oldscsc Posted July 21, 2009 Report Share Posted July 21, 2009 '94 3.4 convertible.. For quite a while I've had these symptoms, but have never figured it out. I'm finally tired of it. I average about 13 MPG and have terrible power output..it's sad. I ran it on the Dynolicious and it ran a 17.78 quarter It's reliable as ever, but it is just no fun to drive. I have done plugs and wires already. There is no code and O2 sensors almost always throw codes. What could case this? Quote Link to comment Share on other sites More sharing options...
sloick Posted July 21, 2009 Report Share Posted July 21, 2009 its out of time. i had a 97 monte that did this and the belt broke. Quote Link to comment Share on other sites More sharing options...
oldscsc Posted July 21, 2009 Author Report Share Posted July 21, 2009 How does it just "come out of time"? Bad tensioner? The belt was replaced at 69,500 miles; it currently has 75,6xx miles. Quote Link to comment Share on other sites More sharing options...
jake91 Posted July 21, 2009 Report Share Posted July 21, 2009 mabey it wasnt timed right when replaced Quote Link to comment Share on other sites More sharing options...
oldscsc Posted July 21, 2009 Author Report Share Posted July 21, 2009 mabey it wasnt timed right when replaced I had never driven this car until after the belt was replaced by my mechanic, and seemed to have great power (it would burn 'em). Now it doesn't. I guess I'll hit up my friend for his timing light and knowledge. Quote Link to comment Share on other sites More sharing options...
Pontiac6KSTEAWD Posted July 21, 2009 Report Share Posted July 21, 2009 ICM, Coil packs, injectors, are the places I would start checking. Also a compression test. Quote Link to comment Share on other sites More sharing options...
Lumineer Posted July 21, 2009 Report Share Posted July 21, 2009 How about catalytic converter? Might it be backed up with broken catalysts? That'd be an easy start. Quote Link to comment Share on other sites More sharing options...
White93z34 Posted July 21, 2009 Report Share Posted July 21, 2009 fuel filter? Quote Link to comment Share on other sites More sharing options...
sloick Posted July 21, 2009 Report Share Posted July 21, 2009 fuel pressure regulator? does it smell like its running rich? Quote Link to comment Share on other sites More sharing options...
slick Posted July 21, 2009 Report Share Posted July 21, 2009 Coolant temperature sensor would cause it to dump fuel if it thinks it is cold. Although, you wouldn't have any lack of power. Quote Link to comment Share on other sites More sharing options...
hotrodolds Posted July 21, 2009 Report Share Posted July 21, 2009 Sure you would. Too much fuel will kill power. Quote Link to comment Share on other sites More sharing options...
slick Posted July 21, 2009 Report Share Posted July 21, 2009 True. But a bad CTS would not read cold enough to dump near enough fuel to cause that poor of performance. Quote Link to comment Share on other sites More sharing options...
Regal_GS_1989 Posted July 21, 2009 Report Share Posted July 21, 2009 Knock sensor? Although you would figure it would throw an SES light if that were the case. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted July 21, 2009 Report Share Posted July 21, 2009 Knock sensor? Although you would figure it would throw an SES light if that were the case. Knock sensor would almost certainly throw a code. Quote Link to comment Share on other sites More sharing options...
hotrodolds Posted July 21, 2009 Report Share Posted July 21, 2009 True. But a bad CTS would not read cold enough to dump near enough fuel to cause that poor of performance. You'd be surprised. I am not familiar enough with the GM system to say definitively, but I know in a VW when the ECT sensor fails, it reads a coolant temp of like -38* F. It does all sorts of bad things, including hard starting, poor mileage, low power, and all that stuff. They typically set a code as well. If the guage in this 3.4 DOHC car is functioning, it SHOULD be OK. But, you never know. Probably cheap enough to just replace it and make sure. Quote Link to comment Share on other sites More sharing options...
oldscsc Posted July 21, 2009 Author Report Share Posted July 21, 2009 I just changed the fuel filter. It needed to be done, as the old one appeared to be original, after 75,000 miles. I could not blow through it. BUT it didn't cure my problem. It feels a little more responsive at part throttle but I don't notice a difference at WOT. So I plan to pull the o2 sensor to eliminate the possibility of a clogged cat, as per Jman093's recommendation. Any tricks to pulling the o2 sensor? I know it's on the exhaust before the cat, but where exactly? Quote Link to comment Share on other sites More sharing options...
slick Posted July 21, 2009 Report Share Posted July 21, 2009 Sit on top of your engine, and look straight down behind the engine. You can tackle it one of two ways- 1: Tilt the engine as far forward as possible and get it from the top, 2: Go at it from underneath. Quote Link to comment Share on other sites More sharing options...
hotrodolds Posted July 21, 2009 Report Share Posted July 21, 2009 Pulling the O2 sensor won't tell you a thing. What you NEED to do is remove the cat. Cut it out, and put a test pipe in its place. I can believe that being the problem. You may want to REPLACE the O2 sensor. But, pulling it, and running it is a very good way to kill your engine, as that is what determines fueling. Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted July 22, 2009 Report Share Posted July 22, 2009 True. But a bad CTS would not read cold enough to dump near enough fuel to cause that poor of performance. You'd be surprised. I am not familiar enough with the GM system to say definitively, but I know in a VW when the ECT sensor fails, it reads a coolant temp of like -38* F. It does all sorts of bad things, including hard starting, poor mileage, low power, and all that stuff. They typically set a code as well. If the guage in this 3.4 DOHC car is functioning, it SHOULD be OK. But, you never know. Probably cheap enough to just replace it and make sure. The CTS failed in my 93 CSC 3.1, and it ran so rich, it wouldn't idle at all, and would stall out without throttle input. Quote Link to comment Share on other sites More sharing options...
oldscsc Posted July 22, 2009 Author Report Share Posted July 22, 2009 Pulling the O2 sensor won't tell you a thing. What you NEED to do is remove the cat. Cut it out, and put a test pipe in its place. I can believe that being the problem. You may want to REPLACE the O2 sensor. But, pulling it, and running it is a very good way to kill your engine, as that is what determines fueling. Any alternate opinions on this? I find it hard to believe pulling a single sensor will be too very hard on anything.. Quote Link to comment Share on other sites More sharing options...
Pontiac6KSTEAWD Posted July 22, 2009 Report Share Posted July 22, 2009 If you are just checking exhaust flow, go ahead and pull the O2 sensor, and drive it for a short distance. No damage will come from that. Just remember to put it back in. Quote Link to comment Share on other sites More sharing options...
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