[D94]

Hello all. I am experiencing something strange, and I don't know if it make sense at all. Back in April I added the Hyperspark ignition to my existing Term X. After a few minor hiccups, got it running. At that point I had it tuned by Andrew ( Dr. EFI ), and it's been running awesome ever since ( still have to get back with him to go over stuff). Here's where it gets weird, last week I decided to change my tailight bulbs and marker bulbs to LED replacement bulbs they needed to be replaced anyway. Car was running great, I shut it off and changed the bulbs. Tried starting it and no dice. It will crank, fire, then die unless I pedal it to keep it running. When it briefly starts all lights on the ECU are green ( normal ). After going back and forth, and going over everything I could think of, took the bulbs out, then I tried re-flashing ECU and re-installed map from both the laptop and SD card. Still nothing. Then I remembered an article by Chris from EFISYSTEMSPRO, that mentions to check to see if IAC is working, you should be able to see it move with intial key on. Checked that, and IAC does not move either. Is it possible that the bulbs could effect something? I didn't touch anything else before this happened. Any info, thoughts , ideas would be appreciated. Thx.

​​​

[JLMounce]

When you installed your LED tails and markers, did you also replace your flasher can/s in the fuse box. If so, did that require you to do any wiring (there may be an auxiliary ground with some LED flashers). If this is grounding to a circuit that the ECU is using to control the IAC, I suppose that could be possible.

Many LED's have specific polarity, was this taken into account?

I'd check to make sure you didn't actually de-pin something at the ecu if you were crawling around under the dash at all.

[D94]

Thx. Yes I did also switch out the flasher can which came with a reverse polarity adapter if needed sometimes it s not necessary but I hadn't used it yet at this point. I didn't touch any wiring anywhere. First thing I did when it wouldn't start, was put everything back the way it was to try it.

[JLMounce]

Start checking pins and any fuses in the system. If the IAC is closed too far and isn't receiving power, those are the two most likely culprits. I suppose it's also possible that you have a coincidentally defective IAC motor. I know you reloaded your tune, but you may want to get into it and personally check to make sure the system is commanding IAC values above zero. Typical engine start ranges are from 30-60% or so.

[Gator67]

I don't see how switching to LED bulbs would impact your EFI system unless maybe you were pulling power from the same circuit (and this shouldn't be the case if you followed the Terminator X wiring instructions)..

My car acts more or less the same way as yours when I forget to switch the fuel pump back on (I installed a switch between the fuel pump wire from the ECU to my fuel controller). Just enough fuel pressure in the system to start and run for a few seconds. Also did something similar when I had the wrong cam sensor setting selected in the software.

[D94]

JL - Thx. I thought fuses as well, just trying to figure out which one. ECU is getting power so I don’t think it’s the main. but I’ll check anyway. My Tune calls for 95 open on cold start but it’s all the way back so I think that’s full closed? but without it running can’t tell if it’s graduating down, have to look into that. I have a spare IAC , was hoping it didn’t go bad it’s a mother to change.

Gator- I thought the same thing. Lighting is on its own circuit. Pretty sure it’s not fuel pump, I can keep it running if I peddle it so it’s getting fuel.

Thx for your input on this mystery…greatly appreciated. I’ll keep you posted.

[D94]

Just wanted to post a quick update :

I don't know how or why, but I changed out the IAC with the spare one that I had and wouldn't you know it fired right up like nothing happened. Back to running great again.I still don't know what would cause the IAC to go bad by changing bulbs, but I did read somewhere that LED bulbs can give off RF interference and they also send pulses and signals. I don't really know much about it but maybe the IAC was somehow affected by that? Who knows but all good now. Thx again.

[JLMounce]

Probably just a failed IAC and a coincidence. I really wouldn't think the LED changes would cause this. Especially considering a new IAC works as intended. That's a physical motor.

[D94]

You're probably right. What timing, go figure..