alia176
SILVER Star
Yup, the FPR is still capped.
I'm going to check the FT on my way to work this morning since I'll be on the hwy for about half hour or so. I"ll get you more data.
P0171 with Landtank's MAF
- Thread starter NLXTACY
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Yup, the FPR is still capped.
I'm going to check the FT on my way to work this morning since I'll be on the hwy for about half hour or so. I"ll get you more data.
alia176
SILVER Star
Need more data!
Rick,
Here's a pdf of few screen shots on the way to work this morning. The drive to work is easy on the engine due to going from 6500' to 5000' elev. I'll do another screen capture going home when the engine is working way harder. Let me know what you think. I think some of us could use some education on the O2 sensor reading. What are we looking at and what should they be, that sorta thing!
One thing to note is that the FT at idle (after a hwy run) is -1.6% short term and 16.4% long term. Are these numbers any better?
Thanks.
Rick,
Here's a pdf of few screen shots on the way to work this morning. The drive to work is easy on the engine due to going from 6500' to 5000' elev. I'll do another screen capture going home when the engine is working way harder. Let me know what you think. I think some of us could use some education on the O2 sensor reading. What are we looking at and what should they be, that sorta thing!
One thing to note is that the FT at idle (after a hwy run) is -1.6% short term and 16.4% long term. Are these numbers any better?
Thanks.
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You need to add the Short Term and Long Term together to get the total compensation. If you look at the highway driving you are at around +5.0% trim. But at idle you are over 15% trim. For whatever reason you have a deficient fueling condition at idle which at times causes the PO171. Because the AFR at idle is close to what is expected for an unsleeved MAF mod it is a problem somewhere else in the system.
I think you, clownmidget, zukinut nxatasy and JFZ80 are all experiencing a similar failure and without seeing the vehicles in person I can't be much help.
I would jumper the high side of the fuel pump relay and see if the FT% drop during idle.
I think you, clownmidget, zukinut nxatasy and JFZ80 are all experiencing a similar failure and without seeing the vehicles in person I can't be much help.
I would jumper the high side of the fuel pump relay and see if the FT% drop during idle.
I'm not sure what you are asking. The stock MAFs and the GEN II LT housings report Air Flow Rates near identical to each other. The original LT housing reported slightly lower air flow rates which was compensated for by capping the vacuum line to the fuel pressure regulator.
All three installed properly would result in comparable fuel trim percentages and not produce a code and work within the boundaries of the factory parameters.
alia176
SILVER Star
Thanks for the analysis. So, I don't have to order a sleeve just yet but should get one anyway.
Hopefully Mike can figure out some stuff after he borrows your stuff this week.
What is the thickness of your sleeve, it looks to be about 1/8"? Still got any left?
I woke up this morning and might have a revelation. This could be nothing more than a vacuum leak 
.
That would account for the low AFR and the high fuel trims. Being at idle where vacuum is it's greatest it would likely be rather small and not effect the engine during running.
I would suggest getting the engine up to temp and get the OBDII scanner going to monitor AFR, STFT and LTFT.
Start by depressing the brake pedal. Maybe this is in the booster and only exhibits itself when the pedal is pressed.
You will want to see a change in STFT where it moves several % points. You will need to give it some time as the ECU will need to react.
If that doesn't yield any results start unplugging hoses one at a time and plugging the nipples on the intake and start the engine and watch those indicators. Again I'd start with the hose going to the brake booster.
If you do find the line that has a leak what you will eventually see is the AFR increasing to around 6.9, STFT eventually settling around 0.0 and the LTFT coming back down to around 10.0 or where ever the driving LTFT is. This whole process might take several minutes as the values in STFT are migrated over to the LTFT values.
.That would account for the low AFR and the high fuel trims. Being at idle where vacuum is it's greatest it would likely be rather small and not effect the engine during running.
I would suggest getting the engine up to temp and get the OBDII scanner going to monitor AFR, STFT and LTFT.
Start by depressing the brake pedal. Maybe this is in the booster and only exhibits itself when the pedal is pressed.
You will want to see a change in STFT where it moves several % points. You will need to give it some time as the ECU will need to react.
If that doesn't yield any results start unplugging hoses one at a time and plugging the nipples on the intake and start the engine and watch those indicators. Again I'd start with the hose going to the brake booster.
If you do find the line that has a leak what you will eventually see is the AFR increasing to around 6.9, STFT eventually settling around 0.0 and the LTFT coming back down to around 10.0 or where ever the driving LTFT is. This whole process might take several minutes as the values in STFT are migrated over to the LTFT values.
alia176
SILVER Star
Excellent info, thanks.
I was going to check my vac lines and also check to make sure that the intake manifold bolts are still tight. Interestingly enough, I'm getting P0325 on both of my 80's since the head gasket so I'm thinking somewhere along the vacuum leaks as well.
I was going to check my vac lines and also check to make sure that the intake manifold bolts are still tight. Interestingly enough, I'm getting P0325 on both of my 80's since the head gasket so I'm thinking somewhere along the vacuum leaks as well.
the hose that I always see as a problem is the one located just behind the throttle body and plugs into the intake from under neath. t's like a 5mm J shaped hose that plugs into a plastic T. The T nipple is just a straight slip fit and over the years the hose gets hard and is a loose fit. I change these on every HG job I do now.
I'm not getting into a design theory discussion on the MAF housing I designed. If you have a GEN II housing then it directly replaces the stock unit and if you have a first GEN I have made sleeves available so it will be the same as a GEN II.
I've posted data logs on mud and their links here so you can see how the different housings compare to 3 stock units and how the ECU responds to altering fuel pressure.
You have a stock MAF and one of my housings so you can measure the ID of the chambers yourself.
If you are not comfortable with the MOD I would suggest that you don't use it.
alia176
SILVER Star
Yeah, I did the same thing as well - changed all hoses. However, it's a simple thing to check and cross off the list.
I met with Mike (clownMidget) tonight and gave him 2 knock sensors, ecu and a crank sensor. I suggested that he shot gun all of them in and let me know the results. I might be traveling further west and could spend a night in Ithaca on the return trip to look over his truck one night with him.
I wish I had brought more diagnostic gear with me.
I wish I had brought more diagnostic gear with me.
alia176
SILVER Star
knowing Mike, you probably could've just brought him your 80 and left it there for him to part swap and experiment with
I don't know about that, but Rick did have an intriguing theory on the data that you worked on your 97, your 96 and my 95.....?!?!? Coincidence?
alia176
SILVER Star
There's some truth to that, EXCEPT, you assembled YOUR engine .
TrickyT
Hate that mud...
I'm missing the association between vacuum leak and knock sensor malfunction code. What's your line of thinking that ties these things together?
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knowing Mike, you probably could've just brought him your 80 and left it there for him to part swap and experiment with
I really don't think that adding another truck to the list of trucks with a knock code is very productive.
I'll be available Thursday night for wrenching.
Ok, switched out the knock sensors, the crank position sensor and the ECU. I'm going to post my pics on my knock sensor thread https://forum.ih8mud.com/80-series-tech/544876-cel-p325-330-knock-sensors.html#post7260253 but so far with 4 start cycles and driving it ~5 miles with engine rpms from 2-4K, no CEL!
Unfortunately it look likes any one of my components could be to blame and I was too rushed to try this one at time.
Unfortunately it look likes any one of my components could be to blame and I was too rushed to try this one at time.
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fzjconvert
one hand, two ducks
I'm still with the filter as the cause... To date I have indtalled Rick's sleeve , reconeted the FPR and all is well!
I will tell you this I even run a proto type oiled filter that is the exact same size as a factory filter. That said, I have yet to throw the PO 171 code since I changed the fuel filter and the above!
Side note: With Rick's sleeve and the above mentioned air filter. I have a 210,000+ moter that I rev the shart out of way past the 5,000 point of no return and it just asks for more!!! I can't wait until I rebuid and go forced.
Amyhow that's what wored for me ! NLXTACY you are not far from 20 . I'd be glad to help, shoot me a PM next time you are in town...
I will tell you this I even run a proto type oiled filter that is the exact same size as a factory filter. That said, I have yet to throw the PO 171 code since I changed the fuel filter and the above!
Side note: With Rick's sleeve and the above mentioned air filter. I have a 210,000+ moter that I rev the shart out of way past the 5,000 point of no return and it just asks for more!!! I can't wait until I rebuid and go forced.
Amyhow that's what wored for me ! NLXTACY you are not far from 20 . I'd be glad to help, shoot me a PM next time you are in town...
