Just replaced all timing chains, guides and tensioners. Was running great. I was driving home and was accelerating into a turn and it felt like it missed several times and then the yellow engine light came on with a message "Restricted Performance". At the same time my coolant temp gauge dropped to zero. The car continued to run without problem. When I got home I checked under the hood and found that the plug on the coolant temp sensor had come loose. My question is: Would that cause the RP warning?

 

Yes it would. The ECM needs input from that sensor to manage fuel enrichment and saw it missing. Probably disconnected or loosened as you were working in that area. Put it back on and enjoy.

161k miles on the original plastic tensioners ? ? ? ? You live a charmed life.

Any chance of getting a picture of the condition of the tensioners?

 

Here are some pix. I just bought the car about 8 months ago. The first and only other owner told me that the tensioners had been replaced before in around 2002 at the dealer. They replaced them with plastic! All tensioners were cracked. The guide on the left secondary was completely gone. I found the pieces of it in the front cover when I removed it. The secondary chain on left had jumped one cog on the exhaust cam. I was lucky!



The guides were cracked in several places.





You can see bare metal under secondary chain.

 

for the life of me, on ANY car on such an important part that can cause major damage if the part breaks why they would use PLASTIC. STUPID STUPID

 

Car was running great and pulled up to stop sign. As I pulled away, I felt it miss and then went right back to normal except the "check engine" light was on. I was only a couple of blocks from work, so I drove on there. When I got to the parking lot I put my code reader on and 2 stored codes came up : P0171 & P0174 indicating both banks were too lean. I cleared the codes, light went off and everything was fine. Drove 3 more days and today I didn't even feel it misfire, the light just came on. Checked codes, same ones. Suggestions?

 

Start at the air filter and look for leaks in the duct work. The 'accordion' section off the duct is famous for cracking on the bottom as it is only about 4 inches directly above the exhaust manifold. Take it off and inspect the bottom for splits.

If you find splits clean with brake cleaner and wrap tightly with black electrical tape. Completely invisible. I ran a Volvo with tape for years as it held up better than the plastic. The duct is not expensive.

Beyond that look for leaks around the big 'O' ring around the throttle body. You disturbed all that doing the tensioner work which is probably related.