Help with throttle hesitation

B

bbrickham

Member
Need some opinions on what I have going on. Motor is an Ls and is having problems at low rpm. When getting on the gas it hesitates really bad and runs really rough until you give it a punch on the throttle. It’ll run on pad like normal and cruse all day but that range from 1-3k Is where it has a problem running smooth. Have checked sensors and installed a new fuel pump just to try and check things off the list. But still stuck where we started. Motor is about 2 years old and has been flawless besides overheating from cracked radiators a couple times and bad fuel pumps.
 
EFI?

An intake air leak would be my #1 possibility for low speed issues that clean up when the throttle opens. Keep in mind that the leak could be under the intake.

Next on the list would be the idle air control valve, confirm proper operation and no trash in it, perform a reset cycle.
 
Slidin Gator said:
EFI?

An intake air leak would be my #1 possibility for low speed issues that clean up when the throttle opens. Keep in mind that the leak could be under the intake.

Next on the list would be the idle air control valve, confirm proper operation and no trash in it, perform a reset cycle.
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Yeah efi holley terminator. I’ll see if I can find something
 
Did you have good throttle response in the beginning. If it ran right before and now it doesnt with the holley system it's pretty simple. 1ST OFF IF YOU LEFT THE O2 IN 99% OF the time thats it. Hook a laptop to it or a hand held and read your O2 A/F If you left it in I bet its reading dead lean max range. That is the most common part to fail then next is the air temp sensor, the 3nd is the map sensor. If you can connect just start up the motor and read your sensor out puts. People running the O2 and leaving it in learn mode is the biggest problem we see it's 95% of all issues. We got around that 10 years ago this is why we tell ALL our customers run 1 tank and remove the O2.
 
Waterthunder said:
Did you have good throttle response in the beginning. If it ran right before and now it doesnt with the holley system it's pretty simple. 1ST OFF IF YOU LEFT THE O2 IN 99% OF the time thats it. Hook a laptop to it or a hand held and read your O2 A/F If you left it in I bet its reading dead lean max range. That is the most common part to fail then next is the air temp sensor, the 3nd is the map sensor. If you can connect just start up the motor and read your sensor out puts. People running the O2 and leaving it in learn mode is the biggest problem we see it's 95% of all issues. We got around that 10 years ago this is why we tell ALL our customers run 1 tank and remove the O2.
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Dave, Interesting information right here, gotta say this site has a breadth of knowledge like no other.
 
What I did to find an issue with my terminator x is plug in the handheld and start a data log and put the engine through variety of rpm’s and make a metal note of rpm when you experience the issue. Turn off and disconnect the handheld and remove the SD card and put in laptop and review the data. That is assuming all koeo and koer data shows no signs of the problem first. The laptop software is free to download and you can look at the data with an open mind and not while staring at the engine.

Has anyone wrote a file in the terminator x for your boat or have you just allowed the wizzard to do its thing.

As Dave stated above after the computer has a handle on the engine for 1-3 tanks of fuel I plus the oxygen sensor. I was loosing oxygen sensors about every other ride and got tired of changing them. I would always plug in the handheld and if o2 was good I would ride and if not I would change sensor. Did that for the first month since inception and then haven’t run an o2 since. I ran into Dave on the water about 3 months after running without an o2 sensor and he confirmed that once it learns take it out of the equation just pay attention to what your engine tells you don’t just crank and run
 
Waterthunder said:
Did you have good throttle response in the beginning. If it ran right before and now it doesnt with the holley system it's pretty simple. 1ST OFF IF YOU LEFT THE O2 IN 99% OF the time thats it. Hook a laptop to it or a hand held and read your O2 A/F If you left it in I bet its reading dead lean max range. That is the most common part to fail then next is the air temp sensor, the 3nd is the map sensor. If you can connect just start up the motor and read your sensor out puts. People running the O2 and leaving it in learn mode is the biggest problem we see it's 95% of all issues. We got around that 10 years ago this is why we tell ALL our customers run 1 tank and remove the O2.
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I’ll do that! It’s your motor so we don’t have o2 in that was taken out per your instruction. I did swap air temp sensor last time I had you on the phone that’s what you said but Its an off brand cheapy and that’s all I could find in the time we needed it. I’ll grab an oem map and air temp and see what happens and I’ll plug it in and see what I can’t read. if not I’ll give you a call!
 
90chevy396 said:
What I did to find an issue with my terminator x is plug in the handheld and start a data log and put the engine through variety of rpm’s and make a metal note of rpm when you experience the issue. Turn off and disconnect the handheld and remove the SD card and put in laptop and review the data. That is assuming all koeo and koer data shows no signs of the problem first. The laptop software is free to download and you can look at the data with an open mind and not while staring at the engine.

Has anyone wrote a file in the terminator x for your boat or have you just allowed the wizzard to do its thing.

As Dave stated above after the computer has a handle on the engine for 1-3 tanks of fuel I plus the oxygen sensor. I was loosing oxygen sensors about every other ride and got tired of changing them. I would always plug in the handheld and if o2 was good I would ride and if not I would change sensor. Did that for the first month since inception and then haven’t run an o2 since. I ran into Dave on the water about 3 months after running without an o2 sensor and he confirmed that once it learns take it out of the equation just pay attention to what your engine tells you don’t just crank and run
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For sure it’s Dave’s motor and it’s been flawless for 2 years besides having a cracked radiator and it over heating a couple times and that’s not on him. This is just something new that’s come about so praying it might just be the sensors he stated I’ll definitely take everything in consideration tho! Thanks for the help!
 
make sure to check your key on engine off data and your key on engine running data at idle and if you find nothing wrong do the data log.

data is everything when it comes to EFI.

I had a stumble when I initially set up my terminator and come to find out my map sensor graph was incorrect for the sensor.

Make sure you replace the map with the same part number Dave had in that engine because not all 1 bar sensors use the same graph

For instance mine doesn’t have a linear graph but the sensor actually has a progressive graph when it changes pressure so it is not a straight line but a curved line when looking at the fixed data for given pressure.
 
Found the issue!! Wire harness to the map sensor has cracks and a couple breaks in the wires. Wiggled it a little bit and it runs better. New harness on order! One of those problems that’s really pissed you off right there
 
bbrickham said:
Found the issue!! Wire harness to the map sensor has cracks and a couple breaks in the wires. Wiggled it a little bit and it runs better. New harness on order! One of those problems that’s really pissed you off right there
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That was 100% our problem! The sun really takes a toll on things. Time to be more careful and keep this think covered at all times.
 
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