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Olds 98 1985y 3.8 black smoke no idle

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Old 09-30-2021, 12:31 PM
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Hello,

we have tested and ECT gives 4500 ohms which is proper as it is ~15 degrees celsius.
As well we have tested communication from main ECM to ECT and it is good readings.
We have tried to start by unpluging fuel injectors with starter spray and it backfires from air intake.
we are thinking either timing chain got jumped or it is distributor itself or bad timing.
as well do you know who controls injector injection timing (when put fuel). Is it somehow related to distributor or it is separate module.
and other question if we need to check timing where are these timing marks?
or maybe you have other suggestions where to look additionally?
thanks!
Old 09-30-2021, 01:09 PM
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From your OP, "after I let it sit for more than a week it started perfectly again and there was no issues and drove it couple days." ....and..."After that i tried to start and it never been able to run properly/"
So it was running fine when you shut it off. Did you have ANY issues with it when you drove it for a couple days? Did it shut off normally?
I'm not sure you did the work correctly with all the shotgun parts you installed. Also, how did you check the data line between the ECT and ECM?

Last edited by carfixer007; 09-30-2021 at 01:12 PM.
Old 09-30-2021, 03:11 PM
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Hello.
so that is the stragest thing that when I was driving It was completely no issues so i did not even looked for any root causes because it was fine.
i have removed panel trim because I was checking even ECM how it looks and are there no corrosion on terminal pins. So we checked with wire from ecm those pins which you shared in image and then looked at ECT connector
Old 09-30-2021, 07:32 PM
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Don't know what to tell you. I would use a scan tool and look at input data with KOEO. The one main input to calculate fuel is ECT.
If ECT is good and yet the computer is over fueling I'd look closely at the ECM.

Last edited by carfixer007; 09-30-2021 at 07:34 PM.
Old 10-01-2021, 12:30 AM
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I'm thinking: "Hmmm . . . I wonder if an injector is leaking."
Old 10-01-2021, 01:48 AM
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I assume ECT cintrols richness of fuel but who controls timing of injectors when they inject fuel?
Fuel injectors not leaking as it hold pressure and I have took out fuel rail and checked how fuel injectors ar injecting ar aren't they leaking. For some reasin I am not able to attach sloe motion video where you can see fuel injectors injecting fuel
Old 10-01-2021, 12:08 PM
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Originally Posted by gpow
I assume ECT cintrols richness of fuel but who controls timing of injectors when they inject fuel?
ECT sends it'* info to the ECM. The ECM sends output signals to control fuel delivery (injector on time) and spark timing.
Originally Posted by gpow
Fuel injectors not leaking as it hold pressure and I have took out fuel rail and checked how fuel injectors ar injecting ar aren't they leaking. For some reasin I am not able to attach sloe motion video where you can see fuel injectors injecting fuel
With fuel rail off you can use a timing light to view the spray pattern. If it were leaky injectors causing you over fueling it would clear in short order after starting. If it is the injectors causing your problem it'* likely there'* a short causing them to be on all the time.
Old 10-01-2021, 01:58 PM
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Hello!

we have just checked and it seems that bad timing because we have checked manually when piston goes dows then only injectors injects fuel. Ao we will check timing chain and tensioners of it. It could be that plastic part in timing chain where it is showed in this video:
Old 10-01-2021, 02:21 PM
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I've never seen a timing chain fail by not being used. Shut off and all is good, next time no start and you replace a bunch of parts and have messed with some things. I think you created the problem you are chasing. I would look at the ECM and back probe terminals. Start with ECT.
Old 11-13-2021, 02:01 AM
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Hello, just an update.
we have replaced full timing chain and components and still it is same. What we found is that injectors injects fuel too late when piston is already moving down. Who is responsible for it? Is it ECM? We have took out ECM and checked bisually and no issues seems on it. As well unfortunately no OBD1 codes appear when jumping A and B terminals.
so probably main issue is too late injection. But we need to know who is responsible and how to check it what could be root cause


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