2001 ZR2, lost power, won't upshift

If you want the cheaper/easier possibilitythan place all plugs and wires .. check coil packs If its not that than usually it is either catalytic converters which may need taken off and banged out and put back on or if ya got the money replace them but i never do or camshaft position sensor is bad let me know what you try and what it does .. personally cat conv would be my first try cause more than not it is them

It's really important to have all of your vehicle info. That rpm may be at the rev limiter, and restoring your tune-up parts to A/C delco quality has an important effect. If fuel tests are within, and plugs show affect by deposits or lean/ rich condition, You may need to replace injection parts. This can be simplified by having mr. goodwrench perform the diagnosis. After the tune issues no longer affect engine, then they can evaluate shift points. If you have any data besides codes for pinpoints, please advise. If your car has been altered with off brand parts, advise. If your injection system was already rebuilt, advise. tell your mileage, engine size. Verify what gear you are in and that on the hiway its not in the wrong gear like 4lo or something, advise. See why you need mr. goodwrench? The experienced evaluation saves all kinds of back and forth and asking for test readings but getting no data. I am reading a few threads about this but my q's are turning it out as maybes. has it been worked on? are there warning light conditions or vehicle has other symptoms? GM may get this all the time and fix your injection first, then reevaluate.

Get the diagnosis right before worrying about guess fixes and cost of parts that have not even failed. random misfire that recovers can have alot to do with your vehicles injection design as a cause, the wear and tear of other systems would continue if you did not have the cause known before repair attempts...........Your data can be clouded with confusion by trying to use cheap stuff, then creating intermittants by doing so.

I would also point out besides being in the wrong gear, the evaluation would also include a little research into service bulletins and being sure recalls that may exist have been performed. no diagnosis is completely safe and correct without that. speculating on your injection needs is no help without being able to test and inspect it for you.

Theres just one powerplant, and thats the 4.3L vortec, but theres 2, 4WD systems, the 3 or the 4 button. you want to eliminate issues with controls or malfunctions there confusing isolating the condition, creating the need for more RPM, and delaying an upshift. waiting for answers to all this sstuff. reading up on the latest experiences of other owners.

Saw something about light-off converter, if this has not set related codes but is on the list for random misfire, the need for mashing the carpet with the accellerator could also be plausible. some call it a pre catalyst, theres some discussion about how to uncork, using a hardware kit. During a tune-up the tests for plugged exhaust come up normally during the diagnosis...At GM, I would run those if I noted catalyst related symptoms to accompany the accelleration, or down on power issue. after evaluations hands on, a tech tells you more. after test data, you can advance to a next step, thats all we have for now.

If your engine's condition is determined during normal tune-up prechecks by a dealer technician, your parts are "prescreened" for problems that may not set a code. A tps that has issues sensing throttle opening can affect your upshift and perhaps help explain your upshift under light load only. You can read all about it by googling the mk.ml.yr. and symptom. That would take you from tune-up and engine management issues to trans related pan removal accessible issues, etc. a very good breakdown of both trans and push button 4WD issues are well explained there. for a technician, anyways. Engine concerns with basic diagnostic gauges can reveal a low source for vac when an engine needs tuned. The possibilities with trans internal parts accessible with pan removed would be saved till external indications and causes were off the diagnostic plan. This sstuff is gettin kinda deep for harry homeowner. But learn about it, think about it, and try the inspection and test of parts as you can, and notice how these systems affect one another. Sometimes the simplest answer gets overlooked as we rush to judge. Or the basic tests run during tune up get sidestepped as we launch a pile of replacement parts in its general direction in great haste. ask mr. goodwrench, he loves you.

OK, have replaced the cat and muffler, MAF is new, still has the same problems, not as bad but still not safe to drive on the highwaty

hence, my previous post

I will never understand replacing things that are that expensive without them having failed the tests. This is why all the education and testing of technicians takes place before they are certified to correctly help you save that money, direct it at the cause. there's no guess fix except wrong gear perhaps? why is it using the rev limiter?? (if that is the reality) and what is the test results for TPS ?

Danny, I appreciate your input, however, not everyone has access to the tools to do what you suggest, we do the best we can with what we got. Can't afford mechanics at today's rate of $95 or more an hour. The cat was aftermarket at $54 and the MAF was $57, that only buys 1 hour. Now serious, I have a P0101 and a P0300 code, again, and I am pretty sure it is not the cat or MAF. could be a vacuum leak but I have not found anything yet. suggestions?

can you return the parts and call the service desk at your dealer? ask for someone to read this thread, I had instances when these were nre, and under warranty, where the senior master techs would ask one another to figure out the customers issue. the apprentices were not allowed to help, being they were going to school for it. I watched each one come check the vehicle and answer in ten minutes. Maybe our group of guys were special, sure, that's possible. each time it was a condition to note, the warning light not mentioned, or stuck in wrong gear, some codes come from the existence of the condition but dont, by definition, send you to the condition. The fact that you know what you know could be keeping you from asking what is so. The help you had so far was much more expensive than a diagnosis by mr. G. They may even answer over the phone, I know we did for our calls when we did not have a worry about what they would do with the info. I stand by my entries here, until it gets looked at. thats where you are. They could even lend you a service manual or call someone. never hurts to ask those who see them the most and are required to answer truthfully. if 1 hour was needed, and thats 100 ? best money spent. If component checks before a tuneup reveal something? it would be after the prechecks. must see to appreciate, as they say....did you test the tps?

excuse me, " these were new ( not nre)" But a Q&A over the phone can speed up the process in case its just like the "problem cars" I once saw years ago. The other dealers in the area sent the ones they could not figure out to us, they let me watch, I can tell you....they want it to run right just like you do. hope you try these ideas, and get the answers to the questions i raised and the test readings may help

OK, power issue resolved, shift issue resolved (the cat did it) but, I still get the P0101 and P0300 codes, and between 2500 and 3500, underload I get a rythmic sugre....Think it is something with the control module??? TPS tested OK, plugs and wires changed (long overdue), cap and rotor checked and good.

was your catalyst internally melted down ? clogged with anything ? Did you open it or bang it out into a pan for inspection?

Until you wrote, I had not done anything with the old cat, now I have. The old cat dumped lots of small rusty looking bits (actually a small pile from each end, with more coming when I tapped on the side. I cannot see past the screen. Not knowing exactly how they are constructed, I can imagine these could be trouble in the honeycomb?

The inlet side would look like it had a "screen" That is the effective catalyst material. it is perforated to allow the gases to come in contact with the catalst metals as it finds a way to get through. Metals of a few types may have a "bed" after that first one that you cannot see. A "meltdown" means the issues with engine management, temps, and other systems would have to malfunction to cause conditions of meltdown. Being clogged or also rendered ineffective must have a cause. It's not really a maintenance item. What I am getting at, is the new one could possibly be subject to the same result if the conditions causing the first one to be damaged were to continue. Multiple misfires or short and long fuel trim out of spec can lead to clogged or melted down cat. Engine thermostat out of spec, sensors and actuators out of spec, etc. also lead to internal blockage of a catalyst Fuel system issues with lean, can increase catayst temp or if fuel enters a catalyst and cooks there. Ineffective catalyst just sets a code because an after cat 02 sensor reading. You say you still have the codes resetting? Were they diagnosed, repaired, and cleared, then they came up again?

When it affects the catalyst, like it may have, the emissions authority can send you to a shop they watch. This can ensure you spend only what it takes. Repairs that do not directly affect passing can be refunded. They have advocate people that get it figured out to reduce cost, or they grant waivers. Having them get your codes fixed could be cheapest if that's what you need next. The Cal. resources board had taken GM to tak years ago about the fuel system the 4.3L uses. The aftermarket has offered an alternate multiport system to take place of it. If the emissions authority finds it to be the catalyst choker ??? It would be after the steps were taken in the proper order and effective research was looked into at this time. It's been years and updates since, so you may need their help. Questions are free, you just google, get their # for your county, call, and follow directions. See what THEY say. If you can't ask Mr. G. And reread what we have on here in case you just may have dropped the ball somewhere.

task not (tak)

Some parts of that fuel system are now replaceable. the tests for its correct operation can lead you to find what, how many, and which. That's not a place to use a slingshot.

Having rusted particles tends to indicate you are having a failed part upstream. Unless the exhaust system itself is rusted and crumbling. If your engine eats water between services of any amount, you could consider intake gaskets and the appropriate update parts and procedure as it applies.