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1994 B2300 Ignition, EGR troubleshooting help


tnjeff

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Greetings. I've got a 1994 B2300. So I'm getting codes with the KOEO test. 335 in the self test and 332, 211 and 224 in memory. Truck will start and and run but after a few minutes I get a CEL and the tach drops to about half of the actual rpm. I've read quite a bit on this forum about this specific problem, lots of good information. I have alldata so I can see the test procedures. Here's the thing. I'm kind of an electrical idiot. Rather than ask "How do I test this and how do
I test that", I am wondering if someone could point me to a good tutorial on automotive electrical testing.

I mean, I don't even know how to do the simplest tests but it looks like it's time to learn. I do have one specific question though. Since the DPFE failed the self test (code 335 - EGR sensor circuit voltage higher or lower than expected), wouldn't that indicate that it was bad?

I won't be in front of my computer for a day or two, but I really appreciate any replies. Thanks.

Jeff
 


RonD

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Welcome to TRS :)

You should post the definitions with the codes so we don't have to look each one up and you already have, I assume

211- Ignition PIP signal was erratic or missing
224-Failure in ignition coil primary circuit
332- EGR did not open/respond during test or if memory code, did not open intermittantly
335- EGR feedback signal is/was out of range

1994 was the last year that used separate ICM(ignition control module), 1995 and up used a different computer(OBD2, EEC-V) with ICM built into the computer

ICM is on the front side of lower intake manifold, it controls the spark by getting timing pulse directly from Crank Position(CKP) Sensor

ICMs did have wiring and internal failures, they can be tested at most auto parts stores
Check wiring on connectors they can become frayed.
PIP - profile ignition pickup
This is the pulse signal the ICM gets from the Crank Position Sensor and sends to the computer so it can time the fuel injectors
Tach signal also comes from ICM
Crank sensor wires run from ICM and into/behind Timing Belt cover to the Sensor located just above crankshaft.
No crank pulse would cause a no start, so this is most likely a wiring issue, could be ICM is failing as well but checking wires is FREE :)

And bad wires could also cause 224 code, each coil pack has 3 wires connected to ICM
(heads up, 2.3l 8 spark plug setup only uses Exhaust side coil/spark plugs when engine is cranking for start up, intake coil/spark plugs start working when RPMs are above 400)

EGR system has 3 parts plus computer
1. EGR Valve., it is opened and closed using engine Vacuum
You can put on a longer vacuum hose and then start the engine
As engine idles suck on that hose and EGR Valve should open and engine should start to run rough, and will stall if EGR Valve remains open
Test EGR Valve first, if engine idle doesn't change then remove EGR Valve and metal tube, clean or replace as needed.

2. EGR solenoid, it has 2 wires and 2 vacuum hoses, one vacuum hose goes to EGR Valve the other to intake manifold or Vacuum Reservoir
Check that each hose is "air tight", no leaks
The 2 wires are for the computer to control when EGR Valve gets vacuum, 1 wire will have 12volts when key is on, the other wire goes to the computer
The computer Pulses the Ground on that wire, this causes the EGR Solenoid to open a little or a lot, so computer can control the amount of exhaust gases flowing back into the engine.
You can apply 12v and Ground to the 2 contacts, there is no polarity, and solenoid should "click" open, then "click" closed when power is cut.

3. DPFE sensor, Pressure Feedback Sensor, this has 2 Exhaust Hoses attached and 3 wires
The 2 exhaust hoses are placed at different places on the EGR Valve's exhaust tube, one is closer to EGR Valve
As EGR Valve is opened by the computer, via EGR solenoid, the closer hose will have a higher pressure drop, so lower pressure than the hose that is farther away
The Pressure Difference is how the computer measures the exhaust gas that is flowing into the engine.
Sensor hoses can get clogged up so check them, there is an order so only remove one at a time or mark them
Check wiring connectors, always, for corrosion

Heads up: sensors or parts are often replaced when the only problem was dirty connector, new sensor or part fixes the problem because connector was removed and reconnected, which cleaned the contacts, so check wires first

Your two codes
332- EGR did not open/respond during test or if memory code, did not open intermittently
335- EGR feedback signal is/was out of range

Could mean a few things because both mean there was no pressure change shown when computer activated the EGR Solenoid:
EGR Valve is not working
EGR Solenoid is not working
And yes DPFE sensor is not working

Could even mean computer or its wiring for EGR system is not working
 
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AgPete139

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Get a decent multimeter. This will be your backbone for chasing electrical gremlins in your vehicles. You will have it for years, and a $30-40 unit is much better than a Harbor Freight $4.99 special or even a $20 basic one.

All cars are in DC, with current flowing from the source to a ground. Having something that reads ohms (resistance to electrical flow) between 2 points, a sound indicator/light indicator for hot (live) wires, reads voltages, and replaceable batteries is easiest. This also doesn't break your bank.

As far as issues and how to fix / determine their meaning, RonD summed it up for you pretty well.


Good luck.
 

tnjeff

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Wow, thank you both Ron and Pete. Exactly what I was looking for!
 

tnjeff

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You can put on a longer vacuum hose and then start the engine
As engine idles suck on that hose and EGR Valve should open and engine should start to run rough, and will stall if EGR Valve remains open
Test EGR Valve first, if engine idle doesn't change then remove EGR Valve and metal tube, clean or replace as needed.
If I'm reading this right I need to get a long piece of vacuum hose and disconnect the hose that's on the EGR and connect the longer one right?

You can apply 12v and Ground to the 2 contacts
One of the videos Pete linked showed a guy using a car battery to apply 12 volts. Can I use the battery that's in the truck for this by making two test leads, one to connect to the battery ground and one for the positive side?

Also, when I look at sensors (egr solenoid for example) on Alldata, some of the diagrams say "Test pins located on Breakout Box". That sounds to me like there is a separate terminal somewhere used specifically for testing. Is that correct?

Thanks again, lights are slooooowly coming on.
 
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tnjeff

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So I did a little (very little) troubleshooting using the good advice given above. Got a piece of vacuum hose, hooked it to the egr and sucked on it while the engine was idling. Sure enough the idle got rougher, so the egr valve is good I guess. That's all I did with the egr related codes so far.

Pulled all of the connections that I could get to and cleaned them and added a little dialectric grease. Could not get to the bottom connection on the ICM so didn't do that one.

Cleared the codes and drove it for awhile, still getting an intermittent CEL, but the tach is working. Checked the codes again and the self test passed, but still havethese in memory:
224-Failure in ignition coil primary circuit ( my book says SPOUT circuit ground/coil 1,2,3 or 4)
332- EGR did not open/respond during test or if memory code, did not open intermittently (my book says insufficient egr flow detected).

So possibly making a little progress. Going to work on it this week as I have time. Also looked at a couple of digital multi meters to replace my five dollar Harbor Freight item.
 

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