afr goes to 16 - 17 under acceleration can not keep close to afr target
I have been running my GO EFI 600 for about a year without issues.. Let it self learn and it was working great. I recently busted a piston ring in my stock 350 and had to pull engine. I decided that I would replace the engine with a 383 stroker. This is a crate engine completely assembled. Info below.
Since installing the new engine everytime I take out to test drive the AFR goes to almost 20 and then cuts out and pops through tail pipe. Idles fine and revs fine. I have replace 02 sensor, new pulgs, new distributor reset learning. The last thing I did was reset fitech to default v8 file and reset intial config to CID 383, Cam 2, idle 750. I am not using the timing I have mechanical vacuum advance. Total timing set to 36 deg at 3000 RPM as suggested by manufacture.
Attached is log file from last run after reset to default.
Product Line:ATK High Performance GM 383 Stroker 415 HP
- Horsepower: 415+
- Torque: 460+ lb/ft
- Block: Seasoned OE 4 Bolt Main 1pc Seal Roller Block P/S Dipstick
- Bore/Stroke: 4.040 x 3.750
- Displacement: 383 C.I.D.
- Crankshaft: Scat Nodular Iron 3.750" Stroke Externally Balanced Rear/Internal Front 1pc.
- Connecting Rods: Scat 4340 Forged I Beam 5.700" ARP 8740 Bolts
- Pistons: Hypereutectic
- Piston Rings: Moly Rings
- Compression Ratio: 9.7:1 Compression
- Camshaft: Hydraulic Roller
- Camshaft Specifications: 220/224 @050 .528in/.536ex 112LSA
- Camshaft Bearings: Installed & Clocked to OEM Position
- Cylinder Heads: Dart SHP American Made Aluminum 64cc/180cc 2.02/1.60
From <https://www.high-performance-engines.com/chevy-383-stroker-mid-dress-engine-415hp-p/hp94m.htm>
Running GO EFI 600 with Aeromotive Stealth 340 In-Tank pump
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A couple of observations/suggestions
- You may need to reset "learning" and have the FiTech learn your new engine from scratch.
- Check carefully for exhaust leaks. I've got exhaust cutouts - when I open them at idle & low RPM my AFR jumps to 20+ due to the reversion (fresh air) hitting the O2 sensor.
Good luck & let us know what you find.
Quote from 69_R-Code on December 10, 2019, 2:56 pmA couple of observations/suggestions
- You may need to reset "learning" and have the FiTech learn your new engine from scratch.
- Check carefully for exhaust leaks. I've got exhaust cutouts - when I open them at idle & low RPM my AFR jumps to 20+ due to the reversion (fresh air) hitting the O2 sensor.
Good luck & let us know what you find.
Thanks 69 R-Code I will look for any exhaust leaks, I did reset the All learning, fuel and IAC learning before this last test drive. No change. Will continue to dive into it. Any other suggestions are welcome. I am at a loss on this.
I would double check your timing as you rev it up over 3000 rpm in neutral. Popping through the exhaust and having your AFR reading go that high sounds like it's too far advanced, which will cause it to run too lean, and potentially damage the engine. Another thing to check while you are doing this is your fuel pressure to make sure it doesn't go down. Hopefully you have a pressure gauge at the throttle body.
where exactly is the 02 located,, it should be about 2-3 inches from the header flange in the header at the 10 oclock pos also verify you are getting a good read on the temp sensor, check for intake air leak ,remove the throttle body and shine a BRIGHT light in the plenum and look at where the intake contacts the cylinder head look for the light (I had that problem mismatched gasket) also check your idle vacuume may want to try cam1/cam3 and even though it is "stroked" the base engine cid is 350 I have a stroked 545 and mine runs best at 460(base engine cid
Thanks everyone for your input. I put a fuel pressure gauge on it and was running around 40 psi at idle and it quickly dropped to around 20 when reving it up. I ended up dropping fuel tank to look at the fuel pump and guess I had forgot I installed a fuel filter just after the internal pump. So I pulled it and opened it up and it was clogged. So replaced fuel filter and no running 55 psi after filters constantly. Runs better and my AFR is much better. Now I can get on to actual tuning.
Thanks again this is a a great forum.