Cold start's / bigger cam.. please help..

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Dec 7, 2005 | 05:23 PM

01Z0H6

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From: Hideaway Tx

Cold start's / bigger cam.. please help..

Posted this in another area.. Cold someone please elaborate..?

I have a Comp Cam 232 / 236 .595 .601 114+4 cam with True duals, Yank SY3500, full bolt on's and it was tuned with HP Tuners...

When i start the car in the morning ( on cold days ) the car fires right up but it bucks, sputters, searches for idle... once warmed up ** approx. 5-10 min.. it is running fine....

It jumps from 200rpm to 4000rpm's... & up & down...

Someone mentioned the "Cold start enrichment"...

Any help would be greatly appreciated... Could this damage my recently built motor?

Thanks in advance..

Dec 8, 2005 | 06:54 AM

Somebody09

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I had the same problem but with my stock cam, and my dual cutouts were open. It happened last year in about 25°F or below. This year, with my GT2-3, it did the same thing, but cutouts closed. I wasn't driving but my it stalled on my brother after we backed out of the driveway. In the first situation, what I had to do was hold the throttle down to keep it at about 2000 RPMs for a minute or two before it stopped screwing around. I too would like to know why this happens.

-somebody

Dec 9, 2005 | 02:38 PM

technical

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From: Fat Chance Hotel

You could try a couple of things. Modify the open loop VE and add fuel for the colder temperature ranges and/or increase the timing in the converter light off table which pulls a **** load of timing (~12*) so that the engine doesn't hunt. You could also modify the idle tables to run 1000-1200 or higher until slightly warmed up. Once it begins hunting the PCM will continue to overcompensate (fuel and spark) under and over causing an erratic behavior.

Dec 9, 2005 | 07:10 PM

Ragtop 99

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From: Bethesda, MD

Quote:

Originally Posted by technical

You could try a couple of things. Modify the open loop VE and add fuel for the colder temperature ranges...

My guess is that it is the opposite, that it is running too rich for a big cam. I'd note what tempature it starts to run fine at and work backwards from there, subtracting .02 to .08 from the values in the MAP 55 to MAP 35 to slow down the rate of extra fuel being added. On a cold winter mornings you get some pretty big multipliers and once it starts oscillating you swing into the high MAP areas and it really dumps a lot of fuel.

Start-up enrichment will help if it is sputtering and stinky for the 1st 30 seconds or so. Your problem is 5 - 10 minutes so the enrichment table is not the primary factor.

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