Decided to go pull the plugs myself and take a look. Lo and behold if it didn't have the correct Denso plugs installed. The work order clearly states that they used 6 BSH BH3-9607 plugs. Makes me wonder.... Anyway, all of the plugs looked like they might actually be new when compared to the plugs that came out of my old Chevy at 100K miles. However, plug #6 (closest to the firewall on driver side) looks old and used-up. So now the question becomes: Did they change the plug and use the correct plug despite what's listed on the invoice, and if so, did they change #6 which is difficult to get to.

Never pay someone to do what you can do yourself and know without a doubt it was done. :idea:

 

The #6 spark plug boot is different than the #1-5 plug boots. The coils are all the same, the boots are removable and replaceable. If the #6 boot is used on a cylinder other than #6 it can cause a misfire. The #6 boot is a little shorter than the rest and the part that sits in the plug well is made different as well. The #6 boot typically has the number 5250 embossed on it and 1-5 have 5249 embossed on them. Make sure you don't have #6 on #1 cylinder.

 

Thanks Buster. I know that the #6 coil assembly is shorter on the 3.2L. Are you sure that is the case for the 3.5DI? Unfortunately, I had already reassembled it before I saw your message, but while I had it torn apart, I took the coils and plugs to the shop that did the work and the mechanic adamantly opposed the notion that he may have missed changing #6. When I pointed out the differences between it and the other 5 plugs and compared it with the old Denso iridium plug from my Chevy, they couldn't explain it. However, they offered to take a look at it if I brought it in - which I did today. They did a compression check on all of the cylinders and said that #6 was only reading around 90 psi while the others were all around 125 and suggested that could be the cause of the fouled plug. They went ahead and replaced the #6 plug so I suppose we will know for sure in a couple of months if the lower compression is the cause of the different looking plug. The P0300 and P0301 codes have disappeared for now since I had the battery disconnected for so long. They offered to scan it again if it came back on anytime soon.

 

I though the #6 special coil & boot assembly 8-19005-250-1 fit the 3.5L DI engine but I did some more digging and determined that is not the case. The correct coil & boot assembly for the DI version of the 3.5L is 8-97315-438-0 (CarQuest 52-1803). The 8-97315-438-0 coil & boot assembly is listed as applicable to all six cylinders of the DI engine for Rodeo and Axiom.

 

Are there any suitable substitute plugs for the Denso sxu16hpr9? Not really sure if the original post question was answered.

 

Are there any suitable substitute plugs for the Denso sxu16hpr9? Not really sure if the original post question was answered.

I'm trying out the autolite xp5703 in a 3.5l di. One week no codes or pings. I will follow-up in a month or so.