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Topic What are you using to read the values? |
P1128 and P1130 head scratcher John from MN - 6 years ago |
Re: P1128 and P1130 head scratcher Ed B - 6 years ago |
Possible culprits Boxsterra - 6 years ago |
We are in the same boat. Just yesterday afternoon... MarcW - 6 years ago |
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John from MN
Interestingly, I did try the techron many miles ago and the light went off, BUT returned 500 miles later. I've tried everything suggested here, but nothing works - hence the mystery. The car seems to be running perfectly and the dealer says there are no leaks, exhaust, intake, or otherwise. They say to keep driving it and that it won't the car. All the data looks fine, trim level etc. The only thing I can think of is the non oxy gas, if that's not it I have no idea what else it could be.
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John from MN
in MN, Non - Oxy is available mostly for boats, classic cars, and small engines, but it's tougher to find. I'm lucky in that I have 3 stations near me that carry it. I've been using it in the Boxster because I feel it's better for the car than ethanol. I can find the ethanol blend in Top Tier and boost the octane to 92, non top Tier I can find at 93. But it sounds like the consensus is that the gas isn't the culprit. Based upon what you and Boxstera have mentioned, I have tired the Techron, but I haven't used a second bottle. I'll start with the second bottle. If that doesn't work I'll try a few tanks of regular ethanol Top Tier to see if that impacts it. If that doesn't work, I'll go back to cleaning the MAF again - is it possible the MAF needs to be replaced entirely at 44K?
Also tomorrow, I'll take Pedro's advice and check the fuel pressure, although historically, the fuel trim levels have checked out fine.
Finally, I used to on PPBB and it's great to see so many familiar names and it's also great to see you are all just as helpful as before. I need to spend more time here.
Thanks for your help!
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JMstamford,ct
The MAF seems the most obvious culprit. I am a little surprised the dealer has not checked that.
To satisfy your self, either replace - it is a very easy job. Or find a known good one and swap.
Re: My freeze frame numbers.. John from MN - 6 years ago |
Re: My freeze frame numbers.. MarcW - 6 years ago |
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John from MN
Coolent temp: 215.6
Fuel Trim LT1: 5.47%
Fuel Trim LT2: 4.69%
Fuel Trim ST1: -4.69%
Fuel Trim ST2: -1.56%
I must have been idling, RPMs 680 and speed zero
These are normal numbers Boxsterra - 6 years ago |
Re: These are normal numbers MarcW - 6 years ago |
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Boxsterra
TL;DR Try swapping your MAF with someone else's. If it fixes the problem, you know what to buy. Don't spend over $200 for a replacement.
Here are some fuel trim concepts that may help:
- Positive means it's adding fuel (you'd think it would mean it's "trimming fuel" but that would be too easy to remember)
- Short-term fuel trims are additive with long-term ones. So if you have positive LT and an equal negative ST then your car is running with no net trim.
- Not all leaks are constant. Some depend on the heat of the car, the outside temperature, the pressure/vacuum of the exhaust/intake.
- Fuel trims will vary under normal circumstances. This is because trimming is a reactive adaptation (O2 sensors feeding back mixture data post-combustion)
You have a lean condition (that is the meaning of P1128/P1130). This can be caused by:
- MAF is reporting the wrong number (common Boxster problem)
- Intake leak is letting unmetered air into the system
- Leak in exhaust before O2 sensor makes the car think it's running leaner than it actually is
- Fuel system isn't delivering enough fuel (fuel pump / fuel injectors / fuel lines are faulty/clogged)
The reason I suggested using Techron was not that it was most likely to solve the problem but because it is super easy.
If you want to know if the problem is the MAF, then look at the MAF air flow values at idle and 3000 rpm.
Idle: 12-24 kg/h
3000 rpm: 50-80 kg/h
There are many common intake leaks on the Boxster, including the oil filler tube, dipstick tube, AOS, and anything that was recently touched during service.
What are you using to read the values? Boxsterra - 6 years ago |
"Mass Air Flow Rate" *NM* Boxsterra - 6 years ago |
Those numbers are not what they're supposed to be Boxsterra - 6 years ago |
Be careful that you get teh correct MAF. JM-Stamford,CT - 6 years ago |
Depends on the "lesser known brand" Boxsterra - 6 years ago |
What year is your car? Boxsterra - 6 years ago |
After 2 tanks of techron fuel system cleaner and cleaning MAF twice - the CEL has gone off John from MN - 6 years ago |
Cool, keep us posted *NM* Boxsterra - 6 years ago |
Re: After 2 tanks of techron fuel system cleaner and cleaning MAF twice - the CEL has gone off MarcW - 6 years ago |
Both of those code indicate ... Pedro (Odessa, FL) - 6 years ago |
Re: your assumption was right, techs checked "everything" and said there was no reason the codes John from MN - 6 years ago |
Re: your assumption was right, techs checked "everything" and said there was no reason the codes Petee_C - 6 years ago |
From experience I know gasoline can play a role in some error codes. When I switched from Rotten... MarcW - 5 years ago |
Re: From experience I know gasoline can play a role in some error codes. When I switched from Rotten... Alcantera - 5 years ago |
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MarcW
Robbie gasoline (discount gasoline) to Shell V-Power an intermittent P0430 appeared less frequently.
However, the P0430 error didn't go away entirely.
Then after a few years when I switched from Shell V-Power to Chevron Supreme while the error code didn't become any less or more frequent the Boxster engine perked up some. This is from the better detergent (Techron) in Chevron gasoline.
To permanently eliminate the error code took having the bad converter, bad due to a loose brick, replaced.
You can continue to run whatever gasoline you believe helps the engine run better. While my Boxster engine reacted favorably to Shell then Chevron the Turbo seemed to like Shell V-Power. (My two current cars, a JCW and a Hellcat, the JCW turbo-charged, the Hellcat supercharged, both appear to like Shell V-Power. The difference is not striking but real. However, not enough of a difference to cause me to pay the 20 cents or more premium for Shell V-Power compared to the gasoline sold at a nearby Quik Stop. Now, I do more often than not fill up at a Chevron station (or just yesterday a 76 station) on the way to work, these stations are near work and happen to sell gasoline at about the same price as the Quik Stop station near me, so both cars don't exist on just discount gasoline entirely.)
Anyhow, while I hope I'm wrong, I believe the error code will reappear however.
As for the P1128 I have no real additional helpful info to add. Just an update on my experience dealing with a persistent P1128. Briefly, in the case of my Boxster a new MAF didn't address the cause of a P1128 error code. A Porsche tech found no intake air leaks but did find a couple of loose leaves in the filter air box and removed them, cleaned the throttle body, and while the engine ran better the P1128 would return.
A different dealer kept the car nearly 30 days and tried a couple of things, including replacing the 30K mile AOS with a new one, which was not the problem. (The new AOS was removed and the "old" AOS replaced and I was not charged for this new AOS or the labor to install then uninstall the new AOS.)
After 30 days I was told the problem could be from a number of places/areas, with perhaps the secondary air injection the primary area of suspicion, but I would essentially have to leave the car with the Porsche service department and hand over a blank check. The service department told me the engine might require dropping even partially disassembly to find and fix the problem. At 317K miles and needing a new clutch (the original one had finally reached the end of its service life) I decided not to throw what could possibly be $5K to $7500 or more at the car and got rid of the car.
Re: From experience I know gasoline can play a role in some error codes. When I switched from Rotten... Alcantera - 5 years ago |