idle problems on L98 TPI
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
idle problems on L98 TPI
hi!!
i have had idle problems, since i have the car...in nov i dissassembled the engine and did an upgrade to an Xtreme energy cam, 206/212 @ .050, .3200int/3250ex , 1.52 rollertips and i cannot smooth out the idle...
burned a few different chips today, im successful in tuning the VE tables, near 128 all over, but, i cannot get the idle smooth
i dont mind, when it runs and sound cammed, i dont like the near stall conditions...
now im searching across the board for experiences with that
i hope you can and will help me
i have had idle problems, since i have the car...in nov i dissassembled the engine and did an upgrade to an Xtreme energy cam, 206/212 @ .050, .3200int/3250ex , 1.52 rollertips and i cannot smooth out the idle...
burned a few different chips today, im successful in tuning the VE tables, near 128 all over, but, i cannot get the idle smooth
i dont mind, when it runs and sound cammed, i dont like the near stall conditions...
now im searching across the board for experiences with that
i hope you can and will help me
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Re: idle problems on L98 TPI (corvette90)
update:
i bumped up the idle to 875rpm, and now it idles fine, a bit loping, but it idles..
hope, it idles also when weather gets warm....
i bumped up the idle to 875rpm, and now it idles fine, a bit loping, but it idles..
hope, it idles also when weather gets warm....
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Re: idle problems on L98 TPI (Aaron's 87)
hi
i setted the throttle stop, the commanded idle is 875rpm, idle timing is according to TC : 875rpm@ 32-128°C, IAC counts are around 40..
yes thie IAC works for sure, i can see it in my datamaster, and i set the base IAC, so it must work!!!
can someboby give me tips and tricks about PE mpde tuning, and spark advance tuning??
many thanks
i setted the throttle stop, the commanded idle is 875rpm, idle timing is according to TC : 875rpm@ 32-128°C, IAC counts are around 40..
yes thie IAC works for sure, i can see it in my datamaster, and i set the base IAC, so it must work!!!
can someboby give me tips and tricks about PE mpde tuning, and spark advance tuning??
many thanks
Burning Brakes
Joined: May 2001
Posts: 790
Likes: 2
Re: idle problems on L98 TPI (corvette90)
I have a 92 LT1. Basically stock. But same thing. It would not idle when cold, but as it warmed up would idle...but still not good. Drove me nuts. My problem was in my Quad Driver Circuit 1. I finally broke down and bought a Tech 1 off of ebay and discovered it was my Purge Control Solenoid. Replaced it and it smoothed the idle right out. You might try that...it's around $16 US, so not an expensive fix...even if it doesn't work, it's a cheap try.
Good luck.
Good luck.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: idle problems on L98 TPI (corvette90)
PE and spark timing tuning isn't going to help your idle.
Did go adjust the idle speed per the factory procedure ?
Did you set the base timing with the ESC wire disconnected?
Even with those things correct the engine isn't going to idle like stock with your cam.
Did go adjust the idle speed per the factory procedure ?
Did you set the base timing with the ESC wire disconnected?
Even with those things correct the engine isn't going to idle like stock with your cam.
Racer
Joined: Jul 2002
Posts: 401
Likes: 1
From: Aptos CA
Re: idle problems on L98 TPI (VetNutJim)
Corvette90 - Did you get my email?
VetNutJim is sorta right about the cam making the idle lope, I think I mentioned that to you. There are a couple of "tricks" to help.
For everyone having inconsistent idle. Mess with the temp tables- both water and MAF, especially for idle and start-up. I think GM over compensates for cold and hot weather. The system "hunts" around for proper running when the temperatures are on the borders in the tables. Another 2 cents from me.
VetNutJim is sorta right about the cam making the idle lope, I think I mentioned that to you. There are a couple of "tricks" to help.
For everyone having inconsistent idle. Mess with the temp tables- both water and MAF, especially for idle and start-up. I think GM over compensates for cold and hot weather. The system "hunts" around for proper running when the temperatures are on the borders in the tables. Another 2 cents from me.
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Re: idle problems on L98 TPI (VetNutJim)
hi
yes, i know, it doesnt help my idle when i tune spark timing and PE..but i just do it also one day, and why not ask to get tips...
yes, i adjusted the idle, like it is recommendend..with disconnected IAC, jumpered aldl, aso aso, to set base idle to 600 rpm and let IAC do the rest
base timing was set to 6 °BTDC with EST disconn.
my question....is it normal to have a bit lope at idle with this cam?
the car ALWAYS idled not smooth, it never did...i think, there was a different cam in it when i bought it..i will take a look at the numbers and let you know
yes, i know, it doesnt help my idle when i tune spark timing and PE..but i just do it also one day, and why not ask to get tips...
yes, i adjusted the idle, like it is recommendend..with disconnected IAC, jumpered aldl, aso aso, to set base idle to 600 rpm and let IAC do the rest
base timing was set to 6 °BTDC with EST disconn.
my question....is it normal to have a bit lope at idle with this cam?
the car ALWAYS idled not smooth, it never did...i think, there was a different cam in it when i bought it..i will take a look at the numbers and let you know
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Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: idle problems on L98 TPI (corvette90)
206/212 at 50 is j-u-s-t barely getting into the area where it won't idle perfectly. Is the LSA 112 degrees?
Did you try re-adjusting the valves and using 1/4 to 1/2 turn past 0 lash?
Is the fuel pressure 38-43 PSI?
Injectors 22 or 24 lbs/hr?
If they are stock you have the Multec injectors.
Have you done a resistance test on the injectors?
Resistance test won't tell you if they are not flowing right but if you find one or two out of spec. it may offer a hint.
Edit: You will probably have to install an adjustable fuel pressure regulator to compensate for the lower manifold vacumn you will have with your cam.
It may be running a bit rich. What are the BLM & INT values at idle in CLOSED LOOP mode?
[Modified by VetNutJim, 3:35 PM 4/13/2004]
Did you try re-adjusting the valves and using 1/4 to 1/2 turn past 0 lash?
Is the fuel pressure 38-43 PSI?
Injectors 22 or 24 lbs/hr?
If they are stock you have the Multec injectors.
Have you done a resistance test on the injectors?
Resistance test won't tell you if they are not flowing right but if you find one or two out of spec. it may offer a hint.
Edit: You will probably have to install an adjustable fuel pressure regulator to compensate for the lower manifold vacumn you will have with your cam.
It may be running a bit rich. What are the BLM & INT values at idle in CLOSED LOOP mode?
[Modified by VetNutJim, 3:35 PM 4/13/2004]
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Re: idle problems on L98 TPI (VetNutJim)
thank you for your replies...
yes, ive done everything
LSA is 112 degrees, adjusted valves a 1/2 pastb zero, fuel pressure ist about 40psi and 22lbs/hr injectors..stockers
did also an injector balance test, and they are very close..resistance is about 14.5 ohms, all off them
this cam pulls about 30kpa of vacuum, more than the cam before, i adjusted BLM to 126-128 and they stay there, the Int values goes from 125 to 130
ok, thats my knowledge for so far, if you saythe idle come f´rom the cam and will never get better, i can live with it, i just want to get rid of the hot weather near stall conditions...
thank you
yes, ive done everything
LSA is 112 degrees, adjusted valves a 1/2 pastb zero, fuel pressure ist about 40psi and 22lbs/hr injectors..stockers
did also an injector balance test, and they are very close..resistance is about 14.5 ohms, all off them
this cam pulls about 30kpa of vacuum, more than the cam before, i adjusted BLM to 126-128 and they stay there, the Int values goes from 125 to 130
ok, thats my knowledge for so far, if you saythe idle come f´rom the cam and will never get better, i can live with it, i just want to get rid of the hot weather near stall conditions...
thank you
Racer
Joined: Jul 2002
Posts: 401
Likes: 1
From: Aptos CA
Re: idle problems on L98 TPI (corvette90)
yes, i adjusted the idle, like it is recommendend..with disconnected IAC, jumpered aldl, aso aso, to set base idle to 600 rpm and let IAC do the rest
base timing was set to 6 °BTDC with EST disconn.
my question....is it normal to have a bit lope at idle with this cam?
the car ALWAYS idled not smooth, it never did...i think, there was a different cam in it when i bought it..i will take a look at the numbers and let you know
(This RPM is a guess and you need to find this rpm by old fashion tuning. Meaning disconnect the ECM, warm up the engine. Adjust the throttle opening to make sure the 6 degree advance is at YOUR idle and running smooth.)
After you fill the chip with the same values you can warm up the engine and make sure the Engine is at 6 degrees at YOUR idle. This syncs the actual engine specs to the ECM.
I think it was Beth396 that passed this along to me. If it was someone else - chime in and take approprate credit. Otherwise another thanks to Beth396
P.S. You are way off by setting 6 degrees advance at 600 rpm. The ECM uses the IAC, fuel mixture and timing to hit the target idle. If you set it at 600 the ECM has to compensate timing for 250 RPM just to be "normal". Center it at "normal" (YOUR idle), and things will be much easier to tune. You're confusing your ECM. I hope I'm not doing the same to you.
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Re: idle problems on L98 TPI (Skippy Stone)
i setted the timing with the engine running about 800rpms...did the IAC thing later...my engine wont idle with 600rpm, at this time, ialways had to help a bit with throttle to avoid stalling
i will check my idle SA again, and let you know what turned out!!!
a good thing what you say about matching the engine to ECM!!
thanks again
one more question..where does ist come from, when air is hot, that idle will get unstable???
i will check my idle SA again, and let you know what turned out!!!
a good thing what you say about matching the engine to ECM!!
thanks again
one more question..where does ist come from, when air is hot, that idle will get unstable???
