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Discussion Starter #1
I have been having a power loss issue with my car. It started out on the freeway as a slight stutter while the throttle was constant, and now it is more erratic. If I start the car up now, it runs rough and the "power loss" light is on. When I push the throttle down halfway the rpms drop quickly and then with the throttle constant it revs up and down around the 1800-2800 range for a few seconds. After this happens and with the throttle still constant, the "power loss" light goes out and the rpms go up like they should. If I let off the throttle the cycle repeats itself. I have a 20sec video of this but can't figure out how to attach it to this post.

No luck pulling codes via the power loss light, and I don't have an obd1 available to pull codes that way either. I put a known good map sensor in place of the old one with no luck. The car is still running with the same issues. I also disconnected the battery and reconnected it to let the computer "learn" the new sensor. Don't know if that was needed but figured it couldn't hurt. I have a multimeter sitting in my toolbox but I'm not sure where to start.

I have gotten the suggestion to check my grounds, but is there any one particular I should be looking at, I mean there has to be a ton of grounds right? Bear with me folks, I'm learning as I go.
 

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I'm curious as to why you can't pull the codes. Is the bulb burned out or is there a computer issue?
As a quick thought to check, I bought a car with a very similar issue that turned out to be a loose coil wire. The power loss light would flash whenever the baro read happened.
It may also be a vacuum leak someplace that is getting worse.
But nobody can really help without a code or two, so that is what needs to be figured out first.

Law
 

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Discussion Starter #3
The power loss light is not burned out. It comes on when I start the car and it is running rough. After I hit the throttle the rpms come down low then fluctuate while I am holding the pedal steady. The light then goes out and the car revs to where it should have initially. Once I remove pressure from the throttle the light comes back on and the cars runs rough again. If I hit the gas again the cycle repeats itself. Being able to read a code would be a plus. I have been patiently awating a friend of mine for about a week now to have enough free time to plug in his OBD I computer. Any ideas I can check until he comes through for me?
 

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I had an 85 GLH-T that had issues as well at one time.
Check the wiring behind battery that goes to the power module.Mine had the coating comming off because of the battery acid ate through it causing shorts simular to what you described.
 

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All of this sounds like a vacuum leak issue and you are losing vacuum to the Map Sensor.
Verify there are no broken/cracked/split/collapsed/disconnected vacuum lines.

If you do not find any then something may have happened to create a low vacuum condition.(timing belt jumped???)

1)What is engine vacuum reading at a manifold source?
2)What is engine vacuum reading at the Map Sensor?
(Map is located on the LM behind the R/S kick panel, the vacuum line runs thru the firewall to the baro solenoid)

VACUUM GAUGE
Super price on KD Tools 2521 at ToolTopia.com

Buy Actron Vacuum and Pressure Test Kit CP7803 at Advance Auto Parts

Search: vacuum tester | Vacuum Pressure Tester | AutoZone.com

 

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Discussion Starter #6
I'll check the wiring by the power module but the battery has been relocated to the trunk. Looks like I will need to pick up a vacuum pressure tester. A local shop used a smoke machine about 4 months ago to look for any leaks and many of the vacuum lines were replaces. I have yet to find a shop that really knows these cars so it is probably in my best interest to get my hands dirty. I'll see what my local parts store has in the way of a vacuum tester tonight. Thanks for the tip. Just FYI, my map sensor is positioned on the RF strut tower inside the engine bay just above the baro solenoid.
 

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Discussion Starter #7
I think I may have found the problem. If I plug the inlet on the baro solenoid the power loss light goes out and the car runs fine. I assume my baro is not closing when it should. 2 questions. Is there anything wrong witcapping off that inlet until I can replace the solenoid, and where can I find a new baro solenoid?
 

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Are you sure the vacuum lines are connected to the proper ports on the Baro Solenoid?

There are 3 ports...
Inlet
Outlet
Vent

The Vent remains uncapped.
 

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Discussion Starter #9
The vacuum lines have been the same the entire time I have owned the car, and I just now started having issues with it.

I thought I had the problem fixed 2 nights ago. Read vacuum to the baro solenoid (17-18psi), then vacuum to the map sensor (10-11 psi). The line from the baro to atmosphere was remaining open. I plugged it with my finger, the "power loss" light went out, revs went to normal, and the car ran great. I'm getting voltage to the baro solenoid with the key on. I pulled the baro solenoid out, hit it with 12 volts and heard the solenoid activate and close the valve.

I then took the solenoid apart and cleaned it out thinking that maybe it was sticking. Once reinstalled the car ran great. I drove it about 30 miles without a problem. On my way home from work the rpms began stuttering again and it sounded like the car was backfiring all at steady throttle. This went away a mile from home and the car ran great. I checked the solenoid before I shut the car off and the vent to atmosphere on the baro solenoid is still closed. Not sure when it is supposed to be open or closed or for how long. It may be stuck closed now, I'm not sure.

I tried to take the car to the store an hour or so later and the car kept dying in my driveway. I almost couldn't get it started again to pull it back up the driveway. That's where I'm at right now. Any suggestions?
 

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Discussion Starter #10
Here's the latest. I got the kids to sleep so snuck outside to start up the omni which would barely start before. It started right up. Of course it did right? I disconnected the battery to reset the computer, started it up again and let it run for a few minutes. No issues at all now. The vent for the baro solenoid still remains closed. If someone could tell me when that thing is supposed to open, it would be a big help. I didn't get a chance to drive it due to my kids being asleep, but maybe I can make a quick run in the morning.
 

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Could not tell you exactly when the vent is open but it is not at idle.
When the controller updates Baro info it is during a "no load cruise" condition.
It will block vacuum to the Map and vent what is in the line from Baro to Map so it is only seeing atmospheric pressure then it will return to normal, it happens quickly.



 
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