82 SC is running rough, need help

[jasonlee]

Hello,
I have an issue with the SC. This morning, it fired up fine drove without issue, and ran as it should. I made a brief stop, came back out and started her up again. No issue, a couple of minutes later at a light, my idle dropped and it popped sputtered and had no power, limped it home the 6 blocks. Let it sit for a about 5 minutes and fired right up again. Idle was back to normal. Didn't risk driving it again. I know its difficult to diagnose, but anything come to mind? I immediately thought WUR, because it happened after it warmed up. Any insight my fellow Pelicans can provide would be greatly appreciated.

Thanks,

[Jdub]

Did you fill up on gas just prior? Run through a rain puddle? Any actions just prior to this episode?

OTOH, it may be "heat" related, esp. if the car was just moderately warmed up and thus in the range of switching from cold to hot running (bimetallic springs, etc. that rely on heat via engine block mating or direct wire current).

[boyt911sc]

Jason,

What brand of CDI is in the car? Bosch, MSD, or Permatune? Keep us posted.

Tony

[jasonlee]

It has the original Bosch CDI unit.

[jasonlee]

been doing a search, perhaps its the relay under the passenger seat. I am going to check for vacuum leaks and the relay/fuses, and of course I will listen for the whine of the CDI. I will report back. if anyone has other suggestions I am open to them

[Walt Fricke]

Check the fuse for the interior lights in the box up front. That fuse also supplies power to the mini-brain under the passenger seat, and its associated frequency valve unit and the relay associated with them.

The quickest test to see if the frequency valve system is working at all or not (assuming fuse is OK) is to start the engine, and then pull the electrical connecter to the FV. If the control system is working at all, the engine will start to run much worse at idle with the plug pulled.

I just went through this, taking way more time than I should have to find the burned out fuse.
Found the cause in some interior wiring, too.

I think CDIs either work or don't, not much in between? Fuel pumps much the same. And the complicated CIS control system is reasonably robust, and the number of things which can go quite wrong all at once is a bit limited. But no power to the electronic part of the CIS makes for hard starting and a not so good idle.

[jasonlee]

So the electrical connector to the FV is under the passenger seat? Am I correct in that assumption. I will certainly start with the fuse, hoping for a simple fix.

[Bob Kontak]

Originally Posted by jasonlee

So the electrical connector to the FV is under the passenger seat? Am I correct in that assumption. I will certainly start with the fuse, hoping for a simple fix.

The FV connection is on the back of the engine.

I believe you can just pull the 'OXY" fuse in the front trunk to effectively sever the connection to the FV.

If it replicates your symptoms you then can go to work. May just be your relay.

Here is a vid I made of pulling the O2 relay and the result. Noises at end are backfires.

https://www.youtube.com/watch?v=5tdpCYyvqSc

Note it is called an O2 relay but the O2 sensor generates it's own power. Go figure.

[boyt911sc]

Originally Posted by jasonlee

So the electrical connector to the FV is under the passenger seat? Am I correct in that assumption. I will certainly start with the fuse, hoping for a simple fix.

Jason,

The FV is located just behind the throttle body. See attached picture below. Picture taken from MCA's photo library.



Black------for FV
Blue-------for CSV
Green-----for AF switch

There is a convenient way to disable the FV. The FV relay is located under the passenger side beside the ECU. Pull out the FV relay and observe any change in idle performance with the engine completely warmed up. The interior dome lights, clock, glove compartment light should have power from fuse #18.
Keep us posted.

Tony

[Jim Dunham]

For what ever it's worth, I had a similar issue and it turned out to be rust in the fuel tank. Turn it off and let it sit and the rust would fall in the tank. Start it up and it would collect on the pickup and motor would start running poorly after a mile down the road.

[Nick Triesch]

Pop in some techron! Easy stuff first. I have had cars sputter on trips and stopped for some techron and problem solved!!!

[jasonlee]

So updates, pulled the relay under the seat, and the idle got bad, similar to what I am experiencing. So the next question, what does that mean. Th FV is OK, or the relay is ok, and no need to replace? Before I did that though, I notice that the while idling, I removed the oil filler cap, no drop in idle. Not sure if it was because it just started up, but in the past it would drop significantly. Next steps?

[boyt911sc]

Originally Posted by jasonlee

So updates, pulled the relay under the seat, and the idle got bad, similar to what I am experiencing. So the next question, what does that mean. Th FV is OK, or the relay is ok, and no need to replace? Before I did that though, I notice that the while idling, I removed the oil filler cap, no drop in idle. Not sure if it was because it just started up, but in the past it would drop significantly. Next steps?

Jason,

Repeat the oil cap air leak test by doing it when the engine is completely warmed up. After your next drive and has reached the engine operating temperature (fully warmed up), check it again. Note your idle speed and compare it after the removal of the oil cap. Keep us posted.

Tony

[Bob Kontak]

Originally Posted by jasonlee

So updates, pulled the relay under the seat, and the idle got bad, similar to what I am experiencing.

Similar is only similar but may not be the issue.

If you are sucking air, listen to Tony. No drop in idle at all indicates more than a wimpy leak.

Good job on the work.

[jasonlee]

Ok so I have some updates.

1) i pulled the relay under the passenger seat, rough idle and all the symptoms present when un plugged, same when fuse pulled.

2) took the car for a drive this morning, all normal. Stopped, removed the oil filler cap, idle dropped significantly. all good there.

3) continued to drive for another 5 to 10 minutes, symptoms returned, idle drops, gets rough, sputters backfires, and bucks if I try and driver over 2000rpm

4) cap and rotor are new, and pop off valve is all good. No immediately visible vacuum leaks.

When I turned the car off, smelled fuel, like it was running rich. Hopefully someone can point me to the right point so i can diagnose this. All your help is appreciated.

Thanks,
Jason

[boyt911sc]

Originally Posted by jasonlee

Ok so I have some updates.

1) i pulled the relay under the passenger seat, rough idle and all the symptoms present when un plugged, same when fuse pulled.

2) took the car for a drive this morning, all normal. Stopped, removed the oil filler cap, idle dropped significantly. all good there.

3) continued to drive for another 5 to 10 minutes, symptoms returned, idle drops, gets rough, sputters backfires, and bucks if I try and driver over 2000rpm

4) cap and rotor are new, and pop off valve is all good. No immediately visible vacuum leaks.

When I turned the car off, smelled fuel, like it was running rich. Hopefully someone can point me to the right point so i can diagnose this. All your help is appreciated.

Thanks,
Jason

Jason,

How long was the car running when you did test #2? Give us numbers and conditions. For example:
1). Drove the car for 20 mins or longer, stopped and let the engine idle at X rpm.
2). Removed the oil cap and idle speed dropped to Y rpm.
3). Whether there is a change or not, we need numbers.

I have a suspicion that the engine was still cold when you removed the oil cap (?). When did it start to stumble? Give us a reference time frame of how long it has been since you started the engine cold.

Do you know the cold control fuel pressure from cold start to the time the engine starts to stumble? Keep us posted.

Tony

[boyt911sc]

Jason,

Post the WUR # on the engine.

Measure the resistance (Ohms) of the WUR heater at cold condition and post the data. Thanks.

Tony

[BOJAN]

Jason,

I had a very similar situation last year with my SC. After changing ,sparks,fuel filter,rotor cap,testing a fv and along with some other stuff ...i ended taking the car in for a WUR adjustment to a local mechanic (since i do not have the gauges). The car ran much better after that.

[jasonlee]

I will have to get the WUR number.

When I drove the car, it was about 20 minutes, idle dropped from idle at 900 rpm, and dropped to about 650-700 rpm. Oil temp gage was just below the middle mark. Then continued to drive for additional 5-10 minutes, so in total it was about 30 minutes when it started to stumble.

Where and how do I measure the resistance of the WUR?
I am heading away on business for 2 weeks tmrw. I have a sneaking suspicion it has something to do with the WUR, but hoping its just an adjustment, and not a replacement.

[boyt911sc]

Originally Posted by jasonlee

I will have to get the WUR number.

When I drove the car, it was about 20 minutes, idle dropped from idle at 900 rpm, and dropped to about 650-700 rpm. Oil temp gage was just below the middle mark. Then continued to drive for additional 5-10 minutes, so in total it was about 30 minutes when it started to stumble.

Where and how do I measure the resistance of the WUR?
I am heading away on business for 2 weeks tmrw. I have a sneaking suspicion it has something to do with the WUR, but hoping its just an adjustment, and not a replacement.

Jasonlee,

Do you have a USA/Can model car? If yes, then you should have a WUR-090 on it. RoW cars would have a different WUR. Remove the electrical plug from the WUR and use a multi-tester (VOM) and set at resistance (Ohms) Omega sign on the dial. There are two (2) terminals at the WUR and place the probe tips. The car should not be running when you do the resistance measurement. Or you'll blow the fuse of the multi-tester. Keep us posted.

Tony