Heres a wierd one

[Matt McClung]

Thanks guys, I will give the relay cleaning a try and will let you know the results.


Matt

 

[Jerryl]

Ran into this as well. The car does not run bad when the fans kick in. Just posting some numbers and my observations.

IAC set around 15-20 cold, Maf will read 6. Fans activate around 165. When the Fans activate, the RPM drops and the IAC corrects. IAC raises typically around 5 points to make up for the increase in electrical load, and MAF raises 1 point. New alternator, battery, good solid grounds.

 

[Matt McClung]

Okay, I have cleaned out the fan relays, I have taken the fan motor apart and cleaned that and I have checked/cleaned all of the grounds. Still not running good when the fan kicks on, it has to be only one thing and that is the alternator, it was replaced before I got the car and I doubt that it is the 120 amp that the car needs. And when I checked the charging system, it was in the green (good) area on the gauge but just barely. I did check to see if the air was screwing up the MAF and it was not. One more thing, I hooked up a fan unit from a 85 buick electra FWD and it has a lighter duty motor and when that would engage it did not mess up the idle.

Any other thoughts?
Thanks

Matt

 

[Quick6'n'-K.C.]

Get the car to where the fan comes on and is running bad, unplug the fan at that moment..This will let you know if the fan motor itself is the issue drawing too many amps.
BW

I believe your stock fan may be so worn out that its drawing too many amps making your car run like poop.

I would replace the factory fan if the other fan you just installed doesnt make your car act up.
How less heavy duty is it?

BW

 

[Matt McClung]

The other fan unit is quite a bit lighter duty and smaller. I was thinking the same thing about the motor being worn out being a little harder to turn (hardly enough to notice) than the lighter unit, but when I took it apart I can see that it is not worn out, bearings are good and the reason that it seems a little harder to turn is because of the heavy duty brushes that are pushing against the stator (normal). With my charging system gauge being at the very bottom of the normal range, and these cars are supposed to have high output alternators, I really believe that this may be the problem (alternator). I have disconnected the fan at the fan itself when the fan starts up and the engine will smooth out. I am always open to more suggestions


Thanks guys

Matt

 

[Razor]

There was a post a long time ago about the emf from the fan back feeding to the ecm through the fan relay. Think Bob Bailey had written about this.

Bad Fan relay creating ecm havoc.

 

[Matt McClung]

Okay, I have changed the cooling fan and found out that was not the problem.(I know that I mentioned that the lighter duty one would not cause a problem but I found that with driving and getting the car really warmed up it still runs rough when the fan is on but not as bad) I have changed both relays (low and high speed) and still not solved. I had the alternator tested and it is putting out the correct amps. Grounding is good and connectors are good. I am going to try something that I think might work, I know that the relays are supplied with constant 12 volts and the switching wire is what activates the relay (no need to teach you guys how a relay works ) I am going to run a fused wire to both relays straight from the battery and let the switching wires do their thing, I am thinking that might prevent a drop in current from wherever the wires that are providing the main power comes from.

what do you think?

Matt

 

[Matt McClung]

well, I just got done hotwiring the fan relays and it did not help. I am out of ideas, I have tried everything that I can think of and I am frustrated.
I am starting to wonder about the chip, it has an aftermarket chip in it but it was already there when I bought the car so I don't have any idea who's chip it is. I wonder if it is the chip because I have read where other TR owners have solved many idle issues when they installed a new chip.

Thanks

Matt

 

[Matt McClung]

I have been scratching my head all day about this problem and I just thought about the fuel injectors. This thing still has the stock injectors in it and I have my 84 parts car with newer 42 lb injectors that I put in it myself. Since I should upgrade anyway, maybe I should put the newer ones in and I might get lucky and fix the culprit.


Matt

 

[1QuickGN]

I had this problem also, along with a lot of other issues. I found that the fan motor had a poor ground. I ran a extra ground to the frame from the fan connector and it fixed the problem. I found this out by using a DVO meter one wire to fan ground and the other to battery neg you should have less than 50 mv.