94 ATX 3.2 dropping two cylinders

[sgthawkusmc]

I'm new to the SHO game. I picked up a 94 SHO w/ 48k on the clock. Immaculate body and interior, but something isn't right. As soon as it warms up, it drops number 3 & 4 cylinders I believe (Driver's side two. Front and back). They seem to stop firing. I've thrown three coils (just in case two were bad), wires, plugs, DIS, CPS and even a new computer at it. Nothing has seemed to help. The only other thing I could think of is that the injectors might not be pulsing, but flowing freely. It's washing down the cylinders after a while. I just changed the oil because there was a gas smell in it. Any other ideas from anyone. Any help would be appreciated!

 

[sdpatt]

A KOEO test for stored codes should reveal if there are any primary ignition circuit faults. From the coils to the plugs, the EEC on our cars is not smart enough to detect a fault - you'll have to do that yourself. Replacing the plugs and wires would have remedied that possibility, but make sure that the wires are routed correctly (see below).

The cylinder order:
Firewall
1-2-3
------
4-5-6
Radiator

The wiring order on the coil pack:
Firewall
5 | 1
6 | 2
4 | 3

It could also be a bad ground connection to the intake and DIS module. Check that ground path from the braided wire to the top intake bracket bolt on the aft passenger side of the intake to the 12mm bolts that secure the balance tube to the front and rear intake plenums and the four bolts on the DIS module.

Radiator

 

[sgthawkusmc]

You just may have answered my problem! I think I might have the wires going 6-5-4 instead of 4-5-6 on the radiator side. I'm not positive though. If that's all it is, I'm going to feel like a complete meat head...
I'll do a search for the KOEO test. I assume that means Key On Engine Off right? I'll check out the ground too. Thanks for the help!

 

[sgthawkusmc]

So much for the easy fix... I went home and ran my codes, here's what I came up with. My wires were on right...:

KOEO

111 System Ok.

217 Primary Circuit failure coil three

KOER

117 ECT sensor is/was low or grounded - ECT

213 (R) Ignition SPOUT or SAW circuit open or shorted - Ignition Systems

411 (R) Idle speed system not controlling idle properly (generally idle too high) - ISC

538 (R) System did not receive a "goose" test

On the cylinder balance test, there was a long pause after the third cylinder cut out and only one more cylinder cut out. Four all together. Two did not cut out the way it was supposed to. Those codes came out as follows:

20 - Problem with cylinder 2
60 - Problem with cylinder 6

The DIS and intake seem to be grounded well. Anyone have any more thoughts with this new info?

Thank you!

 

[projectSHO89]

A simultaneous failure of two cylinders that are fired from the same coil has to be one of the following:

DIS, Coil, or the wires between them. Nothing else will cause this.

You've tried two of the three possibilities. Time to check the schematic and the third choice.

Steve

 

[revhardSHO]

217 Primary Circuit failure coil three

213 (R) Ignition SPOUT or SAW circuit open or shorted - Ignition Systems

These codes are part of the problem. Chances are coil three controls the two cylinders that are not firing. However, you said you replaced the coil so I would imagine you have a short or a bad ground somewhere, hence the later code. Hopefully, thats all it is. I would even run new grounds from the coil pack and DIS to eliminate the possiblity of a bad ground. Otherwise, look for worn or exposed wires that may cause a short in the ignition system. The fuel shouldnt be anything to worry about, Im almost 100% sure you have an electrical / ignition issue going on there.

 

[projectSHO89]

Focus on the 217 code and ignore the rest for now. The computer automatically disconnects the SPOUT signal while in FFEM. This is the cause of the 213 code.

217 indicates a fault in the Coil 3 (C3) circuit of the coil. C3 fires cylinders 2 & 6. Anyone see the pattern?

Output of C3 from the DIS is on connector 2 (forward facing connector) pin 9 YELLOW/WHITE wire.

Test as follows:

Disconnect connector at coil. Visually inspect for pushed, broken, or corroded pins in the wiring harness. Repair any concerns, then reconnect connector.

Repeat for forward DIS connector

If no faults:

Key OFF.

Disconnect forward connector from DIS module. Check resistance from Y/W wire to ground. If open, proceed to next step. If shorted, disconnect plug at coil. If still shorted, repair short to ground in wiring harness.

Key ON

Measure voltage at Y/W wire. Should be battery voltage. Compare to C1 (Y/BK) and C2 (Y/R) wires as reference.

If voltage is present and proper at all three pins, then the coil and the wiring harness are intact.

If voltage is missing or intermittent, then there is an open ciruit in the wiring harness between the coil and the DIS module.

On the subject of the DIS ground: It is grounded to the crossover tube by the lower right screw and lower left screws. This ground is on the forward connector pin 7 (bottom) and is the source of the ground for the whole ignition system. Make certain it is intact.

After all this, my guess is that you'll find that 1) there is an open circuit in the coil 3 line or it is shorted to ground, or 2) that all those DIS modules you swapped in and out are defective.

Steve

 

[sgthawkusmc]

I definitely came to the right place. Thank you guys!
I'll run these tests tonight or tomorrow morning and let you know what I come up with.
The DIS was only swapped out once, but the coil was changed at least 3 - 4 times. The DIS sounds kind of suspect. The ground strap is there and attached.
Thanks again, I couldn't have asked for any better help.

-Dave

 

[sgthawkusmc]

I ran the tests and here's what I came up with:

No pushed, broken or corroded pins. Both connectors were very healthy.

Key off.
1. Y/W wire at DIS. Shorted when coil connected. Not shorted when coil is unplugged.

Key On.
1. Voltage 11.73 at all three wires at DIS.

Grounds are all intact.

I checked the plugs and wires. Seemed fine, but I swapped plugs between cylinders just in case two were bad. Car was good and warmed up at this point. After that, the problems have grown. I'm thinking it's because whatever the problem part is got hot and is now breaking down. I tried to run a second KOEO test and I could not. When I would try to "goose" the gas to display the codes, the car would cut out and die. The codes would run, but they weren't the same as when I first brought the car in the garage and ran the codes. I could never get to the cylinder balance codes tonight.
Here are the codes I was able to get.
411 Idle speed system not controlling Idle
167 No TPS change in "goose" test.
225 Knock sensor not tested
521 Wheel not turned in test (must not have turned it enough)
213 SPOUT or SAW open (this one only appeared after the car was hot. 411 disappeared.) I did try resetting the codes by unplugging the battery, but the same thing kept happening. It was nothing like when I ran the codes yesterday. I don't think I got the car as hot yesterday though.

Was the test with the DIS to tell if it was good or just to rule out the harness between the coil and DIS? Could this all still be the DIS?
Any more thoughts?

Thanks.

 

[projectSHO89]

Hmmm,

That key off test and the key on test results contradict each other.

If the Y/W line was shorted to ground under the static test, it should not have read battery voltage during the key on test. With the short to ground's disappearance with the disconnection of the coil connector, that should have indicated a shorted coil. Yet, in the voltage test, it passed.

Verify the integrity of your multimeter. Then redo the key off test. Add comparisons to the other two coil signalling wires above. Use only the lowest ohms range on your meter. Make certain you are not touching the conductive portion of your test lead. A PASS of this test requires an OPEN circuit to ground on all three coil wires.

Pull the 10A IGN COIL fuse from the underhood fusebox before testing just to be certain there can be no electrical power to the coil while making resistance readings.

If you are still getting a short to ground reading with the coil plugged in, repeat the test measuring at the coil's input connector itself (remove connector first). Also test using the higher ranges on the meter, again avoiding skin contact with the probe leads. I am concerned that the coil may be breaking down internally if the testing results you provided were valid.

Some of the tests I have just given you are to validate the readings and to see if the experiment is repeatable.

If the engine is still running on only four cyclinders, then the DIS, coil, and wiring are still the possibilities.

Steve

 

[sgthawkusmc]

The multimeter is a good quality meter. You're right though, I'll check it out just in case. When I get home from bringing my son to karate this morning, I'll run the tests again. I'll do it when it's barely warm first (to see if I can duplicate the codes from the other day) and then I'll do it again when it's good and hot to see if what happened last night happens again.
If it winds up being the coil after all, I'll be happy, but I think someone at Autozone needs to eat it! Three or four bad coils? Bah...

Thanks.

 

[FuzzyFish]

If that doesn't solve it you may want to try testing the resistance of the wires from the computer to DIS, and DIS to the coil pack. Odder stuff has happened you never know what you'll find.

Happened with my ranger had one inch of bad wire (rpm signal) preventing my ranger from running. Still though less wiring same concept.

 

[RStalveyARFF]

I'd definitely check another DIS or as others have mentioned the wiring related to these functions. Good luck and OOH RAH! Where are you stationed at anyways sgt?

LCpl Tremblay

 

[sgthawkusmc]

Ooh rah LCpl! I've been out for a couple of years (1997), but I might be going back in as an O1E when I graduate from college this summer (hopefully...). I was with 1st SRIG for my last unit. I miss it every day.
Sorry I haven't gotten back to everyone quicker. My wife was in the hospital all weekend. Luckily she's home now and will be alright. Before I had to bring her to the hospital on Saturday, I ran all the tests and here's what I came up with; everything changed since the other night when I checked the codes... I unplugged the battery again and started from scratch again. The first set of numbers was before the reset.

KOEO

111
217

KOEO

116
213
167
225

It wouldn't let me run the balance tests at all. It kept on giving me a code 538. Several times it would quit when I'd goose it.

Post reset:

KOEO

117
217

KOEO
111
213
538

I ran the test several times and I got the same thing every time.

DIS info

Battery unhooked:

DIS w/ coil unplugged -no resistance to ground

DIS w/ coil plugged in - 3.8 ohms each wire.

Battery hooked up:

DIS w/ coil plugged in & key off 8.8 mv each

DIS w/ coil plugged in & key on 12v each

After all these tests I started messing around with the plug wires again looking for a bad wire. I found a couple of them were arching. I checked for that before, but I couldn't find anything. I put a screw driver between ground and the plug wire in a few spots and got them to arc several times. At one point it smoothed out the idle. I think at this point the plug wires are very suspect even though they were brand new. When they were initially put on it was at my buddies shop and he had a kid doing the work. I suspect he might have been a little over zealous trying to route them. There's a couple spots you obviously have to work at it to get them through. It's easy to route them if you do it right though.
The new wires should have been in today, but the guy forgot to order them after I called... should be in Thursday I hope! I'll let you know once I get them in there.
Do the original codes make sense with arching wires? It doesn't seem like that would set a code?

Thanks again for all your help!

 

[sgthawkusmc]

I put the new wires on and nothing really changed. I had the battery unplugged while I changed the wires to clear the codes.
When I first started the car it ran a little rough and sounded like it had an exhaust leak. It smoothed out and I took it for a ride. From the start it didn't have much power at all and it did the same thing as before when it warmed up. It dropped the cylinders and lost a lot of power. Here is what I got for codes this time:

KOEO
111 System checks ok
215 Primary Circuit failure - Ignition coil 1 (this one is new)
217 Primary circuit failure - Ignition coil 3

KOER
213 SPOUT or SAW open

When I tried to run the cylinder balance, it didn't work and then gave me a code 538. System did not receive a goose test.

Where should I go from here? Another coil? 4th or 5th? DIS?