2004 Tahoe Check Engine Light On

[savage]

2004 Tahoe Check Engine Light On Please Help

First, we had the transmission rebuilt on this about 2 1/2 yrs ago, only had about 58K on it at the time.

A couple weeks ago, I changed out the spark plugs after the truck flipped to 100K. Then the truck started running kind of sluggish and then it started shifting real hard into 1 & 2 and it did this after we stopped every time we began to accelerate and the check engine light came on. So we took the truck back to the guy who rebuilt the transmission. At first he said that it was throwing a code that meant the RPMs were not matching up with the transmission. He said he tested all the sensors in the transmission and they tested fine. He ended up replacing 1 & 2 shift solenoids, EPC solenoid and then changed out the transmission fluid, filter etc. Got it back from the shop yesterday.

Today I am driving it and it still feels as though it is running sluggish, almost like it isn't getting enough power and now the check engine light came back on. My code reader isn't picking anything up. Any suggestions or ideas? Thanks!

 

[Physh1]

Really need a code to at least narrow the search parameter.

What plugs did you install? What gap?

 

[savage]

They are autolite irridium, gap .40. It is running as if it doesn't have the power it had before and my code reader isn't picking up a code.

 

[bkboatnsleds]

There has to be some code if the check engine light is on... Unless I am way off here.

 

[savage]

It has been a couple weeks, no check engine light, running great. Now today the check engine light comes on and throws a P0894 code, which is transimssion slippage...

---------- Post added at 08:34 PM ---------- Previous post was at 08:27 PM ----------

I am wondering if it is something electrical causing this since it isn't staying on all the time and starts driving like crap when it comes on. For instance, today when the check engine light came on, it started actually sluggish and slipping and harsh shifting.

 

[bkboatnsleds]

Maybe when that light comes on it sends it into a "limp mode" ?

 

[dunbar_john]

same problem happened to me, my check engine light was on too but it was the 4x4 senor not working right. it would slip the engine into that sluggish type symptom your having and it wouldnt accelerate sometimes. All i had to do was replace the 4x4 sensor so that it wouldnt slip the engine into the sluggish mode.

 

[savage]

Please help!!

4x4 sensor? I am not famaliar with that one, where is it located?

Now I have changed the speed sensor on the transmission and checked the wires and the light went off and then after driving for about 30-40 miles, the check engine light came back on and started acting weird again... It seems to be fine unless you go a long distance and everything gets heated and then the check engine light pops back on... Any suggestions would be great!!

 

[Bedore]

4x4 sensor? I am not famaliar with that one, where is it located?

Now I have changed the speed sensor on the transmission and checked the wires and the light went off and then after driving for about 30-40 miles, the check engine light came back on and started acting weird again... It seems to be fine unless you go a long distance and everything gets heated and then the check engine light pops back on... Any suggestions would be great!!

Just a thought since it seems to happen once its warmed up; have you felt the transmissions lines that run to the cooler, or felt the cooler itself? I am wondering if a plugged up cooler could cause the problem.

Have you dropped the transmission pan and inspected the pan for debris? From the research I have done on that trouble code, it could be an issue with the torque converter, the cooler, or the trans itself could be headed out.