Cold start with MAF
10-26-2005, 10:21 PM
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Cold start with MAF While tuning in SD, my car had no issues what-so-ever with cold starts.
After getting my VE tables right, took car out of SD, now it totally surges on cold startups...warm is fine, no surging.
I have the SLP 85mm MAF with the resistor removed..loaded Z06 tables & calibrated from there.
Anyone know why this is?...this cold start surging is driving me nuts.
I've tried about everything I could find...nothing made much difference with the cold start surging.
TIA
After getting my VE tables right, took car out of SD, now it totally surges on cold startups...warm is fine, no surging.
I have the SLP 85mm MAF with the resistor removed..loaded Z06 tables & calibrated from there.
Anyone know why this is?...this cold start surging is driving me nuts.
I've tried about everything I could find...nothing made much difference with the cold start surging.
TIA
10-27-2005, 09:09 AM
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Originally Posted by GuitsBoy
Have you leaned out your OL F/A table? I had to do that when i put y maf back on and it started getting colder outside
I've added timing...took away timing....my IAC is around 30 when warm...although it is around 310 during cold starts..I assume this is normal.
I've downloaded a ton of bin files & compared every aspect of idle items against mine...made some changes...no help.
10-27-2005, 09:16 AM
#4
310 sounds a bit high even for a cold start... 310 is maxxed out completely. Do you have a ported TB filled in with epoxy? My guess is that the holes in the epoxy might be too small, as I had a similar issue. I opened my IAC hole up to a full 1/2" whereas before it was like 3/16" and no matter how much the IAC opened up the hole was restricting idle airflow.
10-27-2005, 09:22 AM
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Originally Posted by GuitsBoy
310 sounds a bit high even for a cold start... 310 is maxxed out completely. Do you have a ported TB filled in with epoxy? My guess is that the holes in the epoxy might be too small, as I had a similar issue. I opened my IAC hole up to a full 1/2" whereas before it was like 3/16" and no matter how much the IAC opened up the hole was restricting idle airflow.
Thanks.
10-27-2005, 12:52 PM
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Originally Posted by GuitsBoy
310 sounds a bit high even for a cold start... 310 is maxxed out completely.
Thanks
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10-27-2005, 09:37 PM
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Originally Posted by GuitsBoy
Do you have a ported TB filled in with epoxy? My guess is that the holes in the epoxy might be too small, as I had a similar issue. I opened my IAC hole up to a full 1/2" whereas before it was like 3/16" and no matter how much the IAC opened up the hole was restricting idle airflow.
IACs were off, but luckily I flipped that screw a while ago, so adjustment was easy.
This was with the car sitting for over 24 hours...I hope it learns this new adjustment...I don't like this 2000 RPM on cold start ups...guess I'll find out tomorrow.
Thanks again.
Keith
10-28-2005, 06:12 AM
#12
Yeah, dude, the 2000 RPM starts arent permanent. Youre long idle trims are sky high because of the small hole you had. Now with more airflow and a high idle trim, its flowing way too much air. Like Jerflash said, you can reset the computer, but at this point, id just let it idle for a few minutes to relearn a new idle trim. (EDIT: Actually, come to think of it, resetting the computer will put you back at the IAC park position which is 310 - exactly where your IAC counts were pegged anyway, so not much difference.) Next time you start it should be pretty much right on. From there you should still do the normal idle tuning to get everything dialed in across all temps. Glad its working out for you.
10-28-2005, 08:49 AM
#13
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i think im going to do this as well if it works out for him
because i also ahve low rpm surging when driving in first gear which is probably from this aswell
because i also ahve low rpm surging when driving in first gear which is probably from this aswell
10-28-2005, 09:08 AM
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Started it up this morning...around 40 F ....fired right up to 1100 RPMs and slowly came down to 900 with no surging....this is fixed as far as I'm concerned.
Thanks
Thanks
10-28-2005, 09:33 AM
#15
Originally Posted by jerflash
i think im going to do this as well if it works out for him
because i also ahve low rpm surging when driving in first gear which is probably from this aswell
because i also ahve low rpm surging when driving in first gear which is probably from this aswell
10-28-2005, 10:05 AM
#16
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ya thats when mine happens around 1600 and i ahve the f13 as well
the cam runs great and drives like stock other then low rpm first gear
i think that problem may have to do with the maf readings at that speed espesialy with maf ends or ported mafs. its like at that speed its addin to little fuel of fuel becasue it cant sence the extra air at that speed
i remember when i was runnin this cam on my old trex+heads tune the car ran rich as hell and i was using a buddies stock maf when it was tuned for a ported maf. like i said it ran really rich but no low rpm buckin and the car started up and idled awsome but it was also an open loop tune
the cam runs great and drives like stock other then low rpm first gear
i think that problem may have to do with the maf readings at that speed espesialy with maf ends or ported mafs. its like at that speed its addin to little fuel of fuel becasue it cant sence the extra air at that speed
i remember when i was runnin this cam on my old trex+heads tune the car ran rich as hell and i was using a buddies stock maf when it was tuned for a ported maf. like i said it ran really rich but no low rpm buckin and the car started up and idled awsome but it was also an open loop tune
10-28-2005, 12:18 PM
#17
I dont know that it's got anything to do with the MAF. Pull it and find out for yourself. I was running SD for a while and I did see any noticable difference between MAF and MAFless. Are you using HPTuners? If you are, Id love to see your buddie's TRex tune and your F-13 tune and see what the discrepency is between the two, and why the Trex tune didnt buck on your f-13 cammed motor. I have heard that throwing a ton of extra fuel at it will calm it down a bit, but I havnt had luck yet. Its hard to trick it into adding fuel and keeping the closed loop. Also, a ported / ended MAF will be inaccurate until you calibrate it against a dialed in SD tune. Once the MAF is calibrated, the cam still has a lot of reversion in the lower rpms which actually makes the MAF read more than normal since the same air cools the hot-wire maf on the way in, then again on the way out (during reversion). This makes the MAF read more "gross airflow" that moves in both directions vs. the "net airflow" that actually goes into the engine. I hope I explained that correctly.
Originally Posted by jerflash
ya thats when mine happens around 1600 and i ahve the f13 as well
the cam runs great and drives like stock other then low rpm first gear
i think that problem may have to do with the maf readings at that speed espesialy with maf ends or ported mafs. its like at that speed its addin to little fuel of fuel becasue it cant sence the extra air at that speed
i remember when i was runnin this cam on my old trex+heads tune the car ran rich as hell and i was using a buddies stock maf when it was tuned for a ported maf. like i said it ran really rich but no low rpm buckin and the car started up and idled awsome but it was also an open loop tune
the cam runs great and drives like stock other then low rpm first gear
i think that problem may have to do with the maf readings at that speed espesialy with maf ends or ported mafs. its like at that speed its addin to little fuel of fuel becasue it cant sence the extra air at that speed
i remember when i was runnin this cam on my old trex+heads tune the car ran rich as hell and i was using a buddies stock maf when it was tuned for a ported maf. like i said it ran really rich but no low rpm buckin and the car started up and idled awsome but it was also an open loop tune
10-29-2005, 08:00 PM
#18
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i had the trex cam with heads then changed to the f13/stock heads becuase of some problems i had
i does look like with alot of fuel and the stock maf the car stoped buckin though but as soon as i got my ported maf on there i got the buckin back
the tunes were done in hptunners but i ahve not gotten my tuning software yet
i does look like with alot of fuel and the stock maf the car stoped buckin though but as soon as i got my ported maf on there i got the buckin back
the tunes were done in hptunners but i ahve not gotten my tuning software yet
