2002 Runs rough and lacks power

[bcstoy]

Yep and they are costly, but I rather make them myself. This version is really difficult to do it, has a column shift.

 

[bcstoy]

short update, damn truck nothing makes it run better. Still p1152, p0171, p0175. Lean on bank1 rich on bank 2. I am actually thinking about looking at the old motor to see if the rings were not installed correctly. It looks like it was recently rebuilt.

I did install a ford O2 and a Bosch O2, with the PCM re-flashed, I am really sick of it.

 

[Brain75]

where did you land on injectors? did you pull em and test, clean & test the OEM and reinstall?

 

[bcstoy]

Yes B75 I had two sets, a cheap brand I got in offer up for $20 bucks and the factory ones. Tested both and measure resistance. Ended reinstalling the factory ones. For a truck that had three bad cylinders the truck ran well except for the rough idle. So I did not think the injectors were bad before. My scanner did not find any issue with the injectors either or any other sensors. The only thing I can think of is that the PCM is trying to compensate for a lean condition in bank 1 and in doing so it ends up opening all the injectors longer than it should resulting in a rich condition for bank2. I do not know how the PCM activates the injector drivers so I am merely speculating here.
I graphed the traces for SFT from both banks. The one on bank 2 was always above the one of bank1 suggesting something I already knew, rich condition.

At this point I doubt the lean condition is caused by something outside the engine. It could be something related to the valve train in bank1. I will pull the head to see if there is something going in there. There is a video where a guy found the seat receding too far into the head causing a lean condition, not quire remember now. Will search for it and watch it one more time.

I cannot give up on this. My friend wants his truck running. I should have sold him one of mine. I have 3 tacomas & 4x4 85 EFI long bed. There are more but will keep the list short since some of the are work in progress.

 

[Brain75]

RE:injectors - accepting that the resistance is good, how did they spray? fog of mist, jet streams or?

valves getting recessed is something known on 4.0L's if I remember right... I have no idea how common it is in 3.0L's. If you had valves that weren't closing due to recess you would be getting misfire codes too. The 4.0's/2.9' (cologne block) have nothing in common with the 3.0's (vulcan block) - so issues common to the 2.9 (head cracking) are almost non-existent on the 3.0's

A leakdown test will show you the valves. Unless you love tearing into the engine and replacing gaskets I would do a leakdown before opening it up.

A systematic look at what those 3 codes have in common:

P0171:

• Air intake/vacuum/boost pipe leak (Most common)
• Faulty PCV Valve
• Low fuel pressure (Caused by a bad fuel pump, filter, or fuel pressure regulator)
• A faulty EVAP purge valve
• Faulty O2 sensors
• Faulty EGR valve
• Faulty MAP/MAF sensors
• Exhaust leak (Before Front O2 sensors)
• Coolant temperature sensor
• Faulty sensor wirings
• Faulty ECM/PCM (Rare)

P0175:

1. Faulty oxygen sensor
2. Clogged fuel injectors
3. Fuel pressure regulator issues
4. Vacuum leaks in the intake system
5. Malfunctioning mass airflow sensor

P1152: (I had to look this one up - not ran into it)

• Faulty upstream heated oxygen sensor bank 2
• Air leaks after the MAF or PCV or between them, which would cause a lean condition resulting in Rich Bank 2.
• Bad MAF sensor
• Faulty fuel pump
• Lack of Upstream heated Oxygen Sensor Switch Sensor Indicates Rich Bank 2.
• Bad PCM (less likely)
• Vacuum leak on engine

Well as you can see all 3 have a bad O2 sensor on their list, that is the most likely in my books. Your aftermarket new O2 sensor could be like your 1 bad new injector - crappy aftermarket junk.

MAF shows up on all 3 lists... I've re-read 3 times now trying to get a good handle and I can't remember by the time I get to the post screen - where are we on MAF, cleaned the old, installed new?

There's something else that has to be on all 3 lists and you already said "the harness is lousy" - this all could be a wiring nightmare. I've never had to deal with any wiring problems other than breaks/cracks.... benefit of living in the desert (but at 30 years in the desert all plastic,rubber, wiring insulation is just about done - you only touch what you absolutely have to, and plan on replacing everything you touch...)

 

[bcstoy]

OK, it has been more than a year since I stumbled into this mess with this truck. Today it was the first day that it ran like a normal truck.
I was in a dead end so I decided to have checked by a shop. The guy asked me all the things I have done. Two hours later and & $169 out of my wallet, he said the y pipe was the problem. Dam, I was mad at myself for being unable to figure that out. I could not test for that nor did it occur to me when replacing the sensors to look inside the y-pipe to check the condition of the catalitcs . I took the pipe off and this time checked with a flash light the catalitic from the RHS showing the lean condition was totally gone, so I figure the one in the middle had to be clogged. Thus I installed a new pipe system, an after market version, and the thing runs fine. The after market part made struggle it did not fit like the original one but eventually figured out how to seal the exhaust leak on the LHS. Another thing I noticed was that the shaft for the throttle had a lot of play and the smoke from the smoke machine was leaking at the air housing. The guy at the shop was kind enough to adjust some of the play. Still has some but not enough to affect the idle significant. I am still puzzled why these problems were showing as p0171 (lean bank1) and p0175 (reach bank2).

I learned a lot I downloaded the forscan and bought the elm327 code reader that communicates with forscan. But obviouly it was a truly mechanical problem not an electrical one: injectors, sensors, pcm, wires and coilpack were all fine. My desperation made me doubt of my knowledge and the scanner I use. I should not have veered into replacing those parts.

I did reach a decision not to open the engine cause never overheated and had good compresion, only 1 piston was sowing 120 psi. The other ones were 150 or higher. I do have the old motor and I think it has the rings installed wrong, I have seen that before. If time allows I will plunge into another ford adventure. But for now I have to get back to what I know & like Tacomas and old toyota pick ups.

That's all for the day folks. Thanks, B75 for suggesting things even when not in the right direction. It is hard to figure things even when in front of the vehicle, more difficult when that is not the case.