new to me, 98 M3
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****PROBLEM MAF is showing a flowrate of 0.01 lb/sec. my math says that 0.15 lb/min should be roughly 2hp. At idle your engine should be creating at least 15-20hp. So your MAF is borked, your wiring has an issue, or there is a SEVERE air leak somewhere.
Throttle Position is at 17% which tells me that you have to keep your foot on the throttle a bit at idle to keep it alive because of the presumed MAF problem.
At idle with my foot off the gas my '99 M3 sits at 17%/18% throttle. Not sure on the rest of the numbers though. When I get back from my trip I can see what my car reads for the rest of the parameters you posted to compare
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hi all, back from the weekend. Update. Hooked up a DIY smoker. Paint can with some tubes hooked up to a compressor at 4 psi then blew smoke into the chamber. Worked well except I couldn't introduce enough smoke with just a cigar. Didn't really need the smoke I was able to hear one small leak out of one of the SC tubes. Fixed that and checked again couldnt hear any air leaking out of anywhere else and pressure definitely built up. Intake tube fix held fine. Drove car again and light still came on, this time only code P1188.
Filter is a K&N that probably needs to be cleaned and lightly oiled again. But not sure that would be my problem. Next step is to check injectors I suppose. I put some injector cleaner in the tank. Also tried to clean MAF. For the O2 sensors I only unplugged 1 at a time so I know I put those back in the correct spots.
Car still seems to run just fine, drove it about 250 round trip up north. who knows on this one! Kind of stumped at this point.
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Did a little more testing on the code reader. For my MAF reading i watched it while driving home. At 55 mph it would hover between .04-.05 lb/s Not sure if that's normal or low. Under reasonably heavy acceleration it'd get to .11 lb/s. So, it appears to at least be reading something. I unplugged it at idle and the car started to spit and sputter badly, so it's regulating a little bit I assume. Would software for the SC mess with this? No one on here around Madison I could swing by to test a known good MAF before dropping a couple hundred on one? I'll also be around brookfield this Friday about 2pm and heading back to Madison
I tried the screw driver on the injector trick to see if they're ticking properly. Couldn't really hear crap over regular engine noise. You'd think they'd be OK since they're only 20K miles old when the SC was put on. Haven't flow tested them yet. I suppose that's next.
Happy to entertain other ideas! New fuel filter comes Friday as well, maybe its not getting the fuel it needs?
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What's the part number on your maf, I might have one.
Real OEM is saying
but I'll double check what's actually on mine since the SC kit supposedly came with a new one.
Another note, I see my reading is .01 lb/s. I'm looking online for normal readings and see readings are all recorded in lb/hr. Not sure if that makes my reading OK.
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thanks for pointing that out, lb/min is the most frequently used unit for engine airflow (besides CFM) and I totally overlooked the fact that your scanner outputs lb/sec. .05 lb/sec is roughly 30hp which is reasonable for cruising. "reasonably heavy acceleration" at .11 lb/sec is only 60hp which is only considered reasonably heavy acceleration in an air-cooled beetle.
if you can get a WOT reading and give an approximate RPM during the reading we can get a better gauge as to whether the MAF reading is reasonably or not. So far it appears reasonable at low throttle openings but not heavy acceleration.
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thanks SNAP, i'll do that today!
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OK, took out for lunch. A bit hard to read while driving and going to WOT but I noticed it as high as 24.1 lb/s. If I had to guess my rpm around 4500-5000 range at that point. Again hard to drive and not crash while watching three things. So, it may have peaked higher I just didn't catch it. I also took some revised data while cruising at 55 mph. Not sure if that tells anymore of a story.
One other little thing I've noticed. When I come off throttle and into neutral from stop and go traffic the rpm will dip very briefly to about 400 rpm and recover immediately to normal idle. Only does this in stop/go. Doesn't do it if I come into neutral from higher gears like 4 and 5 and drop into neutral.
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24.1 lb/sec is an absurd value which equates to 14,500 HP
24.1 lb/min is a very realistic value which equates to 240 HP
You should be seeing 0.35-0.40 lb/sec at WOT for that rpm.
rpm dip upon return to idle means the engine isn't idling efficiently. Most of the time this means a vacuum leak. Sometimes it means check your idle control valve, clean it and inspect the plumbing on it and make sure it works.
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Yeah, my car is really fast!
sorry meant .24 I'll take a passenger with me who can watch more closely to see if it gets up towards .35I'll keep searching for vac leaks. Going to have get it up on ramps. Because of the SC the ICV is located under the SC and very hard to get at. I was hoping in the back of my mind i wouldn't have to deal with that, but am realizing I'm probably going to need to inspect it. Not sure how i'm going to get at it. ugh......
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Ok, finally got some time to pull a bunch of numbers from my car. It was not fully warmed up, but idling around 750rpm.
Absolute throttle position: 18.8%
Voltage: 14.00
B1S1 O2 voltage: 0.125 (bounced between this and 0.950, probably an issue with my reader)
B1S2 O2 voltage: 0.960
B2S1 O2 voltage: 0.115 (bounced between this and 0.950, probably an issue with my reader)
B2S2 O2 voltage: 0.940
Short term fuel trim 1: Between -2.4 and 0.8
Long term fuel trim 1: 2.34
Short term fuel trim 2: Between -.8 and 2.4
Long term fuel trim 2: 1.56
Timing advance: between 15 and 17.5
Mass airflow 1 (g/s): Between 3.57 and 3.85
Mass airflow 2 (g/s): Between 3.43 and 4.9 (4.9 was just after startup, rpm's not fully settled)
Hopefully this helps!
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Thanks M42B32. I've discovered I have the 803 Porsche MAF because of the supercharger and upgraded injectors. So, not sure my numbers will give much of a comparison. I'd say the MAF appears to be functioning though. That would have also been new at the time of SC install.
I haven't had a chance to drive much since this weekend. Summer tires on the M and snow don't mix. Hopefully tomorrow I'll be able to get it out of the subdivision. Spent the weekend tearing down to the ICV. Cleaned that real well, it was pretty dirty. Put everything back together real tight, added hose clamps to vacuum lines that didn't have any just to be safe. Not hearing any leaks. Cleaned the air filter. It was filthy. Still getting crap out of it after using the K&N cleaner three times. Cleared codes and only took for a couple short trips. Pending codes didn't come back. Not holding my breath though, codes seemed to appear when I'd get to highway speeds, which I didn't do yet. Tomorrow should be a good test.
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Does your chip tune account fort the different MAF?/did this MAF and chip tune come from the vendor that sells the SC kit?
according to the website yes
http://www.eurosporthighperformance.com/supercharger.html
also, car was running fine with no CEL for about 500 miles when I got it, so hopefully tune is good. TRM Tuning in Cummings, GA did the install work. Apparently they're reputable and they did respond to me that they worked on this car, so i know that's true. Keeping fingers crossed it was a vacuum leaked.
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ok, code still there. Update on some numbers I noticed while driving today.
Seems my short term fuel trim 1 is out of wack. It stays around -18-20% while in gears 1-3 when going upto 4-5th gears at highway speeds it drops to -10.6-12% which still seems like a high number compared to SHRTFT2 which stays in the -3-6% range. Long term still holds steady at -8.6% for both.
Thoughts if that might still point to a vacuum leak or fuel delivery issue?
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Maybe the coolant pump or lines?
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Your STFT is an instant reading of fuel being used and should remain similar across both banks. If you have one bank out of wack then that bank may have an issue. Running that far negative would point towards an over fueling issue and the ecu is trying to pull fuel away but you want to evaluate the numbers at idle and at 2500 rpm. Leaky injector, bad maf, bad 02, those are a few items that could cause this.
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Morning all, no fun updates, rims will go on next week so I'll get pics up when that's done!
Still working on this dang CEL. No vacuum leaks, changed fuel filter as well. I rented a fuel pressure test gauge from Orileys to make sure I'm not getting low pressure. Here's what happened. T'd it into the fuel line at the fuel pump in the back seat. Turned pump on and no reading on the gauge. Perhaps fuel isn't going through? So, I start the car and car starts right up and runs, but still no reading on the gauge. OK, well maybe it's just a bad gauge. So, we return that one and get a second one from Autozone. Hook that one up, same thing. No pressure on gauge but pump is clearly working and fuel it flowing through the "T" connection because car runs fine. We could be idiots and hooked it up wrong, but I don't really see how that would be possible, you just put the "T" fitting inline and connect the gauge. Two gauges wouldn't both be bad you wouldn't think.
So, maybe this means something, I'm not getting enough back pressure to register on the gauge? Fuel pressure regulator? If that is shot wouldn't I be running rich? I thought having the negative short term fuel % mean that I was running lean. Or does that reading mean I'm actually running rich and the computer is trying to Lean out the fuel? That might make sense then if the FPR is shot.
Thanks again for all the help, Andrew
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