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500 rpm idle!

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o0GuitarKid0o

Proven Member
1,063
152
Dec 12, 2013
Winnipeg ,MB, MB_Canada
First off couldnt figure out where to post this a moderator can move this if its better suited for a differnt location.

Alright so I was in the car wash to check my oil level , tire pressure tthe basic things and after when I was leaveing I was waiting for The door to open and I couldnt beleve my eyes my car was idleing at 500 rpm perfectly! Like I mean perfect had great voltage 14.1 volts, and it sounded like nothing like I could barely hear my engine so I just got out to hear it and ive never heard it idle so cleanly it was like I was driveing a hybrid , it didnt bog once or even try to die from being 300 rpm below spec in gear with wheels slightly turned as I was waiting to go forward and straighten out and leave so my question is , why did it run so clean My car used to Run like crap b4 I replace a bunch of stuff 5 month ago so Would it be a bad idea to adjust my biss (THE right way) to lower my rpm car was fully warm at this point and I kinda liked it idleing that low , only thing im worried about is oil pressure tbh
Car usually idles from 1500 fully frozen and goes down to 950-1000 in park and usually when im In gear nd stop at a light it idles like 750 -900 rpm , my car is a non turb swap from turbo (I know lame as f*ck ) but still has the original turbo transmisson ( same vin as mine) and is the f422 or what ever the turbo trannys are and its a good ol 1991 laser rs with 239000 km ish engine has been swapped accordi g to prev owner
 
The idle on these cars can be adjusted to be lower or higher via the BISS. If all is perfect with your engine, it very well could idle that low without a problem. You'll just have to adjust it back to 800rpms.

Not if the car is working the way it was designed. The whole point of the idle control loop is to maintain about 750 rpm @ idle. If it isn't doing so then one or more part in that system has failed.

It's great that the car idled well that low but it's still broken to be do so.
 
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If it wants to idle there and your ECU is telling you that the ISC is open all the way, which is very likely, then you have some adjustments to make as you're not getting nearly enough air or your ignition timing is incorrect.

If you're not using any kind of tuning/flash package, and you're idling in park at nearly 1000rpm, you have adjustments to make anyway. The ECU wants to idle at 750 +/- 50rpm unloaded as steve has already pointed out. If it can't, it's going to close up the ISC until it can't close it anymore (but will still try as it's a zero feedback system). If it's fully closed, and you're still at 1000, you're way out of adjustment and don't expect idle to be consistent.

Did you wash the engine bay?

Do you have the ability to, at the very least, log ECU data?
 
Not if the car e they way it was designed. The whole point of the idle control loop is to maintain about 750 rpm @ idle. If it isn't doing so then one or more part in that system has failed.

It's great that the car idled well that low but it's still broken to be do so.
Alright so I should maybe check some stuff then with my (dmm) anything.to look for that I should know? Ive also noticed my throttlebody is either grounded somewhere I cant see or the previous owner didnt add this plate that ive been trying to locate that 91 throttle bodys have tempted to get a wire and.just ground it, heres what I mean
http://forums.ds-map.net/electronics/grounding-locations/

Apparently it can cause idle fluctuations if.the bolts are the only ground ill get some pics if the.local car wash is open its.like -33c outside atm
If it wants to idle there and your ECU is telling you that the ISC is open all the way, which is very likely, then you have some adjustments to make as you're not getting nearly enough air or your ignition timing is incorrect.

If you're not using any kind of tuning/flash package, and you're idling in park at nearly 1000rpm, you have adjustments to make anyway. The ECU wants to idle at 750 +/- 50rpm unloaded as steve has already pointed out. If it can't, it's going to close up the ISC until it can't close it anymore (but will still try as it's a zero feedback system). If it's fully closed, and you're still at 1000, you're way out of adjustment and don't expect idle to be consistent.

Did you wash the engine bay?

Do you have the ability to, at the very least, log ECU data?
I had a palm pilot but it broke sadly ,
also ive never washed my engine bay because hot water under high pressure on a 24yr old car/ wires is a big no no imo.
and since its an auto should the idle be adjusted in gear/drive? (Im about 99% saying no ) or neutral? did it last year in park but ive replaced my injectors since then and in drive my car idles at like 750-900 thats why I never touched my biss by grounding out the odb pin (cant remeber off hand) and the timeing thing on the fire wall to center the isc if I remeber correctly
 
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Always good to have a ground off the tb directl, plate or no plate. Simple screw with wound wire or a crimped eyelet will do.

Idle has to be adjusted in park or neutral, but park is "more safe".

I think I have a good m515 still with the aldl cable
 
Always good to have a ground off the tb directl, plate or no plate. Simple screw with wound wire or a crimped eyelet will do.

Idle has to be adjusted in park or neutral, but park is "more safe".

I think I have a good m515 still with the aldl cable
Do you use.the.palm? I think my palm pilot was a m505 worked good till I accidnetly used the wrong charger LOL ive got the keybord still I think . And ill add a good solid ground then ive acually noticed a small crack in my valve cover.near the pcv so im acually grabing a cover from an evo 3 tmmr and a gasket set from part source (hopefully) so that might explain high idle.but not to sure about the 500rpm idle tho ill have to see what happends after I fix my cover (jb welded for now) just incase
 
What is the accepted norm for the idle?

Basic idle speed is spec'ed as 750 +- 50rpm in neutral or park with the two adjustment terminals grounded or the ECU in BISS adjustment mode.
 
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