Question about 2005 Cadillac CTS
I have 122K+ on my CTS 3.6L. I have made a few change recently to better the performance, I thought…
This model requires removal of the upper intake manifold to change plugs or injectors. What a pain! Anyway, I installed E3 spark plugs and replaced the factory mufflers with Thrush turbo units. Shortly after this I started experiencing sputtering during acceleration at shift points. It seems to be just before it shifts. I need to put my foot into it for the sputtering to occur because slow city driving it is almost unnoticeable. Today, the problem (sputtering) is getting worse. It seems to occur sooner (mid-RPM) and continue longer. Gas mileage definitely decreased.
Since the “check engine” light does not come on I have not put the scanner on it. I have an Actron CP9180 scanner.
A few items that should be noted:
1) At about 100K miles I replaced the computer with a used one (but thoroughly tested by independent performance shop).
2) Shortly after replacing the mufflers (about 105K), the “check engine” light did come on. The fail code was P0420 and P0430. I assume that was due to muffler change. I reset the codes and light has never reappeared.
3) I am very hard on the vehicle. It is pushed 5 days a week 50 miles a day (to and from work) at high speed highway miles 80+.
4) Poor acceleration at any speed compared to performance at 100K.
I am just not sure of where to start. I don’t want to just start replacing everything. Thanks for your time and guidance in advance.
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Posted on Jan 02, 2017
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