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Discussion Starter #1
I have a 1991 5.0L that shakes pretty bad intermittently and loses power. I had it driven by a transmission shop and they said it is due to a misfire but that's all I got.

I went through all plugs, wires, cap, rotor, coil and everything seems okay.

I have KOEO codes 334 and 212.

Any advice?
 

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Discussion Starter #3
I got the truck for $500 not running. Had to replace a couple relays and plugs, the exhaust, and ects and got it running.

Now this is the only remaining issue.
 

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Discussion Starter #5
The plugs that relays went into. Two relays were corroded, as were the plugs they went into. This is why the truck was not running.

Now that it runs it has the aforementioned shake. I do not believe it is anything I did.
 

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Pull codes first. Then post what codes you have.

Then check your spark plugs and spark plug wires. Make sure the firing order is correct.
 

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Discussion Starter #7
I posted my codes and posted that I went through all plugs and wires already... Is anyone else familiar with this?
 

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"I went through all plugs, wires, cap, rotor, coil and everything seems okay."

We don't know what "went through" means. Did you do a resistance check on the wires, clean and gap the plugs, check firing order etc? If all these test ok, given that it already had corrosion issues, I would clean all the grounds under the hood.
 

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yo b,
DTC 334 EGR (EVP) closed valve voltage higher than expected; "...Failed sensor, & as rla2005 wrote; carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. the egr is not closing properly which can cause detonation. remove the egr and clean off any carbon built up on it with carb cleaner and a brush if necessary. read more http://fullsizebronco.com/forum/showthread.php?p=2135529&posted=1#post2135529

DTC 334 EGR (EVP) closed valve voltage higher than expected; "...Failed sensor, & as rla2005 (Randy) wrote; carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. the egr is not closing properly which can cause detonation. remove the egr and clean off any carbon built up on it with carb cleaner and a brush if necessary. read more
Source: by rla2005 (Randy)

==


DTC 212; "...IDM is a feedback signal generated by the ignition system and is monitored at pin #4 of the ECM. Its purpose is to diagnose missed ignition primary pulses at the time the ECM commands the Spout signal to fire the coil. Since it is used solely for diagnostic purposes, if this circuit is not operating properly, it will not affect vehicle driveability; & by Seattle FSB- The Ignition Diagnostic Monitor (IDM) signal is a diagnostic signal for the PCM to to verify a coil firing for each PIP signal. If an erratic or missing IDM signal is received, a Diagnostic Trouble Code (DTC 212) is set. An occasional IDM signal may not affect drivability, but can still throw a trouble code. As SigEpBlue has stated, check for an intermittent ground on the spOUT and/or IDM circuit. Also, ensure that you have the correct Ignition Control Module (ICM) and it is wired correctly to the PCM..." miesk5 NOTE; use BLACK modules in 1994-1996 Broncos
Source: by SMP via SigEpBlue (Steve) & by Seattle FSB (SeattleFSB) at
http://www.fullsizebronco.com/forum/showthread.php?t=127508
READ MORE


DTC 212 (Ignition module circuit failure-SPOUT circuit grounded); "...Check to see if the spout connector is good by running a piece of wire where the connector is supposed to go. If that doesn't help any try checking the wiring all the way until it goes into the connectors..."
Source: by NoSlow5oh
 

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yo,
ok, now check all vacuum lines;


incl EGR & EGR Vacuum Regulator (EVR); also called EGR Vacuum Solenoid

Location pic by SeattleFSB (Seattle FSB)
http://www.supermotors.net/getfile/848247/fullsize/tab-tad-evr-coil2a.jpg

see my vacuum leak test at http://fullsizebronco.com/forum/showthread.php?t=206824&highlight=Vacuum+Leak+Test;+idling
post #11
The EVP EGR Valve is required in EEC systems where EGR flow is controlled by the Powertrain Control Module (PCM) through an EGR Valve Position (EVP) sensor attached to the valve.

The valve is operated by a vacuum signal from the EGR Vacuum Regulator (EVR) Solenoid (9J459) which actuates the valve diaphragm.

As supply vacuum overcomes the spring load, the diaphragm is actuated. This lifts the pintle off its seat allowing exhaust gas to recirculate (flow). The amount of flow is proportional to the pintle position. The EVP sensor mounted on the valve sends an electrical signal of its position to the PCM (12A650).
by Ford via Steve83

read more @ http://www.supermotors.net/registry/media/826382
 

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Discussion Starter #13
All of the vacuum lines are okay or sleeved where they were broken. I did not test any of them yet though
 

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yo,
EGR Valve Position (EVP) Sensor Testing & Replacement
http://www.fullsizebronco.com/forum/showthread.php?t=218407
by Seattle FSB


Normal Engine Vacuum at Idle is 15-22 in-Hg
see if you can borrow a gauge from local parts store w/refundable deposit.
Also ck inside cab and under hood for HVAC vac lines and other vac op devices as listed in my test.

defective EGR valve, most likely not seated properly

The EVP sensor voltage is greater than the closed limit voltage of 0.67 volt. Because of the preload on the installed EVP sensor, it is difficult to determine whether the EGR valve is seated or the EVP sensor is in contact with the EGR valve stem.

Possible causes:
Poor continuity in EVP sensor harness.
Non-seated EGR valve.
Damaged EGR valve.
Damaged EVP sensor.
Damaged EVR solenoid.
Damaged Powertrain Control Module (PCM).
 

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If you can't find anything wrong with the engine at this point, try pulling out the PCM and checking the board for corrosion. Its not hard to find if it does have any. Usually the capacitors in them will leak onto the board and corrode the connections, not to mention that the capacitors will fail if they leak, making the computer throw codes.

If its just the capacitors, and you're not afraid of a soldering iron, you can pick up new capacitors from radioshack and just replace the bad ones and it should work fine.
 
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