1995 Jeep Wrangler Vehicle Loses acceleration on inclines.

Tiny
EMBRYODAD
  • MEMBER
  • 1995 JEEP WRANGLER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 157,000 MILES
Vehicle ran fine up until recently. I did some checks on it, but daughters BF did the physical work after conferring with me.
Changed fuel filter / checked rail pressure = 20-37psi
variably. Checked fuel pump sock. Found ok / checked and found fuel spray (leak) from supply 90 ° fitting on top flange of pump, and unbelievably shooting back into tank from a dime size hole in the pump mounting flange. Wierd situation. OK
Changed out the pump (new). Fuel pressure 43#psi.
NG. Found vacuum hose from manifold intake broken / replaced / re: Fuel press=33 psi. Good
Run the car to fill up gas. Now engine cranks, won't fire. / Found bad cam position sensor in the distr. / Replaced / started right up. Loses power on acceleration / shifts up / down ok. Reset TV cable adjustment /ok / still loss of power. Engine cold starts on 1 revolution of crank, and idles perfect. No smoke / revs. Up ok in neutral.

DD's BF. Comes over today, and we were talking. He said his buddy thinks the engine needs a rebuild, and he would do it free cause he's done them before.
THEN. BF tells me he needed to borrow the battery for his pickup, and he pulled it out of the jeep, and installed it but found the battery dead. (0) volts. Hmmm? How could the jeep start?

No battery in the jeep (and I almost fell off the porch hearing this). He reached in and turned the ign switch.(Key). And The Jeep STARTED*****
Right then and there, I knew there was something not right. Come to find out. The big amplifier she has in the entire back of the jeep. Was blowing the alternators, and BF replaced two of them within a month. Another Buddy.(A car radio installer) said the way the amp was hooked up, it would spike the alternator and could cause rectifier problems on the alternator. He installed like two 2,000 mfd. Capacitors in parallel with the power circuit supplying the amplifier. So the Jeep was starting on the energy (Weird) stored in the capacitors!/? I don't know, but I would suppose a bleed resistor should be put across the terminals on the Capacitors so they would discharge after power is removed.(Amp shut off)?
Still, the alternator puts out 14.6 volts while running, and with all the other power functions, I would think that there is not enough reserve voltage, or shall I say high enough voltage to supply the ecm and the fuel injectors. I tested firstly the output of the TPS and that was ok. Also I did a resistance (ohms) test with a simpson 260 analog ohmmeter to watch for poor wiper contact on the TPS, and I found it to function perfectly as described.
I didn't do a output (amp) test on the alternator, and that can be done simply. I have a little experience with electricity and voltage, being a retired HVACR mechanic 45 years.
Any Help would surely be appreciated. Maybe a diode inline feeding the voltage to the amplifier so there would be no noise (back emf) from the capacitors.
I mean It's scary watching the engine run, and on the ground there sits the battery, Not Connected to the vehicle.
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Friday, April 16th, 2010 AT 12:59 AM

3 Replies

Tiny
MERLIN2021
  • EXPERT
What I can tell you is the PCM isnt getting it's required power to operate correctly, and if you continue to run it without a battery, you will need a new pcm. Is this amp grounded properly? I would consider a diode in the line to insure the current travels one way! Then reinstall a NEW battery and make sure the ground to the block is a good one! PCM may not be performing up to peak.
Try reading the codes just for kicks. Turn the key from off to on three times, on the fourth one leave it in the on position, count the flashes.22 would flash as 2 blinks, then a short puase, then 2 more blinks. If several codes are stored, the pause is longer between codes, code 55 will be the last code. Do this and post all codes found. My next question is how is the amp powered? My understanding about amps is it's normally attached to the positive battery terminal, and fused at that connection.
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Friday, April 16th, 2010 AT 8:55 AM
Tiny
EMBRYODAD
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Merlin 2021. Thanks for the great answer and help here!
#1. Charged battery to full overnight
#2. Installed battery and standing volts DC = 12.5V
#3. Started engine. (One crank revolution to start) and let engine idle. Just to double check. Had 31 psi fuel press. At the rail which was good.
#4. Now I got a trouble check Eng Light.
#5. I checked the code flash ***----*** = 33
then after a pause code flash*****----***** =55
#6. Drove the vehicle a short distance. And still a noticable loss of power / like holding back from moving out as I pressed further on the accelerator.
It appears to point to Generator Field Switching not working, and or the worst (I cry!) A bad pcm module, which may have been punished after installing the power amplifier.

One Note* though! In the fall when this all happened and with a new fuel pump / filter / fixing the cracked vacuum hose to the fuel press. Regulator, the vehicle drove perfectly for around 4 days with no incident of power loss. Then again. DD said to me, "Dad, the jeep has no power again!".
(((Head down in disgust, and biting of tongue, and coming out with a choice explitive&**%&*!)))

Again. Thanks for the recommending of a diode to allow one way and no backfeed on the capacitors on the amplifier install. First though I will disconnect the amp. And see if I can get the jeep to run without the power loss. Also the amp. Is fed direct from battery power and is fused with a inline fuse!

BTW.I do have reference to a jeep manual and etc. With Alldata website. But that sometimes runs one in circles. *<* L@@KING !
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Friday, April 16th, 2010 AT 12:32 PM
Tiny
MERLIN2021
  • EXPERT
33=a/c cutout relay or relay circuit, this could be the power loss problem, if the a/c clutch isnt de energized at WOT(wide open throttle, it will rob engine power, that's why it's there in the first place, 55 is just the end of codes indication. Try disconnecting the a/c compressor plug and test drive it. And cripple the amp while your at it.
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Friday, April 16th, 2010 AT 5:16 PM

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