[Siggy89]

So I pulled a 3G from a 95 mustang on Friday. Installed on Saturday and upgraded the charger wire to 4 gauge with a 175 mega fuse coming off the starter relay. All seemed to be well. Drive an hour up to my sisters house. On the way back all was still well but the truck died when I came to a stoplight. Started right back up, but kept dying when I came to a light.

any ideas?

 

[Siggy89]

I’d normally just say replace the IAC but with the 3g swap it seems to contradict that. I’m debating just buying a new 3G to install.

 

[Skitter302]

Might need to try a different 3g. When I did my swap it was all plug and play, no stress.

 

[fodder]

Stop by one of the parts stores and get your alternator (and battery) tested before buying a different 3G. (Or, even better, get any JY alternator tested before installing it. ) The symptoms don't sound like an alternator issue to me, so replacing it without verifying that's the problem doesn't seem productive.

 

[Siggy89]

Might need to try a different 3g. When I did my swap it was all plug and play, no stress.

I drive it an hour ago and no issues. Can’t figure out what was causing the stall after an hour of highway driving. Voltmeter show 12.6 on battery and 14.7 while running.

 

[Siggy89]

So I've been driving around for a few days now with no issue. Maybe it was just a one time thing? Or maybe its a fan clutch issue? Like once it warms up and the fan locks it is too much strain? I've ordered a new fan clutch cause even though mine will spin at idle it seems to run ALL THE TIME. So perhaps that will help.

 

[Narve]

Could it be as simple as the battery was disconnected and the idle needed to be relearned?

 

[92broncoboy]

I’d normally just say replace the IAC but with the 3g swap it seems to contradict that. I’m debating just buying a new 3G to install.

Sorry if this is a dumb question but why does the 3G swap contradict the IAC potentially being the culprit?

 

[jermil01]

Sorry if this is a dumb question but why does the 3G swap contradict the IAC potentially being the culprit?

The two aren't related, but I think he was saying that if he hadn't swapped the 3G, he would have thought the problem was related to the IAC..I'm not sure about that logic..

@Siggy89, do you have any codes?

 

[GetBent4x4]

Could be the green wire is broken that does to the cluster from the alt.

 

[Siggy89]

The two aren't related, but I think he was saying that if he hadn't swapped the 3G, he would have thought the problem was related to the IAC..I'm not sure about that logic..

@Siggy89, do you have any codes?

That's exactly what I was saying. No codes unfortunately. I'm hoping it was just a one time thing. I suppose it's possible the green wire connection might be loose, but I use a good butt splice and heat shrink. Then covered it with a plastic wire sheath and put some electrical tape around it. I'll just keep my fingers crossed for now.

 

[GetBent4x4]

should be soldered + shrink wrap.

 

[Siggy89]

should be soldered + shrink wrap.

If it becomes a problem again I'll take apart the wiring and look at it. I've also considered the distributor could be the issue. I have no idea if it's the original or if/when it was changed, but the truck is 31 years young, so could be worth it. At any rate I'll wait to see if the issue reoccurs, so far so good..

 

[Jetski247]

i think he was saying when you disconnect the eec from the battery, when you start it up, it will relearn how to run and shift.......slightly. as long as the battery is connected, the computer runs off the last memory of running. if you disconnect it, it has to start from scratch. although usually doesn't die but the eec controls the iac and if the eec is relearning engine load while in gear or such/things like that, it might die until it learns what it needs to be done in order to run properly.

usually doesnt take long and doesnt explain while driving it a while it continued to die when coming to a stop, perhaps the g3 is sending more voltage to sensors making them operate differently until the eec can adjust them??? bumped/cracked a vacuum line slightly? who knows.

 

[Siggy89]

i think he was saying when you disconnect the eec from the battery, when you start it up, it will relearn how to run and shift.......slightly. as long as the battery is connected, the computer runs off the last memory of running. if you disconnect it, it has to start from scratch. although usually doesn't die but the eec controls the iac and if the eec is relearning engine load while in gear or such/things like that, it might die until it learns what it needs to be done in order to run properly.

usually doesnt take long and doesnt explain while driving it a while it continued to die when coming to a stop, perhaps the g3 is sending more voltage to sensors making them operate differently until the eec can adjust them??? bumped/cracked a vacuum line slightly? who knows.

I appreciate the thoughts. It was just that one day. Weird. Once I got off the highway and came to a stoplight ti would die, but start right back up. Happened at all four lights on the way home. Hasn't happened since, so perhaps the EEC has learned its lesson? I'm still planning to change out the fan clutch just in case. It's the original. Got the part yesterday, but the rain is stopping me for today.

 

[Jetski247]

i don't think its the fan clutch, usually as it gets old it gets less locked up and free spins. when the engine is off, you can spin it by hand and see how it spins, if it spins freely and makes several revolutions its probably worn out but if it stops itselft like it still has resistance its on to the next test. after driving it and it warms up, turn the truck off and give the fan clutch another spin test now that its warm and see what it does. now that the fluid is warmed up it will react differently.

when mine doesnt cool as good, when cold it has resistance when you spin it and when its warm it free spins which i think that should be opposite.?? maybe im backwards?

 

[Siggy89]

I replaced the fan clutch anyway. Runs a bit better now, but no big change. That wasn’t the issue.

 

[Jetski247]

has it still been dieing at a stop?

 

[Siggy89]

has it still been dieing at a stop?

After driving for about an hour, couple days ago, same thing happened. Think I may need to replace the IAC.

 

[Jetski247]

yeah you can clean it first before you replace it. mine did that a couple times since ive owned it which has been over 20 years ago. for the most part these trucks are very dependable. im on the same a/c compressor, transmission, power steering, smog pump, hell my tensioner just went out.

very subtle small changes in intake vacuum can set things off a lot more than people think. i put an aftermarket tripple pillar with a vacuum, trans temp and air intake temp on mine to monitor those. although my baumanator has a tranny temp and the e40d came with the sensor in the trans but no where to read temps.

cracked vacuum lines are a big one, gunk and goop on stuff attached to the intake, those sort of things sets it off.