First, would like to say that I'm new and was drawn here due to an issue i'm having. So hello all!

Bought a 2004 Blazer, 4.3 with 4l60e Tranny. I really shouldn't have bought it, but was having a bad day and the seller neglected to tell me a few important things.

At first, P0301 Cylinder #1 misfire according to my mechanic and local autozone. I also picked up a p2761, open TCC circuit. I started with general maintenance, which it was in serious need of. First symptoms were low power, idling rough and trouble shifting into 3rd when starting up a hill, until I let off the gas, then it shifted and drove fine aside from a noticeable miss.

Changed plugs/wires. No Change.
Flushed nasty water out of radiator. No change.
Changed oil, actually noticed some improvement, but considering it was black as can be, it would about have to. Still a misfire though and same tranny issue.

Changed Tranny fluid and filter. After dropping the pan, noticed someone unplugged the TCC solenoid, solves the mystery behind the P2761...plugged it back in. It was in serious need of the fluid change, was brown and old but didn't smell burnt and no metal in the pan...unless someone took the pan loose, disconnected the TCC, removed anything in there and dumped the old fluid back in. Assuming tranny issue is electrical since plugging TCC back up made a difference, and that someone unplugged it for a reason, but who knows why. Could be a clue. Would have been easier if the seller had been honest. Mentioning this in case it's another clue: After putting it back together, gas hand did a total reversal up until I disconnected the battery and reconnected, then it went back to normal.

Put it back together, misfire still there of course, but change in shifting. It now feels as though it starts out in 3rd, but I can get second if I pull it down in L2. I believe I can actually drive it by shifting manually, though I haven't taken it too far to know for sure, also not very safe to do this. I'm thinking it's in limp mode. Still kicking myself for not testing the solenoids before putting the pan back in, but my meter crapped out. All fuses appear to be good, though I'm not sure which specific fuse I should be checking. I do hear that's sometimes a problem though.

Just not certain if it's 2 different issues, or if it's in limp mode due to the failing cylinder. I suspect it's got a leaking intake gasket, but have yet to confirm (ideas to test?). I plan to connect a scanner to it later to perform a live data test. I will also do another spark test. Previous spark test showed a bright orange spark on cyl 1, could have been better I suppose, didn't think it should affect it this bad though. I didn't check the other cylinders though I plan to in order to see if they spark any better. (I ran out of daylight)

No overheating, white smoke, water in oil or other conventional head gasket symptoms. All cylinders, including #1 have good compression according to my mechanic, but he did not diagnose. Looks as though someone attempted an intake gasket change using gasket maker from the looks of it. Assuming it has a leaking intake, could this trigger limp mode? (if that's what this is doing)

Any ideas or suggestions on other tests that I should perform? I really wish I knew more about the history of this vehicle.

Thanks in advance.

 

Still struggling with this. Here's some more engine data.

Pending codes: P0301, has yet to store since clearing. I don't know what a lot of the numbers need to be. Wish Dashcommand would tell me which gear it should be shifting into, unless i'm just not reading it right. Used to working on engines the old fashioned way.

These settings on idle:

RPM: 694
BST/VAC: -10.6 psi
Timing: +16
Intake: 111 F
Coolant: 198
MAP: 28 kPa
MAF: .6 lb/min

 

Agree your trans is in limp in mode after hooking up the TCC solenoid.

limp-home mode: This is a fault mode in which the transmission either loses electrical power or the PCM deactivates all of the electronics. P0301 would not cause it.

Looks like you blew the fuse that feeds all the trans solenoids when you plugged in the TCC solenoid. In this case, you lost electrical power to the transmission and that forced the limp in mode.

Fix the short in the TCC circuit or put it back the way it was and replace the fuse - until you get the misfire solved. I wouldn't be afraid to drive it short distances - just pull the shifter down to get it into second and then manually shift to third.

As far as getting a scanner for a 2004 Blazer..... If you have Android phone or tablet get Car Gauge Pro and the BAFX OBD2 Bluetooth Adapter as sold on Amazon - about $30 total. If you have iPhone get Dash Command and a WiFi OBD2 adapter (cheapest is seldom best - one from Foseal on Amazon is highly rated). With Dash Command you will have to buy the GM PIDs for your particular vehicle for $10 more and activate them - about $40 total. Torque Pro is useful, but it won't read cam sensor retard in your Blazer. Most of the other phone apps are complete junk and will do very little for you other than very basic OBD2 PIDs and read/clear powertrain codes. Any of these three will read the misfire counters and do a lot, but no crank sensor relearn or other bidirectional control functions. Be aware that Car Gauge Pro has #1 and #2 cylinders switched in the misfire counters and also that it has a lot of unfiltered PIDs and modules and functions displayed that will not work with your vehicle. It is definitely the most difficult to use, and will not work for enhanced PIDs on 1996/1997 Blazers, but it does the most by far for 1998-2004 Blazers. Dash Command will do 1996/1997 Blazers and comes as both Android and iPhone apps, but is most expensive and requires purchase of PIDs for each year/maker.

 

Thanks for the reply. I don't "see" any blown fuses, but if I knew which ones to check specifically, I can check with a meter.

Been paying attention to the engine miss on Cyl #1 since I heard that can cause tranny issues. Just to be sure, did a chemical test on the head gasket and it checked out okay. If the computer is accurate, it's running lean. With regard to the engine, I'm still suspecting intake gasket. Computer says vac holds around 19, but got a vac test kit to confirm. Will do this when weather improves, too cold and windy right now.

I'm using torque as you suggest, is it worth upgrading to Pro?

Thanks again.

 

The computer says the misfire goes away after unplugging the MAF, does that mean anything? Why would it only affect one cylinder? Intake bolts were also loose, but in either case computer still reads same lean conditions. Does seem to run better if I'm not mistaken. Not sure if mileage has improved, afraid to take it too far.

 

I'm sorry but on your problems you're not listening. See post #2

To answer your question about Torque..... I don't recommend Torque or Torque Pro for Blazers. I can say that without the Pro version of Torque, you are not able to read any of the live misfire counters or any other GM enhanced PIDs. Really limits what you can do. However, remember that Torque Pro cannot read the Cam Sensor Retard on the Blazers and that is why I don't recommend it. Other than that it works quite well for an inexpensive OBD2 scanner.

 

On the tranny, I checked ALL the fuses both under the hood and on the dash, they look fine. It may help if I knew exact which fuses to check as mentioned in #3...I've looked everywhere. It's referred to as the "transmission fuse", but nobody mentions specifically which one it is. All the gauges work. I'm also using DashCommand. I think I'm getting close to the misfire issue. I'm resetting the computer again for the heck of it. I'll check to see if the tranny is getting power when I figure out which line to check. Currently, the only code being thrown after unplugging the MAF is for the airbag.

 

 

I have a 2002 blazer is and it was in limp mode for about a month went through every forum YouTube video and mechanics advice I could get and never was able to get a good answer as far as your tranny im not too sure but I had the same misfire code and put a new rotor distributor distributor cap plugs wires ignition coil ignition control module maf sensor map sensor crankshaft position sensor changed all fuses and relays I could think of and nothing sometimes it would start up and run ok for 20 30 minutes then start looking power sometimes it would have no power at all from start up after doing the timing on the engine myself it ran a lot better but still had problems untill I got a computer safe test light from scosche and tested all the wires I could see. ended up being the connector for the ignition control module cut it off spliced in new wires and now I have a brand new engine lol has 175000 miles and you can't even tell when its on or off. Don't know if this will help but just thought I would save you all the money I spent if I can the timing is easy to do let me know if you need help ill guide you through it