Engine won't rev past 2000 RPM(?) (4 Viewers)

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Sep 30, 2021
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Location
Colombia
Hi everyone, recently I was driving my 93' 80 series and I had to go up a pretty steephill so I put it in 1st gear and I noticed it was not getting any throtle response even after flooring it. The rpms just slowly went to 2000 -1900 RPM and stayed there the whole way.
When I rev it in neutral it revs fine and in flat land the throtle response is fine too. I only notice this when going up hill, depending on the grade of the incline it max revs to 3000 or 2000 RPM.

Any suggestions
 
Hi everyone, recently I was driving my 93' 80 series and I had to go up a pretty steephill so I put it in 1st gear and I noticed it was not getting any throtle response even after flooring it. The rpms just slowly went to 2000 -1900 RPM and stayed there the whole way.
When I rev it in neutral it revs fine and in flat land the throtle response is fine too. I only notice this when going up hill, depending on the grade of the incline it max revs to 3000 or 2000 RPM.

Any suggestions
Do you have a CEL? If so, what is the code?

Your truck should be OBD1. You will need to check it with a short wire or paperclip type thing and check the number of light flashes.

CEL=Check Engine Light

Have you done any recent work on the truck? Particularly on the VAF on the intake or near the air filter?
 
Do you have a CEL? If so, what is the code?

Your truck should be OBD1. You will need to check it with a short wire or paperclip type thing and check the number of light flashes.

CEL=Check Engine Light

Have you done any recent work on the truck? Particularly on the VAF on the intake or near the air filter?
No, no check engine light, did the paper clip thing and no error code showed up.

No recent work around there but that doesn't mean the problem wasn´t there before. I have always noticed low power going uphill but the problem became more evident on this particular hill. I have replaced the MAF sensor for another reason about 6 months ago and also repaired the ECU that caused some fueling issues around the same time.
 
No, no check engine light, did the paper clip thing and no error code showed up.

No recent work around there but that doesn't mean the problem wasn´t there before. I have always noticed low power going uphill but the problem became more evident on this particular hill. I have replaced the MAF sensor for another reason about 6 months ago and also repaired the ECU that caused some fueling issues around the same time.
What engine and transmission do you have?
 
4.5L 1FZ and A442f transmission
Try here:


You can do a search in the upper right of the screen and check by typing in different symptoms. I found this by "2000"
 
Check your Cats. I have had this happen twice with Dodge trucks of this age and both times the catalytic converters shattered and plugged the exhaust.
It's the first thing that came to mind that fits your symptoms to a "T".

Does the engine feel like its loading up, like it wants to run harder but just can't?
 
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Check your Cats. I have had this happen twice with Dodge trucks of this age and both times the catalytic converters shattered and plugged the exhaust.
It's the first thing that came to mind that fits your symptoms to a "T".

Does the engine feel like its loading up, like it wants to run harder but just can't?
I heard that before but the 93 model doesn't have catalytic converters
 
I heard that before but the 93 model doesn't have catalytic converters

Unless someone has cut them out, it should have them.

Edit...you're in columbia...different deal. checked the parts book and lo and behold...no cats. strange for those of us in NA.
 
An exhaust restriction can cause the rev limit. For those with cats, that is a good place to start. Without cats, any chance the exhaust pipe has a large dent or crushed outlet?
 
An exhaust restriction can cause the rev limit. For those with cats, that is a good place to start. Without cats, any chance the exhaust pipe has a large dent or crushed outlet?
I don't think so, recently I took it to an exhaust shop to repair an exhaust leak but I didn't see any dents
 
Very interesting, the plot thickens.
 
Check your Cats. I have had this happen twice with Dodge trucks of this age and both times the catalytic converters shattered and plugged the exhaust.
It's the first thing that came to mind that fits your symptoms to a "T".

Does the engine feel like its loading up, like it wants to run harder but just can't?

If you floor it on level ground, will it rev out close to redline in each gear?
yeap in flat ground it has no problem revving up to red line
 
yeap in flat ground it has no problem revving up to red line
Again, it could be fuel filter and sock issues because the rev is instantaneous, whereas a load is sustained and it cannot hold it.
 
By that I mean if 1 put it in 1, 2 or 3 and hold the gear it will rev up to red line, not too fast but it gets there

I'm trying to figure out if your vehicle pulls to redline (or close to it) under significant load. This will tell us if it's simply an inability to accelerate under load or if it's some kind of uphill versus flat issue.

It doesn't matter if you can force the vehicle slowly to redline by manipulating the shifter while it weakly accelerates.
 
I'm trying to figure out if your vehicle pulls to redline (or close to it) under significant load. This will tell us if it's simply an inability to accelerate under load or if it's some kind of uphill versus flat issue.

It doesn't matter if you can force the vehicle slowly to redline by manipulating the shifter while it weakly accelerates.
It is exactly that... uphill versus flat issue, if I floor it in flat ground the car behaves just fine and doesn't lack power or struggle to get RPMs. But lets say its a medium incline road, I would problably have to drop it into 1st gear since 2 gear starts loosing rpms easily
 
What sets spark advance on these beasties? Just tossing it out there, but I had an old Yamaha with a bad ECU that acted like this, with no load you could blip the throttle and it would act fine, but under load it bogged down. Turned out to be spark advance, or lack there of.
It sounds like an exhaust restriction, poor fuel or air flow or lack of spark advance under load.
What does the 93 engine diagnostics section of the FSM say to look at?
 

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