Topic: 22re lopes around 1200 rpm... any ideas?

[newie]

This happens when wheeling (low rpm). I will be cruising in any gear and around 1200 rpm, the engine will lope back and forth between 800-1200 rpm. It is extremely annoying, especially in low range.
I have searched with no luck to anything real specific.
FYI I have an '84 that I converted to EFI. The upper plenum is late model ('89-'95). The tuck has always ran very well up until this point. Thought I would ask you guys before really diving into the problem.
I suspected the coolant level issue, but the problem occurs during that rpm range and not other time. The engine runs fine at all other rpm's and speeds.
My next guess is the TPS... but like I said, I thought I would ask you guys before I get into it!
Thanks in advance for your input!
Jon

[79coyotefrg]

i would say  tps  unplug it  while its running and see if it makes a difference

also  pull the engine codes

[Hottrod81]

Possibly a vacuum leak somewhere.

[93tonkatoy]

you should test the tps. it's position has everything to do with how it operates. It's circuits include the closed throttle fuel cut. also read this
http://board.marlincrawler.com/index.php?topic=35469.0
This solved the problem with my truck. when I pressed the brake, the idle cut would engage and the rpms would drop. once it got to about 1000 rpm it would get power again and speed back up. sounded kinda like someone impatient at a light trying to let someone know he's getting....   vroooom......vroooom......vroooom......vroooom.


p.s. also, this never stored any codes on mine.

[DeMented Toys]

Hey, this is exactly what mine is doing.  vroooom......vroooom......vroooom......vroooom  But only when the brakes are on.  Other than that the idle is just too high... 

you should test the tps. it's position has everything to do with how it operates. It's circuits include the closed throttle fuel cut. also read this
http://board.marlincrawler.com/index.php?topic=35469.0
This solved the problem with my truck. when I pressed the brake, the idle cut would engage and the rpms would drop. once it got to about 1000 rpm it would get power again and speed back up. sounded kinda like someone impatient at a light trying to let someone know he's getting....   vroooom......vroooom......vroooom......vroooom.


p.s. also, this never stored any codes on mine.

[emsvitil]

Hey, this is exactly what mine is doing.  vroooom......vroooom......vroooom......vroooom  But only when the brakes are on.  Other than that the idle is just too high... 

The ECU will cut fuel if the TPS indicates that the throttle is at idle, the brakes are on, and the rpms are above a certain speed.    Fuel is cut until a lower rpm is reached.   

So if your idle speed is to high, you get stuck in a loop of fuel off, fuel on, fuel off......

[DeMented Toys]

Yes, that is exactly what is going on with it.  Guess I need to adjust or replace the TSP.

The ECU will cut fuel if the TPS indicates that the throttle is at idle, the brakes are on, and the rpms are above a certain speed.    Fuel is cut until a lower rpm is reached.  

So if your idle speed is to high, you get stuck in a loop of fuel off, fuel on, fuel off......

[newie [OP]]

The ECU will cut fuel if the TPS indicates that the throttle is at idle, the brakes are on, and the rpms are above a certain speed.    Fuel is cut until a lower rpm is reached.  

So if your idle speed is to high, you get stuck in a loop of fuel off, fuel on, fuel off......

Do you the brakes have to be on??? This loping occurs when I am in gear and cruising without hitting the brakes. It makes sense though, the loping is extreme as if the engine is briefly starved for fuel.
Are you thinking it is a TPS adjustment, or is the TPS bad and maybe gumbed up and getting stuck???
Thanks again for the help!!!!!!
Jon

[emsvitil]

I'd go thru the TPS adjustment procedures first.

[93tonkatoy]

if that all checks out, check the coolant hose i described. and the barb beside the thermo housing. that valve allows extra air to go by the throttle plate to idle the engine up until the water starts warming up. if you are getting no water through there, it will not close that valve after the engine is up to temp. and the idle will STAY high.

[Yota4life]

I replaced my TPS recently with a brand new one (yea i know expensive) I had a hard time adjusting it because i dont use a volt meter too often. And i still get a small lope around 3000 rpm. But my motor has a WEAK idle. It dies even in low low on both cases. Could this just be because the TPS isent set right or is it something else.?