RPM pulsing and Idles rough with black smoke at start up

[Wolf3591963]

sorry moved posting to correct forum

thanks

James

 

[Seabronc]

It is best to start by pulling the codes.  There may be some even if the, "Check Engine" light isn't on.

Good Luck,

>-

 

[Wolf3591963]

I have been having troubles with my 1991 ford bronco. It always starts fine but once I shift it into gear it starts idleing from 5 hundred to 15 hundred then the truck like to stall out. When I restart it the problem returns, The motor runs just like it would if it was really wet. when the bronco warms up to running temp the problem all but goes away except for the idle still pulses from around 5 to maybe 8 hundred. any ideas what this could be???

 

[miesk5]

yo JAMES,

As Seabronc advised, Check for Codes;

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?&pid=74587&mode=threaded

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.
 

Without a Code(s), Ford's basic EFI Rolling Idle troubleshooting routine is;

 

BTW, Diagnostic Sub-Routine Step 10 is perform  Test for Diagnostic Trouble Codes (DTC)s

Try a Vacuum Leak Test;

see my post here @ http://broncozone.com/topic/23994-90-58l-getting-continuous-code-33-and-running-code-44/

Post #20

 

[Wolf3591963]

I took the Bronco up to the O'Rielly store they hooked it up to there code reader and guess what ,, it came back with no error codes, but the technician said it read the code prompts very strangely. He said it looked like there wasn't any codes to read at all. Almost like the computer wasn't working but yet it told him what to do next in the sequence. I just had put in a new starter selinoid that was defective and after the 3rd or 4th day the thing didn't disengauge which kept the starter squealing and the battery to cook by the time I had a 1/2 inch wrench and got the battery disconnected it was boiling and the starter was squealing like a wildcat. Could the programing in the onboard computer been wiped out while I was putting in the new battery and it had no power?

 

[miesk5]

yo, Check ground cables around & on battery (incl the small gauge wire to inner fender)

 Scan Tool Won’t Initiate Self-Test Due to Poor Grounds, Corroded Wiring, etc



by Jeremy

NO CODES Troubleshooting by Ryan M (Fireguy50) at http://oldfuelinjection.com/?p=44
excerpts;

Check Battery voltage, must be above 10.5 volts.
•Replace battery if not.
•Check battery connections, corrosion, ground faults, and wiring.
• Fix all wiring.
•Check alternator output, must be between 13.5 and 14.5 volts.
•Replace Alternator if not.
•Any recent voltage irregularities from electrical charging system can cause failures.

Check EEC relay, must show battery voltage when engaged.
•Replace relay and damaged wiring if not.
•Make sure pin 30 on the computer is hooked up correctly.
•Manual transmission computers need to sense SIG-RTN on pin 30 when in neutral.
•Automatic transmission computers need to sense Ground on pin 30 when in neutral.
READ MORE

to help go thru the steps;

Here is Ryans EEC IV PIN LEGEND
http://oldfuelinjection.com/truckpinouts.html

& EEC IV Connector Pin Outs
http://oldfuelinjection.com/?p=3