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Help with 1990 f150, have searched, black smoke running rich

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1990 f150 swapped in a 5.8 from 5.0 over a year ago, correct ecm, correct distributor with swapped on correct gear and grey icm. Has ran stunningly perfect until 2 days ago.symptoms are black smoke, rough idle, still happily goes up to speed but stumbles/bucks with light throttle input. initially thought I had thrown in bad gas, drained tank, swapped the fouled plugs, no improvement. Checked fuel pressure at rail. 31 at idle, 40 with vacuum removed, loses about 2-3 psi after shut down over 7-10 minutes. Coils tested out (msd) was .7 on primary, 3.3 on secondary, stock coil I have for spare tested .7 primary, 7~ at secondary. No cel- not even at koeo since owning it. Leading me to believe the bulbs out. Here’s what the plugs I pulled look like. And oddly enough I found a 6 prong plug underdash with this clip that has 2 jumpers plugged into it. If pulled it won’t start, but if pulled while running idle jumps to 1500, and gas tank goes to full. smooths out and stops all smoke- the hell is this.


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heavydoc

Instigator
Staff member
1,994
69
WNC
I had one doing kinda this it was running rich like it was staying in choke mode. I found there were 2 coolant temp sensors. One for the gauge and 1 that told the ecu what temp it was. The one for the ecu was bad and always reading the engine temp to be very cold causing the ecu to overfuel. Hope this helps
 

SuperCab

Moderator
Staff member
10,067
543
Montana
Need to get a bulb in the CEL and see what codes it's throwing... I'd bet money there's at least one. As for the cause, I'm with heavydoc. Coolant temp sensor would be my first suspect. Could be other things like O2 sensor though. Need to know what codes it's throwing
 
Need to get a bulb in the CEL and see what codes it's throwing... I'd bet money there's at least one. As for the cause, I'm with heavydoc. Coolant temp sensor would be my first suspect. Could be other things like O2 sensor though. Need to know what codes it's throwing



Yea, tried to pull codes and lost count after the 50th digit. Ordered a ford obd1 scanner off amazon.


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dustybumpers

don't play well w others
Coolant temp switch, not the 1 wire switch, but the one with all the wires on it by the thermostat housing in the heater hose outlet.

Codes run in pairs. first one you see is 1-1, that's 11, system pass. it will do that twice, then go on to codes. Some codes tell you to pump brakes, turn wheel, cycle trans switch , etc.
If the check engine light were working I could tell you how to check codes with a test light.
 
Coolant temp switch, not the 1 wire switch, but the one with all the wires on it by the thermostat housing in the heater hose outlet.

Codes run in pairs. first one you see is 1-1, that's 11, system pass. it will do that twice, then go on to codes. Some codes tell you to pump brakes, turn wheel, cycle trans switch , etc.
If the check engine light were working I could tell you how to check codes with a test light.



It is working- threw a bulb in and viola. I haven’t yet but will be testing the ect tomorrow, but that was replaced about 8 months ago with a Napa one.


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dustybumpers

don't play well w others
is the light coming on, and staying on ?
if so, under the hood, by the air cleaner, pull down the test harness, and find the single wire hook up in there.
 

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dustybumpers

don't play well w others
then put a test light from there to ground.
once there, go inside, turn key on, start counting check engine flashes
 

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dustybumpers

don't play well w others
Like I said before, flashes codes twice. first you will get 11, system pass.


it will go 1...… 1.………….. 1......1...………….. then will flash codes. example will be 1......1.....1...….……...1...….1...…...……..1......1...…..1...………….1.....1...…….. that would be 32. you look up 32, and that is egr code. that 32 is just an example. the 11 will always be there.



If bad pcm, it will not give you the 11, OR will give you all kinds of crazy codes that your truck don't have.



Post your codes, I'll tell you where t look, what to try next...DON'T unhook the battery, you will clear the codes, and the truck will have to relearn and start over without fixing the problem
 
Like I said before, flashes codes twice. first you will get 11, system pass.


it will go 1...… 1.………….. 1......1...………….. then will flash codes. example will be 1......1.....1...….……...1...….1...…...……..1......1...…..1...………….1.....1...…….. that would be 32. you look up 32, and that is egr code. that 32 is just an example. the 11 will always be there.



If bad pcm, it will not give you the 11, OR will give you all kinds of crazy codes that your truck don't have.



Post your codes, I'll tell you where t look, what to try next...DON'T unhook the battery, you will clear the codes, and the truck will have to relearn and start over without fixing the problem



I’ll go out, record it while I count this time so at least I can reference the video. One thing is, it’s. Going to pop a ton of trans codes possibly- when I did the 5.8 swap I used a computer from a 91 bronco with auto and it’s in a 5 speed.


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dustybumpers

don't play well w others
Saw the trans codes. That makes sense. The other codes are mostly grounding problems.

I would say a bad ground took it out. I sent you pictures in the email of the 2 grounds to check.

Not sure how you would proceed. I would probably get the correct unit for the 5.8 5 spd truck.

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dustybumpers

don't play well w others
Sent you some info on a ecm

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dustybumpers

don't play well w others
Ok, so let us know here how this plays out with the reman ecm.


Sorry to everyone else it happened on phone. We will post up what all we did so the next person to read this thread can diagnoses their problem too
 
So hilarious turn of events, not directed towards it miraculously working but rock auto up dated my shipment, and they changed the delivery from this Tuesday, to oct4 so I decided to check amazon just for the hell of it. Low and behold they sell it and I got one of the random discounts for being a prime member and it came out to 55 bucks- will be here Monday,and I can still get the mail in core rebate at 65 dollars. Cardone is essentially paying me 10 dollars for getting a new ecm [emoji23]
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So the ecm showed up yesterday but the gasket for it going through firewall basically fell off- I glued it back in with some e6000, and set the plug into it to keep it in place, this morning I got the ecm in and fired it up, instantly shot to the appropriate high idle for cold, no smoke, no miss or stumble. Coulda shed a tear I was so stoked. Only drove it a couple miles, but i don’t think it’s ever ran this good. It does seem to hang the throttle up at 1500 a little longer then it should I’m thinking throttle cable has a bind. Cause if I jab it, a few seconds later it falls down to a very steady 800rpm. It still has a check engine light, but I have egr by passed and not hooked up so that’ll be addressed at a later time. Big thanks to everybody that helped, especially dustybumpers!!!


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dustybumpers

don't play well w others
No problem, glad to help.

Go ahead and pull the codes again, let's see what you have.
There are some tricks for the egr if you come up with a code 32

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No problem, glad to help.

Go ahead and pull the codes again, let's see what you have.
There are some tricks for the egr if you come up with a code 32

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It didn’t pop the the 1....1 .... system check but it’s not ran more then a mile and a half, it threw 31,85


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