PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

tuning question

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Old Jan 24, 2007 | 09:54 PM
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Alright guys, here's the scoop. I had a cam in my old engine when I first bought the car. I grenaded that **** and I had a warranty. Bam! 2 weeks later I picked up my car with new engine from the dealership. I am assuming that the car was tuned for the previous engine and it was bone stock down to the manifolds (other than the cam & catback at the time.) It's idled at about 950-1000 ever since. Fast forward two years, most of which the car was sitting in storage. I came back from Iraq and put on everything you see in sig, except the 85mm MAF and the 160 Tstat. It ran like a raped ape for a bolt on car. Well, today I was bored so I put the MAF and the thermostat in. I know you have to tune for the fans to turn on at the right temp with the new thermostat. I cycled the coolant through like you are supposed to and got it all up to snuff. No problems. I walk away and come back. Start it up again and it's idling like sh*t, hesitating when I tried to hit the throttle and backfired when letting off. Water temp gauge doesn't work, SES also came on. Knowing that the current tune probably isn't correct, does anyone think flashing it back to stock would cure it for the most part, or should I just man up and dyno tune it?
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Old Jan 24, 2007 | 10:10 PM
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man, of course you should dyno tune it....
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Old Jan 24, 2007 | 10:11 PM
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I'm confused. Is your PCM still calibrated for your cam'd motor that blew up or has the PCM been flashed back to stock? If it's still tuned for the previous setup, I would assume you're running rather rich with the current setup. If not, chances are you're a bit lean and need a tune.

1st, I'd go over everything closely. Check the plug wires and the various electrical connectors that you had apart recently. Make sure everything is connected securely. Then, check for exhaust leaks and find a way to pull the PCM codes. If everything looks snug and you're not dealing with crappy NBO2 sensors, you need to ask yourself what you want to do. Spend some money for someone to tune your current setup or spend a little more and do it yourself. A stock tune with a little bump in the AFR and that car should run strong. Then, you can do the simple things like kill the SES codes, set the fans, dial in the speedo for the 4.10's, etc. So, what do you want to do...?
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Old Jan 24, 2007 | 10:17 PM
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Ok, I've gone over everything..as I am a bit obsessive compulsive to be honest. Everything is tight, topped off, locked, cocked, and ready to rock. I did have the the little things done as far as the tune for 4:10s, AIR, rear 02's. Even spent the money on Bosch 02's a few weeks ago just to get rid of my extensions. Everything ran great until I put in the tstat and MAF. I think the SLP MAF may be clashing with my tune. What do you all think?
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Old Jan 24, 2007 | 10:54 PM
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It's entirely possible, just a quick swap can confirm or break the suspicion
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Old Jan 25, 2007 | 07:49 AM
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that stupid maf... the stock maf will do fine... i still don't understand why people replace them....

the MAF could be causing some of ur problems, but hell, since you got it together go get the thing flashed with a new tune and dyno the sucker
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Old Jan 25, 2007 | 09:24 AM
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i know the stories..the stock MAF will support 500 HP....Well, there's going to be one bad **** NA motor within the year sitting between the wheel wells. Again, anyone have any earthly idea why my water temp gauge would stop working suddenly?
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Old Jan 25, 2007 | 10:12 AM
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Sender for the guage is likely.... If there is gonna be one "bad **** na motor" why not just ditch the MAF and run SD?

Just switch the MAFs and check it out; it'll take all of 10 minutes
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Old Jan 25, 2007 | 10:24 AM
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I don't want to run SD because I like to drive the car, a lot. And here in Oklahoma the weather has a bad habit of going from 70 one day to 20 the next. There's a little too much error involved in it for me. I'd rather just have it tuned and have the peace of mind.
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Old Jan 25, 2007 | 12:40 PM
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SD uses IAT in the equation, so if it's really tuned, it's really tuned, regardless of temp.
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Old Jan 25, 2007 | 03:09 PM
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Yes, but you also have humidity and elevation. Does that not affect it?
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Old Jan 27, 2007 | 12:19 AM
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The MAP sensor reads pressure. It doesn't matter what elevation it is as long as the VE table is setup for all MAP variables it will be fine at any elevation.
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