'88 2.9 won't Idle after stereo install

[DisturbedMXer8]

So, I just put in a brand new Kenwood headunit in my truck today. As soon as I finished everything and took it on a test drive, I noticed it was idling unusually low. The further and further I drove, the lower it got, until it would start to stumble, recover, stumble and recover, then stall. It would stall every other light. Now, my battery was already going bad, so by the time I got home the truck wouldn't even crank. So, I went ahead and spent 100 bucks on a new battery that I can't return. It starts wonderfully now, but I can tell it's still idling low. So, my question for you guys is, WHAT THE F***?! This is just a 99$ unit, nothing special, so is it possible that it's pulling too much power for my truck to handle? Any thoughts guys? After the $100 unit and $100 battery, I don't have the money to take this thing in. I don't have any other aftermarket accessories other than the new deck, and it does this even in neutral with all accessories off. If it helps, this is the deck: http://www.crutchfield.com/p_113KDC248U/Kenwood-KDC-248U.html?tp=5684

 

[Duane867]

Re check the wiring to the head unit and have your alternator tested.

 

[DisturbedMXer8]

Wiring seems fine. All it has is Battery positive, negative, ignition positive, and the speaker positive and negatives. All of them work perfectly fine. And last time I had my charging system checked out, it was working ok. What I basically need to know is if it is possible for this headunit to pull too much power for my factory alternator to handle. It seems very unlikely to me, but I'm going to check again tomorrow when I have more light.

 

[Heavyfire14]

ha no the head unit wouldnt do that, sounds like its either your altenator or a dirty maf sensor.

 

[Ozwynn]

Time to upgrade to a 3g alt.

 

[killj0y]

Keyword last time...as in it's time to check it again lol

 

[cody93]

sounds like your alt is not working right, 2 things make me think so
1- slowly dying then not cranking cause of no power, cause- alt not recharging battery
2- engine idleing low, not only caused by lack of power, a bad alt can sometimes sieze up partialy, usually caused by an internal short.. imagine turning over a generator by hand with no load, then turning it by hand with a big electrical load on it.

go have your alternator tested, autozone can test them for free. i heard somewhere that ranger factory alts were only 40 amps, but im not for sure.

if your alt passes, then you have electrical/wiring issues

 

[DisturbedMXer8]

Well, here's an update: Took out the new stereo (and wiring), and my truck still won't idle. It will run if I keep my foot on the gas, but as soon as I let up, it stalls. It almost seems like my IAC went out for some reason, but it's almost brand new. It still cranks and fires up just fine, it just stalls immediately. I'm getting fuel, getting spark, getting air... just not enough of one of those things at idle, I guess.

Oh, and it doesn't have a MAF.

 

[cody93]

get a voltage meter and tell me how many volts you have when the vehicle is running, and when its off.

 

[Ozwynn]

its the alternator ......... get it tested and replace it with a 95 or a 130 amp 3g from a taurus. you can get them from a wrecking yard for $10

 

[Vanner1993]

Yeah definately seems like alternator. Had a mustang for an exhaust and did the same exact thing.

 

[DisturbedMXer8]

So even though the headunit is out now, the alternator will still cause it to stall? I just moved my truck a few minutes ago, and it's even idling low while it's cold. It's usually around 1500 when I first fire it up, but it barely manages 900...

Like I said, it now has a brand new battery, and cranks and fires up perfect. It just wont stay running.

You want voltages at the battery? Like I said, once it's warm, I have to give it gas to keep it running, so I can only try to keep it at 800 rpm.

 

[Ozwynn]

just replace the damn alternator with the taurus upgrade 3g 95 or 130 amp. you can swap the pulley on the taurus alt with the one you have and its not that difficult to figure out how to mount. you can get it with a 30 day free replacement for $10-15 at most wrecking yards. do a search for ford fuel injection.com to get the wiring instructions. that will be cheaper than buying a digital multi-meter and I would almost stake my life on that being your problem. that stock 2.9 alt is a 38 amp unit and dies a premature death in an EFI environment.... that IS your problem.

 

[cody93]

900 is not that low, i had an 88 with a 2.9 that seemed to like to idle at 500-750 rpms no matter what, but the headlights would dim unless reved up, kinda reminds me of the dynamos used in old cars..

 

[Ozwynn]

http://fordfuelinjection.com/?p=75


there, found it for you



http://fordfuelinjection.com/

^^^^^ thats just a plain good resource to have if you own a fuel injected ford.