P1128 P1130, MAF cleaning and more

[hucqym]

Hi,

I've had P1128/P1130 come on a while back on my 2001 boxster (94K miles). Digging a bit on the forum and following mike focke's guide on MAF cleaning, I tried that out and drove around. The codes came back again. To check if the MAF has gone completely bad, I disconnected the wiring, reset the codes and drove around a little and this time P0102(MAF) and a little later P0112(intake air temp sensor) came on. I guess both are only indicating that my MAF is disconnected.

Now the question is, is this convincingly a case of bad MAF and in need of replacement? How do I test if the MAF is really bad ..some multimeter test perhaps?

Also what goes bad in a MAF? Is that a diode i see outside? Can I replace just that? I have the durametric kit, in case I could learn something from the live data?

Another annoying issue I've been noticing. at idle engine rpm is around 900 but then after the engine is a little warm and when i stop at a red light, the rpm shoots up arbitrarily to 1600-1800 and then back down without my foot on the gas (let me know if there is a apt jargon for this behavior).

I also suspect some coolant disappearing every now and then (its may be just bleeding since I had coolant overflowing, replaced reservoir cap and had topped it up). Some smoke at startup but havent ever noticed it while running. A lot more smoke at startup when I was experimenting with MAF disconnected.

[N41EF]

I've had more MAF issues on my VW than the Boxster, but here's what I know. As a MAF goes bad it may or may not throw codes, but what you notice is idle inconsistentcies and I had a loss of power with no codes.

From my understanding, the MAF measures air flow into the engine by heating a wire in the air stream and measuring how much current it takes to keep it hot. As the MAF ages, strange things start to happen. On one of my VW's it started thinking there was less air flow than actual, so started running lean. I know VAG-Comm can measure MAF air flow compared to air flow desired, not sure if durametric can, but that's the first thing I would check. I checked the MAF flow at idel, on acceleration, and at 3k RPM in cruise, that's where mine started showing bad, wasn't telling the computer that as much air flow was there.

I've also had a MAF show more air flow, I assume because the MAF had aged and it took more current to keep the wire hot, so the computer thought there was more air, and it made the car run very rich.

A surging idle might be indicative of an intake air leak, and the idle will surge with one because the electronic idle circuit will hunt becasue you are getting more air flow than it thinks it is letting in.

Some people have had success with buying just the MAF element instead of the element and housing. VW guys have posted the Bosch part number for most VW elements, you might look around and see if you can find it for your Boxster.

If you have someone close with a similar car you might try swapping them to see if the codes come back. When you clean it with MAF cleaner make sure it is completely try before you turn it on. Also, it helps to disconnect the battery when you play with the MAF, cleaning it or changing it will change the computer inputs, unless you have the ability to re0initialize the computer, it may take several drive cycles for the computer/MAF etc to get used to each other.

Just my opinion, YMMV. Chuck

[hucqym]

Thanks for the info Chuck. So I tried to experiment with durametric's actual values on MAF sensor voltage and air flow. Hooked up my laptop and took it for a spin (20 odd miles) the code hasnt come back on. On earlier occasions, it came back by then. One guess is your point about the computer still being confused about the values since I hadn't disconnected the battery after cleaning/replacing the MAF, and probably now its gotten it right.

The logged actual values seem to be more or less fine. flow ranging between 10 to 130 with the corresponding voltage between 1.25 to 2.7 and corresponding rpm ranging between 750-2500. If the CEL comes back again, i'll test more, especially the cruise at 3k+ that you mention.

On the other hand, I'm thinking if it is not the MAF at all but a vacuum leak that is my real problem? That would explain the idle surge. could it also possibly trigger P1128/P1130?

[mikefocke]

Recall in my writeup

that there must be at last a half dozen causes that lead to the same symptoms/codes. Only by following the flow chart and checking item by item can you determine which one is the true cause. This makes sense when you think that a sensor can be reporting the correct fact but what caused the excess air to be reported may well not be the sensor but something else like a leak which caused there to be truly excess air.

Know anyone who would loan you his MAF for an afternoon? A temporary swap would rule the MAF in or out.

When you did the fluids replacement in your coolant tank, did you burp the cooling system? Evacuate the air trapped in the system with a machine designed to do that? Run with the pressure relief valve open for a day or two?

[hucqym]

Thanks for your reply Mike. I dont know anyone personally with a porsche around to swap test a MAF.

I do have some updates.

It does look like yesterdays drive probably threw up the fault codes (P1128/P1130) again. I was deceived by the fact that the CEL did not come up also (would there be a lag between the fault codes being generated and CEL coming up?).

I also checked for suction at the oil top-up port in the rear trunk and that was indeed slightly difficult to open due to excess pressure and a clearly evident suction could be felt when I placed my palm on the mouth. I think I'm also noticing an increased startup smoke. AOS issue?

[hucqym]

Also what is P1128/P1130 saying exactly? I've seen the table on renntech and the title doesnt make too much sense to me. My bentley guide says "short to B+/above upper limit/rich mixture threshold"

As I understand, these codes are coming from the O2 sensors. So is the "above upper limit" saying there is too much oxygen (and hence air) or is the "rich mixture" saying there is more fuel than the required stoichiometric ratio?

[Loren]

Also what is P1128/P1130 saying exactly? I've seen the table on renntech and the title doesnt make too much sense to me. My bentley guide says "short to B+/above upper limit/rich mixture threshold"

As I understand, these codes are coming from the O2 sensors. So is the "above upper limit" saying there is too much oxygen (and hence air) or is the "rich mixture" saying there is more fuel than the required stoichiometric ratio?

P1128 Oxygen Sensing Adaptation, Idle Range, Bank 1 – Above Limit

P1130 Oxygen Sensing Adaptation, Idle Range, Bank 2 – Above Limit

Possible fault causes:

– Incorrect signal from MAF sensor

– Intake air system leaking

– Fuel pressure too low

– Volume supply of fuel pump too low

– Fuel injectors fouled

– Exhaust system leaking

Bottom Line - in most cases we are looking at an air leak or a bad MAF. If the MAF is bad then it is sending the wrong signal to the DME.

Further diagnosis has been covered here many many times.

[RolfHarris]

Hi,

I've had P1128/P1130 come on a while back on my 2001 boxster (94K miles). Digging a bit on the forum and following mike focke's guide on MAF cleaning, I tried that out and drove around. The codes came back again. To check if the MAF has gone completely bad, I disconnected the wiring, reset the codes and drove around a little and this time P0102(MAF) and a little later P0112(intake air temp sensor) came on. I guess both are only indicating that my MAF is disconnected.

Now the question is, is this convincingly a case of bad MAF and in need of replacement? How do I test if the MAF is really bad ..some multimeter test perhaps?

Also what goes bad in a MAF? Is that a diode i see outside? Can I replace just that? I have the durametric kit, in case I could learn something from the live data?

Another annoying issue I've been noticing. at idle engine rpm is around 900 but then after the engine is a little warm and when i stop at a red light, the rpm shoots up arbitrarily to 1600-1800 and then back down without my foot on the gas (let me know if there is a apt jargon for this behavior).

I also suspect some coolant disappearing every now and then (its may be just bleeding since I had coolant overflowing, replaced reservoir cap and had topped it up). Some smoke at startup but havent ever noticed it while running. A lot more smoke at startup when I was experimenting with MAF disconnected.

Hi

Did you ever resolve the problem, as I have the same P1128 and P1130 with poor engine performance?

Thanks

Rolfy

[hucqym]

Hi

Did you ever resolve the problem, as I have the same P1128 and P1130 with poor engine performance?

Thanks

Rolfy

Yes I did. Sorry that I did not update on the post. It turned out it had nothing to do with the MAF. My AOS had blown and everything has been good after I had that replaced. Unfortunately I had to take it to a shop as reaching it while having the car on a jackstand was a quite a task and I gave up after an hour or so of struggling. The shop charged me $450 for labor which was pretty annoying.

Which also brings me to an unrelated question to this post, are there places where one can rent a shop/lift/some tools by the hour and work on their own?

[RolfHarris]

Hi

Did you ever resolve the problem, as I have the same P1128 and P1130 with poor engine performance?

Thanks

Rolfy

Yes I did. Sorry that I did not update on the post. It turned out it had nothing to do with the MAF. My AOS had blown and everything has been good after I had that replaced. Unfortunately I had to take it to a shop as reaching it while having the car on a jackstand was a quite a task and I gave up after an hour or so of struggling. The shop charged me $450 for labor which was pretty annoying.

Which also brings me to an unrelated question to this post, are there places where one can rent a shop/lift/some tools by the hour and work on their own?

THANKS for the update..

The Air Oil separator, is there a definitive way of diagnosing this as the cause of my lack of power and rough running?

I did have a lot of smoke when it start up and started running rough? did clear away though, I do know thats a symptom of the AOS problem.

mmm I think I'll start with the MAF clean tomorrow, have a visual inspection of the AOS and then go from there.. sounds like a plan?

thanks again

Rolfy

[RolfHarris]

ALSO mine is a UK spec car, will that make a difference?

cheers

Rolfy

[hucqym]

THANKS for the update..

The Air Oil separator, is there a definitive way of diagnosing this as the cause of my lack of power and rough running?

I did have a lot of smoke when it start up and started running rough? did clear away though, I do know thats a symptom of the AOS problem.

mmm I think I'll start with the MAF clean tomorrow, have a visual inspection of the AOS and then go from there.. sounds like a plan?

thanks again

Rolfy

With the engine idling, try taking oil filler cap out in the trunk. you might find it a little stiff if there is excess pressure due to an air leak (possible sign of AOS failure). Once you have it open place a palm on the mouth and feel for suction. I could distinctly feel it in my case. Now technically that may mean air leak anywhere in the intake system but combined with your excess smoke at startup, I would guess AOS. A little more extensive check is to look for oil deposit in the throttle body. That, I am told, is a conclusive test.

Search for a whole bunch of threads and info on AOS on this site. The part itself is not expensive and a lot of people manage to swap it on their own. I didnt.

[RolfHarris]

OK New update:

Engine is misfiring bad now! More than a MAF problem..

Yesterday I had cleared the codes, and took on a drive this morning and when cold it would hardly run.. Check Engine light flashed then stayed solid.. new set of codes!

1. P0300 Misfire Detection

2. P0306 Misfire Cylinder 6

3. 04889 P1319 Knock Sensor (KS1) circuit G6 1:Short to ground

4. 0488 P1318 Cylinder 14 Ignition Circuit Limit attained

also found an invoice for the this car (I've just purchased the Boxster this last week) all 6 spark plugs and ignition coil packs were replaced on December 02 2008 but only 9,000 miles ago

All my running problems started AFTER I cleared some codes (P1128 and P1130) with the Launch X431 Diagun... Only hooked it up to see if it works with a Porsche Boxster 986

Have I deleted some adaption values or ruined an ECU, I managed to drive it to a Porsche Specialist that is 5 miles away, Told him all the info he said that Porsche have been known to change the pin configuration in the DLC3 connectors and may have damaged something... If I had fried an ecu then I wouldn't be able to drive it would I?

what's your thoughts?

Thanks

Rolfy

[hucqym]

I did have some misfire code turn up at one point too. I had ordered the part but kept driving around (after resetting P1128/P1130) till that came in and I guess it wasnt such a great idea to be running with a bad AOS. So after this happened, I brought it home and then waited till AOS got replaced before driving it again. Bottom-line: possibility of bigger problems while running on a bad AOS.

I am not an expert and can only help share my research/experience on the issue I faced. I'll let the more experienced folks answer your other questions. But logically thinking - a wrong pin configuration would have probably messed up your system even before you could read codes and reset so thats unlikely but I am just thinking aloud here.

Good luck

[RolfHarris]

I did have some misfire code turn up at one point too. I had ordered the part but kept driving around (after resetting P1128/P1130) till that came in and I guess it wasnt such a great idea to be running with a bad AOS. So after this happened, I brought it home and then waited till AOS got replaced before driving it again. Bottom-line: possibility of bigger problems while running on a bad AOS.

I am not an expert and can only help share my research/experience on the issue I faced. I'll let the more experienced folks answer your other questions. But logically thinking - a wrong pin configuration would have probably messed up your system even before you could read codes and reset so thats unlikely but I am just thinking aloud here.

Good luck

Thanks for the reply!

I will let you know the outcome ... Knowledge is power..

Rolfy

[RolfHarris]

I did have some misfire code turn up at one point too. I had ordered the part but kept driving around (after resetting P1128/P1130) till that came in and I guess it wasnt such a great idea to be running with a bad AOS. So after this happened, I brought it home and then waited till AOS got replaced before driving it again. Bottom-line: possibility of bigger problems while running on a bad AOS.

I am not an expert and can only help share my research/experience on the issue I faced. I'll let the more experienced folks answer your other questions. But logically thinking - a wrong pin configuration would have probably messed up your system even before you could read codes and reset so thats unlikely but I am just thinking aloud here.

Good luck

Thanks for the reply!

I will let you know the outcome ... Knowledge is power..

Rolfy

UPDATE

I have replaced the MAF, cleared all the codes and now is running like a dream!

The MAF had caused all the drive-ability problems and Missfire codes..

Now having the clutch replaced has I have a "Heavy Pedal"

I purchased the Boxster at Auction to sell on.. This will be in tiptop condition with a warranty once the clutch is replaced and also while I'm there I will be replacing the rear main seal as well "Not leaking but should replace while the clutch is out" as they are prone to leaking..

I'll keep you posted ...

Rolfy

[hucqym]

Thanks for the update and nice job. Do make sure you check for codes again after about 50 miles or so. I was deceived after my MAF cleaning as the CEL did not light up but the codes showed up when I checked with my scanner.

Happy boxtering!

[RolfHarris]

Thanks for the update and nice job. Do make sure you check for codes again after about 50 miles or so. I was deceived after my MAF cleaning as the CEL did not light up but the codes showed up when I checked with my scanner.

Happy boxtering!

To day was a beautiful sunny day here in the UK and as I've never really driven a Boxster I went a little 100+ mile drive today roof down and decent tunes on the radio "Car is sweet to drive" I really did enjoy it today...

Could see my self keeping this one, well maybe for the summer!

[Wayne R. Dempsey]

Now having the clutch replaced has I have a "Heavy Pedal"

Before you spend hundreds if not thousands of dollars on a clutch replacement, you may want to check out your clutch hydraulics first. They are easy to replace (relatively), and may fix the problem (see info on clutch hydraulic troubleshooting here: http://www.pelicanparts.com/techarticles/Boxster_Tech/45-TRANS-Clutch_Hydraulics/45-TRANS-Clutch_Hydraulics.htm . Usually, I have found that clutch pedal problems are not typically related to the actual clutch mechanism, but instead are related to problems with the pedals, and/or the master/slave cylinders. When a clutch fails, you will often find that the car slips in gear, or the clutch engages, and will not let out, or you will get through-out bearing noise. Sometimes a pressure plate that's on its way out will cause a "heavy pedal" but not that often.

Hope this helps,

Wayne

[RolfHarris]

Now having the clutch replaced has I have a "Heavy Pedal"

Before you spend hundreds if not thousands of dollars on a clutch replacement, you may want to check out your clutch hydraulics first. They are easy to replace (relatively), and may fix the problem (see info on clutch hydraulic troubleshooting here: http://www.pelicanparts.com/techarticles/Boxster_Tech/45-TRANS-Clutch_Hydraulics/45-TRANS-Clutch_Hydraulics.htm . Usually, I have found that clutch pedal problems are not typically related to the actual clutch mechanism, but instead are related to problems with the pedals, and/or the master/slave cylinders. When a clutch fails, you will often find that the car slips in gear, or the clutch engages, and will not let out, or you will get through-out bearing noise. Sometimes a pressure plate that's on its way out will cause a "heavy pedal" but not that often.

Hope this helps,

Wayne

Hi Wayne

The problem is not a hydraulic with mine it's the Pressure plate, The fingers on the pressure plate has lost there tensile springiness... I have come across this before with other makes of cars..

I also spoken with the local Porsche specialist to me and he states this is common for the 986 Boxsters if they have done a lot of town / city driving through out the years...

I got the parts for £212.09 all in (SACHS kit) then having fitted for £300 labor that includes VAT as well..

Thanks for all the reply's !

Rolfy

[hucqym]

so after over a year of happy boxtering I am back on this thread! :)

The last time it turned out to be AOS and I had replaced it with genuine/OEM part from sunset.

Since then, I've changed oil, brakes, tires and a waterpump.

Recently I had P1128 come up and I cleared it once to see if it comes back again and kept monitoring for any unusual signs.

I do sometimes hear a faint high pitch sound at first start in the morning and then as I drive out of my street it fades away. Its not something that comes at low rpm or something but just first in the morning.

After about another 50 or so miles, CEL came back on again last week and this time the codes were P1128, P1130, P1126 and P1133

I dont have any excess smoke at startup or something and besides my AOS is just a year old so that doesnt look a likely candidate this time.

Strange thing was my engine wouldnt start next day morning. I left it as is and returned to it this weekend. It started up ok.

I checked for live values of MAF sensor (at idle - about 800rpm) using my durametric kit:

MAF sensor value: 1.3V

MAF - 16.2 kg/h

I roughly recall that this is what I had observed last time. Can one say if these values rule out the MAF as the problem or not?

I checked the oil filler port in the trunk and do see some deposit on it which doesnt look like oil (coolant mixing perhaps?). Attaching picture of that

I can distinctly feel suction there and can infact even hear it hiss. So i guess my problem is leak in the intake system?

Now can someone tell me what are the typical places I can visually check for leaks? Could it be the AOS again?

Also the engine starting problem returned. I couldnt start it again after that first time. As for background, I have swapped my halogen headlights out for stealth auto HID upgrade.

It worked fine for a while but off-late I was noticing that the headlight wouldnt turn on immediately. I would have to drive for a while and then try again and it would turn on.

This made me suspect an independent battery trouble and so I took it out now and got it recharged at autozone and they confirmed it was drained and returned saying it is now good and charged.

I put it back in and measured with a dmm and it was about 12.7V. I tried starting and it wouldnt start again. I measured again and it was back to around 12.1

seems like something is draining the battery rapidly?

Any chance that my two problems are connected?

[BoxsterTaff]

I'm not sure about the 'gunk' at the filler cap (maybe mixing coolant but i'm no expert) but I recently went through similar codes - see this thread:

I also had a 'hissing' noise - checked all the vaccum lines, took apart and cleaned the TB and intake, new AOS and MAF and eventually found the hissing was a split oil filler tube....was pretty loud. Another good couple of tricks for finding an air leak ar to spray Carb cleaner (careful, it flamable so do this at your own risk) on the intake pipe joints etc, if there is a leak the engine will rev up, or take a length of hose pipe (say 3-4 ft), and use it like a stethescope.....sounds dumb but its how i found the leak on the oil intake! :rolleyes:

[hucqym]

Thanks for the suggestion but I really am stuck because the engine wont start and so cant look further.

I cleaned the TB (didnt need much cleaning since the last time I did before chaging AOS - a year ago), cleaned MAF.

oil filler tube (996-107-273-04) looks fine with any cracks

wasnt able to get the oil hose (996-107-254-03) out but the end connecting to the lower hose looks fine. was a lot dirty, cleaned it and put it back. sits snug alrite.

Cant get to the other end, near the filler tube so cant take it off completely.