Just got done with my swap from the 870 to the 165 ECM with the ABWT Prom (stock '87 GTA bin), I am having trouble with the fan, it is on all the time. I have tried taking the pin from D11 (A/C fan request) and putting it back in C9 (fan request) but the fan is constantly running still.
Any ideas on why this is? The Prom has not been reprogrammed as far as I know.

Also, the car runs like crap now, surging idle, surging at part throttle and idling rough. I'm going to recheck my timing and reset minimum air and see what that does for it.
I would have thought that the change in ECM's and Prom's would have made it run better, not worse.
The engine is a 350 running 9.6:1 compression, 24 lb injectors, TrickFlow heads and a Summit cam that specs out at 204/214 dur @ 0.050 .442/.464 lift (nothing too big)
Any help appreciated.

 

Is the Check Eng light lit? Sounds like it's running in limp home mode.

 

Nope, no ck eng light, WinALDL says no fault codes and only the ALDL mode box is checked. The ECM does give code 12 when jumped.
This one has me stumped, it is acting like it has the corvette chip in it, fan working backwards and all.

I was able to get the idle and surging problems straightened out by resetting minimum air and TPS & timing.

Also another strange thing. WinALDL says the BLM's and Int are both at 160 even though I can smell that the car is running rich and the O2 mv are high and the rich flag is set.
160 is indicating lean correct? With the 870 ECM in it had BLM's at 116 and int in the 130's. When I give it gas the BLM's go to 128 but then start creaping back up to 160 if I keep my foot on it. When I increased the fuel pressure the BLM's wouldn't ever come off of 160, with it set at 33 PSI, idling it will change when I give it some gas.

 

Sounds like a mess

My swap was flawless, however I deleted my AC and I recommend to fix your fan try to pull your AC high pressure switch plug and either leave it lay unplugged and see if that fixes it, and if it doesn't then jump the two wires with a paperclip and see if that fixes it (With the fan wire at the ecm in the right spot for the 165 ecm).

That worked for me untill I could prom burn and fix the N/O flag.

 

I don't have A/C, never did have it. I tried removing the A/C fan request pin from the ECM but it still runs the fan all the time. I only have the one fan since this car never had A/C.

 

Follow the ac wiring diagram in the tech section, find where the pressure switch pin WOULD have been, and jump it. Its not whether the vehicle had it, its whether the ECM thinks it does or not.

 

Can't find any wiring diagrams in tech section, got a picture of the connector or a location of it? I don't have any loose connectors back by the firewall where the condensor would be.

 

http://92b4crs.tripod.com/86wiring/86wiringindex.html

There's an entire section on AC, If your using a stock unmolested 85 wiring harness then chances are it still has an AC pressure switch connector. It normally is connected to the AC hardline that follows the passenger side frame rail in the engine bay up to the condensor in front of the radiator, the plug is circular, with a clip, and has 2 small pins in the center (female) that you can easilly jump with a paperclip, If you can't find that connector maybe you can find in the link above the wire color for an 85 harness for the AC pressure switch, its found under the tech article section, under electrical, 85 wiring diagram.


Good luck

 

Ok this was an absolute shot in the dark, so I apologize if this only makes things worse, Its not a good enough picture for me to make a deffinitive guess, but it certainly looks close enough to get an idea.

 

OK, found it, jumped it, no good, fan still runs all the time.
I finally found the $32 mask and had a peek at the ABWT.bin. The N/O for the fan isn't checked in it, just like the ARAP.bin. Did all the 350 .bin's use normally closed fan operation?
Guess I'll just have to wait till my programmer gets here and see if changing the flag to N/O fixes this.

My harness is "unmolested", but I did however move all unused connectors out of the waywhere they didn't dangle and wern't easily seen.

 

Does the fan come on with just the ignition on? or does the car have to be running for it to come on?

 

Engine running is when it comes on, with just the key on the fan is off.

 

Ahh ok, I believe if the pressure switch is triggered the fan will come on when the aux is on. I've ran into so many different weird fan problems that I'm drawing a blank, I'll keep tooling it over and see if i can figure out what combination of problems would cause a scenerio like that

 

I'm thinking it might be the Prom, I looked at the .bin for it and it shows the fan N/O box unchecked. I'm going to look at some of the other F body .bin's and compare 305 to 350. I'm thinking the 350 .bin's might all be normally closed operation, like the 'Vettes.

 

I was thinking about the PROM too, but never mentioned anything earlier because I thought the ARAP bin was the only one that was backwards, but if your BIN has the n/o unchecked just like the ARAP, then you might have your problem. In my 85 I'm using a modified ARAP bin that's had the fan constant changed, and my fan works fine.

BTW, all 85s got 1 fan regardless of whether you got AC or not.

 

Yep, but I wasn't sure about the '86-89 MAF cars.

Now I just have to figure out why WinALDL says the BLM's are at 160 with 24 lb injectors while I can smell that it is running rich and the O2 mv are high.

 

Try running craig moates to verify between the two scanners to see if its a bug or not.

 

Was thinking of that, but I don't think the cable I made for WinALDL will work with his software, I think I need to build a new cable.

 

 

Actually I did build a 2 trans cable, but it didn't work with WinALDL so I made a cable for that and used the DB9 connector from the 2 trans on it. So, I just need to hit the Ratshack cell phone store and get another DB9 and hope the cable works.