No Spark at 2 coils
New motor with Ultimate LS system. Engine runs rough and rich even though the AFR is 14.5 at idle. Check the plugs and 2 don't look like they are firing, so I disconnect the fuel pump relay, remove the plugs and use a spark tester to check for spark at each coil thinking that one or more are bad. Cylinder 4 and 7 show no spark. I swapped plug wires first still no spark, then coils, still no spark and finally switched the harness connector. Found the issue, I thought, well the Holley LS harness was okay after checking for continuity at each terminal especially the one for the cylinders that weren't firing. My next step is to test for continuity on the Fitech Harness. Before I go insane testing the harness does anyone have a wiring diagram or the pin outs for the Ultimate harness? This would speed up the testing.
Post 4 in the information thread has what you need.
Let us know how this works out.
https://fitechefituning.com/fitech-efi-tuning-forum-2/topic/ultimate-ls-systems-700xx-information/
Thanks for the link to the wiring diagram. I couldn't get the connector loose from the ECU so instead I used a test light to check the 2 coil circuits that weren't firing. The circuits were good power to the correct pin with the key on and a signal when I cranked the engine. My next test was the resistance on the plug wires, turns out the resistance was 1.5 ohms for a 9 inch wire. I compared this to some an unused MSD set I have and those tested out to o.02 after I divided the number to match the LS wire length. So I replaced the plug wires with MSD LS1 wires, that has restored the spark to the 2 plugs that weren't firing. Now I just have to fix the rich AFR setting to get the motor running properly.
Decided to replace the coil wires with MSD wires since they have the lowest resistance on most wires available. This helped with the spark issue.
Now to figure out why the AFR shoots up to 10.2 within 10 seconds of starting the engine.
No expert but I found super rich at idle was a vacuum leak on inlet, icu compensates for extra air, need to do a smoke test as I also found squirting starter fluid had no effect because I assume it was already overloaded with fuel..
I started building a simple smoke test machine to test the exhaust system. I didn't know that a vacuum leak at inlet could cause the rich condition. I was focused on the header connections at the head.
Thanks.
I had a bad flat spot from idle and on acceleration while cruising especially after backing off, would spike lean 20 before it went over rich 10, that was a small exhaust leak at the O2 sensor.
I see now there is a much better O2 sensor fitting than the fixed diameter Fitech supplied one, it is a stainless strap tightened with 2 bolts similar to the stainless repair/joiner fitting available, has a boss welded on. Boss welded directly on the pipe is the preferred way.
I built a smoke test machine using a wide mouth glass jar with a plastic screw lid [to insulate two 3/16" bolts to fix resister wire inside and 12v power outside], wrapped resister wire around a bit of exhaust wrap as a wick, put a tubeless tyre valve [tire] in the lid and used a cheap [lower pressure] 12v tyre pump to pressurise jar, added mineral oil, attached a length of clear plastic hose in hole of lid and tested both exhaust inlet and exhaust, surprised how effective it was, even had small leak out of throttle body shafts. Used bits laying around, bought oil and wire, less than $10.00.
I built mine with an old canning jar, used a cotton sock for the wick and baby oil for the fuel. Used gasket sealer to hold a cheap soldering iron (4.99) to the lid. I had a tire valve that threads in that I used for several pressure testers and a small fitting for the hose. I will be blowing smoke through the throttle body first then through the exhaust using a rubber glove to seal the entry point. I already bench tested my X-Pipe from header flange to muffler flange and plugged a couple of pin holes. The O2 bung is welded to my headers but that doesn't mean there is not a leak around the bung.
Ran first smoke test and found that all theleft side injectors have a leak at their base. The injectors do not look square with the manifold boss, so I think I need to bend the support bracket a little to correct the injector alignment and get them to seal properly.
After fixing the injector vacuum leak and tightening up the header collectors the system is leak free from the inlet to end of X-pipe which should keep the O2 sensor from causing the AFR to go so rich after startup. Reset tune on ECU back to factory default then completed initial engine setup. AFR still quickly falls to 10 or 11 within minutes of startup. Fuel pressure is steady at 58 PSI. The rpm is all over the place on the hand held unit but seems stead on my tach. Fitech is sending me an RMA so they can test the ECU and handheld unit. The ECU came with the harness connected, any secret to removing the connector from the ECU?