Idle Rpm Question.......Crome
09-04-2005, 04:05 AM
#1
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Idle Rpm Question.......Crome
Can you have the ECU set the idle at 1000-1200 rpms using Crome?
The cam I just put in the NA D15B7 loads up at 700-800 rpm, it is THAT big.
Owner/friend with BBC was suprised you could get "THAT" sound from 91 cid 4 pooper.
The cam I just put in the NA D15B7 loads up at 700-800 rpm, it is THAT big.
Owner/friend with BBC was suprised you could get "THAT" sound from 91 cid 4 pooper.
09-04-2005, 04:12 AM
#3
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Re: Idle Rpm Question.......Crome
loads up on fuel..........
ever played with a BIG cam and carbs
??
The cam has such low vacuum, the FPR adds more fuel. Instead of 35 psi with normal vacuum, I'm seeing 45 psi fuel pressure at idle. With a big cam this means a shitty idle from hell.
FYI it is the largest NEW cam for the SOHC non-VTEC you can buy without special ordering.
ever played with a BIG cam and carbs
??The cam has such low vacuum, the FPR adds more fuel. Instead of 35 psi with normal vacuum, I'm seeing 45 psi fuel pressure at idle. With a big cam this means a shitty idle from hell.
FYI it is the largest NEW cam for the SOHC non-VTEC you can buy without special ordering.
09-04-2005, 04:39 AM
#5
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Re: Idle Rpm Question.......Crome
Crane 251-0016, grind number HON-271-2S-10
.425/.416, 244/242......... 110 lobe sep
http://www.cranecams.com/?show=brows...16&lvl=2&prt=5
.425/.416, 244/242......... 110 lobe sep
http://www.cranecams.com/?show=brows...16&lvl=2&prt=5
09-04-2005, 04:53 AM
#6
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Posts: 602
Re: Idle Rpm Question.......Crome
wow thats a pretty big shaft for that size of an engine!!!
can you adjust your idle at the throttle-body? how much compression you got?
how does your plugs look?
i know when my nova did that loading up ( i just called it hesitation ) my plugs always read rich.
how big are your injectors?
can you adjust your idle at the throttle-body? how much compression you got?
how does your plugs look?
i know when my nova did that loading up ( i just called it hesitation ) my plugs always read rich.
how big are your injectors?
09-04-2005, 04:34 PM
#9
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Re: Idle Rpm Question.......Crome
loosen up the lash, that helped......still a beast cam though.......for a 1.5L!!! and stock valvesprings.......
Idle air bleed screw was backed out 2 full turns, stock injectors, yet to pull plugs.......
Time to contact Blundar for some tuning.......
Idle air bleed screw was backed out 2 full turns, stock injectors, yet to pull plugs.......
Time to contact Blundar for some tuning.......
09-04-2005, 11:01 PM
#10
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Join Date: Dec 2002
Posts: 3,830
Re: Idle Rpm Question.......Crome
CROME lets you set the 'target' idle for the ECU, but in my exp. the P30 bin that CROME supports does not actively use the IACV to reach a higher than normal idle speed. IE, cold fast idle is not provided via the IACV like Uber does on the P72 rom. I think this is based on the fact that p30 cars have the mechanical thermo fast idle valve. (Ever noticed that an Uber p72 based bin will give you an IACV induced fast idle, but a p30 based CROME bin will not)
The above isnt totally relevent to what your asking, but just pointing out that even though you can define the ECU's target idle with CROME, the p30 code isnt going to actively work the IACV to achieve it. Ask Blundar of course, this is based soley off of my observations.
On a side note, I have had the exp. of a larger cammed NA motor that pulls less than normal vacuum at idle. If you have datalogging/map trace, its a simple matter of finding the cel's that it reads from while idling (both cold and hot), and setting them appropriately. It may still be a bit lumpy, as it was in my case, but you can get it to supply the correct fueling at idle.
Another thing I noticed with this particular engine, was upon closing the throttle after holding revs steady (>1500, or enough to cause the ECU to go into injector cut-off), was the way the map trace behaved at the initial point of idle recovery. In this case the engine idles at about 16-17". At the point of idle recovery it would see a MAP reading of about 2-4" less (reading from the 13-15" column). What this meant was, that the next higher load column had a rather large impact on how well the engine would settle back into idle. I played with diff. values on extreme ends of rich/lean, and my observation was: Too lean of a value just above idle would cause a slight stumble/misfire, followed by the IACV kicking open, revs jumping a bit over idle, and then settlling. Too rich of a value would result in a very very low idle for 1-2 sec. (but not low enough to kick the IACV), and then it would settle up to the normal idle rpm.
I dont know if the above applies to you, but if your noticing diff. idle charactistics based on the running condition just prior to idle, this may help.
Also, if you havent adjusted your timing map for the new idle area, a stockish timing map may be retarding the timing a bit during idle/recovery; further compounding your monster single slammer idle woes.
Dave
The above isnt totally relevent to what your asking, but just pointing out that even though you can define the ECU's target idle with CROME, the p30 code isnt going to actively work the IACV to achieve it. Ask Blundar of course, this is based soley off of my observations.
On a side note, I have had the exp. of a larger cammed NA motor that pulls less than normal vacuum at idle. If you have datalogging/map trace, its a simple matter of finding the cel's that it reads from while idling (both cold and hot), and setting them appropriately. It may still be a bit lumpy, as it was in my case, but you can get it to supply the correct fueling at idle.
Another thing I noticed with this particular engine, was upon closing the throttle after holding revs steady (>1500, or enough to cause the ECU to go into injector cut-off), was the way the map trace behaved at the initial point of idle recovery. In this case the engine idles at about 16-17". At the point of idle recovery it would see a MAP reading of about 2-4" less (reading from the 13-15" column). What this meant was, that the next higher load column had a rather large impact on how well the engine would settle back into idle. I played with diff. values on extreme ends of rich/lean, and my observation was: Too lean of a value just above idle would cause a slight stumble/misfire, followed by the IACV kicking open, revs jumping a bit over idle, and then settlling. Too rich of a value would result in a very very low idle for 1-2 sec. (but not low enough to kick the IACV), and then it would settle up to the normal idle rpm.
I dont know if the above applies to you, but if your noticing diff. idle charactistics based on the running condition just prior to idle, this may help.
Also, if you havent adjusted your timing map for the new idle area, a stockish timing map may be retarding the timing a bit during idle/recovery; further compounding your monster single slammer idle woes.
Dave
