Bronco Forum - Full Size Ford Bronco Forum banner

1 - 2 of 2 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
hey i got a 92 FSB 5.0 5spd and it's got a power surge from somewhere. my cousin thinks the ECU is going bad. it'll start and run. if you turn it off when it's warm it won't start back up until it's cold. i've already swapped out the ignition module for a new one though and it still does it. it just won't pop. it's getting plenty fuel.

while it's running, every 3-4 minutes or so it'll get a surge. the only gauges it affects though are the volt and tach. the tach gauge will raise up 1200rpm(not the engine, but the tach itself) and the volt will drop to about 8-9, just for a second. and then go back to normal.

if i roll into the throttle it'll do ok up about 42-4500rpm but if i stand on it, it starts to run like [email protected] (misses alot) at around 24-3000rpm. it's got a new distributor in it. my cousin put it in while i was overseas to see if that would help. it kinda feels worse though now.

please help oh guru's of the FSB!!

thanks
 

·
Super Moderator
Joined
·
26,988 Posts
yo jk294
WELCOME Here and WELCOME HOME!

Start w/a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
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.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:
KOEO
&
KOER

Have alternator & battery tested for free @ NAPA, etc.

Diode Pattern Waveforms, Bad; "...This waveform was captured using the diode pattern test located in the engine tests menu. This particular alternator has a bad rectifier, causing an AC voltage to ride on top of the DC voltage signal. This AC voltage affected the pip and spout signals (Ford primary ignition signals) causing a no code driveability problem. The fix was to replace the alternator. This waveform was captured using the diode pattern test located in the engine tests menu. This alternator, like the previous alternator, has a bad rectifier. This is another example of how a bad rectifier can affect the diode pattern. The fix was to replace the alternator. This waveform was captured using the lab scope. This is a good example of how an alternator with a bad diode can affect other signals that the ECM looks at. In this case it is an IAC motor. When viewing waveforms that have a lot of hash always look at the alternator diode pattern as a possible cause..."

Source: by omitec.com

Bad Diode Pattern 2
This waveform was captured using the diode pattern test located in the engine tests menu. This alternator, like the previous alternator, has a bad rectifier.

This is another example of how a bad rectifier can affect the diode pattern. The fix was to replace the alternator
 
1 - 2 of 2 Posts
Top