Wild MAF swings only at WOT

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Wild MAF swings only at WOT

Unread postby GT_Rich » Sat Jan 05, 2019 10:57 pm

I have a 97 Cobra driveline in a 62 Comet. It's been together and running well for 3 years. The motor was tired (lots of miles) so I freshened it this winter. I run E85 so I went with 11:1 compression. The only other change I made was cam timing. I put the intake cams at 109 and the exhausts at 114. Very common mod on these engines.

This thing is not running right and I am stumped. I have low speed drivability issues that feel like misfires and then at WOT my MAF curve has 1 volt fluctuations. Completely untunable. This is the same MAF and same tune I was running a couple months ago with zero issues. I am not logging any misfires. It still uses the factory coil pack/wire setup.

When cruising around the MAF voltage is smooth/consistent but at WOT it goes crazy. See attached log (which is a .csv file...don't try to unzip, just change the extensions). At 46.6 seconds ET and then again at 62.6 seconds ET I go full throttle. IMAF is everywhere.

What am I missing? I've never seen anything like this.
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GT_Rich
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Posts: 69
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Name: Rich
Vehicle Information: 65 Mustang Vert, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, F-cam, ported GT-40 lower/tubular upper, Vortech T-trim s/c, 60 lb/hr inj, Methanol injection, PMAS HPX blow-thru MAF, 400 lph pump.
Vehicle 2 Information: 92 Mustang GT, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, B-cam, ported GT-40 lower/tubular upper, Powerdyne BD-11 s/c, 42 lb/hr inj, 75 mm Pro-M MAF, 255 lph pump.
Vehicle 3 Information: 95 Lightning, ICY1, Moates QH, Innovate LC-1 WB
393 w/ TF heads, custom cam, GT-40 lower/tubular upper, 30 lb/hr inj, speed density. E4OD trans.
Additional Vehicles: 62 Mercury Comet, LLX4, Moates QH
32V 4.6L, IMRC delete, stock rebuild

Re: Wild MAF swings only at WOT

Unread postby decipha » Sun Jan 06, 2019 1:31 pm

be sure to read the forum rules

thats severely lean for E85 you were only commanding .875 lambse at WOT, should be closer to 0.80

it looks like your maf is either dirty or bad, if you oiled the filter it then thats probably why. First I would remove the maf element and clean it very well. You can use a qtip with alcohol and swab it gently until its clean. Then GENTLY spray it out with some electrical parts cleaner or brake cleaner. Let it sit over night to dry out re-install it and see if its better.

Be sure the maf connector is clean and the contacts in the pigtail don't have any corrosion in there and that it snaps to the maf tightly. Check over the wiring up there as well and just give it a good tug and bend test to make sure its not brittle or anything.

Otherwise if all checks out then most likely you have a bad maf sensor.
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Re: Wild MAF swings only at WOT

Unread postby GT_Rich » Mon Jan 07, 2019 9:27 am

First, thank you for opening the datalog and taking the time to reply. I always appreciate your input.

The demanded lambse is wrong b/c MAFV is off and the computer is not correctly calculating load. I think my top two rows are set to .82 lambda. Obviously, you are only looking at a log and not my tune, so I understand your concern.

I find it hard to believe the MAF died while it sat on my shelf for a month. I never even unclamped it from the intake tube. The filter hasn’t been oiled in a long, long time.

I did a leak down test last night and all showed perfect. HOWEVER, if I do a leakdown test with each piston at TDC on the off stroke (in other words, measuring the leak down of the cam overlap), I get very different bank to bank results. One bank has moderate air flow. The other bank has no air flow.

I’m starting to wonder if I had a chain jump a tooth. It would explain how poorly this thing runs. Would it also explain my MAF fluctuation at full throttle? Could it be that I’m pushing air out the intake or flowing very little air on each cylinder of the bad bank? Given the 13726548 firing order, it would be fairly noticeable since 3 out of 4 cylinders in succession are from a single bank.

I’m tearing it all down to check. Such a pain.

Last comment – in my humble opinion your forum should allow small (maybe less than 500 KB or 200 KB) .csv files to be uploaded. What’s the point in zipping a file that’s already this small? Some of us, such as myself, make sure to datalog small chunks before uploading.
GT_Rich
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Posts: 69
Joined: Sun Dec 06, 2015 8:16 am
Name: Rich
Vehicle Information: 65 Mustang Vert, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, F-cam, ported GT-40 lower/tubular upper, Vortech T-trim s/c, 60 lb/hr inj, Methanol injection, PMAS HPX blow-thru MAF, 400 lph pump.
Vehicle 2 Information: 92 Mustang GT, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, B-cam, ported GT-40 lower/tubular upper, Powerdyne BD-11 s/c, 42 lb/hr inj, 75 mm Pro-M MAF, 255 lph pump.
Vehicle 3 Information: 95 Lightning, ICY1, Moates QH, Innovate LC-1 WB
393 w/ TF heads, custom cam, GT-40 lower/tubular upper, 30 lb/hr inj, speed density. E4OD trans.
Additional Vehicles: 62 Mercury Comet, LLX4, Moates QH
32V 4.6L, IMRC delete, stock rebuild

Re: Wild MAF swings only at WOT

Unread postby decipha » Mon Jan 07, 2019 12:46 pm

the point is csv is all text so it zips up nicely. it only takes a second to right click and compress
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decipha
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Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Wild MAF swings only at WOT

Unread postby GT_Rich » Tue Jan 08, 2019 3:39 pm

Time to admit my stupidity. I had a bank of cams 180 degrees out. I'm surprised it ran at all. It was apparently pushing air back through the MAF.
GT_Rich
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Posts: 69
Joined: Sun Dec 06, 2015 8:16 am
Name: Rich
Vehicle Information: 65 Mustang Vert, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, F-cam, ported GT-40 lower/tubular upper, Vortech T-trim s/c, 60 lb/hr inj, Methanol injection, PMAS HPX blow-thru MAF, 400 lph pump.
Vehicle 2 Information: 92 Mustang GT, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, B-cam, ported GT-40 lower/tubular upper, Powerdyne BD-11 s/c, 42 lb/hr inj, 75 mm Pro-M MAF, 255 lph pump.
Vehicle 3 Information: 95 Lightning, ICY1, Moates QH, Innovate LC-1 WB
393 w/ TF heads, custom cam, GT-40 lower/tubular upper, 30 lb/hr inj, speed density. E4OD trans.
Additional Vehicles: 62 Mercury Comet, LLX4, Moates QH
32V 4.6L, IMRC delete, stock rebuild

Re: Wild MAF swings only at WOT

Unread postby decipha » Tue Jan 08, 2019 6:37 pm

damn hope u didnt hit anything
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decipha
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Posts: 16194
Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Wild MAF swings only at WOT

Unread postby GT_Rich » Tue Jan 08, 2019 9:59 pm

The only good thing about being 180 out is the piston to valve clearance is the same. And with a waste spark system it will even run! Just not well.
GT_Rich
General Poster
 
Posts: 69
Joined: Sun Dec 06, 2015 8:16 am
Name: Rich
Vehicle Information: 65 Mustang Vert, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, F-cam, ported GT-40 lower/tubular upper, Vortech T-trim s/c, 60 lb/hr inj, Methanol injection, PMAS HPX blow-thru MAF, 400 lph pump.
Vehicle 2 Information: 92 Mustang GT, A9L, Moates QH, Innovate LM-2 WB
302 w/ TF heads, B-cam, ported GT-40 lower/tubular upper, Powerdyne BD-11 s/c, 42 lb/hr inj, 75 mm Pro-M MAF, 255 lph pump.
Vehicle 3 Information: 95 Lightning, ICY1, Moates QH, Innovate LC-1 WB
393 w/ TF heads, custom cam, GT-40 lower/tubular upper, 30 lb/hr inj, speed density. E4OD trans.
Additional Vehicles: 62 Mercury Comet, LLX4, Moates QH
32V 4.6L, IMRC delete, stock rebuild


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