The car has a really nasty lean condition right now, that's not the fuel pressure or vacuum leak related. The two last possible things I'm looking at are PCM and MAF. MAF I'm already all set for, but I still don't know which PCM I can use to replace mine, if I have to. Are they year and model specific, or can I just use any 94-95 GT/Cobra stock PCM?
Which PCM can I run?
- Thread starter ReplicaR
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Using stock everything. The car is in 14-15 AFR range through the whole band. The motor is completely stock, other than a cold air intake and a catback. I just need to know which PCM I can use. I really don't like chips, because tuning is usually shit on them. I've seen them lose power on Dyno time after time.
What is your engine combination?
If you have a modified engine but your fuel and timing tables are still stock, then of course the tune isn't right. The PCM can only change fuel/timing within given parameters. The chip is there to change the baseline and make it more appropriate for the combination. Not only that, the OEM tunes on the SN95 5.0 cars leave something to be desired anyway.
I don't know what kind of tuners you've been around, but if folks are losing power "time after time" then they must be using an idiot tuner.
Paul.
If you have a modified engine but your fuel and timing tables are still stock, then of course the tune isn't right. The PCM can only change fuel/timing within given parameters. The chip is there to change the baseline and make it more appropriate for the combination. Not only that, the OEM tunes on the SN95 5.0 cars leave something to be desired anyway.
I don't know what kind of tuners you've been around, but if folks are losing power "time after time" then they must be using an idiot tuner.
Paul.
As I said in the previous post, the engine is absolutely stock other than cold air intake and a catback. Regarding mail order tunes, I've never seen one work. It is very rare that you can buy a chip for your application supposably, and have it work perfect. Something is always going to be off. Unless the chip has been burned from a dyno-tune, I would not even touch it.
Dmitry why don't you get a dyno tune from Greg at racersedgetuning.com if you feel you need a dyno tune. But i remember some where but not 100% sure that our computers have a happy medium of a A/F of 14.7 but don't quote me on that.
14.7 AFR is extremely lean for an open cycle at WOT. Most stock 5.0s I've seen dyno over at Haddad put were in high 12s low 13s at the highest point. 14.7 AFR is good for partial throttle, because that's when the computer is reading the o2 sensors, and trying to get that perfect mixture. But under WOT it should be way richer than that. Besides Steve, my car is absolutely stock. It should not need a dynotune.
I never said you should get a mail-order tune. I said you should get a chip, ergo, one burned while on a dyno.
How are you currently reading your AFR? What are your readings at various loads and various throttle angles?
For a naturally aspirated performance combination, you'll typically want to be on or around 13.2:1 AFR. 14.7:1 AFR is a perfectly "stoichiometric" AFR and is just fine for smaller throttle angles and cruising.
Although your car is absolutely stock, and shouldn't need a dyno tune, the stock tables aren't that great (as mentioned previously) and many stock 94-95s detonate at WOT and normally run a tad lean. You can always try backing the timing off and increasing fuel pressure a few PSI to see if that helps.
Paul.
How are you currently reading your AFR? What are your readings at various loads and various throttle angles?
For a naturally aspirated performance combination, you'll typically want to be on or around 13.2:1 AFR. 14.7:1 AFR is a perfectly "stoichiometric" AFR and is just fine for smaller throttle angles and cruising.
Although your car is absolutely stock, and shouldn't need a dyno tune, the stock tables aren't that great (as mentioned previously) and many stock 94-95s detonate at WOT and normally run a tad lean. You can always try backing the timing off and increasing fuel pressure a few PSI to see if that helps.
Paul.
Addermk2
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if you are still running cats, your readings will be severly skewed... I hope you were trying to read the exhaust from one of the stock O2 bungs, instead of the tailpipe
Addermk2
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did you ever think about just bumping your fuel pressure a little bit? Thats what I had to do with my car.
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