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Topics - captain slow

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Naturally Aspirated Tuning / Struggling to find a balance
« on: February 01, 2015, 10:59:09 AM »
Hello all, first time poster here!

So i've got a super nice E30 with the following mods:
M20B25, 60k miles
Miller PSIK
Miller tune selector
BBTB (I believe it's 3", but cannot confirm)
Dinan intake manifold
Euro spec cam
Euro spec pistons (iirc, 9.7:1)
Bavauto long tube headers
Single/custom 2.5" exhaust, high flow cat
Stock injectors (as far as I know)
Miller Adjustable FPR
Euro spec plugs gapped to 0.032"

So, here's the story!

Since I bought the car back in July, I've always noticed that it idles a bit weird.  First off, it idled around 900 rpm and I noticed a slight miss, almost a gentle cough from the engine when it idled.  This has always bugged me.  I scanned the chip to evaluate the tune it had on it and found that it was running a 19lb injector tune.  I studied the records and found no evidence that the injectors were ever upgraded but the car does have an adjustable FPR.  After getting familiar with all the ins and outs of the car, cleaning the ICV and ensuring I'm not chasing a possible vacuum leak, I thought to myself that the issue may be some fuel starvation.  I attempted richening the mixture very slightly (1/4 to 1/3 turn) and found that it didn't really help anything.  Today, as I was buttoning up the car from an oil change, I noticed that the car seemed to be running rich (brown/blackish smoke, an abundance of steam) so I elected to assume the car had stock injectors and turn down the FPR as far as it would go.  Immediate improvement!  Car is idling much better and doesn't cough or hiccup under load.

Another problem that was occurring with the old FPR setting was on cold starts, the car didn't high-idle whatsoever.  Idle would start at 1,200-1,500ish right at startup but immediately drop to 900, where it would remain indefinitely. I haven't had an opportunity to start the car cold yet since I've messed with it but it should be noted that it was happening.

Now, I'd like to ensure the tune is matched to the car's mechanical setup before I get it on a dyno and it gets properly tuned.  Is there a tune out there that is well-matched to my setup?  It's currently on the 19lb injector tune with the high flow exhaust and intake, but I'm not certain that's right for me since I'm running such low fuel pressure (relatively speaking, of course).  Is it OK to run the 19lb tune on stock injectors or am I messing with the ECU's/chip's potential?


Obviously, the solution here is to swap over to 19lb injectors, but I will have to wait for those as some other issues are coming first :)

Any help from the collective would be greatly appreciated!

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