Taurus Car Club of America : Ford Taurus Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
Hi everyone,
I have been using this forum for great info ever since I bought a used 2001 taurus with the vulcan engine. Now, however, I have a misfire that I can not figure out.

Wife was driving the car and told me she thought the alternator was going out because it started acting very sluggish etc. There was no check engine light at this time. I checked out the whole charging system and that wasn't it. I checked the plugs and they were fine.

I took the car to a local shop and he diagnosed it as a bad ignition coil pack, and told me I had a bad cell in my battery. I replaced the battery and picked the coil pack up from autozone and installed which made no difference. I took the car back to autozone to see if they could read the codes for me even though there was no check eng light. They found a misfire on cylinder 3. I checked all plug wires and I found a gash in cylinder 3 plug wire so I replaced them all. That didn't fix the problem either. While I was driving down the road the Check eng light came on flashing. Had the codes read again at autozone and they said I had a misfire on cylinder 1,2,3, and the bank was too lean. (I checked 2 times to make sure I didn't mix up the plug wires). I took the car to NTB for a diagnoses which was bad MAF sensor and bad TPS ($725 quote to replace! holy crap!). Tried cleaning MAF which did nothing so I replaced both the MAF and TPS. That didn't fix it either. I haven't found any hiss for a vacuum leak, so what in the heck could it be? Burned valve?

Any wisdom you can bestow on me would be greatly appreciated! With all the time I have spent staring blankly at the car or replacing parts to help autozone's stock price, the mosquitos in my neighborhood are getting well fed!:lol2:
 

·
Registered
Joined
·
10,929 Posts
Misfire

Hi everyone,
I have been using this forum for great info ever since I bought a used 2001 taurus with the vulcan engine. Now, however, I have a misfire that I can not figure out.

Wife was driving the car and told me she thought the alternator was going out because it started acting very sluggish etc. There was no check engine light at this time. I checked out the whole charging system and that wasn't it. I checked the plugs and they were fine.

I took the car to a local shop and he diagnosed it as a bad ignition coil pack, and told me I had a bad cell in my battery. I replaced the battery and picked the coil pack up from autozone and installed which made no difference. I took the car back to autozone to see if they could read the codes for me even though there was no check eng light. They found a misfire on cylinder 3. I checked all plug wires and I found a gash in cylinder 3 plug wire so I replaced them all. That didn't fix the problem either. While I was driving down the road the Check eng light came on flashing. Had the codes read again at autozone and they said I had a misfire on cylinder 1,2,3, and the bank was too lean. (I checked 2 times to make sure I didn't mix up the plug wires). I took the car to NTB for a diagnoses which was bad MAF sensor and bad TPS ($725 quote to replace! holy crap!). Tried cleaning MAF which did nothing so I replaced both the MAF and TPS. That didn't fix it either. I haven't found any hiss for a vacuum leak, so what in the heck could it be? Burned valve?

Any wisdom you can bestow on me would be greatly appreciated! With all the time I have spent staring blankly at the car or replacing parts to help autozone's stock price, the mosquitos in my neighborhood are getting well fed!:lol2:
Misfire on one bank likely vacuum leak. Bad one. And in a location that lets air in only on one side, or mostly one side. MAF and TPS do not effect one side only. That is coil, wires, vacuum.

-chart-
 

·
Super Moderator
Joined
·
8,732 Posts
^^^^ +1

You have a vac leak on bank 1 only.
 

·
Registered
Joined
·
1,339 Posts
I read this from my phone and wanted to reply the same thing sheila said.

Look for the pcv elbow, it may just be that. This happened in my car and that was the cheap solution. They wanted to change the MAF and IAC after I checked them to be fine.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #7 ·
Thanks for all of the replies. I still haven't gotten my car back from NTB. I took it back to tell them that the diagnosis they gave didn't seem to help because I followed their advice and it made no difference. They did not give a crap. I asked if they would at least look at the car again since I paid for a diagnosis but got an incorrect one, and he finally agreed to that, but he had a ton of attitude about it. That was a week ago and I hadn't heard anything, so today I finally called them to ask if they had checked for vacuum leaks etc and he said it's STILL the idle air control valve. I told him that wasn't what they diagnosed before so it isn't STILL anything. Then he says he's sure it actually needed the other sensors too.

Could the IACV cause the symptoms I described? I haven't had the car back to check for the vacuum leaks myself but are they possibly correct that the IACV is bad and causing this?
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #8 ·
ok, I got my car back and spent yesterday afternoon looking for vacuum leaks. I can't find anything and I don't hear any obvious hissing noise. I got a 5/8" hose and tried listening all over with that but didn't hear anything. Does anyone have any advice? Do you think it could be the IACV? That darn check engine light is still flashing!!
 

·
Registered
Joined
·
697 Posts
IACV problem would affect both banks.

Just a wild thought but is your oil fill cap on snugly? That would be a big source of vacuum loss if it were loose or leaking. There is an O-ring that is supposed to seal it against the lifter cover.

The flashing MIL is somewhat serious according to the OBDII info on the web so needs to be fixed ASAP. The car is in limp-home mode so you will have poor mileage and risk possible cat damage.

I would also suggest replacing the bank 1 upstream O2 sensor - you can do it yourself - and see if it helps.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #11 · (Edited)
Yes, I read that the flashing means the cats could be damaged by the unburned gas. Is there a good way to find a vacuum leak? Does anyone have a vacuum hose diagram so I can be make sure I don't miss any?

I will check the oil filler cap- thanks for that suggestion. I didn't think a bad oxygen sensor could cause all this but I might try that next.
 

·
Super Moderator
Joined
·
8,732 Posts
A word of advise..... NEVER take your car to any big chain store for a "diagnosis" of any problem. The mechanics, in general, at those places couldnt successfully hang an air freshener on your rear view mirror, much less diagnose an engine electrical / sensor / activator problem. Find a trusted local "mon & pop" shop to repair your car if you cant or dont want to do it yourself.

The IAC CAN NOT cause a lean or rich condition (unless the IAC gasket is leaking) as all the air flowing thru the IAC has been metered by the MAF.

You likely have leaking intake gaskets on the effected bank. To verify, you need a scan tool that can read long term fuel trims for each bank. One bank near 0% and the other at high positive % (like +22%) indicates a bad vac leak on that bank.

Just for giggles, as the mechanics what the long term fuel trims were for each bank. If they look at you funny, as them if they know what fuel trims are.
 

·
Registered
Joined
·
1,339 Posts
Check for the all famous PCV elbow first. You may just have a tiny problem that doesn't need expensive and labor intensive repairs.

Also, the IAC can cause rich or lean conditions, if it was stuck. But if that was the case, expect extremely rough idle and more then just a misfire. It's most likely not the case.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #16 ·
The idle is extremely rough like it wants to die at times. Barely has enough power to get going; gets slightly better at higer RPM's but the car is extremely weak and idles very very roughly.

PVC elbow seems fine and I can't hear any hissing around it but I will give it another look in the morning before I start the intake manifold gaskets.
 

·
Super Moderator
Joined
·
8,732 Posts
Also, the IAC can cause rich or lean conditions, if it was stuck. But if that was the case, expect extremely rough idle and more then just a misfire. It's most likely not the case.
Please explain to me exactly how an IAC problem can cause a rich or lean condition. All air flowing thru the IAC has been metered by the MAF. PCM adjusts A/F ratio based on MAF and other parameters (TPS, ECT, IAT, etc) Lean condition is caused by excess unmetered air getting into the engine, low fuel pressure, clogged injectors, etc. None of these have anything to do with the IAC. Rich is caused by excessive fuel pressure, leaking injectors, or fuel getting into the engine in some other way, such as leaking FPR diaphram on the older return type fuel systems, etc. Rich has nothing to do with the IAC.

Stuck shut IAC (or IAC open less than commanded due to gummed up, etc) will cause low idle speed, stalling, rough idle, and can set phantom missfire codes due to the poor idle quality. Stuck open IAC (or IAC open more than commanded) will cause high idle, hanging idle, etc.
 

·
Registered
Joined
·
1,339 Posts
Please explain to me exactly how an IAC problem can cause a rich or lean condition. All air flowing thru the IAC has been metered by the MAF. PCM adjusts A/F ratio based on MAF and other parameters (TPS, ECT, IAT, etc) Lean condition is caused by excess unmetered air getting into the engine, low fuel pressure, clogged injectors, etc. None of these have anything to do with the IAC. Rich is caused by excessive fuel pressure, leaking injectors, or fuel getting into the engine in some other way, such as leaking FPR diaphram on the older return type fuel systems, etc. Rich has nothing to do with the IAC.

Stuck shut IAC (or IAC open less than commanded due to gummed up, etc) will cause low idle speed, stalling, rough idle, and can set phantom missfire codes due to the poor idle quality. Stuck open IAC (or IAC open more than commanded) will cause high idle, hanging idle, etc.
Ah, well I had an older car that had an IAC that was stuck in an almost open state, and for the longest time it gave me lean codes. I assumed it went neck and neck.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #19 ·
The IACV most likely isn't it because I grabbed one from a junkyard for $9 just to be sure and it made no difference. I didn't start on the intake yet because it looks like a time-consuming job. I will get to it soon though.
 
1 - 19 of 19 Posts
Top