Please help. When I key up, my engine stalls!

[Tony LI]

I've had the radio installed for a few years and never a problem, now when I key up it stalls at a light or "bucks/sputters" while driving. I had work done to my truck (1999 Suburban 2wd) including new map sensor, coil, cap & rotor. I'm not quite sure if it started acting up before the work or not because I was having odd ignition problems before it, hence the work done. The radio (Cobra 200 with Wilson 5000 magmount) is directly wired to the battery with 8 gauge wire and fuses on both sides using HD quick-disconnects. I tried a different radio & antenna (Grant LT & Firestick magmount). SWR's are fine with both set-ups...about 1.2 Is it possible they forgot a grounding strap or maybe some replacement part isn't shielded properly?

This is driving me nuts as I've never had any problems before. Any help would be greatly appreciated.

 

[Robb]

RF may be getting into the ignition/control box.
Might be an RF leak from the coax/connector at the radio - due to proximity effect.
Run a ground wire directly to the control box to the ground - as a guess.

I've never had this problem, but I've heard only a few with this particular/similar complaint.

 

[Radio Tech]

RF may be getting to the ignition/control box.
Might be an RF leak from the coax/connector at the radio - due to proximity effect.
Run a ground wire directly to the control box to the ground - as a guess.
I've never had this problem, but I've heard only a few with this particular/similar complaint.

Sounds like they left a ground loose or your ground itself if faulty.
I never run the ground wire from any circuit all the way back up to the battery. Keep the ground as short as possible.

I had a Nissan pick up before that lost it's ground on the computer. A standard 2 meter rig would shut the truck down on high poweer. The rf was getting into the computer .

 

[Tony LI]

Thanks a bunch guys....

....I'll check out what you said when I get a warmer day. It's 29 degrees out today (NY)....brrr.
This thing is driving me nuts....miss having my radio and I'm taking a road trip down to GA in Jan. Thanks again.

Respectfully,
Tony.

 

[Robb]

The control box may need replacing; but I'd be sure first - they are a bit pricey.

 

[jesse10x]

how much power are you running.no worry fcc is not watching.

 

[Tony LI]

Stock Cobra 200 & Uniden Grant XL....

More so with 200 on high power, but does it on low & with the Grant.

 

[9C1Driver]

As stated, he's running a Cobra 200. So no amplifier.

 

[jessejamesdallas]

I'm having the same problems with my 97 Suburban....Only I am trying to run a Davemade 16 pill...I have 3-220 amp alternators, and have added RF Snap-on Ferrite chokes to the wiring harnesses going into the computer and still when I start talking on the radio with the 16 pill, the thing tries to die, sputters, and the Tachometer jumps all over the place! I even added a ground strap off the trasmission to the frame but no luck.

I can run tthe driver amp by its self just fine...But kick on the 16 pill aand all heck breaks loose.

On the Bird meters, they show the 16 pill to be doing between 1600 and 1800w's, with less than 20w reflect.

Volts are holding around 13v's, and thats with just the starting battery up front, and two more in the back.

 

[jessejamesdallas]

Tried adding more RF grounds off the Amp's and back batterys this weekend, but No luck...I'm thinking most of the RF problem is in the Transmission, because I can disconnect the back batterys from the alternators, and just run the 16 pill off two batterys and as long as I'm in PARK, I can talk! (probably not for very long tho...)

But drop down in DRIVE, and everything go's to hell again...:headbang

 

[packrat]

Did the shop use cheap aftermarket replacement parts? Have your charging system and battery checked by a PROFESSIONAL. Not a parts changer.

LMK.

 

[jessejamesdallas]

Did the shop use cheap aftermarket replacement parts? Have your charging system and battery checked by a PROFESSIONAL. Not a parts changer.

LMK.

I checked my alternators myself with my volt meters...no need to take them to the local Autozone when I can see myself that the volts are dropping under a load...The alternators are fairly new and custom built by Iraggi Alternator's in Nashville. He has been building alternators for the Car Stereo crowd for years...They are AD 244 GM Delcos

 

[packrat]

Yes, you can test them, but not well. You need a good tech to tell you what is going on. If the alts draw too much current on keydown, it is like putting the brakes on the engine and it will stall. Remember, there is not a whole lot of hp available at idle. Have the charging system checked, maybe by the builder of the alternators. If the battery(s)are subpar, they can cause the same problems. There are ways around it, but the best answer is to find and fix the problem correctly.

 

[dudmuck]

The best way to know if its an RF problem or a DC current draw problem is to key the amp (full power) into dummy load instead of antenna.
You need to have the full DC load without any RF radiation.
If you still have problem with non-radiating dummyload, then you need to look at alternator.

 

[jessejamesdallas]

Yes, you can test them, but not well. You need a good tech to tell you what is going on. If the alts draw too much current on keydown, it is like putting the brakes on the engine and it will stall. Remember, there is not a whole lot of hp available at idle. Have the charging system checked, maybe by the builder of the alternators. If the battery(s)are subpar, they can cause the same problems. There are ways around it, but the best answer is to find and fix the problem correctly.

Right...OK. I had "3" 300 amp alternators, which in a perfect world would give me 900 amps to draw from...The 16 pill only draws a Max of 320 amps.

The driver another 110...the truck, maybe 60 or so. So give or take I would need a alternator that is rated at 490 to 500 amps, "or" several alternators...So by that, I should have about 400 amps to spare! (In a perfect world)

Now, If those alternators are dropping volts with around a 500 amp draw, then either one or two of them are bad...OR, the RPM of the motor is not turning fast enough to get everything out of the alternators...

So...If I rev the motor up to 2500 RPM, then the volts "Would Not Drop"...Rev the motor to 1500 RPM, then you see the drop. At 500 RPM, Key the amplifiers up and before you could say AUdio, the motor would die and the volt meter would go from 14v to about 10v.

Next I get out the Clamp DC Amp meter to check and see just what the 3 alternators are putting out under a load at a RPM of around 1000...The 3 300 amp alternators showed little over 100 amp's being produced while I was keying the 16 pill, right before the motor started cutting out. (I needed at least a couple of hundred amps out minimum)

So this tells me the 300 amp alternators don't have a very high amp-out at lower RPM speeds. They would probably work just fine if you can keep the motor rev-ed up over 2500 RPM all the time. But at highway speeds, your RPM after you get your speed up and in high gear, is usually closer to just 1000 RPM.

Volt meter at the battery, and amplifiers both showed volts dropping from 14 to 10 on the 300 amp alternators under just a 500 amp load.

NOW...I replace the alternators with 3 220 amp alternators which have a higher amp-out at lower RPM's, and guess what? NO MORE VOLTAGE DROP...Even at idle which is 500 RPM, the voltage keying the 16 pill only drops from 13.65v to 12.85v...Kick up the RPM to 1000, and the drop was almost non excistant....13.65 dropping to 13.35v...

So here is the problem...High AMP alternators like the Delco AD244's have lousy amp's out under 2500 RPM. when they are wound for 300amp...

To fix the problem, you have to go with something around 200 amps, and just have more alternators to get where you need to be for what your draw demand is.

It's not rocket science...Higher the rating is on the alternator, the lower the idle amps are going to be (or lower RPM amps)

Like I said, by switching to the 220 amp alterantors, I fixed the voltage drop...Only problem I have now is RFI issues which has nothing to do with the alternators.