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Found small leaks in the intake hoses.
Oil filler cap o-ring was leaky.
Spark plugs fouled. Crud on the pistons.Crankcase ventilation seems good. EGR valve seems good. Didn’t check the IAC.
After fixing the above, the car still wasn’t running better. Pressure tested the intake and plenum 3 more times and there were no leaks anymore.
Scoped the MAF voltage again, and it looked the same as before with the same responsiveness. Idle was still around 1.1 volts. I have the Chilton service manual, and it doesn’t say what it should be normally; it just gives the values that trip the ECU.
Engine ran better at idle with MAF unplugged. Figured that the MAF was the last thing. Took a chance and replaced it with a Delphi resold MAF (Bosch).
Car immediately started running better. Test drove it for 30 miles and got 3.9/3.1 for LTFTs. So on this car the MAF sensor can be skewed badly with no MIL but it has to be shot to make the ECU throw a code. :woohoo:
O2 values —
Took a look at the codes again. Some junk codes were in there from the car sputtering after changing the FPR and getting air in the fuel rail. Erased the codes. The trims got zeroed out.
Drove around. The sensors put out lots of values, and as far as I could tell without running over neighbors walking their dogs, the values were between 0.15-0.67 volts. And the 0.15 was nearing a stop sign. If that is right, then there is a leak hiding somewhere that I haven’t found. Also, it took around 5 minutes for LTFTs to get up to 18.
I’m going to diddle around with smoke testing and vacuum hoses.
MAF sensor —
Finally able to tap the sensor. Um, because it’s a Bosch part, f 00c 262 930, it turns out it’s a DC signal. I myself was expecting a square wave.
Funtionally the output looks OK. I don’t have spec values to verify it with, but it reacts as anybody would expect. There is also a noisy pulse that happens now and then, but it’s pretty short. I doubt the ECU internally notices this.
After testing I hosed the sensor contacts with MAF cleaner like crazy. Let it dry thorougly. Drove the car. Fuel trims not better.
Fuel pressure regulator —
Removed the upper. Tested the fuel pressure. Changed the FPR.
Went for a drive the next day. Fuel trims not improved, but at least the regulator is out of the way.
The scanner reads 99 PIDs but only displays a fraction of them. Dipslayed ones are:
MIL statys
throttle
RPM
calc load
MAF lb/m
coolant temp
IAT
IGN ADV
secondary air
fuel trims
o2 sensors 12 and 22
fuel sys 1 and 2Sorry, no misfire counter.
So I got the boot off of the wiring harness. It turns out that where each wire meets the pin inside, it’s covered in plastic sleeve. It won’t push through either. Why do that? There was already a boot over it. Overdone.
Thanks for the heads up about the torx. I don’t have torx plus. I also don’t have external torx. I also don’t have security torx. Ordered a master torx set by OTC and it should be here Wedensday. Having to get more drivers is sort of OK, but not great.
I think I want to change out the fuel regulator. It has a bad symptom already, and it seems to be the only definite one so far. Do I need to get new intake rings? I’ll also get some scanner telemettry with some driving, and smoke the vaccum again.
Yes, clear liquid fuel dripped out of the vacuum hose.
Auto Parts Warehouse says the Delphi equivalent for the MAF sensor is DELAF10160.
OK, I will clean the MAF along with continuing testing. I’d like to make sure that if the MIL can go away that it stays away for a long time.
I’ve got an older Tektronix handheld. Not purpose-built for this problem, but with the right information verification may be done. The Modis has a sensor waveform database? That’s really, really nice. I’m not comfortable with you going out of your way to scope the Saturn. If the Modis can specify expected parts of signaling that already sounds beneficial.
For probing the MAF, I need to introduce some wire shunts that I can clip onto, or get some alligators. The harness end has a soft rubber boot and I’m not confident I can pull it back without damaging it.
So I got an extension cable for the scanner. I set the Actron to watch the PIDs and repeated with the carb cleaner. The RPMs did not noticeably change on the belt as far as I could see, and like last time, the pitch variation was about the same. I’m not sure if the scanner is good at looking at live fuel trims. It reported changing values for RPMs and the MAF in real time just fine, but LT FTRM1/2 was 24.5 and ST FTRM1/2 was 0.0 and these 4 FT numbers just sat still there like rocks. I revved and blipped and they just sat there.
I think you’re right about the smoke machine. I’ll take a look at it and do another pass.
The earliest I’ll be able to touch this car again is Friday evening I think. Other than that feedback at your leisure is welcome.
– MAF sensor looks clean but not sprayed yet.
– Air filter looks like an orange FRAM. Dry, no visible clogging.
– When smoking, areas around the motor patrolled with 2-tube work
| light; 1-2 minutes per spot. When duct was pulled from throttle
| body afterwards, smoke was in the hose. Worth noting that no
| particular attention was paid to the breather b/c I didn’t know
| about it.
– Before smoking, I was looking for vacuum access around the upper
| manifold. I undid the booster hose fitting on the manifold
| side, and dismissed it as a vacuum hose because gasoline came
| out.I drove the car today. It seems noticeably worse by a small notch. Hoping that it will help shoot the problem easier.
Got my hands on a can of B-12. With engine cold, started it up and began spraying from the driver side to under the upper manifold, from the passenger side to under the upper manifold, front of throttle body, left side of throttle body, right side of throttle body, under throttle body onto the breather hose clamp, brake booster hose manifold-side fitting, brake booster hose booster side, above the 2 cylinders near the timing cover on both sides, straight past behind the upper manifold, and onto what looks like the variable control vacuum solenoid. No big swings in RPMs were noticed.
The Danner video I saw was one where he squeeze-tested the booster hose and it showed a gross amount of leakage. Because of your comments, I found his video for MAF sensor output testing on a Buick.
Once I figure out access to the MAF connector I can easily scope it. But I don’t know where to get the datasheet with the normal output characteristics.
Thanks for all the help. Makes the process much more stable. Yes, damn Saab motor.
