Engine Multiple engine codes

StratTone

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The fact that you got that KAM code is telling. Pretty sure that computer is gonna fix things right up. You may still have some codes but it will run at least. It's really an easy fix. Most times it's just replacing those caps and fixing one trace that burnt up. You can just add a jumper wire in it's place and it will be fine.
 
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TTSaleen05

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where is the trace located On the ecm? I’m having the hardest time finding someone to install the capacitors professionally here local. I’m considering following the advice jrichker sent and tackle this myself.
 

StratTone

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I'll have to watch the video and see if it shows it otherwise I'll need to look at one again to tell you. If you can't find anyone I'll fix it for you if you send it off to me in GA.
 

TTSaleen05

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Awesome, I appreciate the help. One electronics store said just to look at it is $40 bucks plus the service fee. Then a two week wait! so im still shopping around.
 

StratTone

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That's not crazy really but I'd assume it's probably a $100 service fee. Where are you located?
 

StratTone

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Ok well if you can't find anything just PM me and I'll get you an address to send to and Ill fix it and get it back out to you.
 

TTSaleen05

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So I Found an electronics repair company that will inspect the circuit board and replace the capacitors for $75 bucks. He said it will take about 3-5 days. while I’m waiting, I’m wondering could this misfiring be the cause for my vacuum fluctuating between 5-10 inches? I replaced all gaskets:upper, lower, TB gaskets, all hoses, blocked off and isolated the brake booster etc. Even though my compression test looked good p, could it be a blown head gasket that cause this low vacuum or is it simply the misfire or perhaps multiple cylinders not firing? I have a feeling that when I get the ecm back, the same symptoms will persist
 

StratTone

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For now just fix one thing at a time. I personally feel like most of your problems will be solved with the fixed computers.
 

Blown88GT

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So I Found an electronics repair company that will inspect the circuit board and replace the capacitors for $75 bucks. He said it will take about 3-5 days. while I’m waiting, I’m wondering could this misfiring be the cause for my vacuum fluctuating between 5-10 inches? I replaced all gaskets:upper, lower, TB gaskets, all hoses, blocked off and isolated the brake booster etc. Even though my compression test looked good p, could it be a blown head gasket that cause this low vacuum or is it simply the misfire or perhaps multiple cylinders not firing? I have a feeling that when I get the ecm back, the same symptoms will persist
It probably takes a few days for the repair shop to get the parts. Probably takes an hour to do a good job, so $75 is very fair.
Are you saying that your vacuum at idle is 5-10 inHg or that it varies 5-10 inHg? It should be around 15-18 inHg & hold steady.
You probably have a vacuum leak. Likely one of the hard vacuum lines is broken. You'll need a smoke tester to find it. You test with the engine off.
 

TTSaleen05

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Blown88GT, I inspected and triple checked lines in the engine bay, even started blocking off lines. Such as to the EGR, the canister purge system and the vacuum tree. Still no change. I don’t have a smoke tester though. Also, when I blocked off the EGR vacuum line, it had vacuum to it. Is it supposed to have vacuum pulling at idle from the EGR to the solenoid? I replaced the solenoid and it still pulls vacuum
 

Blown88GT

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img_2057-jpg.jpg
 

jrichker

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Blown88GT, I inspected and triple checked lines in the engine bay, even started blocking off lines. Such as to the EGR, the canister purge system and the vacuum tree. Still no change. I don’t have a smoke tester though. Also, when I blocked off the EGR vacuum line, it had vacuum to it. Is it supposed to have vacuum pulling at idle from the EGR to the solenoid? I replaced the solenoid and it still pulls vacuum
Some basic theory to clarify how things work is in order…

EGR System theory and testing

Revised 29-Sep-2013 to add code definitions for EGR sensor and EVR regulator.

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions. It does this by reducing the amount of air/fuel mixture that gets burned in the combustion process. Less air from the intake system means less air to mx with the fuel, so the computer leans out the fuel delivery calculations to balance things out. This reduces combustion temperature, and the creation of NOx gases. The reduced combustion temp reduces the tendency to ping.

The computer shuts down the EGR system when it detects WOT (Wide Open Throttle), so the effect on full throttle performance is too small to have any measurable negative effects.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

The resistor packs used to fool the computer into turning off the CEL (Check Engine Light) off are a bad idea. All they really do is mess up the data the computer uses to calculate the correct air/fuel mixture. You can easily create problems that are difficult to pin down and fix.

egr-system-legal-size-paper-55-gif.gif


Troubleshooting:
There should be no vacuum at the EGR valve when at idle.
. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)
88Stang5.0Vacuum.gif


The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt. A defective or missing sensor will set codes 31 (EVP circuit below minimum voltage) or 32 ( EGR voltage below closed limit).

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid. A defective EVR will set codes 33 (insufficient flow detected), 84 (EGR Vacuum Regulator failure – Broken vacuum lines, no +12 volts, regulator coil open circuit, missing EGR vacuum regulator.)


EGR test procedure courtesy of cjones

To check the EGR valve:
Bring the engine to normal temp.

Connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).


Apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

If the engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

If the engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

If the engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
Snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
Did the vacuum gauge show about 2-5 in vacuum?
If not the EVR has failed

EGR test jig
egr-test-jig-gif.gif


To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.
 

TTSaleen05

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Sep 7, 2019
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Ok guys, so I got the ecm back from the electronics shop with new capacitors installed. I plugged it back up to the car and cranked it up. It’s still stumbling as it goes up in rpm but the difference is I can now go above 1500 rpm at part throttle. Prior to the new capacitor’s installed, I could not even get above 1500 RPM without it breaking up. I am now able to go all the way up in the RPM range for throttle. Tomorrow morning, I will pull the plugs out and get them cleaned up because I know they’re fouled. Double check everything, do the EGR test and re-pull the codes.
 

TTSaleen05

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Sep 7, 2019
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Ok so repaired ECU is no longer allowing vacuum to the EGR at idle, I pulled the codes again and got 12, 21 and 26. So I replaced the MAF with a spare one and still no change in the stumbling across the rpm range. Now I didn’t let the car warm up fully before I did the KOER test. But it’s important for me to note that I checked the oil level and it was way above the full mark....again. So I smelled the oil and it smelled like fuel. fuel is leaking into the oil pan...lots of it. I checked the FPR again, no fuel is in the vacuum line. It doesn’t even smell lime fuel. Fuel pressure is steady around 40 psi. i pulled the plugs and they were fouled with fuel. What the hell. It idles like it’s cammed