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'02 Vulcan running rough. 3 codes

5K views 37 replies 8 participants last post by  ohiohouston 
#1 ·
My 02 Vulcan is running really rough. Just bought it for $200. It's been sitting for a year because it needed a water pump. Got the cooling system working great and replaced plugs and wires since they were old and wore out. Now to address the poor idle and lurching while driving. I am getting codes P1131 p0401 and P0136. I was idling with 15-16 inches of vacuum and 35-38psi fuel pressure so I replaced the egr and pcv valves because they both leaked during a smoke test. Now I'm at 20-21 inches vacuum and fuel pressure is now steady over 40psi. But I'm still running really rough and get a pulsing lurch while driving 20-40mph. I also checked my o2 sensor voltages and both bank 1 sensors are steady between .02 and .04 volts. waaaay low. Any ideas? I know I don't have any more vacuum leaks.
 
#3 ·
ForScan does do more for the Taurus. This is a guide that may help you out. http://easyautodiagnostics.com/ford/4.6L-5.4L/how-to-test-the-egr-system-1

I would say check the vacuum lines for the EGR. My gut instinct is a something is wrong with one of these lines so look at all the vacuum lines that run to the intake, the vacuum solenoid lines to the EGR and Fuel Rail, and also the 2 hoses going from the EGR Sensor to the EGR tube. Those 2 tubes right there at the end are VERY good at screwing things up.

And check the condition of that intake around the EGR valve with a mirror. And consider cleaning the throttle body while you are at it. Vulcans love to get carbon and crud there thanks to the PVC design. I think there is a how to on this on the forums.

It could be the EGR solenoid which controls air flow. Seeing if it has suction may help. My educated guess is the vacuum solenoid. This could also be checked by applying vacuum and opening and closing the valve. The link I provided will be much more helpful than what I said.

While the 02 sensors are throwing a code, it's the EGR code makes me want to look in that direction. So cover your bases and inspect the wiring going to the o2 sensors.

Hopefully I helped you out to a degree. I'm a bit tired and making what I am thinking make sense is a little bit of a challenge right now.
 
#5 ·
Today things were much worse. I was misfiring on cylinders 456 all day so I did those tests and my DPFE didn't have any output at all. So I went ahead and replaced the DPFE and solenoid with new BWD parts. Now my whole egr system is new. Disconnected battery and kam fuse and applied a load for a couple minutes and started it up. Now all codes are gone besides a pending p1131, and I'm still running rough
 
#6 ·
Have you gotten all the year old gas out of it? That will make it run rough.
 
#7 ·
Are the new parts functioning correctly? If you have ran a tank or two of gas than I also recommend replacing the fuel filter as ethanol attracts water. Which then fouls up the fuel filter. Did you unplug the EVAP line to the upper intake and forget to plug it back in? The Fuel injectors should be checked as well. I would also measure fuel pressure at the rail. Some Gen 4 Vulcans can only be checked using OBD2. ForScan is perfect for this. Next up after the fuel system is testing for Vaccume Leaks.

If the wiring to the sensor is good, the sensor could be going bad.
 
#8 ·
I've ran 2 tanks of Techron through it and replaced the filter. Today I have p0171, p0305, p0306, p0316. Tested all the new parts and they are good. Fuel pressure is good and stays up when the car is turned off. Been through all the vacuum lines multiple times. I just don't get it. Should I try changing the coil?
 
#10 ·
One of my thoughts as well. I would be making sure I had good spark, good compression and good fuel to those cylinders.
 
#13 ·
Any crack in the coil will cause a misfire, just a matter of when. I had a very slight misfire feel in my '03. I spritzed the coil with a fine mist from a spray bottle, car idling and it went crazy. Replaced the coil, did the same and no issues. Old coil had 3 small cracks. Of course a coil could be bad with no cracks, but cracks are a fail in the present or future.

-chart-
 
#15 ·
If you Scanner shows Mode 06, then I'm sure it show Fuel Trims. I like this guy's videos showing how to evaluate methodically what's happening in conjunction with the other sensor input so you don't just start changing parts.

It is a multi-part video and he definitely takes his time with explanations.


 
#16 · (Edited)
If you Scanner shows Mode 06, then I'm sure it show Fuel Trims. I like this guy's videos showing how to evaluate methodically what's happening in conjunction with the other sensor input so you don't just start changing parts.

It is a multi-part video and he definitely takes his time with explanations.


https://www.youtube.com/watch?v=5WnM_NsOtd8
Mode 6 does NOT show fuel trims. That is a function of OBD 2 Mode 5. OBD 2 doesn't really get a lot of fun until you get into factory levels of Mode 8. It's pretty killer to do some of that stuff. The problem when you get into oxygen sensor monitoring, is that it can be difficult to analyze that as a rookie. It's best to handle maintenance items that were neglected first and then move into the advanced stuff. At this point he's resolved the 1st issue with the EGR. And has found a 2nd issue involving misfires. I bet this issue is the result of neglected maintenance items.

Okay, my next step will be to replace the coil pack. It has a couple very fine cracks, and its original with 179k miles.
I have a funny feeling the plugs and wires are original Motorcraft. Might as well do them too while you are at it.

Since this is a Vulcan and removing the upper intake makes it a lot easier to do plugs, I recommend doing that, and replacing the plenums while you are in there.

At least you have moved away from the EGR codes.
 
#19 ·
Today when my wife was visiting me at work the car didn't want to turn over. I held the key and it slowly started turning over and eventually got spinning fast enough to start. Coil will be in tonight. But now I'm concerned about this issue because my wife uses the car to transport the baby
 
#24 ·
It's worth the shot at this point. I would hit upstream and downstream both. Also check your wiring to the coil. I've made that mistake a couple of times lol. I've purchased bad wires before. What brand did you use?

For your slow crank, I would check the starter. If its covered in oil, there is your problem on the slow start. It's probably had a ton of oil leaking on it for a year. If you want to redo the battery cables and are time constrained like me, Rockauto sells the Motorcraft battery cables as well. Ones listed as a ground strap. I bought them because I had a similar problem, they looked frail, and I had just had the stitches taken out of my hand a few days before from a hand surgery, and had absolutely zero business making a cable. It helped until I replaced the starter. The grounds are VERY important on the Vulcan.

If the oxygen sensor don't help, than I hate to say it but you may have a compression issue. Probably a burnt valve. You'd need to do a compression test to verify.
 
#25 ·
I have denso plug wires. And I plan on getting new battery cables. Mine look like they have been trimmed a time or 2. Almost not long enough. Replacing the bank 1 upstream sensor tonight. Been pb blasting for a couple days since I figured it would come to this. I'll post back with results.
 
#27 ·
You have too much air on one side of the engine. The other one is allegedly "Normal". What happens on bank 1 can effect bank 2. You could also have bad 02 sensors on bank 1. It just doesn't know that their bad.

I would start checking for vacuum leaks. Start with a can of carb cleaner and spraying it around the intake manifolds, and the vacuum hoses. At least you will have that base covered.

Next I would replace the sensor if I had it. OR I would go get a cylinder compression test. I think you find your problem in one of these areas.

I'd also try testing the resistance of the fuel injectors.

Is there any new codes pending?
 
#28 ·
Alright. So I replaced the bank 1 o2 sensor and replaced the plenum gaskets including the iac and throttle body gaskets. I also cleaned all 6 injectors while I had it apart. Now it's a bit better. My bank 1 o2 sensor is switching properly and the voltage stays pretty close to bank 2. Perfect idle before it warms up. When it's cold I have way more snappy throttle and a smooooth idle. Warm is still a little rough, and power is lacking. Now I only have code P0171. Fuel pressure, spark, injectors, o2 sensors all good. Compression test next, if that's good it HAS to be lower manifold gasket right? I can feel the end is near!
 
#30 ·
In theory, yes. Comp test on both banks rules out the really hard stuff. On the LIM the Fel Pro gaskets require to be glued to the heads in order to stay put. They like to work their way up otherwise. The Victor Reinz gaskets however are like the Ford ones and do not require it.

I think you are VERY close. This should help with that code. Ford P0171 & P0174 Lean Codes

I would take ForScan and check the fuel rail pressure. As well as check the Fuel Injector timing. That ones tricky and I have not done it in a while. So I would have to remember it or relearn it to tell you. I would also inspect the PCV Elbow, replace the valve if you had not already, and I would clean the MAF sensor while I was at it.
 
#33 ·
I wondered about the syncro and cmp having an issue. Since it came with issues, it's possible someone tried to replace it, failed, and then parked it. If there is enough rust dust on the cmp it wont always set a code or chirp, but could still be off enough to be noticeable.

I think he is most likely looking at a vacuum leak. But there is a lot of parts manglers out there.
 
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