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Discussion Starter · #1 ·
Ijust got rid of my 86 trans am because we are down to one car and need something bigger. I recently purchased a 99 taurus station wagon with the 3.0 vulcan engine. Vin code U.

When I start the car and whenever im idling the engine shakes pretty bad. When i got the car it had a code showing lean on left bank and misfire on every cylinder except 2. I replaced the plugs and wires and it is alot better but it still shakes pretty bad at idle and at cruising speed (not under acceleration though). The only code showing is misfire on cylinder 4. I ohmed the coil and it seems to be ok. I also ohmed the injectors and they seem to be ok as well. Any other ideas before i start throwing parts at it? thank you so much guys and look forward to being a part of your community.

also, car has 140K miles, no overheating and seems to be good on gas (but I have only had it 3 days so its kinda early to tell.
 

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I would replace the coil and check for vacuum leaks. Pcv and other hoses, manifold gaskets (upper and lower), clean the maf sensor with crc maf cleaner spray, etc.
 

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Ijust got rid of my 86 trans am because we are down to one car and need something bigger. I recently purchased a 99 taurus station wagon with the 3.0 vulcan engine. Vin code U.

When I start the car and whenever im idling the engine shakes pretty bad. When i got the car it had a code showing lean on left bank and misfire on every cylinder except 2. I replaced the plugs and wires and it is alot better but it still shakes pretty bad at idle and at cruising speed (not under acceleration though). The only code showing is misfire on cylinder 4. I ohmed the coil and it seems to be ok. I also ohmed the injectors and they seem to be ok as well. Any other ideas before i start throwing parts at it? thank you so much guys and look forward to being a part of your community.

also, car has 140K miles, no overheating and seems to be good on gas (but I have only had it 3 days so its kinda early to tell.
John,

Did you check the coil for external cracks on it ?
 

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OK, you ohmed the injectors and they appear to be firing, but are any of them possibly clogged?, a known lean code setter. Also, the night time, pitch-black coil check. Small cracks in a coil will make little arc flashes you can see in the dark, so will plug wire faults on non-COP systems.
PS - Sorry about the TA.
 

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Discussion Starter · #5 ·
I did check the coil tonight when it was dark and there was no noticeable sparking externally. It is possible that the injectors are dirty but when i purchased the car the previous owner had a stack of receipts in the glove box and one of them was for injector cleaning (although it was a few years ago and it looks like it was just a tank additive).

I did visually inspect the hoses for any cracks and they all look VERY good (not cracked or spongy in any way) the previous owner seems to have had them all replaced not too long ago. I will clean the maf and replace the pcv valve just to be safe but if those were my issue wouldnt they cause more codes other than misifre on #4?

I also ordered a USB obd2 scanner tonight that should be here wed so I can log all the sensors in real time and get a better feel for everything.


ALSO should note that today the tach seemed to drop to almost 0 and jump up and down between 100 and 250 RPM a few times but there was no change in the way the car has been running so it might be a seperate problem. eventually it goes right back to normal and it happened at random times. Where does the tach get its signal from? ecu, coil, separate ignition module?

Thanks again for the help guys. I miss my TA already but dont miss only having 2 doors and having to stop at every gas station that i cam across.
 

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Tach gets it's signal from PCM (ECU). If it's bouncing around funny but everything is running the same, it could be an early symptom of an electrical problem (groan) possibly a dirty ground somewhere.
(Nice looking F body. I had a Z-28 that just never looked right once it needed a car seat in it.)
 

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Discussion Starter · #7 ·
today is the olny time i noticed the tach doing this and it only did it a few times and for about 30 to 45 seconds each time. I will have to chase it down eventually but if it isnt related to the misfiring 4th cylinder than I can live with it until I get everything else straightened out.
 

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Discussion Starter · #8 ·
Ok guys. I hooked up my OBD2 scanner and the only code popping up is the misfire #4 still. I also cleaned up the maf sensor but still no change. My scanner allows me to see all the sensors real time input/outputs and they all seem to be within normal range and acting normal. I also notice that when the car is cold the check engine light with throw the code only when im barely into the throttle (just enough to maintain current speed). When its warm it seems to throw the code at idle and when i try to maintain speed. if im accelerating it doesn't misfire (or throw the code). Any body else have an idea?
 

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run a compression test on all cylinders.

check the fit on the vacuum host from the PCV valve to the
nipple on the underside of the intake manifold.
if the pcv is plastic and looks like FORD part, replace it with metal one and new hose.

regards
 

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+1 on the compression test.

Possible a dumb suggestion, apologies if so, but you took your lean left bank and five cylinder misfires down to just one after the plug and wire change, right? Is there any chance that the plug in the #4 cylinder was mis-gapped? It'd be easy to tell, just swap it with another one. Depending on the quality wire you bought, you might even double check if there's a problem with the wire.

To my knowledge, and please correct me if I'm wrong, localized misfires are most likely caused by:

1) Bad Spark Plug
2) Bad Spark Plug Wire
3) Bad Coil
4) Clogged Fuel Injector
5) Bad Fuel Injector
6) Damaged Fuel Rail
7) Compression Problems

If you don't want to throw any more money at it until you have a better idea of what's wrong, and if you're doubting it the coil, injectors, or rails, it seems like performing a compression check would be the next logical step, along with a wishful thinking double-check of the replacement #4 wire and spark plug :)

Hope that was in some way helpful!
 

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Discussion Starter · #11 ·
Thanks for the help guys it is VERY much appreciated. I was actually thinking the same thing myself that it is kinda wierd that every code except cyl 4 disappeared and so i plan on swapping the plug and wire out with another cylinder to see if anything changes.

also I will go ahead and try to get my hands on a compression tester so I can run a test on the engine.
 

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Discussion Starter · #12 ·
ok I tested the compression and cyl 4 was a little low. I also noticed that it was starting to get a little warm when sitting at idle so I figured I would pull the heads and replace the headgaskets just to be safe. I pulled the heads and had them checked and they seem to be in good shape. BUT I also found that when i took off the head for cyl 4,5 and 6 that it had a bent pushrod so i replaced the pushrod as well. now it seems to be running pretty good. it seems a tad shaky at idle but im not sure if that is normal or not since this is my first vulcan motor I have ever owned.

so I guess the headgaskets and bent pushrod were my issue if anyone else runs into these issues. Now I just need to find out if the vibration at idle is normal or if i have some more tweeking to do.
 
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