- This topic has 47 replies, 10 voices, and was last updated 8 years, 7 months ago by
.
-
Topic
-
-
Replies
-
freeze frame data
P0174
TPS 0%
RPM 641
Cal Load 3.1
MAF .95
MAP 10.0 hg
coolant temp 174
LTFT1 19.5
STFT1 0.0
LTFT2 18.8
STFT2 -2.3I cleared the codes and drove the van up to operating temps and the light didn’t come on until I restarted the van after having breakfast with the wife for about 30 minutes.
It was a foggy morning at about 56F outdoor temps and we had had some precipitation the day before, the van ran the same as it has been. On the way back however, we started to smell the exhaust again about halfway back from where we were, about a 8 or 9 mile drive. Didn’t smell anything on the way there however. I’m beginning to wonder if it isn’t the exhaust donuts causing the problems. If both sides were leaking after they warmed up a bit, but leak at different rates, then it would make sense that we’d start to smell fuel as well as get the lean codes. I guess I’m going to replace the donuts just to be sure, since they are only about $12 and a half an hour to replace and we’ll see what happens.
Well, no change, the code still comes on, but this time it came on while driving down the road. Haven’t got the specs on the freeze frame data, but it’s pretty much the same as before, with the exception of at speed and higher RPM.
I’m getting the smell of exhaust in the van if I crack the windows, which is more of a problem then anything. I can’t detect an audible exhaust leak at the engine or exhaust. I’m going to reset the fuel trim with our shop scanner on Monday and see if that gives me any different result.
On thing that did occur to me, I figured out where the thin spring probably came from. I had an issue with the IAC valve where I had pulled it and lost the small o ring for it. I had found it, but wanted to check the operation of the valve out of the engine. Turned on the ignition and the pintle flew out of it and across the engine to the passenger side of the van. I didn’t realize at the time that there might have been a spring in there as the pintle is moved within the IAC via a screw drive type of mechanism. I can only assume that that thin wire spring came out of that and landed on top of the manifold and I had just now found it. The van has idled just fine, but it took a few times of disconnecting the connection and cycling the key to get the pintle to move into the proper spot to get my idle down where it needed to be. However, I can’t test the operation of the IAC since I don’t have any way to put a load on the engine at idle ( no A/C ) and the last time I used Genisys OTC scanner, it didn’t respond to the commands from it. I don’t know if it’s at all related to my lean code being set or not as there is no issue with the idle and it’s been running this way for the last few months.
I’m not in the position to be throwing parts at the van and I don’t want to throw parts at the van to fix it. What I do know at this point is this:
The van ran fine, got 15.5ish mpg consistently.
I replaced the mechanical fan with an E fan and wired the relay to a KOKO source in the fuse panel under the hood of the van. In the process I also tried to tinker with the air filter set up as I currently have a cone style filter for my air filter and tried to see if I could find a way to get the stock airbox to work…which I did not…I put the air cleaner assembly that was on the van when I got it back on. IN the process of tinkering, I had bent the tabs that hold the air horn on the intake, to which I adjusted and reinstalled and verified the seal.
Shortly after finishing the wiring job and getting the van running again with the E fan, I started getting the P0171/174 lean bank codes and my mileage dropped to 14.5ish mpg over 2 tankfuls and I started smelling rich exhaust fumes in the van. The idle is stable, no fluctuations. Spraying around the intake, air horn and upper plenum areas did not change anything in the running condition of the van. It set the code just sitting still, Idleing and when I changed the exhaust donuts, the van idled fine, set no code, but as I drove down the road and the engine got up to operating temp to where the E fan should have kicked in, the code set.
Prior to this happening, the van ran flawlessly…no hiccups, no indications that something was wrong with the van.
The only other thing I can think to do is to wire the trigger 12v source up directly to the battery, but that means that the E fan will run with the key off if the thermostatic sensor still detects enough heat to trigger the fan. How long that could keep the fan running, I don’t know. If that’s what I end up having to do, then I guess that’s what I end up having to do.
I’m certainly open to suggestions on things to look at, inspect, test or probe. I just doesn’t seem probable to me that I suddenly developed an air leak to the point where I’m running unmetered air into the engine between the MAF and the O2 sensors seemingly overnight. Logically in my thinking, there either has to be something going on with the air horn or the breather hose coming from it to the passenger side valve cover, or there is something that is interfering with the computer electrically from the E fan that is causing a sensor to read out of range.
Oh, and no video fo the idler arm removal/installation…last minute weekend work that pressed me for time. Unfortunately, I still have a pull to the left even after replacing both idlers…the old ones seem to be in good shape still. I need to figure out what’s wrong with that still, but I’ll start another topic for that.
Quoted From redfury:
freeze frame data
P0174
TPS 0%
RPM 641
Cal Load 3.1
MAF .95
MAP 10.0 hg
coolant temp 174
LTFT1 19.5
STFT1 0.0
LTFT2 18.8
STFT2 -2.3Holy cow!
The long term fuel trims are out of this world and are adding fuel to compensate for something.
Is the maf measuring grams per second (gs)?
Is there a map pid in voltage?
Can you do a screen shot of all the o2 sensors @ idle and 2500 rpm?If that MAF pid is gs then it either isn’t working well or there is a huge bypass air leak after the maf.
I believe the second set of values is after I reset the fuel trim with the scanner. If there is something in particular you want to see, I’ll get a picture of it ASAP.
Here’s what I did today. I listened as hard as I could for any vacuum leaks. I couldn’t find any that were audible. So, I retraced my steps to where I was before I started getting the codes-which was trying to get the stock air box to work with the van instead of the elbow and spectre cone filter set up that I bought the van with.
Found that the clamp for the connection between the MAF and the air horn wasn’t very tight, I could rotate the MAF by hand. The Airhorn to thottle body fit was a little loose also. When I was trying to fit the airbox on, I managed to force the airhorn off the throttle body. It’s held on by a screw down clamp on the rear of the engine side of the TB and has a forked clip that holds the front down, so you essentially tilt it down onto the stud and tighten it onto the motor. So, I made a gasket to fit underneath it since the rubber on the inside of the body of it seemed suspect. The gasket helped snug everything down nicely, I got the MAF tight and gave it a whirl. My STFT seems to stay around 3-4 on the Actron scanner, but will occasionally spike upward of 6 or 7 at idle. If I run the engine up to 2500rpm, I can see double digits pop up on the scanner before it levels itself off.
fuel pressure test
http://youtu.be/6TP49B2oWMofreeze frame data from my Actron and Live Data
http://youtu.be/WHW4rzoyVGYSince I’ve never actually taken any classes on reading most of this info, I’m usually just taking a stab at what it means ( I just figured out the LTFT and STFT acronyms recently )
The problem is, I’m still coming up short putting all the pieces of the puzzle together as easily as someone with learned knowledge of such things. It’s helped me to become a better home mechanic, but I still have a lot to learn when it comes to computer diagnosis. It’s the relationship amongst the sensors that I still havne’t gotten a complete grasp of yet. What I need to do is probably do more baseline testing to know where the numbers “SHOULD” be so that I can recognize when they aren’t where they should be.
BTW, not to make a long thread longer, but it seems that anytime I have a problem with this van, it seems to become a protracted issue and not something that is just easily solved. Reassigning wires to the new computer went really well, except that the O2 sensors wouldn’t come online. It took me a couple of weeks to find that the sensors I had in the van weren’t compatible with the computer I was using…whodathunkit? Wired in the proper sensors ( of course, I couldn’t get them with the proper plug, that had to be redone too! )
Then the waterpump springs a leak at the gasket and after the 2nd failed gasket, I finally figured out how to put the water pump on without damaging it..hasn’t given me a problem since.
The original broken mechanical fan was a fun one to get off the water pump, but once I figured that out…piece of cake….only to have it break 8 months later and bring me to my current ordeal….Isn’t life grand?
I’ll eventually get this figured out, but in the meantime I’ll be scratching the remaining hairs on the top of my head out.
MAP sensor voltage should be 1V or less at idle (.86 or so would be great), your fuel trim should also be closer to 10%. From the look of things the computer thinks your lean and is trying to richen the mix. Do you have any exhaust leaks before the O2? If so you might want to address them.
Do you have any way to graph the 02 bank 1 sensor 1 and sensor 2 readings? Some, not all, lean conditions occur when i 02 sensor is being lazy or has failed. The 02 pre-cat 02 sensor voltage work on a 1v REF and should fluctuate between 0.1 to 0.9. Again graphing those readings will show if the 02 sensors are switching or not. When you raise the engine RPM up, the 02 voltage should increase on both banks.
You could also try using propane to see if the STFT and LTFT numbers change as well as manual creating a vacuum leak and again reading the numbers.
As you see from the scan tool data, the ECM is trying to correct a lean conditon.
Do you have a smoke machine at your shop?
- You must be logged in to reply to this topic.