Hunting idle after fixing charging issue
A little background first...It's a 68' Camaro, Go EFI 4 600hp system that's mounted to an LT1 out of '96 Vette. I put the Fitech system on a couple of years ago and never had an issue with it from day one(except for the fuel command center, but that's another story that ended with me removing it and running an in-tank pump). Idle has always been smooth since initial start-up. My biggest issue has been charging. Basically I didn't have my 3-wire alternator hooked up right. I assumed(yeah, I know) that the voltage sensing wire from my Painless harness had power to it, but it took a shop and their notes from other installs to know that it doesn't. Anyways, got that problem solved after burning through a couple of alternators. Car was now getting charged properly, however when I went to pick it up from the shop it had the roughest freaking idle it has ever had. Idle wasn't this bad when I first started it up. RPMs were all over the place. Anywhere from less than 100 and almost dying up to around 1800. I can hear the injectors firing fuel into the throttle body when the RPMs get super low, then it surges up and does this dance for a while. It will settle down somewhat after 5 or 10 mins idling. Vacuum issue? Haven't found a vacuum leak anywhere. Keep reading where the plot thickens, lol.
On top of the idle issue, my electronic tach shoots up 1,000 RPMs or so and returns. This does not match the surging RPMs of the engine. When it does this, I can noticably hear what sounds like a hard click from somewhere. Now get this, when I turn the headlights on, it almost completely goes away(ALMOST, not completely, but damn close most of the time). Idle levels off and calms down, tach stops jumping around. Leaves me scratching my head. None of the above issues were present until I picked my car up from the shop. After I started it up at the shop, I went back in and talked to the guy. Told him that it had never done this before, but he didn't have an answer(he mentioned that he didn't have Fitech experience, and it would be costly for them to troubleshoot). He said that it might need to re-learn since it was seeing 14 volts now and now low voltage as before. I was out of time to argue any further as I had to get to school conferences for my boys. It has never gone away since then.
Any ideas? It doesn't effect the way it runs. Runs it's ass off like it always has. It is literally just an idle issue. Any ideas, thoughts, suggestions would be appreciated.
You are getting electrical interference most likely. Since you are running an LT1, you must be using timing control, so blue wire wouldn't be the issue.
Here is something to try. 2ga ground battery to block, 10ga battery to frame, 10ga battery to body. Also ground the blue wire.
Not using timing control. I am running an MSD 6A box. Battery is in the trunk. 2ga ground battery to frame rail, 10ga ground battery to body, 2(if i remember right) grounding straps from block to front frame rails(one might be going to the body, struggling to remember), 10ga ground from front frame rail to body.
Should note that this LT1 isn't what it was when it was in the Vette. Block and rotating assembly are stock, but has Chevy Performance heads on it with a Chevy Performance intake. Had a Holley carb on it before I bought the Fitech.
1) I assume that you are talking about the blue wire in the Fitech harness?
2) How would I have this issue all of a sudden when everything had been running so smoothly?
Temperature and humidity can be a factor. Can cause intermittent problems.
I see builds all the time where the ground cable is on the frame. Some have issues some don't, but I always suggest going directly to the block.
When you say LT1, I think of the 93-97 Optispark LT1. You must have an old school LT1. In that case, without timing control, your blue wire should be shielded and kept away from plug wires, coil and other electrical.
I'll take a look at the blue wire tonight. Suggestions on what it best to use to shield it?
It is an LT1, 2nd Gen, out of a 1996 Vette. Optispark is long gone. Running a MSD Pro Billet distributor. MSD 6A box. MSD Blaster SS Coil. This is the setup that was on it when I bought the car.
Oh ok, never seen one set up that way. Interesting...
There is a Sticky topic on blue wire shielding in the Electrical section.
Yeah, I never had either til I bought the car.
Ok. I will find that and read it. Thanks for the help. I will update as I go.
Did some calling around and that metal braided shielding is not very common for places to carry. Ordered it off of Amazon, so once I get it, I will put it on and see what happens.
Can you send me the link to the shielding on Amazon. I will add it to the Parts and Accessories and Accessories list.
https://smile.amazon.com/gp/product/B01BIBQESG/ref=od_aui_detailpages00?ie=UTF8&psc=1
It is a link that was posted in the sticky thread you suggested to look at above for shielding the blue wire.