Home stretch, couple issues.

[Flubyu]

I almost have my 5.3/4L60E swap completed in my 71 C10. I have two issues that I can't seem to figure out. The first is the engine runs PIG rich. When I say rich, I mean the LTFTs are pegged at -18 and it will kill any mosquito in the 4 state area! Not sure whats going on with that. Unplugging the MAF does not change it. Mind you, I have NOT driven the truck yet. This is just sitting in the garage running.

The second issue is my fans arent running. I was told all I needed was to connect the fans to ground and the wires coming from the reworked harness were positive. I connected them as stated, and I get nothing.

Any help?

[TomMLSx]

Needs a tune fore sure....

As to the grounds, you may have that backwards. Usually on all harnesses I have seen, the grounds are switched from the ECM/PCM...

T,

[kipps]

Originally Posted by TomMLSx

As to the grounds, you may have that backwards. Usually on all harnesses I have seen, the grounds are switched from the ECM/PCM...

Maybe not. Depends on whether that harness includes relays or not.

[mongocanfly]

Are the o2 sensors plugged in?
Do the fans run thru relays?

[Flubyu]

In the fuse box, there are 2 fan relays.

Yes, O2s are plugged in.

[OutlawDrifter]

Make sure O2 harnesses are not swapped L to R. That happened to me once, and had me chasing issues for awhile. Finally the tuner realized one side was pig rich and the other totally lean.

[Wgesnerjr]

My O2 on drivers side was LAZY. it would report to the computer, but would not fluctuate as much as it should have. I saw this when comparing each side on a graph in Torque Pro app on my phone and a Bluetooth OBDII plug off amazon. (VeePeak) Another thing to keep in mind is that LS do not like Denso O2 sensors. Check the brand you have now.

Here is my thread on my issue with my swap running rough and being rich and smelling like gas. http://67-72chevytrucks.com/vboard/s...=774609&page=3 #65 is where its solved.

[TomMLSx]

Originally Posted by kipps

Maybe not. Depends on whether that harness includes relays or not.

Relays shouldn't matter, the outputs from the PCM/ECM are ground, not positive......

Who's harness is it and what PCM are you using, red/blue or blue/green?

T,

[nsb29]

Are these new injectors or old ones that have been sitting you could have one stuck open?

[kipps]

Originally Posted by TomMLSx

Relays shouldn't matter, the outputs from the PCM/ECM are ground, not positive......

The OP says in post #5, that there are fan relays in the fuse box. I assume the fuse box was included as part of the reworked harness.

Thus, the wires he's working with are switched 12v, and are fused/relayed heavy enough to power the fans directly.

[Richard]

Fan wires are easy enough to check with a dmm. Wire from relay to ground for +12v or wire from relay to ground continuity. Check for +12v first to avoid blowing fuse. Obviously relay has to be triggered to check this.

[Flubyu]

Thanks for everyones input. The injectors are orginal to the engine, and the engine starts great hot or cold. Engine/computer are from a 04 Yukon. The harness was reworked by S&S Performance in northern Ark. They also worked the PCM (deleted VATS, EGR, and enabled fans)

[Flubyu]

I should also note that I contacted S&S and he indicated that the fan outputs should be 12v.

[TomMLSx]

Can you post a picture? I'm confused, which is not hard to do...lol.

The actual fan motors should be +12V into the relay via a fuse, then out to the actual fan motor from the other side of the relay. These would be big wires.

The trigger for the relay (think coil on the relay/small wires) should be +12V to each relay, then the other wire should be the ground to the coil switched from the PCM for each relay. This is assuming you have a two fan system.

I would be interested to see what actual wires you have hanging out of the fuse block or wherever it comes from that you are talking about.

Another question, how do you know the fans aren't coming on? What tool are you using to simulate fan run, or are you just waiting for the engine to warm up? Do you have access to HP tuners, or EFI Live so you can force the fans on manually, and also, can you check to see what the fan on/off temperature settings are?


T,

[cebra]

I went through several tunes before I got my fans to work, BP automotive provided the worst tune of all but a ebay tune ended up the best and getting my fans to work. The fan activations doesn't always take per the half a dozen tuners I talked to trying to get mine sorted out. Come to think of it, the guy that was able to tune and resolve all my issues was from Arkansas.

[Flubyu]

Blake was the guy's name at S & S.

[mongocanfly]

I think someone already stated it but since you have the o2 hooked up, make sure they're on the proper side...there is a left and right

[Flubyu]

On the topic of o2 sensors, pretty sure there wasn't a way to hook them up wrong as they would not reach IIRC. How do I tell if they're hooked up correctly?

[mongocanfly]

Not sure on a reworked harness... mine had the harness plugs marked driver side and pass side

[87chevy.com]

What year is the pcm. More than likely it needs to be turned on in the tune or word wrong.
Clint

[pilotXC]

Fan signal from PCM is negative... You need relays to run them, can not just run power to the battery and negative to the PCM.

[Flubyu]

I am running dual fans from a 2007 Grand Prix. I bench tested them, and they both work. I have fan 1 and fan 2 relays in the fuse box, wires coming out of the box labeled fan 1 and fan 2. S & S said these wires are 12v positive. What temps should the fans kick on? I've let the engine idle and warm up to around 220 and nothing came on.

As for the o2 wires, I really don't see how I could have swapped the wires with the way the harness lays, but the labels are no longer intact to be sure.

[Flubyu]

PCM, engine, and harness are from a 2004 Yukon 5.3

[pilotXC]

In my harness the fan signal was (-). I highly doubt it's different in yours. Hard to explain without a visual and I don't have time to draw out the schematic, but basically mine went something like this (Windstar dual fan set up, fan 1 triggers 1 fan, fan 2 triggers second and both stay on.) There are 4 contacts on the relay, all need to be used or it won't work.

10g power wire from relays (need one elay for each fan) with 50amp fuse to battery.
20g (+) coil wire from relays with 5amp fuse to battery.
20g (-) coil wire from relays to fan signal from PCM (I have 1 relay for fan 1 signal and 1 relay for fan 2 signal).
10g (+) power to fans from relays.
10g (-) ground to core support from fans.

I think that's it without looking at it to double check. It's not just a ground an a power like turn signal or something.

The temp they come on at is programmed into the PCM, so I have no idea on yours. Mine is set up for 196 for fan 1 and 212 for fan 2, something like that...

[Rich84]

When I bought my harness it came with relays to hookup the electric fans. The Pcm sends a ground signal to the relays which sent a 12v signal out. Since I had a factory set of the 3 relay set up wired to my fan I had to remove his relays to get to the Ground signals from the PCM. I hope this makes sense.