Gonna wear you all out, new problem, completely stumped......

[jakecat22]

So, bout a 92 SHO, knew it would need work, but it drove home(45 miles) great, ran great everything.

Car had oil in plug seals, so I changed the valve covers and plug well seals. After I put it back together, the car ran like crap, sputtering and back firing. Took it back apart, and realized I had pinched a vacuum line under the intake to the heads. Replace line, rebolted down the intake, car starts right up, idles great. Did not drive due to getting ready for a brake job.

Got done with the brake job today, took it for a drive. Here is where the problems started. It has crappy power in low RPM's under load. It is also backfiring something bad. Once it gets up into the higher RPM's it seems to drive better with more power. I also have a very very strong smell of fuel out of the exhaust.

Got it home, hooked up my scanner. I am getting codes 50 and 60 on the cylinder load test.(cylinder weak or misfiring) Keep in mind, I did change the spark plugs and wires when I changed the valve cover gaskets.

What I have done:
Checked compression 3 TIMES in all cylinders, all cylinders test between 180 and 210.
Checked spark at the plug, good spark.
Checked spark at the wire, good spark.
Listened(with a stethoscope) to the fuel injectors, all see to be working.
If I remove the plug wire from cylinders 5 and 6, nothing happens, in fact, the engine seems to run slightly better(weird) and the back fire(while reving) kinda stops.
If I remove the plug wire from any other cylinder, the engine bogs down and back fires and bucks.

I have compression. One part of getting a cylinder to fire.
I have spark(I am 99% sure) two part of getting a cylinder to fire.
The fuel injectors seem to be firing, so I think I have fuel, that is 3 parts.

I have tried switching up the spark lug wires from good cylinders to bad, the problem stays on cylinders 5 and 6. I have tried different spark plugs, no change, same problem, same cylinder.

I am getting no other codes on my scanner both with KOEO and with KOER except for O2 sensor always lean, which I think I am attributing to the cylinder not firing.

I am 100% stumped, frustrated and in a bad mood. I consider myself to be slightly good mechanically, have been working on cars for a while(just mine mind you) and this has me stumped. Maybe I am missing a secret formula somewhere, I don't know.

Please help, I am really at the end of my rope hoping I didn't buy a huge problem someone was just trying to dump off.

 

[SHOdded]

What plugs/wires did you use?
Are the wires connected to the coil pack in the right order?
Checked and cleaned DIS/intake grounds? The one at the firewall?
No leaks at the intake? Wires get pinched all the time.
No oil at the cam sensor?
Pulled the MAF connector, any difference?

 

[mrecoolgar]

Check the male/female connections you had to separate.
May be miss lodged, bent pin/terminal.

 

[jakecat22]

What plugs/wires did you use?
Are the wires connected to the coil pack in the right order?
Checked and cleaned DIS/intake grounds? The one at the firewall?
No leaks at the intake? Wires get pinched all the time.
No oil at the cam sensor?
Pulled the MAF connector, any difference?

Plugs: Autolite PP 3924, wires Taylor 8.2mm Thunder Volt

Wires to coil pack at in right order, have checked them 4 times

DIS/intake grounds: This I have not done?? Where is it at the firewall? Gonna need some help on this one

No leaks at intake, that was the first problem I am sure there aren't this time.

How do I check for oil at the cam sensor?

Pulling the MAF connector makes the engine idle go up very slightly.....but no change in performance.

 

[SHOdded]

If the car is running properly, disconnecting the MAF should make a noticeable difference in performance. If it does not, then likely the MAF needs to be replaced.

The DIS/intake ground is a woven strap, connected between a bolt on the passenger backside of the intake on one end and the firewall on the other. Basically the DIS grounds to the intake, and the intake to the firewall.

Not sure if we have enough people using the Taylor wireset to comment on their viability ...

 

[jakecat22]

If the car is running properly, disconnecting the MAF should make a noticeable difference in performance. If it does not, then likely the MAF needs to be replaced.

The DIS/intake ground is a woven strap, connected between a bolt on the passenger backside of the intake on one end and the firewall on the other. Basically the DIS grounds to the intake, and the intake to the firewall.

Not sure if we have enough people using the Taylor wireset to comment on their viability ...

Would a bad MAF cause 2 cylinders to basically be dead? I have another MAF that I can throw on to check it off my son's mustang, but I didn't that before this problem and my MAF seemed to be working correctly.

Got ya on the DIS intake ground, it is hooked up to the back intake bolt that holds the intake down, and also to the firewall.

I can't imagine the wires are causing this problem, I have switched them around and the problem stays on the same cylinders.

 

[SHOdded]

Sure doesn't sound like a MAF problem, more like a DIS problem or a coil pack problem. Coil packs on the SHO rarely fail, but I suppose it does happen. They should be replaced by OEM coil packs, avoid ACCEL! Is the Mustang MAF the same as the SHO's MAF? If not, the PCM might not know how to handle the tables correctly. Try spraying the MAF sensor with copious amounts of MAF cleaner first.

Not saying you have it incorrect, but since it can't be repeated often enough, here is a link to the correct wiring order:
http://www.shoforum.com/index.php?threads/plug-wire-routing.89091/

 

[jakecat22]

Sure doesn't sound like a MAF problem, more like a DIS problem or a coil pack problem. Coil packs on the SHO rarely fail, but I suppose it does happen. They should be replaced by OEM coil packs, avoid ACCEL! Is the Mustang MAF the same as the SHO's MAF? If not, the PCM might not know how to handle the tables correctly. Try spraying the MAF sensor with copious amounts of MAF cleaner first.

Not saying you have it incorrect, but since it can't be repeated often enough, here is a link to the correct wiring order:
http://www.shoforum.com/index.php?threads/plug-wire-routing.89091/

The MAF's are the same, I cross referenced the parts and the same MAF for the sho also fits the mustang. I will try switching them tomorrow after work and see if anything changes. I honestly don't think it is the MAF, but everything is worth a try at this point. FYI, I have already sprayed the MAF with a half a bottle of MAF cleaner LOL.

Coil pack is something I haven't changed....and to be honest, the one in the car may be original LOL, but I can't find a part number or anything else on it. Would a bad coil pack send a good spark to the plug and still be the problem? I have good spark to all the plugs.

I am thinking more and more the DIS maybe the problem. I have not removed it from the intake at all since getting the car. I removed the intake but left the DIS intact and just removed the two connections. I have double checked those connections and they seem to be fine. I also checked the ground from the intake to the firewall and it seems good. One thing I did notice on the DIS, if looking at it from the passenger fender, the top left bolt(is that the ground bolt??) looked like at one time someone had hooked a wire or something to it as it had some copper wire wrapped around the bolt between the bolt and the DIS. I removed that bolt, and took out all the copper wire, and replaced the bolt, but that did look a little strange as to why anyone would put a wire on there.

I removed all the plug wires and put them all back on again, and double checked the routing, I am 100% sure they are correct.

I really hope someone can help me solve this.....I am seriously stumped and I am not the type of guy to spend money on parts unless I know 100% the part is bad, so I am not gonna go out and buy parts and "hope" it fixes the problem.

Been working on it all day, I sometimes find walking away and coming back a day or two later is the best solution, LOL, hopefully someone has some answers or solutions that I can try tomorrow after work.

 

[sperold]

Make sure this is correct, and note that 5, 6 are the ones out of order.
http://www.shoforum.com/index.php?threads/plug-wire-routing.89091/
Is there a chance the wrong coil pack is on the car, like maybe from a Mustang or some other unit.

 

[jakecat22]

To everyone that responded thank you for your help, I....jake...am a stupid idiot. I think I have dyslexia. I after looking at the wiring routing 50 times, finally saw how the 5th and 6th cylinder were SWITCHED on the coil! I mean, WTF? Who decided to put them all in order except those two cylinders???? I guess all the times I looked at it, I saw the front bank as 4 5 6 and the coil from bottom to top as 4 5 6 instead of 4 6 5. So, I had the 5th coil hooked to the 6th cylinder and vice versa. I feel like a complete and total idiot for missing something so simple, when I thought I had checked it about 20 times. I will put myself in the dunce corner for a few hours.

Again, thank you all for constantly harping on me checking the plug routing, for some reason, when I looked at it the last time, it just "clicked". I just took it for a drive around the block and....yea, it is good to go!

 

[Toolman]

I'm glad you got it working. After your first post I knew it to be 5/6, and was feeling bad that I didn't see thread earlier, but it looks like it was only a couple of hours (rather than a couple of days).

And don't feel bad, we have all overlooked what seem to be simple mistakes.

Enjoy the ride!

 

[kevinspann]

Yep, I was going to say if it was 5/6 then the firing order is switched. They're 5/6/4 down the left side of the coil (looking at it from the front of the car) but some manuals have it listed as 4/5/6.

 

[SHOdded]

Nothing better than hitting the sweet spot in the SHO! On to the next challenge ...