2000 blazer cuts out, possible Rev limiter problem?? HELP

[hunter4ever12]

I have a 2000 blazer that is having major issues. We have tried replacing a large number of sensors and engine parts and still cant fix the problem. It cuts in and out at 3k rpm's and won't throw any codes. The only code its given was crankshaft position sensor fault that was replaced and the problem still exists and recently the crankshaft position sensor fault code came up again. We have tried literally everything possible short of replacing the ECM, the engine and the transmission. So we were thinking it could possibly be the rev limiter. Is that a valid thought? The transmission was replaced with a junkyard one about 4 years ago so thats why we are thinking the rev limiter. If so where in the transmission is the rev limiter located and where is the best place to buy a replacement for it. I checked rock auto and they dont have it. Thanks for any help

[old_master]

Have you checked fuel pressure and leakdown? If so, what were the readings? Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for 10 minutes after the pump shuts off. Have you checked/replaced the fuel filter? Have you checked for a restriction in the exhaust system? Each of these could cause what you're describing, and NOT turn the SES light on or set a DTC in memory.

Not that it will make any difference with cutting out, but, whenever the crankshaft position sensor, (or the timing cover) is moved, removed, or disturbed in any way, the crankshaft position sensor relearn must be performed. It can only be done using a bi-directional scan tool. The PCM uses the sensor data for several things... if the relearn is not performed, the PCM will incorrectly interpret data from the new sensor. The engine will usually start and run, but not correctly.

[hunter4ever12]

Originally Posted by old_master

Have you checked fuel pressure and leakdown? If so, what were the readings? Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for 10 minutes after the pump shuts off. Have you checked/replaced the fuel filter? Have you checked for a restriction in the exhaust system? Each of these could cause what you're describing, and NOT turn the SES light on or set a DTC in memory.

Not that it will make any difference with cutting out, but, whenever the crankshaft position sensor, (or the timing cover) is moved, removed, or disturbed in any way, the crankshaft position sensor relearn must be performed. It can only be done using a bi-directional scan tool. The PCM uses the sensor data for several things... if the relearn is not performed, the PCM will incorrectly interpret data from the new sensor. The engine will usually start and run, but not correctly.

Thanks for the reply and help! Yes fuel pressure tests have been done and they were all withing the chevrolet specs and nothing was out of the ordinary with the readings. Fuel filter has been replaced and problem still exists, as well as catalytic converter being removed and still has the problem. After it was removed it did improve the performance of the blazer but the problem was still there. The muffler has not been removed so I suppose that could possibly be plugged but I dont think it is. How would I check?

Also the relearn was performed and no improvements were seen in the problem at all.

Another thing I forgot to mention in my first post is that the cutting out condition only occurs when the blazer is warmed up at operation temperature, but it is also worse when the outside air temps are colder....Now that makes absolutely no sense to me lol

[old_master]

How many miles since the last good tune up? By "good tune up" I am referring to using AC Delco spark plugs, plug wires, distributor cap and rotor. Usually if there's a problem with secondary ignition, a DTC is set, but not always. Fuel delivery problems however, rarely set DTC's. Fuel pressure is critical on these engines, what is your fuel pressure and how long does the pressure remain above 55psi?

[hunter4ever12]

Originally Posted by old_master

How many miles since the last good tune up? By "good tune up" I am referring to using AC Delco spark plugs, plug wires, distributor cap and rotor. Usually if there's a problem with secondary ignition, a DTC is set, but not always. Fuel delivery problems however, rarely set DTC's. Fuel pressure is critical on these engines, what is your fuel pressure and how long does the pressure remain above 55psi?

Last "good tune up" was done less than 200 miles ago and the problem still exists. I have literally done everything to this blazer that I can and my dad can think of short of putting a new ECM, Engine, or transmission in it. I know fuel pressure is important with these engines and the pressures were checked and were all within GM specifications I know that for sure. My dad is the one who performed the pressure tests and I was gone while he did so....so i dont know the exact fuel pressure but I know my dad has been a mechanic for 25+ years so when he says the fuel pressure test showed they were fine I tend to trust what he said. So I guess the next question I have for you is could it be a transmission or ECM problem and if so how could that be determined or ruled out?