383 not getting enough air

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Idaho_z71

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I swapped an HT383 stoker in my 98 Sierra in October of last year. I just put in a new exhaust last weekend with fresh cats (my old ones were burnt out) and I'm still running the same cold air intake I've had for about 3 years. I've heard mixed things about having to retune the computer for the bigger engine. I have not because it seems to run great with lots of power. After the new exhaust I'm getting a P0102 code for insufficient air through the filter. In the mornings when I'm leaving the driveway, the truck will bog down for about 10 seconds then pick up and runs like a new engine should. This never happened until I put the new exhaust on. I know for sure the MAF sensor is good. I'm woundering if my computer needs to be tuned for the bigger engine. Anybody got any suggestions before I start throwing money at possible but not likely causes?
 

L31MaxExpress

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Double check your grounds. The one on the back of the cylinder head and the one down low on the passenger front of the engine. The MAF gets its ground from the engine block. Also make sure you do not have any vacuum/intake ducting leaks. You may have a bad MAF as well. P0102 is for a low MAF input into the PCM. Usually a MAF tuning issue shows up as a P0101 not a P0102. P0102 and P0103 are usually a problem with the MAF or the wiring for it.
 

Schurkey

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Download a service manual from the links on this site.

Follow the diagnostic procedure for that code.

P0102 is almost certainly NOT "insufficient air through the air filter". I'd believe that it's a low-air-mass signal from the MAF sensor; or other MAF-related issue.
 

Idaho_z71

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I feel pretty stupid for making this thread because my problem was a broken power wire to the MAF sensor. I had to extend the wires for my cold air intake and the wire had broken at the butt connector. A couple minutes with a soldering gun fixed it pretty quick.
 

Pinger

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Just to add.... when I had P0102 it was an electrical fault (missing fuse). When sorted, the hard upshifts softened. Hard upshifts can be included in the symptoms of poor MAF functioning.
 

Idaho_z71

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Just to add.... when I had P0102 it was an electrical fault (missing fuse). When sorted, the hard upshifts softened. Hard upshifts can be included in the symptoms of poor MAF functioning
Checks out. Mine would slam into gear going from park to drive
 

Hipster

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I feel pretty stupid for making this thread because my problem was a broken power wire to the MAF sensor. I had to extend the wires for my cold air intake and the wire had broken at the butt connector. A couple minutes with a soldering gun fixed it pretty quick.
+1 for soldering it. It's always a debate....but shouldn't be.
 

LVJJJ

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Just seeing this now, so I hope its not to late to reply. Before I installed the 383, the first thing I did when I bought the 94 350 Burb was rip out the restrictive air box and put a 4'"smooth dryer duct directly from the fender inlet to the air cleaner. Got rid of the choke flat and anything in the way of air flow. Then cut an oval hole in the other side of the air cleaner then glued and used the pleated original rubber adaptor and ran a 3" flexible pleated pipe down thru the splash guard in the wheel well for a second air intake. The 3" pipe fits into the stock adaptor perfectly. Since engines are air pumps need all the air you can get. As for the computer, you should get it reprogramed. There is an expert computer guy in this forum who will reprogram it for you. I think his name is Old School EFI or something like that. It took about a month to get it done. I bought an OBD 1 plug in adaptor (Yours is probably OBD 2 so don't know if it works the same way). Anyway, I downloaded some program that worked thru my computer. As I drove around it recorded what the engine was doing. Then I sent the computer chip to OLD School EFI and he tweaked it a bit. Helped a little, so he sent it back and I recorded another run. Took about 4 times back and forth till we got it right. Made a huge difference in how it runs and power. Happened to be during Covid so I wasn't going anywhere anyway. Bought a used extra chip to use while it was being tweaked. Heck of a trailer tower now.
 
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