96 Blazer engine dies under acceleration

[kmacmmac]

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?

[dmbrisket 51]

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

[kmacmmac]

Originally Posted by dmbrisket 51

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.

[BlazerLT]

TPS or the MAF is shot.

[kmacmmac]

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

[wolfox]

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.

[kmacmmac]

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.

[wolfox]

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.

[kmacmmac]

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.

[BlazerLT]

Originally Posted by kmacmmac

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.

[LJP_GURU]

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” no replies yet

[kmacmmac]

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.

[LJP_GURU]

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.

[BlazerLT]

Originally Posted by LJP_GURU

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.

[LJP_GURU]

Originally Posted by BlazerLT

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?