Got a 2000 blazer 4x4 ls. like 230k on it
so the issue is, it coasts at 40 in drive but idles normal in park and in neutral, doesn't take off in reverse either. Also shifts really hard from 1st to second. I read a post somewhere that had a problem similar to this and he traced it back to his fuel pump because his fuel gauge was acting up also. I find it hard to believe that the fuel pump is causing this, but my gauge is also messed up. Jumps all over.

 

So in drive it wont go below 40mph when you take your foot off of the gas?

What happens when you first put it in drive with your foot on the brake at a standstill?

The reverse gear does not engage or it does but the trans slips when you apply gas?

George

 

I forgot to ask if you have any codes and have you checked your ATF level?

Not going into reverse is almost certainly an internal trans failure and not easily addressed by the DIY mechanic. The other problems can also be trans related but can also be sensor related like the TPS, VSS, ECT, etc. I'll wait for your answers but if you want to start checking things like sensors I can help you but you will need a scanner with live data capability.


George

 

No it goes into reverse, it doesn't take off like in drive though. Sorry could have been more clear.

Trans fluid is good.

When I put it in drive it jumps to 2k rpm, sometimes squeeks the rear tires and then levels out at 1500 and stays there.

Cel is on for 3rd O2 sensor.

 

I have a scanner that reads some live data. I noticed my manifold pressure stays at about 9psi. My tps sensor always goes back to zero.

 

There are a few possibilities here.

Go in order until we find something squirely:

What is your TPS live data value at idle out of gear and then right as the idle jumps going into gear? - Is your throttle position moving or reporting to be moving?

What is your IAC value, same two conditions? - is your IAC causing this from the PCM or a malfunction.

What are your fuel trims, all 4 numbers, same two conditions? - is this a vacuum leak

What are your MAF sensor values, same two conditions?

ECT value?

MAP value?

So the transmission goes into reverse but the truck wont move or it moves but slips (rpm goes up)?


George

 

Reverse is normal. When I put the truck in drive it starts to take off right away like I'm on the throttle. But reverse acts normal. I'll get all the values next time I go for a ride

 

So it only revs up on its own going into forward gear at idle but the idle rpm stays normal going into reverse?


George

 

Yes.

Also, I've found that a mouse or something ate through the wires for the MAF and whatever that sensor is next to the MAF. I fixed those and now it runs amazing. I'm surprised I didn't get a fault code for it though. Also found a few vacume lines that were disconnected.

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Now the problem is the suppension. Every part of it. Lol