs and they are soaked. So either over fueling horribly or a lack of spark .. I took a timing light to each coil insert and connected the plug wire back in line. Spark at all 6 with no cut outs. I am lost at this point. I know the oil needs to be changed but that is not causing the no start. I clearly have fuel and i have spark. I guess how good is the spark is the real question. Although the coil, wires and plugs are newer. I tried to pull a few vacuum lines to create a leaner condition thinking maybe the iac was choking it . No change, i also pulled FPR line off intake. appears dry.

**** I have also swapped all 4 DIS modules i received and none helped it start. When cranking almost 80% of the time, it will pop off on a couple cylinders and sometimes run on what sounds like 3 or 4 and then die out and the starter motor catches up. . .
 

Mranalla07

Registered User
***UPDATE 4.22.22****

For anyone wanting to know, or having issues I will keep this updated. Vehicle went to a shop with scope access and a tech that had a couple of these SC's . They changed the oil and plugs of course. They found that left side O2 was reading open. Right side O2 was shorted. No fault codes or other symptoms. Replaced o2 sensors and it runs. Brother has been driving it for the last 3 days. I will update in a week and hopefully that conclude the issue
 

Mranalla07

Registered User
Wow, thats all they found? I've never heard of O2 sensors causing a no start?
I thought the same thing. working for Chrysler they use a 5 volt reference to sensors .i could see if the reference voltage ]was shorted but you would think other sensors would set a fault during key on engine off test. I even checked the reference voltage at the tps and iac which i assume shared with O2 sensors. weird.
 
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