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Discussion Starter #1 (Edited)
Hello, I dunno where to start so I'll just start throwing out what I know.

Off a fresh battery/code reset, the idle STFTs were in good range (+- 10%), same with parked revving, up to 2500 rpms.

Then we took the car driving, well I wasn't able to ride along so I couldn't watch the scanner during the drive. Here's what it looked like upon returning.

LTFT Bank 1 at idle = -19.5%
LTFT Bank 2 at idle = -8.5%,
STFT at both banks at idle were still in good range.

These readings confuse me a little bit, I don't understand why the Bank 1 LTFT at idle would give a -19.5% reading (after returning from the highway drive) if the STFT looked good at a parked idle. Isn't the LTFT an average of the STFT depending on the RPMs? If so, what about the drive would cause the idle LTFT to show a rich condition, that being parked doesn't, on the STFT?

After the return drive, I also rechecked the fuel trims at different RPMS, up to 2500. I didn't write down the numbers but they pretty much told the same story as the idle readings.

Also, upon returning from the drive, we got the codes P0420 and P0430.

Next I cleaned the MAF Sensor just in case that would be the cause. I figured it wouldn't hurt anyway. After cleaning the MAF and starting the car, a P0300 code immediately came on. I don't believe it's from cleaning the MAF sensor but just from the car needing to be restarted (first one since the highway drive) for it to show. I'm not sure though and I hope it's not a careless mistake on my part. When we first got the car, it already had 3 codes and I written them down but I wanted to do a fresh reset to make sure and start from scratch. I misplaced the paper I written them down on but I'm 95% sure it's the same 3 codes.

I'm pretty sure the o2 sensors are working as I did a quick (but probably not the best) test on them. The voltages on the upstream (and downstream) sensors ranged between .100v and .900v at idle, then I shot some carb cleaner into a vacuum line going to the engine and the upstream sensors went and held at .900v (during the spray).

The fuel pressure on the scanner showed 37 psi.

One thing I noticed but I'm not sure if it's a big deal or could cause a rich reading is the box cover for the air filter has a broken tab on the bottom so it isn't sealing like it is supposed to.

Finally here is some random readings I written down from the scanner at idle (in CL).

Idle RPM - 645-740
FP/Vac (PSI) - 61
ECT (F) - 210
Spark Advance 12-15
IAT (F) 96

I'm curious what my next step is. I was thinking I would pull off the plugs and look for a sign of a leaky injector (?). Any help is appreciated. Thanks! :D
 

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61 is high for fuel pressure and would make it run rich
420 and 430 are catalyst efficiency codes likely caused by excess fuel.
300 is misfire, non cylinder specific also likely caused by excess fuel.
 

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Discussion Starter #3
Oh, so FP/Vac is the fuel pressure? Oops :D I dunno what the "37" reading was from, it said fuel something, I just assumed it was the pressure.

Thanks. I'll start reading into what all could cause high fuel pressure.
 

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Discussion Starter #6 (Edited)
No I haven't. I believe the car was driven for about 20-40 mins so I'm not sure if that would be enough time for those codes to appear. I don't recall them being the previous codes though.
 

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Discussion Starter #8
Yeah I believe I read the magic number was like -20 or -25 LTFT for those codes to appear, could be very mistaken though and was reading something else.
 

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Discussion Starter #9
Today I started the car and watched the fuel pressure and it stayed around 40 psi. I didn't do anything to the car so I'm not sure why it wasn't at 60 psi like it was yesterday.

I did a vacuum test after that and it passed, though a little low, fast flutters at about 17-18 in.hg. Throttle snap was good though, dropping very low then going to about 22-24in.hg before returning and settling back to 17-18in.hg.

After this, I checked the scanner again and noticed a more specific misfire code, cylinder 2 misfire.

I really suspected a leaky injector. After turning the car off and continuing to watch the FP/Vac on the scanner, I noticed the pressure actually went up a few PSI but then started to drop steadily, about 1/10th of PSI per second. I didn't watch to see if it would go to zero but I watched it drop maybe 15 psi at that rate. I'm not sure if that is normal or not.

I guess the next thing for me to do is to pull off the manifold and inspect the plugs, and check for spark.
 

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Discussion Starter #10
Well I didn't have to remove the manifold and I checked the #2 plug, it was visually wet and had the smell of gas. I'll do a spark test on it shortly to make sure that isn't the problem. I guess I'll inspect the other plugs and make sure they don't smell of gas now.

One question.

If the spark is good on #2, then would that only leave the culprit as the #2 fuel injector leaking? If so, how would that explain the high fuel pressure from yesterday?
 

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Yeah, 15 PSI drop in a few minutes is way too much drop. You see a rather fast bleed off of a few PSI and then the rate should drop to almost nothing. Like, after sitting overnight you'll probably still have 10 or 15PSI at the rail (if things are working right).

One way to test for a leaky injector for sure is to pull the fuel rail out completely, then prime the pump by turning the key to run. A leaking injector will then start to accumulate liquid on the tip. But a strong fuel smell in cylinder 2 on the spark plug is a pretty good indication already.
 

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Discussion Starter #12
That's what I was thinking also. I'm just worried that the high fuel pressure that we seen yesterday is the cause of the leaking fuel injector and that simply replacing the bad fuel injector is just a temporary fix. I don't understand why the fuel pressure didn't/doesn't show 60 psi today like it did yesterday. Maybe it has to be driven again for the fuel pressure to get that high, I don't see why though.
 

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That's what I was thinking also. I'm just worried that the high fuel pressure that we seen yesterday is the cause of the leaking fuel injector and that simply replacing the bad fuel injector is just a temporary fix. I don't understand why the fuel pressure didn't/doesn't show 60 psi today like it did yesterday. Maybe it has to be driven again for the fuel pressure to get that high, I don't see why though.
Did you measure it while you were cranking? I've seen a spike in pressure to mid 50's during start, that should be normal
 

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Discussion Starter #15
It's a Vulcan.. Motor seems to be from an 06 according to the chalk written on it.
@Ice No, the 60 psi was just from the engine idling.
 

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^+1. 1st, I'd check/replace plug(s), wire(s) and/or coil pack for that p0302. Then, injector(s), compression/leak-down tests.
 

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1/10 psi per second is a fast pressure drop. Swap the suspected bad injector (#2) with another and see if the misfire and wet plug problem moves to that cylinder.
 

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1/10 psi per second is a fast pressure drop. Swap the suspected bad injector (#2) with another and see if the misfire and wet plug problem moves to that cylinder.
A leaking injector will cause a rough idle, like flooded feel on a warm restart after ~10 minutes off situation. The fuel leaks into a hot engine and vaporizes, then that vapor fills the intake plenum causing rich on startup. A fuel pr leak down can be going back to the tank. That would cause a hard to fire on cold startup.

Been there.

-chart-
 
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