I have a 2004 Trailblazer EXT 4.2L that has a surging issue that starts around 45MPH at Low throttle. The car feels like it is searching for a gear, missing revving up and down. I know it is locking up because you can lightly tap the brake and the RPM jumps up a couple hundred and then it stocks bucking on me.
I just had the transmission fully rebuilt last week, And it was doing this prior to realizing there was any issues with the transmission.
I read somewhere something about the TPS can get a burned spot in it which can cause a similar issue but I need advice.
I've been having the same problem. My battery went dead on me and when I jumped it it was shutting off with defrost on. And when driving 45 mph down the road the idle would fluctuate and act as if it was going to die. I Cleaned the throttle body. When taking the connector off the black tab broke. Now most of the time it idles fine with defrost on but every once in a while the idle start jumping up and down. When driving 55 mph the rpm fluctuates a little bit. If I get going 60-65 it starts fluctuating 200-300 rpm. It did not do this before. Check engine light is on but the only code it is reading is a temp code which has been on since 2 yrs ago when I bought it. I've always been told that I don't need to worry about that code.
Do I need to replace the throttle body?
check trans fluid level. Mine developed a very slow leak which I still cant find. It takes about 3 months to get low enough to cause the same surging/bucking you describe. it takes maybe 1/2 qt to do it. Just a thought.
Anyone else having any advice or solution for this issue? Transmission has been cleared/TB/o2 so on to the next thing. I was told maybe the PCU needs flashed. I don't want to keep spending money on BS I need some real advice.
Im not sure what your talking about. The transmission fluid runs through a cooler then back to the transmission. My transmission is freshly rebuilt the fluid is prefect and we have ruled out the transmission.
Post was meant for LMMJ. Hense the post quote. A FYI though.
The radiator and transmission cooler are one unit separated by a wall. If you have an unexplained loss of ATF with no visual leaks then that wall may have a pinhole between the two cavities. It starts with the slow loss of AFT because of the pressure differential between the transmission and engine cooling systems during operation.
Well took the Blazer back to the transmision shop that rebuilt it and they said the TCC soleniod was working according to thier scanner and nothing esle pulls up on any scanner so this is a mystery. But i call bull crap on them. no engine lights and nothing pulling up on the scanner.
This week ill be replacing the TCC solenoid simply because during surging when I tap the pedal lightly it stops surging as soon as i let off it continues.
Ive replaced at minimum with no change and at great expense the following
Throttle body
Spark Plugs
Air filter "K$N"
AIT sensor
Both 02 sensors
All 6 Coil Over Packs
Fuel rail pressure Sensor
replaced the TCC solenoid today and that was a ****ing fail too damn this car is really starting to piss me off..... Im totally out of ideals and have replaced about everything.
Just as an off the wall thought, have you looked at the connections to the accelerator pedal itself, to make sure you do not have any frayed wires or anything?
I am having the same problem my transmission was rebuild 4 times and they can't figure out what's going on. They want to put a bigger transmission cooler on it. I doubt this will fix the problem. I want them to put a whole new transmission in it since they had rebuitit 4 times and have kept my truck for over 30 days. They have replace. cam shaft sensor, cam shaft actuator, 02 sensor fuel filter, plug and wires and cleaned the throttle body.
I have replaced so many things that i finally said F it and just ignore it at this point. I think it is in the transmission but i dont want to spend another 2K to find out.
My transmission has been rebuilt multiple times still no luck. Beside for this problem it runs great. I think I am going to break down and take it to the dealership and see if they have any ideals.
PLease report back what they find. I have a feeling that something is not right in our transmissions perhaps a valve or an upgrade that wasn't performed during the rebuild?
I tried replacing my TPS actually had to buy a whole new Throttle body with it built in and it didnt change anything. I have a spare in my garage ide let go for cheap if you want to try it.
FWIW, I had the same symptom for a couple years and replacing the MAP sensor ($15) fixed it. I read somewhere that a bad MAP can cause the computer to send faulty data to the transmission, causing the surges
FWIW, I had the same symptom for a couple years and replacing the MAP sensor appears to have fixed it. I read somewhere that a bad MAP can cause the computer to send faulty data to the transmission, causing the surges
What you say is (mebbee) true and I admire your spunk in saying it ... put a foot in and go --- right?
Anyway ... you are responding to a zombie post and we tend to get all wrinkled up here when people drag up these DBs and re-energize them.
It would be a lot better to make your observation in a fresh post with a sexy headline --- like:
A Semi-naked Woman Told Me This Is My Problem --- (etc)
See?
Me? ---> I just give some silly suggestions here and I really don't know what I'm saying most of the time.
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