I have a 1996 Chevy Blazer 4x4 4.3L V6 with 135,000 miles. It has had issues with losing power at highway speed for a few months, the only code I have gotten was for a lazy o2 sensor which I replaced and got nothing out of it. I have a done full tuneup on this thing and some more, and still am having the same issue with power loss.

I left from Washington to drive up to Alaska, made it 25 miles and was going about 65 miles an hour in overdrive. Usually the truck slows down a bit going uphill, but no so much that it has to downshift..but this time it was like my truck just gave up on life and decided it didn't want to move anymore! I had the petal to the floor and could barely keep my speed to 45 miles an hour with her pinned. It felt like my brakes were grabbing but the dealer said they are working fine (even tho my pedal is squishy due to the owner before me not knowing how to do ABS brakes). I stopped, pulled over, waited about 5 minutes then turned around. Once I had stopped and headed back home it was driving close to normal again (odd). I stopped at a gas station to check all my fluids, to find that my transmission was just about bone dry. I two days prior I had jiffy lube service my tranny and look for leaks.. they found nothing...the last people to flush my transmission was them, and obviously they do not know the correct amount of fluid to put in there or something, because both times I have gotten it done by them the dipstick shows I am bonedry right after they work on it. IF my tranny is messed up from having low fluid lvl because JIFFY LUBE didn't put enough in...am I entitled legally to make them pay for any repairs needed?

SO....while at the gas station I poured some fluid in my tranny, drove a little bit went through all my gears, then added more (1quart in total) and it seems to be running/ shifting a lot smoother. Could my transmission being really really low on fluid cause it to overheat, thus causing my vehicle to lose almost all its power? And wouldn't this give me a check engine light? I mean the truck's power is so weak sometimes I cannot seriously believe that a check engine light hasn't came on. Been almost 2000 miles still nothing but that o2 sensor a month back. And the dealer is lost as to what is going on... Please. I hate this Blazer, its just been a PITA since I had it. Any help or suggestions will help. I really need to get back up to Alaska, and do not want to drive this vehicle until I find out what is going on with it after what happened the first time I tried to leave within 25 miles. HELP!

The dealer did a drive test with the computer hooked up to see what was wrong and they said they cannot get it to give any codes whatsoever. EVERYTHING passed their inspection and I have no clue what to do! Is it time to just trade it in and get something newer? I have put so much money into it already trying to figure what the hell is going on with it and I have just about had it. Pretty disappointed that I spent 100 dollars at the dealer for them to just tell me nothing is wrong with it, when there definitely is. After I told them I was driving through canada to alaska they said, well just try it out and wait for a check engine light to come on...how stupid do you think I am? Drive my broken truck to break it more and then come to you guys and fork more money over? LOL

 

By any chance have you had the exhaust system, especially the catalytic converter, checked for obstruction?

 

I would never, ever, ever, take any of my vehicles to Jiffy Lube. They are the absolute worst mechanics. There has even been Dateline investigations into their practices, to include fraud. They would charge people for tune ups, tranny flushes, etc, but not actually do the work.

From what you are describing, you may have a burned out tranny. You do have some legal options, but it would be dificult. Most likely, you signed the receipt from Jiffy stating all the fluid levels are good.

I would take your vehicle to someone else, a reputable mechanic. Have him look at your tranny. Running a tranny dry is extremely bad for it.

YOu have changed your fuel filter, plugs, wires?

Have you checked fuel pressure?

 

Yes, they checked it said it was totally fine.

 

Yep changed all my plugs, none of them had out of the ordinary deposits. Changed fuel filter about 4 months ago. I had the dealership do the inspection on the vehicle and they look at basically everything, plugs, wires, etc...I asked and they said they are good, I just put the new plugs in about a month ago anyhow. I don't think my tranny is burnt out, the dealership took it for a test drive with me in the vehicle..I mean we basically TRIED to get my tranny to act up, full throttle going uphill etc...and it would not slip, make any noises, or anything. The guy even said most blazers around the same year / mileage as mine wouldn't have this much power going uphill ever... I am thinking that the tranny got really really hot after a while due to low fluid lvl, because it seemed to get better once I stopped and let my truck just sit for a minute.

 

It sounds like everyone has checked and verified everthing is ok, however it isn't. I would suggest checking the fuel pump pressure when cold and(if you can get someone to do it when it is acting up) also I would suggest changing the plug wires even tho you have been told they are ok($25.00). Your problem sounds a lot like my 86 Astro 160k. I would also suggest if you don't know the history of the service on a auto transmission never have it flushed and get new fluid, it will fail usually within 30 days. If you check the tran fluid on a high mileage auto and the fluid is a pretty red, wipe the stick and stepaway from the auto into clean air and then smell the dip stick if it smells burnt, BEWARE. Have a nice one. Geo

 

if your transmission was only one quart low it probably wasnt low enough to cause much of a problem.
when the vehilce was acting up and you could only get it up to 45 mph did the engine sound abnormal do you no if the rpms of the engine went higher than normal?
would suspect you will have to find a shop willing to drive it long enough to get it to act up and you may have a fuel pump going bad but in order to diagnose the problem a shop will have to see the vehilce lose power while they have a guage hooked up to see if its dropping pressure.

 

This is fascinating. My mini-Ram van did the same thing and I'm sitting here racking my brain what IT had. Hmmm

Fuel filter or any obstruction in fuel line/kink, etc. (I remember years ago certain cars had rubber fuel hoses down by the fuel tank that would suck closed after a while.)

Computer related where injector? is not receiving proper 'instruction' on how much fuel to deliver?

Restriction in fuel pressure regulator? (Just some guesses I'm tossing out there)

Vehicle drag.

Engine overgheating/'piston bind'

A choke- like condition existing

Timing jumped.

Camlobes flattened out.

The 'cat' suggestion...yes. Or crumpled exhaust pipe.

EGR stuck closed?

Vacuumn advance WAY retarded.

..............

Tell us more...like if the problem gradually began to happen or suddenly occured one day.

How is it when you get into the throttle from a dead stop?

Does it primarily do it at highway speed, cruising, not that much engine load?

My mini-van that had this would not misfire when it did it. It JUST started to get where I could not make it up over a hill in the road anymore. It acted like how cars act that get into the mountains and lose atmospheric pressure. It did not have fuel injection but had a carburetor (yours is throttle body injection is it?) and standard fuel pump, but I remember the mechanic did not touch anything with the fuel system. Hmmm. I'm going nuts.

 

I once owned a 94 GMC Jimmy 4.3 (first bad GM experience), same engine and transmission as your Blazer (4LE60). I had a speed sensor go on a trip along I-90 east through NY. Truck was cruising along fine one minute at 65, the next minute the transmission was totally slipping as if shifted into second from 65mph. Like on an old TH350 when you downshifted at too high a speed and the transmission valvebody would not engage the selected gear. Back in the good old days of springs, check balls, and vaccum modulators.

It persisted until I stopped and restarted. Must have done something with the ECM, becuase it was good for the rest of the trip to Albany where I located a dealer to look at it (warranty).

I don't recall if it gave me a MIL indicator or not. In that case it was a speed sensor that went.

 

ok, this is ridiculous! I took it over to a transmission specialist, they did a drive test / inspection...hooked computer up to it...said that nothing came up and they do not know either. they told me they recommended a service..not falling for that one. im sick and tired of this blazer, have pissed away so much money into it all for nothing. this is a terrible experience i have had with chevy. STAY AWAY FROM ALL BLAZERS! i am now forced into buying a new rig. this time i'll spend the money and get something with low miles and a warranty so i dont have to worry about anything! lesson learned

 

I know it can be frustrating. I was the "evil" dealership performance tech for well over a decade and often had to deal with problem children like your vehicle.

Process of elimination. It doesn't lose power all the time, correct? You can rule out clogged converter(s)/exhaust as that would cause the problem everytime you hit the accelerator. A vacuum gauge will verify/eliminate exhaust restriction concerns in 30 seconds.

Ignition problems will usually cause a miss/buck/jerk during acceleration or part throttle/high load driving. Retarded ignition timing will cause loss of power, but not enough of a loss to do what you describe. A slipped/slack timing chain will cause power loss, but not intermittently.

Fuel system concerns would seem to be at the top of the list IMHO. You need to find a competent tech who can ck fuel pressure, and has a scan tool that can capture data while the problem is occuring. Just pulling codes is almost, almost, useless in diagnosing an intermittent concern like this. Pay attention to fuel trims during accel. Rich idle trims combined with lean acceleration/part thottle trims= MAF if equipped. Lean during acceleration only, likely a fuel pressure concern. There are other things to ck later, but this is the quickest/easiest to ck and a good place to start.

Main thing is to get data captures when the problem is actually occuring, and have a tech competent enough to make sense of the data.

I wish you luck .

 

I vote for a cat with loose innards, not totally blocked.

 

It came to me this morning. In MY case with the mini-Ram Van, the fuel pressure regulator was causing the motor to load up (too much gas). Plugs were carboned up. Oddly I can't recollect seeing billowing black carbon being blown out the exhaust unless a cat eats this up or I just plain did not see it, test driving the car unassisted/unobserved. Nonetheles, my vehicle had no top end. It too would only go like 45 miles per hour. I changed out the pressure regulator and this fixed it. I believe the mechanic had first changed out the MAF sensor before this, thinking that was maybe it...I think. But the pressure regulator fixed it.

Can't say this is YOUR problem, but it could very well be like the above poster said who is leaning towards a fuel delivery issue.

 

Had the same problem with a Dodge van a few years back and found that the fuel line coming from the tank going toward the fuel filter was collapsing under full throttle (going uphill). Changed the line and the van has run perfectly ever since.

 

I'm guessing that was an older non-injected engine, easywind?

 

Now engine is making a whining sound as I accelerate. It just started about a block from my house...and I have been driving this rig all day, probably 4 hours solid driving. I know this may be the fuel pump, I wonder if the dealer even tested it...my guess is not, even though they said it checked out OK when I asked.

Hope it just makes in 63 miles on thursday when I go get my truck...

2004 Silverado 1500 z71 4x4 pretty excited!! thank you for all the replies and help!

 

Well, the fuel pump is in your gas tank, so if the whining is up front, you've got something else going on, like maybe an accessory bearing going bad.

Trading the beast in???