96 Blazer engine dies under acceleration

1996 S-10, Blazer LT 2WD, 4.3 ltr (W code), 107K, no "Service Engine" light activated. Runs great accept under heavy acceleration. At 4000 RPM whether full or partial throttle, engine loses all power. No misfiring or sputtering. No red dash lights evident and engine returns to normal after a few seconds of no throttle. New plugs (Autolite double platinum), wires and all standard tune up items installed within 5K. Cleaned MAF and throttle body. Will try another fuel filter next. Anything I'm missing, such as TPS, EGR checkup? Is there a rev limiter that can malfunction?

put ac delco plats in, several threads here on how any other brand in our blazers/trucks just dont cut it

put ac delco plats in, several threads here on how any other brand in our blazers/trucks just dont cut it

OK. Just changed to Delco Plats, new fuel filter, cleaned EGR valve and reinstalled. Same problem. Also noted that engine quits when full throttle applied in park and RPM passes 4500. Is this TPS problem? Partial reduction in gas pedal and engine returns to normal.

TPS or the MAF is shot.

Thanks, I'll try TPS first and go from there. Will let you know what happens.

TPS gets my vote too. Had a strange stumbling problem with my truck as soon as the throttle came off the rest stop up to about 3000 RPM. $25 taken to a local parts shop and a new TPS later, she's running hot and strong. FYI, I too have a '95 4.3. :)

The TPS sends signals at three critical points:

1) Just off throttle to about 3/4 throttle.
2)3/4 throttle
3) WOT

Any problem with signalling at any of those points will force ECU into a wild loop as is searches for "well, where is that butterfly anyway?" fuel metering pattern.

Well....... it's not the TPS. Just replaced it and same problem. Tps showed signs of a problem when I checked it according to Wells test procedure. Replacing it did not change the problem. Out $35 for TPS and almost $40 for new plugs. I suspect fuel delivery system (fuel pump) now. I guess I will break down and take it for professional diagnosis now... as much as I hate to give in. Any other suggestions are welcome. The MAF is really high priced as is the EGR. Thanks for the input.

I would check fuel system pressure next. You might have a delivery problem due to a restricted fuel supply line or a weak and dying fuel pump. Neither of these conditions will light the SES but will hamper performance. A decent fuel pressure test kit can be had for $25. Also check for restricted exhaust from a melted catalyst. Make sure your engine is in prime tune and you don't have leaking injectors or regulator before you go the way of a new catalyst. Catalyst testing can be problematic for the home mechanic, but a good test it to strike the exhaust system with the flat of your palm on a stone dead cold engine. If you hear it rattling around inside the pipe, you definitely found your culprit, it's busted and shifted. Hopefuly the shop can check for you before you get into big $$$'s figuring it all out.

The Catalytic Converter was completely gutted several years ago as I didn't want to spring for a replacement at the time. Never had a problem except for a slight "tinny" sound at low speed from the hollow "can". Mileage and performance definitely improved. So I think the fuel delivery system must be the problem. I will try the pressure test upon locating a test kit. I wish I could rule out the MAF sensor without springing for a replacement. It looks perfect, but that is often times deceiving.

The Catalytic Converter was completely gutted several years ago as I didn't want to spring for a replacement at the time. Never had a problem except for a slight "tinny" sound at low speed from the hollow "can". Mileage and performance definitely improved. So I think the fuel delivery system must be the problem. I will try the pressure test upon locating a test kit. I wish I could rule out the MAF sensor without springing for a replacement. It looks perfect, but that is often times deceiving.

Ummm... this would throw a check engine light.

I have the same problem now with my 99 Blazer. I spent a good portion of the afternoon yesterday (well a friend did anyway I was in charge of cold beverages) checking the fuel pressures. All was fine and I changed the fuel filter anyway as it was a little plugged. My catalytic converter has started to rattle recently and I believe it is plugged up so everyone tells me this is defiantly the problem. I should gut mine like yours to see if things improve before I carve up and weld the new one on I bought. How did you gut yours? I will keep an eye on your post as I have the same issues. I posted today “99 Blazer Acceleration Problems (http://www.automotiveforums.com/vbulletin/showthread.php?t=572016)” no replies yet :frown:

I simply removed the converter (6 bolts) and took a long broom/handle wooden dowel and broke everything out of the inside of it. The rattling was driving me crazy but I had no performance problems prior or subsequent to the "gutting". It ran great for more than 2 years. I did get a SES indicator light shortly afterward. I removed the positive battery lead for 10 minutes and the computer reset itself after several miles of normal driving. I believe this problem of high speed shut down is something else and I'm not totally convinced it is the fuel pump. I'll keep you posted as I continue replacing and spending!! It's killing me that I can't figure this one out.

KMACMMAC,

I took the cat off and broke up the inside as you described. However I could not get ALL of the debris out despite a lot of hammering. It was plugged up pretty bad, I actually took a spin with out the cat on and the muffler hanging disconnected. The cat was defiantly most of my problem as I could be cruising along at 70 mph and hit the gas and it would accelerate fairly quickly. Unfortunately my neighbor has my garage full of his stuff as he is insulating and dry walling his garage this week so I had to work on the driveway. Well it started to pour and I didn’t get a chance to connect the cat back on so I drove to work today and I have a bit of a headache from the noise and probably some fumes LOL. But it sure did have some jam when you hit the pedal.

KMACMMAC,

I took the cat off and broke up the inside as you described. However I could not get ALL of the debris out despite a lot of hammering. It was plugged up pretty bad, I actually took a spin with out the cat on and the muffler hanging disconnected. The cat was defiantly most of my problem as I could be cruising along at 70 mph and hit the gas and it would accelerate fairly quickly. Unfortunately my neighbor has my garage full of his stuff as he is insulating and dry walling his garage this week so I had to work on the driveway. Well it started to pour and I didn’t get a chance to connect the cat back on so I drove to work today and I have a bit of a headache from the noise and probably some fumes LOL. But it sure did have some jam when you hit the pedal.

Just remember that you cannot just remove the cat material without causing your computer to go out of whack.

The O2 sensor after the will see that it is gone and throw a code plus the computer will not be able to fine tune the fuel control without that cat being in place.

I suggest you go on ebay and order a new 2.25" cat and get it installed.

Just remember that you cannot just remove the cat material without causing your computer to go out of whack.

The O2 sensor after the will see that it is gone and throw a code plus the computer will not be able to fine tune the fuel control without that cat being in place.

I suggest you go on ebay and order a new 2.25" cat and get it installed.

I actually have already purchased the cat and I had to delay a day for the muffler as it was not in stock. I am installing a new one of those too. Cat was under $100 at canadian tire. The check engine light did finally come on after I removed the cat and unplugged the o2 sensor. Will it be as simple as a terminal disconnect for 5-10 minutes to reset the computer?

I actually have already purchased the cat and I had to delay a day for the muffler as it was not in stock. I am installing a new one of those too. Cat was under $100 at canadian tire. The check engine light did finally come on after I removed the cat and unplugged the o2 sensor. Will it be as simple as a terminal disconnect for 5-10 minutes to reset the computer?

Unplug the batter and remove the two ecm fuses in the fuse panel.

Wait 30 minutes or so to be safe and then reinsert the fuses, and reconnect the battery.

Many people say you will need a scanner to reset the codes but I have yet to have any of the codes stay in mine after doing this.

Even the GM Mechanic said it will work perfectly.

What brand of Cat did you get? Did you make sure it was a 2.25" in and out?

Unplug the batter and remove the two ecm fuses in the fuse panel.

Wait 30 minutes or so to be safe and then reinsert the fuses, and reconnect the battery.

Many people say you will need a scanner to reset the codes but I have yet to have any of the codes stay in mine after doing this.

Even the GM Mechanic said it will work perfectly.

What brand of Cat did you get? Did you make sure it was a 2.25" in and out?

It is a Maremont universal fit 2-1/2" in 2-1/2" out catalytic converter. Thanks for the reset procedure

You require a 2.25" to fit.

I've decided the days of self or at least, assisted diagnosis of car ailments is definitely over. I just bit the bullet and replaced the MAF snesor at the recommendation of the local AutoZone code reader. It indicated a bad MAF sensor or VFC or VPC(not sure what that was but AZ said I didn't have it on this model). It was the only code showing. I drove it for about 20 minutes and returned to have them eliminate the code. I drove off hoping for the best and was quickly disappointed. Same problem. Full throttle after 4000RPM's , it's as if you turn the motor off. Let up and it runs fine. No sputtering, missing, nothing. Still runs great otherwise. Out $100 bucks for MAF and still counting. Could the MAP sensor create problem? AZ says maybe, and will of course sell me the non-returnable part. Still looking and frustrated!!

You require a 2.25" to fit.

Is the 2.25" imperative for operational reasons or just for fitting purposes? I am assuming the 2.25" is the diameter of the in and out pipes right? I bought pretty much the whole exhaust from the manifold back to the tail pipe and the parts seem to all fit ok.

I've decided the days of self or at least, assisted diagnosis of car ailments is definitely over. I just bit the bullet and replaced the MAF snesor at the recommendation of the local AutoZone code reader. It indicated a bad MAF sensor or VFC or VPC(not sure what that was but AZ said I didn't have it on this model). It was the only code showing. I drove it for about 20 minutes and returned to have them eliminate the code. I drove off hoping for the best and was quickly disappointed. Same problem. Full throttle after 4000RPM's , it's as if you turn the motor off. Let up and it runs fine. No sputtering, missing, nothing. Still runs great otherwise. Out $100 bucks for MAF and still counting. Could the MAP sensor create problem? AZ says maybe, and will of course sell me the non-returnable part. Still looking and frustrated!!

You are being frustrated because you listened to the AutoZone monkeys. They are part pushers.

Take it to the dealer and have them put a Tech 2 on it and go for a drive so they can log what is going wrong.

You are being frustrated because you listened to the AutoZone monkeys. They are part pushers.

Take it to the dealer and have them put a Tech 2 on it and go for a drive so they can log what is going wrong.
g, i thought it was only me that realized that here... az are parts stores, not repair facilitys, the have a code reader, and thats what they do, just because theres a problem in a circuit doesn't mean the sencer is bad, it means some where in that electrical feild something is intorruped, or heaven forbid the sencer is right and there is a real searious issue there

That's my next move, Thanks

I had the same problem about 3 weeks ago on my 95 Jimmy with the vortec. Check your ignition coil, if you are running a system with a distributor and make sure the spark is in the blue range. My coil or ignition module went and i had the same problem. It would cut out on me and then come right back alive. After replacing that it has run fine since, even got the power surge around 3200 back.

I also had problems of out sudden during the march with my Blazer 95. In Autoforum.com I found several cases and the best answer was that of BlazerLT. It fails it it was the ignition module. I replaced it and the problem finished.

Update: My truck stranded me out in the middle of nowhere, doing the weird surge/stall thing again. Backprobing and testing the ignition module when the engine was still hot revealed it was shot. Replaced it and ran the truck hard for a while to get engine heat up - problem went away. Again, may want to test your ignition module when hot, following the procedure in a Hayne's or Chilton's manual. You'll need a DVOM, and a 1.5 volt flashlight cell to do it right. In my case, when the engine is HOT and the ambient air is hot too (In this case, it was 101 degrees where I was when the engine quit totally on me) the transistors in that ignition module wouldn't switch anymore. Replacing it, cleaning the plate in the distributor it goes onto with a brush and brake cleaner and re-applying the silicone grease fresh from the pack that comes with the replacement is a must. She fired right up and took me back home with no problems. I spent yesterday running the truck all around under the same conditions, retracing my route, the problem is gone. The replacement of the TPS was not a waste however, I have good, positive throttle response again and the slight hesitation before shifting gears is completely gone.