Hello Everyone. I have long lurked this forum and recently decided to join and post. I have a 1995 K1500 5.7 Auto in which I just rebuilt the engine and transmission. I talked with a tuner before I built the engine to verify I would be able to have a good smooth running engine, and the guy said it would be easily tuned so I built. Here is what I built; it is 355ci with 2v flat top hypereutectic pistons (9.6:1). The block is zero decked for a nice tight quench of .038". It has Dart Iron Eagle S/S 165cc heads (72cc chamber) with the 87-95 intake face. I installed 1.94/1.50 valves. The cam is a Hydraulic roller cam, 204/209 duration @ .050" and it has .480/.496 lift w/ 1.6 rockers. It also has an Edelbrock 3704 TBI intake, Stock throttle body, stock injectors but with 18PSI fuel pressure per the tuner. I also have an upgraded fuel system to meet the demand of the high pressure and supply needs.
Now here comes the long part. I am on my 5th mail order chip and after sending 8 data logs, I am running no better than the first chip. I am hoping someone on here may have ran into this issue and has a quick fix, or can at least point me in the right direction. First thing I will point out is that the truck is 100% drivable with the stock chip and the base timing advanced 8 degrees. It obviously isn't anywhere near its full potential, but it is run and drives fine. With any of the five tuned chips I have tried so far, I have a nasty stutter/miss below 3,000 and a certain throttle percentage. If I put it to WOT, it runs awesome with all five chips, but pretty much anything below that it is so poor that it is almost not drivable. It misses so bad, it feels like it is dropping multiple cylinders or something. It feels worse than if I were to switch two of the plug wires. And it's more than just a miss. It has almost no power when it is doing it. I can pull out from a stop sign and give it 20% throttle and it will buck and kick all the way up to 55mph until I finally get out of the throttle, and it gets there slowly. It doesn't matter what gear or whether the engine is cold or warm. it will do it constantly while driving. But I can pop the stock chip in, advance the base timing a little, and it accelerates smooth. No issue at all.
The tuner claimed it was bad spark plugs, then a coil, and now saying it could be my heads...which I am almost regretting even doing this now because I've been building and racing engines for 15 years and never had a set of heads that were good cause problems with and engine. It almost seems like he doesn't want anything to do with it and I have been dealing with him since December and he is extremely hard to get in touch with. He won't answer calls and just plain doesn't respond to the emails, another new chip just shows up in the mail after I send on back and let him know what is going on. I may end up learning to burn my own chip but not until I get this thing at least decent from the guy considering he already got $270 from me. I am going to attach some data logs I made in TTS Datamaster 0D. Runs 4 and 5 are chip 3, runs 6 and 7 are chip 4, run 8 is chip 5, and run 9 is chip 5 with new coil and oxygen sensor. Run 10 is the stock chip with base timing advanced 10 degrees. If anyone would have time and be interested in looking at these, I would be greatly appreciative. I would love to hear what you think and any possible resolutions you may have. If you think the engine combo sucks and I am asking too much and it can't be tuned let me know that too. I was under the impression that it is totally tunable, but that is just an opinion. Any feedback with be a huge help, thanks in advance.
Barry
P.S. I having been messing with and building engines my whole life, but I am very new to anything with fuel injection to this magnitude and I am learning a lot as I go. The last thing I want to do is throw a carb on it, which to me is so much easier but I would like to keep the fuel injection so I am here looking for help. Thanks.
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