I just recently purchased a HKS DLI II unit and I’m currently having problems with it. When I first started up the car, it starts up fine. Then after a few minutes at idle the car started stuttering, not quite like it was going to die, but close. Even after giving it some gas the stuttering remained. The light on the unit was on, so I decided to take a quick ride around the block. About a block out the SES light started to blink on and off. I headed back home to recheck the connections.

I didn’t mount the unit where it suggested in the manual. I mounted it on the firewall and ran the harness cables from behind the plenum. I’m not sure if the correct cable has to be plugged in the correct harness, so what I did was plug in the cables as if the unit was mounted where the instruction suggested. I figured this would be the safest route.

2nd attempt.

After returning home, I relocated the ground to another spot, unplugged the car’s ground and waited 30 minutes. Last time I grounded it on the firewall not too far away from the unit. This time I temporary mounted the ground on one of the strut bar studs.

Again, after restarting the car and after letting it idle for a minute the car started stuttering again and the light on the HKS unit was not staying solid. It was kind of fading in and out. The SES light came on again about a block out.

So I unplugged the car’s ground again and now the car sits. Could it be a bad unit, a bad ground (even though I tried two), or didn’t plug in the harness correctly? I can’t see what I could’ve done wrong, it’s pretty straight forward. Any help would be apperciated. Thanks in advance.

 

Hmm...I just installed one of these a couple of weeks ago. It is pretty much a no brainer. I'm guessing that you have one or more of the connectors connected to the wrong cylinder. Either that or one or more connectors are not snapped back together all the way. The stock connectors need a bit of persuasion to snap back together.

 

Yeah, you're right, it is pretty much a no brainer. That's why I don't get it. I'll triple check the connections again, but I'm pretty sure that can't be it. I always check them throughly.
I'll even move some of the connectors to a different cylinder, even though I was under the impression that doesn't really matter as long as the correct sides were connected.

If anybody has any advice please send them this way.

 

Do you have a rev-up motor? What EMS are you running if any?

 

I think the flashing SES means misfires. What's your location, any chance you can test it with another member? I've seen it wired in both directions (front and back of the plenum) so it shouldn't be cylinder specific.

 

No rev-up here. Will be installing the UTEC in several months. But for now I'm stock.

 

That's kind of what it sounds like. What could be causing that? I wasn't having any misfires prior to the HKS DLI install...
As far as I know, I'm don't think anyone here with a 350Z has a HKS DLI unit so I can test out.

 

pull the plugs check gap.
Check the codes thrown by the ecu and clear them out.

Uninstall completely then reinstall and go step by step making sure nothing is forgotten.

this would be my only suggestion without seeing the car.

 

Replaced the spark plugs, reinstalled everything, double checked all connections, and even relocated the ground from the HKS unit and the SES light still came on

I'm hoping that it's a bad unit. But at this point who knows

If anyone has any suggestions, throw some this way.

 

I guess the only thing that you can do now is see if anyone in your area has a DLI installed and see if you can swap it to check to see if you still have the same problem.

 

Looks like that may be one of my only options, although I don't know anyone in my area that has one

I emailed Sharif about the situation. I'm sure he'll replace the unit.

 

Problem Solved!

Incredibly enough it was a bad harness. Sharif@Forged was very helpful with his advice and even replacing the unit and harness.
Car seems to run fine now with no SES light.

Thanks to everyone for their help and mucho kudos to Sharif

 

Glad you got it all worked out. Wonder what was wrong with the harness.