99 GRD MARQUIS LS shaky throttle/engine
 

Hello fellow members,

I need some opinions and comments from someone who may have had the same/similar thing happen. I have a 99 Grd Marquis LS with barely 102,000/miles and I have kept the vehicle in mint condition since I bought it. However, recently, I had washed the car's engine and follow the recommended instructions from the engine cleaner spray product. Also, I went online for advice as well as youtube to see how others have done it before me. So, I washed it and soon after I got done, the engine started to shake and wobble pretty badly. I allowed it to run at high revs so it would dry up and immediately started to drive it. So, soon after an engine light came out and plugged in my trusty OBDII scanner and it said the error codes, after checking with the local autozone, they said it could be that water got into the spark plug well or the coil went bad. So, to test this from the ground up, I decided to do the full tune up anyways. I bought all 8 sparks OEM motorcraft and replaced them all. Cleared the error codes. Drove the car for several miles and the same error code came back. Same bank, #8. So, I went to the next logical check point in the elimination process and moved the coil pack into bank #6. Cleared the error code. And drove the car for a few miles. The check engine light came back up again, same error code but in bank #6 which told me it was the coil had gone bad. I then bought an OEM motorcraft coil from a trusted seller on eBay. Replaced it new and cleared the error codes. Also replaced the air filter, gas filter, pcv valve, oil change and also used seafoam to clean the air intake as recommended, as well as used CRC Air Mass Flow cleaner to clean the air sensor. I also replaced the EGR valve. Drove the car again for several miles. However, this time the car is now shaking than before and yet I have no check engine light or error codes???? I am lost in what to do next! Please help.

Gary
:D

I know you cleaned the MAF with CRC, but that is still my suspicion of your symptom without CEL. These are expensive, so I do not want you to buy a replacement MAF just yet.

Could the cleaning have loosened/damaged any harness connectors to the injectors, TPS, or IAC? I wonder if you could disconnect the battery, and go in and plug-unplug each harness connector and inspect for corrison. Look for light green colored contacts that is a sign of corrison. Get a can of electric contact cleaner, or Radio Shack TV Tuner cleaner and lightly spray the harness contacts.

Next step would be to get a auto shop to drive the car with their scanner and record fuel trim.

Good Luck, Bill