98 TXT sporadic speed with upgraded controller

[vogonpoetry]

I have a 98 EZGO TXT series cart which I recently replaced the batteries in. After replacing the batteries, it ran great for a while, but upon attempting to use it the second time that day I found it wouldn't move at all. After taking apart the accelerator box I found the microswitch arm was broken so it wasn't being activated by the pedal. Replaced it hoping that was the only problem but no luck. (I suppose it's been broken the whole time we've had the cart as the solenoid never activated when depressing the pedal before. What is the purpose of it anyway?) After following a troubleshooting guide I found on here with my DMM, I determined my motor controller was faulty. Perhaps it was almost failing and the surge of power from the new cells finally killed it? Seemed like an odd coincidence to me. Regardless, I ordered this controller to replace the stock 275A Cutis with an upgraded 350A Curtis.

Amazon.com : Curtis 36V 350Amp Golf Car Controller, Upgraded unit for Ez-Go, with 2 years warranty : Sports & Outdoors

Amazon.com : Curtis 36V 350Amp Golf Car Controller, Upgraded unit for Ez-Go, with 2 years warranty : Sports & Outdoors

After installing it, the cart finally worked, and had more torque, however it only lasts for a few seconds at a time and acceleration is very sporadic. For example, you might depress the pedal halfway and be going very slowly and then 2 seconds later you will lurch forward. Then you will be at full speed for 5 or 10 seconds and the cart will drop down to about half speed even with the pedal fully depressed. Sometimes depressing the pedal 3 or 4 times will get you back to full power for a little while and sometimes it will come back by itself with no intervention, but its always temporary. Cells are fully charged and I've checked all connections. It doesn't seem to be affected by bumps either.

Do you think this new controller is defective? Could my solenoid be unable to handle the higher current and is giving low amperage? Or perhaps the ITS just needs to be adjusted somehow after my delving into the pedal box? I had adjusted it according to some comments here and put the rod about 3/16" away from the front of the inductor. I'm at a bit of loss at what to do next. Any ideas?

[cgtech]

If you are still running the stock style solenoid (small silver can), get rid of that for something better. I have seen lots of problems in even stock configurations.

[vogonpoetry]

What do you recommend? Is this one any better?

Amazon.com: E-Z-GO 609428 Heavy Duty Solenoid Assembly, 36-volt: Patio, Lawn & Garden

Amazon.com: E-Z-GO 609428 Heavy Duty Solenoid Assembly, 36-volt: Patio, Lawn & Garden

[mgray70]

Check the 4 pin Molex connector that connects the ITS peddle box to the controller. I had one last week doing the same thing. I tried everything with no luck. I unplugged that connector, looked at it, plugged it back in and it hasn't missed a beat since.

[cgtech]

That solenoid is better, but not the best available. Something like this is very good. Scottyb's solenoids get good reviews on this forum as well, but i have never tried one of his. Forgot to add, this is a "white-rogers" solenoid.

[vogonpoetry]

Originally Posted by mgray70

Check the 4 pin Molex connector that connects the ITS peddle box to the controller. I had one last week doing the same thing. I tried everything with no luck. I unplugged that connector, looked at it, plugged it back in and it hasn't missed a beat since.

Yes, I tried that earlier but it didn't affect the issue. But I suppose it could still be causing problems. I'll check it again.

Originally Posted by cgtech

That solenoid is better, but not the best available. Something like this is very good. Scottyb's solenoids get good reviews on this forum as well, but i have never tried one of his.

Alright, good to know. To test if the solenoid is the problem I could simply bypass it by jumping out the two lugs right? That won't damage anything I don't think... I'll try that as well.

[cgtech]

Controller will not like "jumped relay" test. Some crybaby nonsense about "welded contactor" yadda yadda. Wait, nevermind, you have a series cart, test away...

[vogonpoetry]

Checked the Molex connector and bypassed the solenoid. Same issue. Looks like it might be a faulty controller after all. I was testing the voltage to the white wire going to the controller and, according to the diagnostics sticky, it should read from .5 to 1.5v fully depressed. Mine was reading 1.7v fully depressed when it was going slow but it would jump up to 1.8 or 1.9 when it was at full power. Is that too much voltage? I'm not sure if this behavior is being caused by the controller or the ITS. Considering it worked fine before changing the controller though, I think I will contact the seller at this point.