Engine lugs down in RPM when fan turns on

[evanjp]

Boss intake manifold, steeda 101mm, and Lund tune.

My engine lugs down pretty low in rpm when the fan turns on. If I'm in traffic and coasting in 2 or 1 gear and the fan turns on, the motor will buck and be a bit wild.

I do have a small coolant leak in the area of the water pump, but looks to be coming from a hose fitting.

Motor seems a bit down on power and a little sluggish at times.

Any idea? Tune issue? Related to coolant leak?

 

[evanjp]

When fan turns on at idle it sounds like the car is about to stall out. Just idling.

 

[evanjp]

Anybody?

 

[kcobra]

Tuning usually can fix this. This is a common issue with tuning cars and any reputable tuner should be able to fix this. I have had a problem with even the best tuners with my BOSS at one time. It is a Paxton car and supposedly they aren't the best to tune. Well, I decided that it seemed like there was way too much current draw from my fan so I decided to replace the fan assembly just to try. I figured that would be pretty cheap (found best online price and did labor myself). Guess what? Absolutely fixed my issues. Car idles perfect and never, ever dips in rpm when fan comes on anymore. I think something happened to the fan somewhere, somehow. Anyways, just food for though. Now, if it was the fan relay, which is mounted to the fan assembly, or the actual fan motor, I will never know. Don't really care. The new unit came with relay and fan so I replaced both. I bought online for like $185 shipped or something.

 

[Shaun@AED]

Typically this is a blown low speed fan relay or wiring to / from it.
The fan pulls more amperage than the stock alternator can deliver if going from zero to 100% duty cycle. The low speed must be ON(50% duty cycle) before high speed kicks on or it will pull enough amperage to stall an engine.

Data log the issue and include battery voltage in your log. If you see battery voltage drop drastically (below 12.8 typically) and notice the fan goes from OFF to 100% duty cycle, the low speed relay/wiring is the issue.

 

[kcobra]

The low speed was ok on mine. Just saying. Don't ask me what it was but something was messed up. Easy fix.

 

[evanjp]

Thank you! I messaged Lund about it and he said to do a datalog. So that's what I am going to do.

 

[agony]

I had the same thing happen after my Vortech install. They increased idle rpm a little and it has been fine

 

[evanjp]

Haven't done a datalog yet because I don't want to run the car hard, but my t-connector hose is what's leaking. Could that be causing the fan issue and sluggish power a bit?

 

[evanjp]

So I got the t connector and my upper radiator hose does not tightly fit around the connector. Literally just drips water from the connection (was about to flush fluid, was going to turn car on for the water to cycle). Unreal. Going to get an upper radiator hose in the morning. This t connector is on national back order the parts guy told me and I got one of the only ones in the area. Drove an hour for it. I hope this part isn't defective or something, and hope the upper hose i currently have is messed up and the new one will make it work.