Idling problem

[OneLethal87GN]

When I first start the car it revs up around 1500-2000 rpms. After a few seconds it settles down under 1,000. After revving it up a little or just letting it idle for a minute or so the idle will die down eventually causing the engine to shut off. I was watching my IAC counts before it shut off and they were in the 30s range. I haven't had time to play with the car since having the engine rebuilt so I haven't gotten it up to operating temp. yet to set the IAC counts. My boost gauge shows very good vacuum so a big leak doesn't seem to be the problem. By the way, it did this before the engine was taken out and rebuilt and I did replace the IAC valve with a brand new one.

 

[Mr.Buick]

Idle issues

where is the TPS? needs to be .40-.42 then reset IAC to high 20's and see what the idle is like.

 

[Paul Clark]

Raise the FP and see if that helps.
How do you set the IAC to a certain number?
Not challenging. Just want to learn.

 

[Mr.Buick]

Idle issues

Keep fuel pressure below 43 line off, or 38 line on. To much fuel pressure will cause problems, injectors are designed for correct fuel pressure. IAC adjustments need to be made slowly let the car run for a minute or two after 1/4 turn to let the computer adjust. For details go to turboregal website link:
http://www.rennie-macintosh.com/ and look up IAC adjustments

 

[OneLethal87GN]

The fuel pressure is high 20s to low 30s line on. The car runs great for the first 30 seconds or so. I'll let it warm to operating temperature tomorrow and play with the IAC counts to see what happens. I can also turn my Kenne-Bell boost-a-pump all the way up. This gives me low 40s fuel pressure. The tps is set at .44 at idle.

 

[Mr.Buick]

Idle issues

You need to lower the TPS you are to close to the magic .45, which gets you into problems. set it at .42 and then set the IAC to high 20's raise your fuel pressure to 42 with the vacuum line on and that should do it

 

[Paul Clark]

"raise your fuel pressure to 42 with the vacuum line on"

Did you mean "off".

 

[OneLethal87GN]

I'll try all that tomorrow if I get a chance. I'm trying to get the car looking good before putting it back on the road. I figured .44 was just right. I've always read to go between .42 and .46. I think my main problem is that I haven't tried to set it while the car reached operating temps yet. I've been doing it while cold.

 

[Mr.Buick]

Fuel Pressure

Yes, I mean line off, sorry. 38 with the line on and 45 with line off
Fuel pressure rule of thumb is the number of your injector flow, example #36, plus pounds of boost plus 5 pounds at WOT should equal your fuel pressure.
Example: 20 lbs. of boost, plus 36 lb injectors, plus 5 means you should have 61 lbs of fuel pressure in high gear at WOT. Less pressure means you run lean and goodbye pistons. Rich fuel mixtures suppress detonation and knock retard.
Stock: 12 lbs of boost, Plus 28 lb injectors, plus 5 means you should have 45 to be right on. Hope this helps

 

[OneLethal87GN]

So at, say, 25 psi with my 42.5 lb. injectors I should be running @72.5 psi of fuel pressure at WOT? That would make my idle fuel pressure @47.5? I keep meaning to get out there and mess with my car but I just don't have the drive right now. Maybe tomorrow.

 

[Chuck Leeper]

WHAT???

Injectors are flowed at, in most all cases, at 3 bars, AKA: 43.5psi.
Operating them at other than that pressure alters the flow rates.
There is no known reason for using the PPH rating of the injectors and adding 5# to determine FPR setting.....
Suggest you stay w/ the base number of 42# and then you won't have excessive FP at idle, nor will you be tuning to some injector value other than what the injectors actually are.

Back under my injector bench......