r.knighter
New Member
Hello everyone. Thanks in advance for reading this thread. I'll do my best to articulate the issue (I'm not to mech savvy I'm afraid), and keep it as concise as possible.
Essentially, after driving at running temperature, I experience a sudden loss in power while revving, especially when accelerating from a stop, or when "gunning it" suddenly to pass or merge. The truck feels like it shutters and sputters as if it's running out of gas and can't power itself. But when I let off the gas, the problem vanishes and it coasts.
The first time it happened was after a 90 min drive with the cruise set to 60MPH on the highway. After the last few miles on city streets, I revved it a bit, hard off a light and it first felt as if the tranny was reluctant to shift gears. The problem didn't occur again for a while (several months) and when it arose again, it did in the way I described above. Recently, as the weather has heated up, it has gotten worse - shorter times to exhibit the issue, with rougher idling and shuttering, to the point where she just died while waiting to make a left!
My mechanic diagnosed the cats as being clogged. I took her to an exhaust specialist who said my cats were fine and the temps are in perfect range (after running for 15-25 mins). The exhaust shop mech said it could be my fuel injectors because he'd seen the issue before where guys had changed the cats and the problem came back!
So I went back to my mech while the problem was happening so he could pull off my muffler to rediagnose. Again, he said one of my cats was clogged. I decided to order new cats. He installed those and he was not happy with how the truck was running.
Then, he tried replacing the ignition coil and the ignition module with a good used one off of a GM Safari, but that showed no sign of improvement. He said that my fuel pump runs at 60psi when started and then drops to 50psi when the truck is running well and while the problem is happening, so he doesn't feel that is significant enough to cause the problem. He does not feel it is ignition related. He said the cams are at "-3 cam retard", but they should be between (I think he said) -1 and -2. The front 02 sensors read "extremely lean" when the problem persists, instead of switching between "lean to rich". He thinks it could be the fuel injectors or maybe the spider injector in the manifold.
He is stumped, and doesn't want me to spend any more money on the truck (replaced the fuel tank and transfer case which are now soild) until we know for sure where the source of the issue is. He said I could take the truck to a GM dealer and have them scan the computer for a few hours for tests and diagnostics, but at quite the expense. He did not charge me a dime for his labor on all of this latest visit.
Anybody have any ideas?
1999 Escalade, less than 110K miles.
Thanks!
Essentially, after driving at running temperature, I experience a sudden loss in power while revving, especially when accelerating from a stop, or when "gunning it" suddenly to pass or merge. The truck feels like it shutters and sputters as if it's running out of gas and can't power itself. But when I let off the gas, the problem vanishes and it coasts.
The first time it happened was after a 90 min drive with the cruise set to 60MPH on the highway. After the last few miles on city streets, I revved it a bit, hard off a light and it first felt as if the tranny was reluctant to shift gears. The problem didn't occur again for a while (several months) and when it arose again, it did in the way I described above. Recently, as the weather has heated up, it has gotten worse - shorter times to exhibit the issue, with rougher idling and shuttering, to the point where she just died while waiting to make a left!
My mechanic diagnosed the cats as being clogged. I took her to an exhaust specialist who said my cats were fine and the temps are in perfect range (after running for 15-25 mins). The exhaust shop mech said it could be my fuel injectors because he'd seen the issue before where guys had changed the cats and the problem came back!
So I went back to my mech while the problem was happening so he could pull off my muffler to rediagnose. Again, he said one of my cats was clogged. I decided to order new cats. He installed those and he was not happy with how the truck was running.
Then, he tried replacing the ignition coil and the ignition module with a good used one off of a GM Safari, but that showed no sign of improvement. He said that my fuel pump runs at 60psi when started and then drops to 50psi when the truck is running well and while the problem is happening, so he doesn't feel that is significant enough to cause the problem. He does not feel it is ignition related. He said the cams are at "-3 cam retard", but they should be between (I think he said) -1 and -2. The front 02 sensors read "extremely lean" when the problem persists, instead of switching between "lean to rich". He thinks it could be the fuel injectors or maybe the spider injector in the manifold.
He is stumped, and doesn't want me to spend any more money on the truck (replaced the fuel tank and transfer case which are now soild) until we know for sure where the source of the issue is. He said I could take the truck to a GM dealer and have them scan the computer for a few hours for tests and diagnostics, but at quite the expense. He did not charge me a dime for his labor on all of this latest visit.
Anybody have any ideas?
1999 Escalade, less than 110K miles.
Thanks!
