Okay, so I showing my ignorance here. I am a self described car nut, gear head, motor head, whatever. For fun I restore older cars, I have a '72 MGB, '79 MGB, '58 MGA and my daily driver is an '86 El Camino. All of which I have restored, or am restoring frame-up. I run hi-test (93 octane) in the El Camino and Volvo and 89 octane in the MG's. I never stopped to consider the difference between name brand and generic gasolines as far as additives were concerned. I assumed (wrongly) that as long as I was running 93 octane it was good gas. Wrong. I recently read a AAA report regarding detergent additives and more recently paid a repair shop to clean my throttle body, because the discount gasoline (Sheetz, Wawa) didn't have the detergents that name brand gasoline has. So, I have been saving $0.10 per gallon, or $1.20 a week for inferior gasoline, to pay for a throttle body cleaning, and poor performance for three months whilst I was trying to figure out the cause. Needless to say, I have switched to name brand gasoline.

 

Which car needed the throttle body cleaned? Gas doesn't get on the throttle body in a Volvo..

 

ES6T is correct - on the fuel injected engines, the throttle body is upstream from the injectors - the detergents may help the injectors and diminish tarnish on valves but AAA also reported it only takes 1-2 tanks of high detergent gas to clean any tarnish. Modern engines have knock sensors which allows the car to adjust to the octane so running regular is fine - and if you're worried about Wawa gas, throw in a tank or two of name brand fuel every so often. On your vintage motors its a different story regarding the octane where the higher the compression ratio, the more critical it is to have higher octane (particular for the pre-cat cars which were designed for leaded gas. If you have a dirty throttle plate or MAF sensor in your Volvo then you should be checking the quality of your air filter and whether your PCV system is in good working order.

 

I'd sorta figure a guy who did frame up restorations would know that.
Then again, I also would have thought he could/would have cleaned the throttle body himself......................

 

Sorry for the delay in responding. Thanks to ES6T and MT6127 for setting me straight. You are absolutely correct, the throttle body is upstream of the fuel inlet. I was too quick to jump on the fact that Autozone had given me the code of P0170, "Fuel Trim Bank 1" as an error and when the car was diagnosed with a dirty throttle body I made the wrong connection. For what it's worth, cleaning the throttle body did fix the problem and the CEL has extinguished.

Donf, under normal circumstances I would have cleaned the throttle body myself. Unfortunately there are instances that life happens and time is of the essence. I sincerely hope that you never get the phone call I did that required me to leave in a hurry and drive across 6 states in a car that needed servicing quickly. However if you do, I promise you will not get any snide comments from me.