04 TRAILBLAZER 4.2 WONT REV PAST 3K?

[Repairman77]

Already unbolted exhaust at the manifold to catalytic converter to eliminate cat/muffler restriction-no change in problem.
replaced throttle body with a china copy just to see if symptom's changed- no change
does have a crank shaft position sensor failure code - replaced crank sensor - still sets code?
when starting cranks over for few seconds before starting slow to rev up to about 3k and seems to idle around 650 after warm
I did replace spark plugs and repaired chewed coil wires. car does have old gas in it and I plan to take line loose at fuel filter and jumper the fuel pump relay to drain this out. This vehicle has sat for several yrs and has abs light on and brake light on along with service 4x4. I was trying to sort out this not revving up issue before tackling the other known problems.
Any suggestions on what to look at next?

 

[TJBaker57]

Already unbolted exhaust at the manifold to catalytic converter to eliminate cat/muffler restriction-no change in problem.
replaced throttle body with a china copy just to see if symptom's changed- no change
does have a crank shaft position sensor failure code - replaced crank sensor - still sets code?
when starting cranks over for few seconds before starting slow to rev up to about 3k and seems to idle around 650 after warm
I did replace spark plugs and repaired chewed coil wires. car does have old gas in it and I plan to take line loose at fuel filter and jumper the fuel pump relay to drain this out. This vehicle has sat for several yrs and has abs light on and brake light on along with service 4x4. I was trying to sort out this not revving up issue before tackling the other known problems.
Any suggestions on what to look at next?

Is this in park/neutral??

You know there is a rev limiter in the PCM software?

 

[Repairman77]

Is this in park/neutral??

You know there is a rev limiter in the PCM software?

Yes, in park.. This vehicle is not able to be driven wont shift out of 1st

 

[Matt]

What @TJBaker57 said. Park/neutral is limited to stop people being fools.

 

[mrrsm]

Your Thread Title does not precisely match the information showing in your initial Post and is confusing on the issue of WHY the Motor should be elevating the RPM anywhere near 3,000 RPM just after Start Up. Are you saying that when you step on the ACC Pedal... the RPM stops precisely at 3,000 RPM?

Also, in addition to the Park Neutral Switch mounted on the 4L60E Shift Pawl Armature, there is a Safety Solenoid that prevents the Shift Lever "T" Handle Release Button from being moved whenever there is NO DRIVER present inside of the Vehicle.

The presence of this Solenoid requires that an actual person place his/her foot onto the Brake Pedal FIRST and depress it in order to send an Electrical Signal to that Solenoid. Doing so activates the Solenoid Plunger and withdraws the Locking Pin inside. This allows the Shift Lever to move only after ALL of those Safety Conditions are met. These Videos explains How to replace that Solenoid if it is Broken:

Part 1:

Part 2:

It follows on that the GM 4.2L Engine requires a Specific ACDelco set of Spark Plugs, so knowing what you installed therein will help to guide the advice you might get in return. One Last Thought... Any time a Vehicle has been sitting Dormant and Unattended.... Rodents will have a chance to Chew through Wiring Harnesses and Plastic Connectors that service the MAF & IAT Sensor and Harness, the Throttle Body Harness and the ACC Pedal Harness. ANY interruptions of the PCM communicating with ANY of those Modules will cause the PCM to shunt the Engine to a "Reduced Power" Condition.

 

[Repairman77]

Your Thread Title does not precisely match the information showing in your initial Post and is confusing on the issue of WHY the Motor should be elevating the RPM anywhere near 3,000 RPM just after Start Up. Are you saying that when you step on the ACC Pedal... the RPM stops precisely at 3,000 RPM?

Also, in addition to the Park Neutral Switch mounted on the 4L60E Shift Pawl Armature, there is a Safety Solenoid that prevents the Shift Lever from being moved whenever there is NO DRIVER present inside of the Vehicle.

The presence of this Solenoid requires that an actual person place his/her foot onto the Brake Pedal FIRST and depress it in order to send an Electrical Signal to that Solenoid. Doing so activates the Solenoid Plunger and withdraws the Locking Pin inside. This allows the Shift Lever to move only after ALL of those Safety Conditions are met. This Video explains How to replace that Solenoid if it is Broken:

It follows on that the GM 4.2L Engine requires a Specific ACDelco set of Spark Plugs, so knowing what you installed therein will help to guide the advice you might get in return.

Yes, AC Delco plugs were used. And the vehicle seems to be stuck in limp mode. Low power and limited rev..
I will post scan tool results with a video of car running this weekend I'm leaning in direction of damaged wire harness and or ecm or possible timing issue. When I first started working on this I thought it was a stopped up cat restricting air flow...Previous owner was told it needed a new Throttle body and a crank shaft position sensor, Both have been replaced. Still sets code for csps? I have attempted a case relearn for the crank sensor and my scan tool says option not available for this yr car.

 

[mrrsm]

Bump my reply...(I edited in more information about the reasons causing the Motor to enter a Reduced Power (Limp) Mode. csps? Please use the Error Code Numbers and/or the full expressions of what you are trying to convey as such acronyms can often be too ambiguous.

 

[Mooseman]

Is it actually in Reduced Power Mode (limp) with arrow down light on? If yes, scan for the codes.

If it won't shift out of park, that is another issue. The engine will not rev past 3000 rpm in Park as previously mentioned several times.

 

[Redbeard]

Did you have a chance to pump out all of the old fuel? It wouldn't surprise me at all if it can't get past 3000 rpm with old gas in the tank. The octane has left the gas a long time ago (even when one uses Stabil in the gas, but at least it won't gum up any of the internal workings) the fuel needs to be fresh.

 

[budwich]

some thing funny in the whole "episode"... "won't shift out of 1st".... I take that as it CAN be put into gear (any gear? or just 1st selected?) after it has been started ... because you need to be in park or neutral to cause a start. My guess would be that this is a 4w truck and that it might actually be stuck in 4w lo which would cause some "issues" with tranny shifting AND possibly rpm limits. The OP doesn't indicate if the vehicle can actually move.

 

[Repairman77]

Update, I did get all the old gas out and replaced with fresh and I took the car for a drive around the block it does shift its sluggish and under powered but it is working.
still will not rev up.. with my scanner hooked up it shows absolute throttle position at 33% when holding to the floor this is a new (ebay) throttle body I've checked wires at connector no obvious damage or loose fit
not sure what would be keeping it governed? Do any of you have an 04 trailblazer ls in good working order?
I would like to know if your car will rev past 3k in park or neutral in 2 wheel drive mode?
only code I have is po335 crank shaft position sensor A circuit sets this code instantly. Tonight I plan to inspect the wire to the sensor looks like 1 of 3 wires is 12v to it LT-GREEN, DRK BLU C KP SIG, YELLOW BLK
LOW REF. I should ac delco crank and cam sensor in the mailbox today so I plan to change both and see what happens.

 

[TollKeeper]

Once he gets that sensor in, I think he is going to need a CASE relearn, am I wrong?

@Repairman77 - You didnt finish filling out your profile, where are you located?

 

[TJBaker57]

[QUOTE="Tonight I plan to inspect the wire to the sensor looks like 1 of 3 wires is 12v to it LT-GREEN, DRK BLU C KP SIG, YELLOW BLK
LOW REF. "
[/QUOTE]

The title of this thread says you have the 4.2 engine.

The 3 wire CKP sensor you describe is for the 5.3 V8 engine. As far as I know the 4.2 has a 2 wire CKP sensor.

Care to clear up this mixed information?

 

[Mooseman]

I would like to know if your car will rev past 3k in park or neutral in 2 wheel drive mode?

No it will not unless it's a V8.

Once he gets that sensor in, I think he is going to need a CASE relearn, am I wrong?

Probably but it will not inhibit any use of the engine. May throw a code.

The 3 wire CKP sensor you describe is for the 5.3 V8 engine. As far as I know the 4.2 has a 2 wire CKP sensor.

Care to clear up this mixed information?

Now that's a good catch right there. This definitely needs clarification. Thread will be moved to the appropriate engine section according to the answer.

 

[Repairman77]

No it will not unless it's a V8.

Probably but it will not inhibit any use of the engine. May throw a code.


Now that's a good catch right there. This definitely needs clarification. Thread will be moved to the appropriate engine section according to the answer.

To clarify my vehicle is a 4.2 and it is a 2 wire crank sensor. It would have been help[full if someone would have said the 4.2 have a rev limiter in the beginning of this post. I've never owned one of these, and all my other trucks don't have this option.

 

[Matt]

It would have been help[full if someone would have said the 4.2 have a rev limiter in the beginning of this post. I've never owned one of these, and all my other trucks don't have this option.

2 of us did say it. See post #2 and #4.

 

[mrrsm]

One other thing to check...