1NSIGHT

iTrader: (3)

Seriously need some help.

My 86 s4 wont start. I recently put the AC compressor back into the car and decided to clean off the engine block while I was at it. Afterwords I went to test drive the car and it ran alil funny so I went back and tested the grounds(maybe they were wet) taking off the upper intake manifold.

Put UIM back on and it didnt start and hasnt started since. Ive pulled the engine harness, cleaned every ground, took off the headers (to check if an apex seals broke/starting to get desperate), replaced LIM(the bottom right corner mounting hole broke), bought new spark plugs, checked all the fuses, thermo sensor, tps, poor mans compression test(pulled spark plugs)AFM searched for hours to find something.

At this point I have no idea. I believe it could just be running really rich to the point it wont fire, cause it sounds like it wants to start it will stutter once. i also think I missed something and just dont know what.

I dont have any experience with fc's besides my own so it could be really simple but right now im at my wits end. probably gonna ask for help in the regional section as well.

Thanks for ANY input you might have.

1NSIGHT

iTrader: (3)

Ok I found out that Im getting no spark. Did the poor mans test and pulled the spark plug out and tried to get an arc across a bolt.

What are my options now? How can i test if my CAS is bad, coils are bad, or my ECU is bad.

Thanks for ANY advice.

3vil

iTrader: (4)

none of the four plugs are firing?

satch

iTrader: (1)

next

satch

iTrader: (1)

Take the spark plug wire boot off of the leading coil but leave the boot loosely against the bore, tubular looking part of the coil that it was plugged into, and turn the key to start and check for spark at the bore. If no spark then try checking the voltage on the B/Y wire at the leading coil and check for battery voltage with the key to on. If you have voltage at the B/Y wire but no spark at the coil then turn your attention to the CAS. One way to check the CAS at the ECU would be to "remove" the largest plug, located on the far left, and use a multimeter set to "ohms" and place one terminal of the ohm meter on pin 1N and the other lead on pin 1P and do the same between pins 1T and 1Q and both readings should fall within the range of 110 to 210 ohms and no need for the ignition key.

1NSIGHT

iTrader: (3)

Satch...
I have never done electrical work before so IDK how exactly to test the ECU. I know where 1N, 1p, 1T, 1Q is. but dont know to test.

satch

iTrader: (1)

No problem. Of course you'll need a multimeter, but were you able to check for voltage at the leading coil yet via the B/Y wire? Without voltage on that wire it will prevent the coil/igniter from working and you'll get no spark as a result. To check for voltage on the Black with Yellow stripe (B/Y) wire set the multimeter to volts DC and then place the red lead of the multimeter to the B/Y wire and then take the remaining black lead of the multimeter and put it on a suitable ground and the negative terminal of the battery always provides a good grounding choice and it's within a foot of where your leading coil is so it's a convenient choice. With the key to the "on" position, the multimeter should read about 12 volts. Do this first and then we'll deal with checking the other stuff if necessary.

1NSIGHT

iTrader: (3)

Yes checked both coil/igniters. 12.36v on Leading and trailing. Checked via B/Y wire

satch

iTrader: (1)

To check the pins on the ECU which relates to the CAS you can conduct 2 different tests, one involves ohms and the other involves volts. The test mentioned previously involves ohms and uses the same multimeter but using its ability to measure ohms,resistance. 1N and 1P are to be checked with the plug disconnected from the ECU to do this test. With the meter set to ohms you place one lead into the backside of the plug where pin 1N is and the other lead into the back of pin 1P. When doing this particular test it does not matter which meter lead goes to pin 1N or 1P just as long as there is one lead on each which is different then doing a voltage check. 110 to 210 ohms is the range give in the FSM. The same test can be done for pins 1T and 1Q. And when you do this check you don't want voltage in the system so "no" key is necessary here.

After checking these pins using the ohm feature you can check each pin for "voltage" where the red lead is backprobed to the individual pin and the black lead applied to a suitable ground such as the bolts used to mount the ECU and there are 2 to choose from located at the front of the ECU. This test is to be done with the key to "on" and each of the 4 pins checked should have voltage of less than 1 volt.

1NSIGHT

iTrader: (3)

OK.

Did the test. Unplugged the largest connector. Tested both ways for ohms and Volts. (the plug does not need to be in the ECU for this test right?)

For ohms 1T and 1q worked but 71 ohms.
For 1N and 1P nothing.

Got No Volts for anything though. No voltage for 1:T,P,Q,or N

Also something is killing my battery. (gotten two jumps this week but it was only for <5 mins)

satch

iTrader: (1)

The plug at the ECU doesn't need to be connected for the test.

It's nice to check things at the ECU for various reasons but you can check the CAS at the CAS itself by removing its plug and checking for ohms as follows. Remove the plug at the CAS and look at the plug from the angle where you are looking into the plug where you can see the pins inside the plug as opposed to the back of the plug side where the wires come out of the plug. So looking into the plug turn the plug such that the the nub part of the plasctic plug is located on top. Then check the ohm readout of the two pins on the right side, which would be upper right pin and the lower right pin. The ohm reading again should be 110 to 210 ohms. Once done then check the ohm reading for the two pins on the left side of the plug and see if the reading again falls within the stated range. Again, no key is necessary.

1NSIGHT

iTrader: (3)

CAS is good.

160ohms for both sides.

satch

iTrader: (1)

I would check the ohm readings again at the ECU to try to help rectify the difference in the readings that you are getting. Just to make sure, when you look for pin 1N at the ECU plug are you using the sixth pin from the left on the bottom row and 1P being next to pin 1N, fifth pin from the left on the bottom row? Also, make sure the meter leads are shoved into the respective spots in a snug manner. Remember, plug removed from the ECU and no key in the ignition.

Also, check for voltage on pins 3I and 3J, smallest plug located on the far right, with the key to on and plug removed and also when connected. Voltage should be close to 12 volts but may be less if your battery is running low or if the ECU is draining volts when the plug is connected which may very well give you different readings. And check for voltage on pin 2A, middle plug top row far right with plug connected and key to on. Reading should be close to 5 volts.

And did you know that Fort Worth,Texas is a fine place to live?

1NSIGHT

iTrader: (3)

Weirdest thing. I tried to measure the resistance again and the 1L/1J and 1F/1G gave me the same 160ohms that the cas was giving me. (those are the clutch switch/initial set coupler and AC main relay/ neutral switch). with that said 1P, 1N, 1Q, 1T the same thing.

I officially have no idea whats going on.

Fort Worth is too far from home. though my mum lives in OKC, Oklahoma.(which is kinda close)

satch

iTrader: (1)

What about, "Also, check for voltage on pins 3I and 3J, smallest plug located on the far right, with the key to on and plug removed and also when connected. Voltage should be close to 12 volts but may be less if your battery is running low or if the ECU is draining volts when the plug is connected which may very well give you different readings. And check for voltage on pin 2A, middle plug top row far right with plug connected and key to on. Reading should be close to 5 volts."

And why would you check the resistance of "1L/1J and 1F/1G" for? Beware of checking for ohms for if there is voltage traversing through that particular circuit you can damage it such as wiring, electrical components, and such.

1NSIGHT

iTrader: (3)

My battery is dead so I cant check the voltage to anything.

is there another way to check if the main relay is bad. and whats a V ref(2A). Also I checked 1L/1J and 1F/1G by accident. considering what they are they shouldnt work anyway and was surprised that they were(its like the plug is backwords).

I a forum member came of over to help today and we could not find any reason why It wont start. it almost caught while testing(used his battery) but it . I think Im getting to much fuel but he says its not really possible since my car is stock besides emissions delete.

I have no idea whats wrong.

satch

iTrader: (1)

You've stated that you had voltage at your coils which suggests your main relay is working properly because of the two wires which receive voltage due to the relay working properly are the B/Y wire (connects to coils) and the B/W wire which supplies voltage to the emmision components, and to pin "3I" of the ECU, as well as the boost sensor, and the check connector located by the variable resistor. If any of these has voltage with key to "on" then the relay is okay.

Pin 2A is connected to five engine sensors and the voltage needs to be close to 5 volts with the key to "on" for them will to operate properly. The AFM is one of these sensors.

Were you ever able to at least get spark in your efforts today? And checking the grounds should be on the list of to do's.

SirCygnus

iTrader: (1)

he was getting trailing ignition but not ignition from the leading coils. he gets 12V as the coil power plugs. for some reason, i think his coil might be bad.

1NSIGHT

iTrader: (3)

The AFM works im pretty sure. pressed the flap open and I can hear the injectors spraying.

Checking the grounds was the first thing I did. And I did All of them. not just the ones on Aaroncakes website.(his grounding procedure)

Gryffinwings

iTrader: (3)

I think that would probably be the case, since there isn't any spark, I do not think I've heard an ECU go bad. Might also want to check the connections to see if they are clean or not and firmly in place, just in case this wasn't mentioned.

If you can, hit up the junk yards and pick them up.

HAILERS

FYI: electrical plugs are read from the right to the left from the WIRE side of the plug.

1NSIGHT

iTrader: (3)

how can I test if the coil packs are good? I dont wanna go buying stuff unless I know its broken. And all the connection points are good but i will take a closer inspection tomorrow morning.

Is there any way I can check if Im getting too much fuel? Know its a shot in the dark but i think its getting too much fuel.

1NSIGHT

iTrader: (3)

Yeah I was using this LINK

satch

iTrader: (1)

I'm sure the FSM shows how to measure the resistance (ohms). Should be .2 to 1.0 ohms. Also, if the v-ref voltage at pin 2A is off enough it could cause a misfiring of the coils

If your leading coil is problematic then your fuel pressure conundrum is a bit moot. You can use a fuel pressure guage to measure it.

HAILERS

Lead coil assy has a two wire plug that is white in color. Pull the connector apart.

One wire is B/Y and the other is G/Y (green/yellow). With key ON the B/Y should read approx batt voltage.

Put your meters positive lead into the G/Y wires socket and the meters neg lead on a good ground point.

Key to ON. Now rotate the engine with your HANDS and watch the meter set on dcvolts. As the engine is turned over by hand, the meter should change from zero volts dc to approx 5vdc over and over and over as you turn the engine over by hand. If it does that, that means the ECU is sending the firing signal to the coils assy to fire the sparkplugs.

I'm pretty sure I've done that in the past to confirm the ECU is sending a firing signal to the Lead coil assy.

It's easier to just have the sparkplug wires connected to the sparkplugs. Then pull one sparkplug wire out of the COILS BORE about a 1/16" or less and have someone spin the engine over with the starter while you stare at the gap b/t the sparkplug wire and the coil bore. Spark should occur as the engine is spun over.

Even easier if you have a spare CAS and connect that CAS to the harness on the engine. Then key ON and spin the bottom gear of the CAS by hand. With key On you can hear the primary injectors click and see the spark at the LEAD coil assy if the sparkplug wire is held outside the coil bore a 1/16" or so. Don't have to spin the gear on the CAS very fast at all to see/hear this.

Flooded? Pull the plug off the fuel pump. Buy a can of starter fluid. Spray for no more than three seconds into the airfilter. Try to start the car. Engine goes varoooom for a moment confirming the engine was flooded and that all else is just fine and dandy. Reconnect the fuel pump after doing this starter fluid thing a few times and start the engine.