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Help, 89 FSB Backfiring out the exhaust


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#1 krbjr31

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Posted 26 October 2017 - 08:18 AM

I have an 88 FSB 302 EFI. It was running fine the day before and got in to start it to go to work and it wouldn't start it would only turn over and backfire out the exhaust. I have got #1 TDC and it checks out. got 35# at the fuel rail. I have checked the spark and it is good. Changed the cap and rotor button. pulled the codes and they are 31- Pressure feedback PFE circuit below minimum voltage, 67- Neutral Pressure Switch NPS circuit closed, A/C on, 84- Exhaust Gas Recirculation Vaccum Regulation EVR Circuit Failure. So my question is what is PFE, NPS, and the EVR? What else should I check to see what is causing the backfiring and not starting?


Edited by krbjr31, 26 October 2017 - 08:21 AM.

1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#2 krbjr31

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Posted 26 October 2017 - 08:19 AM

any help would be appreciated.


Edited by krbjr31, 26 October 2017 - 08:22 AM.

1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#3 krbjr31

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Posted 26 October 2017 - 10:13 AM

changed the ECM still backfiring, only other thing I can assume is that it is off a tooth on timing or the cam is shot.


1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#4 miesk5

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Posted 26 October 2017 - 11:32 AM

Yo,

I am having friggin issues posting my entire reply here due to sos error message.  Somhere is just part of the backfire info.  Also removed is the Code info.  Will try to post that part next.

 
Vacuum Line/Hose;"...The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel. Because of the materials used, the vacuum hoses should never be pinched off during diagnosis to locate a leak. Use Rotunda Vacuum Tester 014-R1054 or equivalent to locate vacuum leaks. A wood golf tee can be used as a plug when it is necessary to plug one end of a vacuum hose for leak test purposes..." 

Backfire:

 

HAVE to go with most likely before pulling timing cover, etc.

See  my vacuum leak test in post #20 @ http://broncozone.co...de-44/?p=125535

Excerpt: One way to do a quick check is to grab a vacuum gauge. Bring the engine to normal operating temperature. Connect gauge to the intake manifold tee. BEWARE OF FAN, BELT, PULLEYS & HIT ENGINE. 

The vacuum gauge should read between 15 and 22 in-Hg depending upon the engine condition and the altitude at which the test is performed. SUBTRACT ONE INCH FROM THE SPECIFIED READING FOR EVERY 1,000 FEET OF ELEVATION ABOVE SEA LEVEL.
The reading should be quite steady. .

When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.

When vacuum leaks are indicated, search out and correct the condition. Excess air leaking into the system will upset the fuel mixture and cause conditions such as rough idle, missing on acceleration, or burned valves. If the leak exists in an accessory unit, such as the power brake, the unit will not function correctly. Or Air Conditioning when in MAX mode may switch to Defrost.

Al


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#5 miesk5

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Posted 26 October 2017 - 11:36 AM

Yo,

 

Same friggin error message!!!

 

Will try to PM you the code info

Iggie PFE. It wasn't used on our Broncos


96 XL 5.0 E4OD, Manual BW 1356, manual hubs. See my partially recovered Bronco site. I need to clean up dead links & add many more. Thanks you Mr, Schwim! http://schwimserver5.com/?index=1128
THANKS to ALL WHO SERVE!

#6 krbjr31

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Posted 27 October 2017 - 02:50 AM

Miesk, thanks for the reply. I cant even get the truck to idle. It will only backfire and will not start at all. I will have to inspect each hose by hand instead of trying to do a vacuum gauge type test. Also yesterday the truck while trying to start it, the starter stayed engaged and I had to pull off the hot wire on the battery to stop it. I dont know if this is part of the same problem or something different.


1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#7 miesk5

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Posted 27 October 2017 - 04:36 AM

Yo,

Suspect non-Motorcraft relays that mount to fender; esp. Chinese parts with sub standard metal contacts tyat are known to stick.

Remove all wires from relay and check for continuity between the two large posts where battery cables were attached.  If there is continuity, then the relay's contacts are welded together,
Starter Relay pic in a 90 
100_9803.jpg
by ElKabong

In no continuity;

Pull the red/light blue wire off the starter relay on inner fender.  Disconnect battery; 

Check for battery voltage on that red/light blue wire with ignition key in off position. 
If it has battery voltage suspect ignition switch (not the ignition key's cylinder) or its actuator rod inside steeriing column.

Ignition Switch Mechanical Test
NOTE: Accessories that fail to operate with the key in RUN, or that remain on when the key is turned off, may be the result of a misadjusted ignition switch rather than a malfunctioning ignition switch. 
NOTE: Do not apply lubricant to the inside of the ignition switch.
Test the ignition system mechanical operation by rotating the ignition switch lock cylinder through all positions of the ignition switch. The movement should feel smooth with no sticking or binding. The ignition system should return from the START position back to the ON position without assistance (spring return). If sticking or binding is encountered, check for the following:
burrs on the ignition switch lock cylinder
binding ignition switch lock cylinder
shroud rubbing against ignition switch lock cylinder
burrs or foreign material around the rack-and-pinion actuator in the housing of the ignition switch lock cylinder
insufficient lube on actuator
binding ignition switch

Ignition Switch Adjustment & Removal/Installation in 87-91 (from Factory Manual and the Ford Electrical & Vacuum Troubleshooting Manual (EVTM) 

Source: by Broncobill78 (Dave) @ http://web.archive.o...&attach_id=6659

 

 

Ignition Actuator Removal & Installation w/Tilt Steering in an 85 (also applies to 80-91 w/Tilt; 

Source: by Chris B (Blue, bronco boy) @ http://chrisb.users....ing_Column.html


96 XL 5.0 E4OD, Manual BW 1356, manual hubs. See my partially recovered Bronco site. I need to clean up dead links & add many more. Thanks you Mr, Schwim! http://schwimserver5.com/?index=1128
THANKS to ALL WHO SERVE!

#8 Rons beast

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Posted 28 October 2017 - 08:29 AM

Hey krbjr,

 

I've been thinking of your problem and would like to take an analytical approach to it.

 

I would ignore the codes for now. (They could be the result of the initial problem and the backfire)

 

I'm sure you did a visual check of the vacuum lines and wiring and such.  Also check the battery connections at the battery and starter and solenoid. especially the grounds.  Since you had the solenoid seize I'm thinking there may be an issue with connections.

If they are all ok try the following checks in order: 

 

1- check that #1 is indeed at TDC of the intake stroke.  (your systems sound like a timing issue with it being 180 out......How, we will address after we find out )

assuming the timing is ok:

 

2-connect a test light between the + and - terminals on the coil. ( they HAVE to be connected at the coil for a proper test) Verify 12v at the + side with the key on. Crank the engine and watch for a flash of the test light in a good rhythm with the cranking speed. 

If the light flashes with good rhythm. assume the primary circuit is good and the coil is getting a proper "fire" signal.  If not the problem is in the primary ignition system and could be poor grounding that isn't transferred through the ICM to the coil.  Or a bad ICM or Dist. pick up, or wiring to the same. Remove the dist cap, disconnect the + wire from the coil for safety and crank the engine.  Observe the rotor. Is it turning in rhythm with the engine?  If it is move to 3. If not, the dist gear or cam  gear or timing chain is the problem.

 

3- If primary ignition circuit and dist is good, reconnect the cap and coil primary wire. Disconnect the secondary coil wire at the dist. carefully hold it close to a ground and crank the engine. Check spark. Good strong spark in a good rhythm to the engine cranking clears the coil.  Not good= malfunctioning coil. 

 

4- if coil is good,  reconnect the wire and do the same check at #1 plug. Repeat for all other wires.  If all is good, pull the plugs and observe.  Shake and turn each with electrode down.  ( I had found plugs that had broken electrodes that would be pushed up into place under the compression stroke only to fall down against the ground during the power stroke and cause a miss. looking at the plug upside down showed no problem.  I know bizarre, but its worth the check. )  If all is good, you can eliminate the ignition system as being the problem. 

 

Post results here and we will move on.   I know its tedious,  but its good to know what isn't the problem and eliminate them rather than "shoot in the dark"

Good Luck


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#9 krbjr31

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Posted 29 October 2017 - 04:36 AM

Thanks, I will check step by step. Going to take awhile to get this done, but I will get it done and post results.

1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#10 krbjr31

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Posted 31 October 2017 - 07:39 AM

Thanks all for the help. I have decided to just pull the motor and rebuild it. I hate all the stuff they have added to vehicles to make it more complicated to figure out. I like the old ways where it was much simpler to figure out when something went out. I will go back to the old style when I rebuild the motor. besides it is only to play in and I wont be driving it for long distances, so mpg is not that big of an issue.


1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH


#11 miesk5

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Posted 31 October 2017 - 02:44 PM

Yo K,

YW.

Let us know what the teardown reveals.

GL!


96 XL 5.0 E4OD, Manual BW 1356, manual hubs. See my partially recovered Bronco site. I need to clean up dead links & add many more. Thanks you Mr, Schwim! http://schwimserver5.com/?index=1128
THANKS to ALL WHO SERVE!

#12 krbjr31

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Posted 01 November 2017 - 03:59 PM

Will do Miesk!

1988 Bronco

302ci

C6 Tranny

Manual TC

Manual LH




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