Several P-Codes. Whataya think?

[deliriousga]

Ok, I'm still working on the same no acceleration problem, but I have more info (and corrected info) now. The first P-code I got was P1502. After checking the book again, I noticed I was looking at the DME 5.2.2 list instead of the 7.2 that is in the '00 model so the code explanation was wrong. Here's what I've done so far, and the new codes I'm getting.

1) P1502=Fuel pump relay output stage. Short to B+ / above upper limit / rich mixture threshold. I replaced the fuel pump relay, but still have the problem.

2) After replacing the fuel pump relay, I started it and plugged in the AutoTap to watch what happens. One thing I noticed was the mass air flow rate was ~1.4 lb/min while it was idling at 970-1000 rpm. I watched for a little while and waited for error codes to pop up. The new codes were P1502, P1115 and P1119.

3) P1115=Heating of O2 sensor, cyl. 1-3 and P1119 is the same for cyl. 4-6 so I'm thinking clean the MAF.

Here's the freaky part. I cleared all of the codes then suddenly everything worked beautifully. Suddenly I hit the gas and it jumped to 5K rpm, idled at 700rpm, everything is normal again. Shut her down and restart, and it's back to the problems again.

I pulled the MAF and it was pretty dirty. I cleaned it with electronics cleaner and let it dry then put it back in and cranked her up. Still runs crappy and won't accelerate above 2K rpm.

So, before I order a new MAF at $300+ is there anything that comes to mind that I should try first?

TIA!!

[98Boxster98]

Actually, I think you had it right the first time P1502 for DME 5.2.2 is the fuel pump relay. For MY2000, It's DME 7.2.

You're problem sounds suspiciously like the one in this thread:

http://986forum.com/forums/showthread.php?t=6197

[blinkwatt]

Originally Posted by deliriousga

So, before I order a new MAF at $300+ is there anything that comes to mind that I should try first?

TIA!!

Thats a little high. Steve at 986online sold me my non e-gas MAF for $232 shipped to my house.
I had a similiar problem when my MAF was going bad,every once and while it would the acceleration would freeze for a second or two in the 2k-3k rpm range,but nothing like you state.

[insite]

Originally Posted by deliriousga

I pulled the MAF and it was pretty dirty. I cleaned it with electronics cleaner and let it dry then put it back in and cranked her up. Still runs crappy and won't accelerate above 2K rpm.

So, before I order a new MAF at $300+ is there anything that comes to mind that I should try first?

TIA!!

if your maf reading was only like 1.4 then you have two possbilities:
1. bad MAF
2. vacuum leak

unplug your MAF and go for a drive. when no MAF signal exists, the car goes into a default map mode. it should run much better than you remember. if that happens, you can bet you need the MAF.

[deliriousga]

Originally Posted by insite

unplug your MAF and go for a drive. when no MAF signal exists, the car goes into a default map mode. it should run much better than you remember. if that happens, you can bet you need the MAF.

Thanks insite! I unplugged it and everything worked beautifully. The new MAF will be here tomorrow and we'll be back on the road.

[deliriousga]

I replaced the MAF, but still no go. It runs great the first time when the MAF is unplugged, but the second time you start it with it unplugged it's back to bad. I guess O2 sensors are next.

[insite]

Originally Posted by deliriousga

I replaced the MAF, but still no go. It runs great the first time when the MAF is unplugged, but the second time you start it with it unplugged it's back to bad. I guess O2 sensors are next.

man, that's rough. what codes are being thrown now? disconnect your battery for a few minutes and go for a cruise ('till the MIL comes on). then post your long term and short term fuel trims and your O2 readings (if you have a scanner)

[deliriousga]

Originally Posted by insite

man, that's rough. what codes are being thrown now? disconnect your battery for a few minutes and go for a cruise ('till the MIL comes on). then post your long term and short term fuel trims and your O2 readings (if you have a scanner)

I will try that tomorrow and post the readings. I'm going to pull the O2 sensors too and test them (via the Jim testing method) to see what happens.

Thanks!

[deliriousga]

Originally Posted by insite

disconnect your battery for a few minutes and go for a cruise ('till the MIL comes on). then post your long term and short term fuel trims and your O2 readings (if you have a scanner)

I disconnected the battery, reconnected and took her for a 40 mile drive to the dealer to get some screws today while having the OBDII scanner record everything on my laptop. Here's what was recorded:

Long Term Fuel Trim: -0.8% on both banks, never changed under any load.

Under Higher Load
Short Term Fuel Trim: On the highest load (68.2%, 4675rpm@91mph) the short term fuel trim was -1.6% on bank 1 and -3.1% on bank 2. The breakdown was 0% bank 1, sensor 1, 99.2% bank 1, sensor 2, -3.9% bank 2, sensor 1, 99.2% bank 2, sensor 2.
O2 Sensors: Bank 1, sensor 1 795mV, bank 1 sensor 2 820mV, bank 2 sensor 1 790mV, bank 2 sensor 2 830mV.
Timing Advance: 22.5 degrees.

At Idle with rough idle & MAF plugged in
Short Term Fuel Trim: On idle load (6.7%, 896rpm) 0% on both banks. The breakdown was 0% on banks 1&2, sensor 1 and 99.2% on banks 1&2, sensor 2
O2 Sensors: Bank 2, sensor 1 45mV, bank 1 sensor 2 60mV, bank 2 sensor 1 170mV, bank 2 sensor 2 35mV.
Timing Advance: -8.5 degrees.

I have several other readings if they will help. I ordered new O2 sensors since I have 82K on the clock and they should last about 60K miles. It seems like with the MAF plugged in the flow rate is very high at idle (1.5 lb/min @ 896rpm) compared with the normal idle (.657 lb/min @ 697rpm).

Any other ideas of what to check besides O2 sensors?

TIA!

[insite]

i'm confused. go ahead and post all of your readings. for clairity, when you say:

Short Term Fuel Trim: On the highest load (68.2%, 4675rpm@91mph) the short term fuel trim was -1.6% on bank 1 and -3.1% on bank 2. The breakdown was 0% bank 1, sensor 1, 99.2% bank 1, sensor 2, -3.9% bank 2, sensor 1, 99.2% bank 2, sensor 2.


i'm interpreting:

when the engine load was 68.2%, short term trims were -1.6 and -3.1.
i'm not sure what you mean when you say the 'breakdown' was 0% bank 1 sensor 1, 99.2% bank 1 sensor 2. i'm not sure what the percentage readings you're providing me for the o2 sensors mean.


in the meantime, you mention rough idle. do the follwing before you buy anything else:

1. clean your idle air control valve
2. check for vacuum leaks. obvious culprits are the bellows tube below the oil separator and the oil filler tube

post the rest of your numbers and we'll see what we can figure out.

[deliriousga]

Originally Posted by insite

i'm confused. go ahead and post all of your readings. for clairity, when you say:

Short Term Fuel Trim: On the highest load (68.2%, 4675rpm@91mph) the short term fuel trim was -1.6% on bank 1 and -3.1% on bank 2. The breakdown was 0% bank 1, sensor 1, 99.2% bank 1, sensor 2, -3.9% bank 2, sensor 1, 99.2% bank 2, sensor 2.


i'm interpreting:

when the engine load was 68.2%, short term trims were -1.6 and -3.1.
i'm not sure what you mean when you say the 'breakdown' was 0% bank 1 sensor 1, 99.2% bank 1 sensor 2. i'm not sure what the percentage readings you're providing me for the o2 sensors mean.

I'm not sure what the percentage readings are. They are listed as fuel trim readings and not listed as O2 sensors.

Originally Posted by insite

in the meantime, you mention rough idle. do the follwing before you buy anything else:

1. clean your idle air control valve
2. check for vacuum leaks. obvious culprits are the bellows tube below the oil separator and the oil filler tube

post the rest of your numbers and we'll see what we can figure out.

I will check again for vacuum leaks. I don't think that's the issue this time since the problem goes away immediately when I clear the codes. I'll clean the IACV too and make sure there is nothing freaky going on with that. I'll post the results as soon as I get to these. I'm working on the clutch in the 928 today so we have two cars running again.

Thanks!

[insite]

good deal. let me know if you need a hand.