http://putstuff.putfile.com/63772/5103896/3

Car is throwing Code 48- MAF

Here is the .csv file http://putstuff.putfile.com/63799/7486151/3

Can someone tell me pleeeeeeeeeeeease why my car dies like it does? I am so excited I finally got this thing scanned. Thanks!!

Oh and the re-cap thread here http://web.camaross.com/forums/showthread.php?t=485391

 

I got the .csv file, and you left out too many columns (left O2 mV, CLT, Rt Long Term, Rt short term, etc). So I tried the .uni file since I happened to be in my office this a.m.

Your scan rate is way too low.... you scanned for 4 minutes and only got 324 frames of data, a little more than one frame per second. You want closer to 10 frames per second to see what's going on. And the last 130 frames are not useful, because it appears the engine is not running but the key is on.

Were you goosing the throttle to keep it from stalling? Every time you did that, you got knock retard. Since the interval between frames is so long, I can't see what is happening that causes you to have to push the accelerator to keep it running, if that's what you were doing. I can't see any evidence that the idle is changing just before you open the throttle to keep it from stalling.

You have constant knock retard when you put it under load and push it up to 3500rpm/29mph. I'm almost wondering if you have cross-firing in the wires embedded in the Opti cap.

You have a DTC 48 for MAF system failure. The MAF sensor appears to be working and the numbers look OK, so it must be a stored code. Might want to clear it before your next log.

In the idle Cell (16) its pulling out all the fuel it possibly can with the long term corrections (108 on both sides). Appears it would be running excessively rich without the corrections. The ST's seem to be able to compensate, but you need to find out why the PCM is pulling out 15% fuel at idle. Could it be the O2 sensors are damaged?

When did you reset the PCM? When you go to the other cells, they are closer to 128 or right at 128, but is appears the short terms are pulling fuel. That would indicate the PCM may have been reset recently, and the cells other than the idle cell have not had time to stabilize. In general, don't reset the PCM before you do a data log, if that's what you did.

The IAC counts are bottomed out at "0" in the beginning when its idling. Its holding 800 RPM, which is the stock idle program for an M6. But the IAC shouldn't be bottomed out. It should be in the range of 20-40. May be getting air from somewhere else, but that would show up as higher than 128 LT's and yours are bottomed out. Around frame 108 the idle speed appears to be increasing, but the IAC can't close down any more to bring it back down. When you are actually driving it under load, I'd expect the IAC counts to rise to the 80-100 range, but yours only go to 40 or so.

MAP looks OK. TPS is OK. MAF is OK. Spark advance at idle looks OK. Knock count is not increasing.

When you take it up high enough on the throttle to put it into PE mode, the O2 millivolts climb into the mid/high 900's. In Cell 15 its using 128 for the LT's and ST's, so its doing that because its cutting fuel under part load conditions. That would explain the increasing O2 mV's.

Did you ever check the fuel pressure as suggested in the earlier thread?

Did you ever follow up on the possibility they fried the O2 sensors when they welded on the exhaust?

You need to focus on why the PCM feels it needs to pull out all that fuel at idle. You need to determine if its a "true" rich condition or a "false" rich condition that the PCM is trying to correct for.

 

Ok that was a badass reply Injuneer. What is he using, so I can do the same thing?

 

OK I just cleared the MAF code 48. Car ran excellent for 15 min. It failed again hard and gave me MALF 16 Lo-res fail, MALF 33 MAP high, & MALF 51 EPRFOM/flash checksum fail. What the heck does all that mean?

Injuneer-the fuel pressure was tested and was rich all the way through failure. No I havent changed the O2 sensor yet.

 

DTC 16 is loss of low res pulse pattern from the Opti. When the PCM can't "see" the pattern for 2 revs of the engine, it shuts down the fuel pump and injectors. It isn't unusual to get DTC 16 at startup, as the PCM searches for the signal. But the fact that you have these problems may be pointing to the Opti.. possibly the optical sensor is failing under high heat conditions, the dielectric strength of the cap is disappearing as the Opti heats up, or the harness connector is corroded, bent or damaged.

DTC 33 sets when the MAP sensor reads more than 68kPa at idle. That may be an indication that the timing it off and it fired while an intake valve was open, or could be the harness connector is crumbling and producing an intermittent signal from the sensor. Not unusual for the harness connectors to fail on the MAP sensor.

DTC 51 indicates a PCM malfunction. You may have issues with the PCM ground circuits.

All of these could be contributing to your stalling.

 

Thanks so much for your time & patience Injuneer! Would you do an opti first?

 

I'd check the grounds, check the MAP sensor first.

 

I got the new map sensor install, with a new harness (because of course my old one broke). Anyway, the car failed again and the only code was 16 lo res failure. Does this mean a new opti is my only fix?

 

Have you checked the Opti harness for corrosion or damage to the pins? Check both the connector on the Opti and the gray 4-pin connector on the EVAP solenoid bracket on the passenger side of the intake manifold. It isn't unusual to find a blue/green corrosion on the Opti connector, probably a combination of a bad seal and the ozone generated in the Opti.

 

Problem solved!! Appearently my motor has been swapped for a 96-97 LT1 because my opti spark is VENTED! It appears as though there is a hose that needs to vent back into the intake. That tube was laying open in the engine bay and my mechanic plugged it! As soon as my NEW mechanic unplugged that tube it ran beautiful!!

So I guess I need the part number for the L-shapped plastic insert that goes in the intake elbow for this tube to attach to.

Thanks to ALL those who have helped and offered opinions.

 

Sounds like the opti could have been suffering from too much vacuum with the fresh air vent plugged like that. Excess vacuum can cause the innards of the opti to suck together causing interference where there should be none. If that is your problem, you got an extremely lucky fix.

(see my note about the pic in your thread about the vacuum elbow)