No power until 2K RPMS

[Jacobbish]

So long story short truck has a nv4500 swap from an 01 with an 02 motor that had the auto. Truck is extremely gutless until around 2000 rpms. Once you hit that it’s a completely different truck. Has an air dog that keeps 18psi fuel pressure. Have cleaned both iat and map. Can free rev all day but once you put a load in it there is a very noticeable lack of power. Checked codes and only codes I am getting are for the auto trans. 

[Evan]

Injectors plugged up?

 

My factory injectors just about carboned closed. 

[Nekkedbob]

Sounds like torque management kicking in. You will need to have it flashed as a 5 speed to get rid of it.

[kzimmer]

10 hours ago, Nekkedbob said:

Sounds like torque management kicking in. You will need to have it flashed as a 5 speed to get rid of it.

 

Sounds possible, @Jacobbish what's it like above 25mph low rpm high throttle?

[Mopar1973Man]

19 hours ago, Jacobbish said:

Truck is extremely gutless until around 2000 rpms.

 

Could be "Limited Throttle" which could be a failed ECM and/or failed VP44. I would check for error codes. 

[Jacobbish]

@kzimmer above 25mph low rpm high throttle it does what seems like nothing. Just keeps slowly gaining speed

 

@Mopar1973Man error codes for ecm are 0602 0230. Shows a 1693 on dash but no code with hand held scan tool. Has an air dog that keeps proper fuel pressure

 

i might add it’s an 02 body and motor that was the auto on a 01 chassis and trans that was the manual using the 01 wire harness

[dripley]

Isn't  the 01 wiring harness a bit different from the 02 harness. I believe the oil pressure and MAP sensor are different. A bad MAP will make your truck gutless, but why it comes life at 2000 rpm is strange

[Jacobbish]

@dripley I’ve been thinking map also but I have no code for it. Don’t feel like tossing a 100 dollar sensor at it. Oil pressure on dash is always pegged at max even if engine isn’t running due to the swap. 

[Mopar1973Man]

MAP should trip a code if its out of range. If you had a Quadzilla tuner you can watch the boost pressure on the display to see if the sensor is damaged. Ill admit most MAP sensors are skewed and not very accurate. Like my truck only goes to 47 PSI but Quadzilla shows a max of 67 PSI. Which I know is highly skewed. My 0 to 20 PSI is good but above 25 PSI is starting to skew.

[dripley]

The MAP should toss a code , 237, like Mike says. Mine did both times it failed. Just got replacing mine along with a VP. Did this just happen out of the blue or is this how its run since you created it?

[Jacobbish]

@dripley this is how it has been since it was created. When the motor had the auto tranny it ran fine no issues but since swapped to 5 speed chassis it has acted like this

[dripley]

I bleive @Nekkedbob is probably on the right track. But like @Mopar1973Man said checking the codes might help lead to the problem If it is something else.

[Jacobbish]

@dripley where would one go about programming the ecm? Also only code I’m getting after deleting driving and checking 2 times now is the p0602 

[dripley]

A dealer can flash to the proper transmission and you might can do it with a Smarty if know someone who has one. Some one smarter than I would have to confirm that though.

[Jacobbish]

@dripley ok thank you for all the help. I am going to do that and then more than likely check the splice for the map with a live data read to see if it drops during its issue. 

[Evan]

What if you unplug map sensor and take it for a test drive.

[dripley]

When mine quit, it just ran gutless no matter what rpm you could turn. I could run 80 to 85 untill you caught a hill then the speed would bleed off until you leveled off. About 35% of normal power.

[Jacobbish]

@Evan when unplugged the only change is that I get a CEL otherwise everything else is the same 

@dripley that’s exactly how mine is. You aren’t getting there fast but you can get to most posted speed limits. Ran with a scanner today and the map increased and decreased as it should but only hit a high of 25% engine load. Only concern was engine off key on map shows 21 psi of boost

[Evan]

Engine off key on showing 21psi this is right where it would defuel and show over boost code on a stock truck.

 

Wouldnt a boost fooled truck basically make the map not ever see that 21psi or 22 where ever it actually decides to defuel.

 

If its reading that with key off would that mean its defueiling at idle while running

[dripley]

A lot depends on what you are reading boost with. At idle in my truck the mechanical gauge reads 0. My scan gauge II reads in the high twenties, the same with engine off.  The Quad is very similar in how it reads. With a failed MAP the SC II reads 14.6 constant. Familiar number for us near sea level folks.

 

@Jacobbish IIRC you said your truck comes to life at 2000. Am I mistaken? Failed MAP on mine never comes to life. 

The ECM never sees the numbers my SC II sees, it reads the number properly.