1999 chevy lumina 3.1 v6. Vehicle idles just fine. It will drive at any speed if i accelorate slowly. if i try to step into the gas ANY little bit at all even to enter traffic it will bog down. it does not die though. Just bogs way down and accelorates the speed of a turtle running the rpm way up before shifting. Took it out onto the highway and floored it. seemed to be at worst between 15 and 25 mph. after 25mph it will accelorate more rapidly. What could be the problem?
First make sure the fuel pressure is within spec. A weak fuel pump can cause this problem. Then check for a defective fuel pressure regulator. If the regulator fails to increase the fuel pressure at the injectors when accelerating it can cause this problem.
Tester
How would i check the fuel pressure regulator? I am unsure how to tell if it is working properly or not. If i check the fuel pressure using the valve is that the pressure built up from the fuel pump itself or what the regulator is supplying to the vehicle?
Connect a fuel pressure gauge to the fuel rail. Turn the ignition to the run position but don’t start the engine. Read the fuel pressure. It should be to spec. Leave the gauge connected and start the engine. Remove the vacuum hose from the fuel pressure regulator. The fuel pressure should increase when this is done. If it doesn’t, there’s a problem with the fuel pressure regulator.
Tester
pressure specs are 41-47. while the pump is producing the pressure the system reads 42. it then drops to 40 when the pump shuts off. Also when the vehicle is running the fuel pressure sit at 35. Not sure what it is supposed to be when running. But when i take the vaccume hose off the regulator the pressure then jumps back to 42. Doe this mean its the pump?
Does it sputter and bog down if you rev the engine while stationary?
yes it does
It sounds like a plugged catalytic converter.
How would you check a plugged catalytic converter? ive never dealt with the exhaust system so i don’t know where i would begin at. Also what should i be looking for? just debris or something in paticular?
What usually happens is either they overheat and the catalyst material becomes solid or stuff from a poorly-tuned or oil-burning engine will block it up or if the converter is pysically damaged the catalyst can come loose and plug up the exhaust outlet.
There’s a few ways to check it. The easiest way for a home mechanic is to actually remove the converter and then look through it. You should be able to see daylight when you’re peering straight through it. You should also make sure nothing is rattling around in it. You can also, if you’re on friendly terms with your neighbors, start the car and see if the problem is still there without the converter. This will be very loud.
The other way to do it, and this is what a professional mechanic would do, is to drill a small hole in the exhaust pipe before the converter and hook up a pressure gauge to it. Backpressure more than about 4 psi suggests a clogged converter. The trouble with this technique is you have to weld up the hole when you’re done, so you need a welder.
Another way to check for a plugged converter is with your hand. Start the engine and slowly bring your hand to the tail pipe until you can feel the exhaust pulses. The pulses should be pretty strong. Now try reving the engine. The exhaust pulses should intensify. If the exhaust pulses still feel weak when doing this, the converter is probably plugged.
Tester
Plugged exaust can be tested for by measuring manifold vacuum,do you want to know how?I dont feel like typing in the procedure if you dont even want to try this method.
I took the converter off and shined my flashlight through it. all clear. it was clean i could see right through it. Not sure what to try now. ANY sugestions would be appreciated a million. Thanks to those of you who have helped me so far.