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Discussion Starter #1
What do you guys recommend for Code 174 showing up? In my 97 T bird with a 4.6, I am getting a P174 code. Have changed the O2 sensors on the drivers side but no help. Engine runs fine except the knock sensor is inoperative. I need to run premium in this car or it pings like crazy. Thats the PCM, I think. I have two others 97 Tbirds with 4.6s and regular is fine in those. Anybody fixed this nagging P0174 code?

Thanks, Phil Swanson
97 Bluebird
 

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What's the exhaust like on that side? It could be an exhaust leak, or a leak on that side of the intake.

Also, have you cleaned the MAF recently? Although I'd presume that'd kick the codes for both sides ...

Here's a link on the P0174 code:

http://www.obd-codes.com/p0174

RwP
 

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Discussion Starter #3
So far, I changed the PCM and sprayed out the MAF with electronic cleaner. I was going to clean the PCV but I can't find the darned thing. I thought it was in the left rocker cover elbow, but not there. Where did they stash the PCV in these cars?

Thanks, Phil Swanson
97 T Bird 4.6L
 

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So far, I changed the PCM and sprayed out the MAF with electronic cleaner. I was going to clean the PCV but I can't find the darned thing. I thought it was in the left rocker cover elbow, but not there. Where did they stash the PCV in these cars?

Thanks, Phil Swanson
97 T Bird 4.6L
Its on the pass side valve cover
 

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Years ago my Dad's T'Bird had persistent codes PO171 and PO174, lean on both banks. Several shops worked on it with no results. They ran injector cleaner repeatedly, swapped O2 Sensors, all sorts of things. Finally I installed a set of good used fuel injectors bought via eBay (cheap) and it solved the problem, and it ran better too. It's an easy job.
The major clue was that when my Dad would go to Laughlin, NV and then fill up with non-oxygenated fuel in Arizona the light would go out until he refilled with California gas. The computer couldn't set the long term fuel trim rich enough to overcome the lean (clogged) injectors and therefore would set the codes.
Now I have the car. Good luck.
 

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Discussion Starter #8 (Edited)
Could be leaking intake gasket on bank 2. Is the car missing or running rough?
No, its running perfect. It does have a replacement Dorman intake on it tho. If the light comes back, I plan to check it with propane.
I think the detonation problem is fixed tho. No detonation and it is 90+ degrees here today with zero humidity and no pinging up hills on regular. The fix was the PCM. I keep several on hand for these T Birds because I have had issues B4. Thanks for the help!

Phil Swanson
97 Bluebird
 

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Check for vacuum leaks. Make sure the fuel lines are fine too. Maybe replace the fuel filter too.
 

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I had this exact same code on my 97 3.8, I sprayed my Maf sensor with a special cleaner that's only made for mass air flow sensors. Now, I've heard that your not supposed to use any other type of cleaner,like a carburator cleaner and all others. How true that is I'm not sure. I was able to pass star certification smog in cali 1 month later. Hope this helps.
 

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So far, I changed the PCM and sprayed out the MAF with electronic cleaner.
Did you just spray into the MAF tube, or clean the actual MAF wire?

Just checking. A lot of us (including me) didn't know back in the day that you had to take the sensor out of the housing to clean the wire.

That definitely will clear up detonation issues.

Al
 

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you have to spray the two elements, but don't touch them. They will break, have seen that first hand. They will be black or dark when dirty. White/gray when cleaned.
 

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Discussion Starter #13
I cleaned the MAF with electronic contact spray. Do you think I should do it again with special MAF spray? To get to the element totally, I think you need to take it apart and take the plate off with the two screws.

Phil Swanson
97 Pearl Bird
97 Tan Bird
 

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Discussion Starter #15
Electronic contact spray is fine, but at this point only you can see it to see how dirty it really is.
There is no dirt you can see in the MAF. Never in any of my T Birds. If you see dirt in there, the air cleaner is not doing its job. Going for the leaky intake manifold propane test and fuel filter next. I wish these codes were more detailed and specific.

Phil Swanson
97 Pearl Bird
97 Bronze Bird
95 Babybird (Bluebird Wanderlodge Bus)
 

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I too have developed this issue, the only recent change in the car is I have installed a trubendz exhaust system, while doing so i have replaced both cats and all 4 o2 sensors.

I read somewhere about exhaust gas reversion at low engine speeds with an x pipe. I will check for intake and exhaust leaks this weekend.
 

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Try looking for vacuum leaks first; search for "Intake manifold Cigar Trick"

 

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I will give that a go soon as well. I checked for exhaust leaks this past weekend, and also sprayed some ether around the intake and most specifically around the intake gasket and idle speed never changed.

However i started it this morning and had what felt/sounded like a dead miss for about 30 seconds then it started to smooth out.

Plugs Wires Ignition Packs are all new within 2 years.

I am starting to think i may have a dirty/failing injector.

Fuel filter is new maybe has 20k on it.

I occasionally run lucas or b12 injector cleaner through a tank of gas.

she's a 97 with 130k on the clock now.
 

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On any 97 that is doing weird ****, I'd try a different, preferably 96, EEC.

The FTE3 check-code box that was in my 97 Tbird died, as have many others.

You can see what the code is before you take it out; there's a sticker under the hood on the passenger side, partially beneath the rubber hood seal.

It should have a 4 letter code; Tbirds I've seen FTE1, 2, and 3, Cougars MBE1, 2, and 3.

This list can be programmed for our cars:
Fte1, Fte2, Fte3, Mbe1, Mbe2, Mbe3, Npl2, Npl3

IDK what the last two are from, that's in a post I got years back from Lonnie. :)

I'm running MBE2 EECs in all my cars now; no problems, and I've written tunes to them a bunch of times.
 

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I had a reoccurring P0174 (too lean). Replaced: tps, ecu, maf, 02s, plugs & wires, vaccum tubing, cleaning and rewiring all electrical grounds, etc... Couldn't figure it out for several months because the code would switch between too low and too high on the same bank; then switch to the other bank. After replacing the ecu, I gave up hope on a fully functional car and kept driving.

The car was still kinda driveable but backfired and stumbled, especially when cold. I have a scan tool with "live data" and noticed the 02 sensor graphs were completely wack about 60% of the time but would even out occasionally. The STFTs would peg and reset as well but the issue would rarely form a pattern.

I got lucky one day when the damn car finally threw 2 codes. Too rich bank 1 & too lean bank 2.

Turns out I accidentally attached the 02 sensor harness upside down when I was replacing my transmission. (If you do it wrong, the o2 sensor plugs will actually be easier to get to).

Morel of the story: If you give up all hope, try cross plugging your upstream o2 sensors across exhaust banks. I cranked it and after 10 seconds my 02 sensors were back to making full voltage switches.
 
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