Help troubleshooting rough engine after flat tire repair

[rctx]

Hello friends - looking for some help with an issue:
I own a 99 Explorer, V8 5.0 Limited Edition.
I had a flat tire last Tuesday on the front driver side.
Put the spare on and then drove to shop. Car was running fine.
They put on a new tire and when I left the shop, I noticed it was running really rough.
Even had to put it in neutral at lights to keep it running.
I went straight home and parked it bc I was headed out of town first thing the next day.
Returned yesterday and drove it to auto zone so they could put their fancy diagnostic reader on it.
Code said it was spark plug issue (I don't have the specific code, I'm sorry)
Changed the spark plugs last night (plugs only - not wires)
At first it seemed to be running much smoother, but this morning its back to running super rough.
When I turn the AC on it really starts to falter.
Is it possible the tire guys bumped something while working on tire? The timing is suspect.
I've already called them and made them aware. They think its unrelated obviously.
Note: The cover between wheel and engine is long gone... so you can see the plugs, wires, all components when looking in from tire.
What are your suggestions? Thanks in advance for the help!

 

[EB4X]

Feel and look over plug wires on that side.... when you initially had the flat did the tire shred apart and throw debri or just a controlled slow leaking flat? ....maybe debri hit a plug wire and partially damaged it .... bad plug wires can sometimes be sporadic with symptoms... with it running touch / move plug wires / near boot (with insulated tool or stick) and see if you hear engine start missing even worse.

 

[Mbrooks420]

Try new plug wires. Replace the splash shields.

 

[1998Exp]

Hello friends - looking for some help with an issue:
I own a 99 Explorer, V8 5.0 Limited Edition.
I had a flat tire last Tuesday on the front driver side.
Put the spare on and then drove to shop. Car was running fine.
They put on a new tire and when I left the shop, I noticed it was running really rough.
Even had to put it in neutral at lights to keep it running.
I went straight home and parked it bc I was headed out of town first thing the next day.
Returned yesterday and drove it to auto zone so they could put their fancy diagnostic reader on it.
Code said it was spark plug issue (I don't have the specific code, I'm sorry)
Changed the spark plugs last night (plugs only - not wires)
At first it seemed to be running much smoother, but this morning its back to running super rough.
When I turn the AC on it really starts to falter.
Is it possible the tire guys bumped something while working on tire? The timing is suspect.
I've already called them and made them aware. They think its unrelated obviously.
Note: The cover between wheel and engine is long gone... so you can see the plugs, wires, all components when looking in from tire.
What are your suggestions? Thanks in advance for the help!

There is no specific code for a 'plug issue'. In fact, there are no codes for ignition at all. What they saw was most likely a misfire code - which is likely to be caused by an ignition problem, but not necessarily. My guess would be that you have a defective wire that's arcing to the exhaust manifold or to some other metal part. It might have been moved slightly in the process of replacing your tire, which brought the problem to light. How old are your plug wires? If more than 6-7 years, they most likely need to be changed anyway. Get the good silicone-insulated stuff, not some cheapies - Motorcraft preferred. And make sure to route them properly, without touching the exhaust manifolds.

 

[rctx]

Feel and look over plug wires on that side.... when you initially had the flat did the tire shred apart and throw debri or just a controlled slow leaking flat? ....maybe debri hit a plug wire and partially damaged it .... bad plug wires can sometimes be sporadic with symptoms... with it running touch / move plug wires / near boot (with insulated tool or stick) and see if you hear engine start missing even worse.

Good thought! I'll try that!
The flat was a slow controlled leak. no carnage there

 

[rctx]

There is no specific code for a 'plug issue'. In fact, there are no codes for ignition at all. What they saw was most likely a misfire code - which is likely to be caused by an ignition problem, but not necessarily. My guess would be that you have a defective wire that's arcing to the exhaust manifold or to some other metal part. It might have been moved slightly in the process of replacing your tire, which brought the problem to light. How old are your plug wires? If more than 6-7 years, they most likely need to be changed anyway. Get the good silicone-insulated stuff, not some cheapies - Motorcraft preferred. And make sure to route them properly, without touching the exhaust manifolds.

The wires are 4-5 years old I believe. need to check my records. Yeah ... I'm with you, whatever is the issue seems to have been brought to light by them working around the tire. I think a previous mechanic removed the splash guards without asking... I honestly hadn't noticed until now.

 

[rctx]

Try new plug wires. Replace the splash shields.

Thank you Looks like we are heading that direction

 

[HucklburryRev2]

I wonder if they bumped a vacuum line or something - would be nice to know the actual code that showed up - since you did plugs I'd look all over that work area for what they could have bumped but changing a tire isn't all that intrusive.

Also, you can pop the hood at night in the dark and run the engine, sometimes in the dark you can see a plug wire if its arcing on something

 

[CDW6212R]

What was the actual engine code, such as P0303 etc? A code pointing to plugs would be a "miss" code, and tell you which are an issue.

That still sounds like a spark issue, plug wires are often hurt when removing them. Those should be replaced every five years or so, don't wait till one fails(or the engine runs rough).

Also, how bad were the plugs, the gaps? Very old plugs created huge gaps, and that is very bad for the coils. It is easy to cause a coil pack to fail with very worn plugs. So get to checking the wires by R&Ring one at a time with it running, use an insulated tool to do that right.

The tire, how old were the tires, and is it 2WD or AWD? If it's AWD, how much tread did they have, how much do the three remaining tires have left? You can mix any tires on a 2WD without much worry, but an AWD must have four equal tires(diameter, not brand or type).

 

[J_C]

I too would wonder if they disturbed a vac line and it came off or cracked, if not in the engine bay near the wheel, then at the evap canister next to the spare tire. A scan tool capable of live data should show this as a high fuel trim, trying to compensate for the extra unmetered air, and potentially misfires.

I don't recall what vac lines are near the driver's side front wheel, IIRC the vac reservoir for A/C is on the wheel well liner for the passenger side.