Why negative LTRIMS at idle?
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Joined: Nov 2001
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Why negative LTRIMS at idle? Guys I am a little confused. I am running stock descreened MAF, stock programming with HPP used only for rev limits and gearing etc.
My LTRIMS at idle at -10 on one bank and -4 on the other bank. At cruise they both go to zero. Does anyone know why this is happening?
It is running rich at idle for some reason but I cant pin down why.
I am running a MAC offroad with bullets in the Y and no catback at the present time. O2's look ok and timing is decent as well. Any ideas?
I have my AIR and EGR block off so I dont know if that would contribute to my problem or not. I may put small holes in the block off plates and see if the AIR pump functioning again will help.
Thanks,
Chris
[ December 09, 2001: Message edited by: Chris ARE 360 ]</p>
My LTRIMS at idle at -10 on one bank and -4 on the other bank. At cruise they both go to zero. Does anyone know why this is happening?
It is running rich at idle for some reason but I cant pin down why.
I am running a MAC offroad with bullets in the Y and no catback at the present time. O2's look ok and timing is decent as well. Any ideas?
I have my AIR and EGR block off so I dont know if that would contribute to my problem or not. I may put small holes in the block off plates and see if the AIR pump functioning again will help.
Thanks,
Chris
[ December 09, 2001: Message edited by: Chris ARE 360 ]</p>
Re: Why negative LTRIMS at idle? Chris
What's your fuel system setup now? High fuel pressure can send the LTRIMS south. Mine have come down quite a bit with the addition of the volt blaster. It's just a little too much flow for my regulator at idle.
What's your fuel system setup now? High fuel pressure can send the LTRIMS south. Mine have come down quite a bit with the addition of the volt blaster. It's just a little too much flow for my regulator at idle.
Thread Starter
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
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Re: Why negative LTRIMS at idle? I am running the stock 98 fuel system with stock 98 injectors. <img src="images/icons/frown.gif" border="0">
Not sure why this is happening. I dont think its a vac leak as that usually increases LTRIMS at idle and not decrease them. again cruising is perfect with 0 LTRIMS but idle is -10 on one bank and -4 on the other.
Could TPS voltage or IAC have anything to do with this? Maybe an exhaust leak at idle?
Thanks,
Chris
Not sure why this is happening. I dont think its a vac leak as that usually increases LTRIMS at idle and not decrease them. again cruising is perfect with 0 LTRIMS but idle is -10 on one bank and -4 on the other.
Could TPS voltage or IAC have anything to do with this? Maybe an exhaust leak at idle?
Thanks,
Chris
Staging Lane
Joined: Nov 2001
Posts: 94
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From: Harrisburg, Pa USA#1
Re: Why negative LTRIMS at idle? Chris, mine are at 0 or a little negative at idle which I thought was good. At WOT I average 880's with 0 knock. Joe... <img src="graemlins/fluffy.gif" border="0" alt="[Fluffy]" />
Re: Why negative LTRIMS at idle? [quote]Originally posted by Chris ARE 360:
<strong>I am running the stock 98 fuel system with stock 98 injectors. <img src="images/icons/frown.gif" border="0">
Not sure why this is happening. I dont think its a vac leak as that usually increases LTRIMS at idle and not decrease them. again cruising is perfect with 0 LTRIMS but idle is -10 on one bank and -4 on the other.
Could TPS voltage or IAC have anything to do with this? Maybe an exhaust leak at idle?
Thanks,Chris did you ever get an answer for this? thanks,Dean
Chris</strong><hr></blockquote>
<strong>I am running the stock 98 fuel system with stock 98 injectors. <img src="images/icons/frown.gif" border="0">
Not sure why this is happening. I dont think its a vac leak as that usually increases LTRIMS at idle and not decrease them. again cruising is perfect with 0 LTRIMS but idle is -10 on one bank and -4 on the other.
Could TPS voltage or IAC have anything to do with this? Maybe an exhaust leak at idle?
Thanks,Chris did you ever get an answer for this? thanks,Dean
Chris</strong><hr></blockquote>
Thread Starter
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
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Re: Why negative LTRIMS at idle? Warm idle it is doing it.
Here is an overview of my system <img src="gr_stretch.gif" border="0">
Stock programming with HPP for rev limit, gears, and fans only. NO power tuning
Stock MAF descreened
Stock injectors
Stock pump
Stock lines
NGK TR55 plugs at .055 gap
at idle they are at -10 and -4. As soon as I start cruising they return to 0 on both banks.
soo... My car is adding a lot of fuel at idle (More than necessary) and the PCM is trying to compensate by removing fuel at idle.
Also my car is slow starting when hot sometimes, but I think that is TPS/IAC related. Mechanically everything seems very solid with the car.
Your thoughts are appreciated <img src="gr_stretch.gif" border="0">
Chris
- Maybe it is the AIR pump system. I have it unplugged but maybe the computer is not compensating for the lack of air injected by the AIR pump at startup and idle and is forcing the LTRIMS to remove fuel.
Here is an overview of my system <img src="gr_stretch.gif" border="0">
Stock programming with HPP for rev limit, gears, and fans only. NO power tuning
Stock MAF descreened
Stock injectors
Stock pump
Stock lines
NGK TR55 plugs at .055 gap
at idle they are at -10 and -4. As soon as I start cruising they return to 0 on both banks.
soo... My car is adding a lot of fuel at idle (More than necessary) and the PCM is trying to compensate by removing fuel at idle.
Also my car is slow starting when hot sometimes, but I think that is TPS/IAC related. Mechanically everything seems very solid with the car.
Your thoughts are appreciated <img src="gr_stretch.gif" border="0">
Chris
- Maybe it is the AIR pump system. I have it unplugged but maybe the computer is not compensating for the lack of air injected by the AIR pump at startup and idle and is forcing the LTRIMS to remove fuel.
Re: Why negative LTRIMS at idle? I noticed that with a cam (before tuning), my Ltrims at idle were off much more than any other cell.
Could misfires at idle cause the O2s to look rich so the computer pulls extra fuel trying to lean it out??
Could misfires at idle cause the O2s to look rich so the computer pulls extra fuel trying to lean it out??
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Re: Why negative LTRIMS at idle? I have a bigger aftermarket intank, and see 60 psi at idle.
I recently had to go -10 up to -15% on the base with the MAF T the car was loading up.
I recently had to go -10 up to -15% on the base with the MAF T the car was loading up.
9 Second Club
Joined: Nov 2001
Posts: 1,445
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From: Bay Area, CA
Re: Why negative LTRIMS at idle? weird that it is doing it with a stock descreened maft.... I like my Ltrims slightly negative they drop right to 0 at part throttle just like you observe, if they were postive the numbers bounce around a little, and could possibly skew your A/F ratio at WOT.
I use the darkside. Mainly because it blends in perfectly with the other screens I use at work. This way if my boss or supervisor are walking by, I am one click away from looking like I am working. And if I do not click fast enough on the other screen, they usually connot differentiate just by glancing at my monitor.
Originally Posted by scrmnws6
I use the darkside. Mainly because it blends in perfectly with the other screens I use at work. This way if my boss or supervisor are walking by, I am one click away from looking like I am working. And if I do not click fast enough on the other screen, they usually connot differentiate just by glancing at my monitor.
And holy old post batman.
its funny that I just seen this thread, I was looking at a threads url, changed the number to 1 and hit enter lol, and low and behold this threads already been dug up this year? lol
I am going to be ordering my MWCP 9 at the end of next month. I just need to save a little extra money to get new wheels and tires at the same time.
I am sorry to beat a dead horse, but you have the worst looking under carriage I've ever seen. With the lift I'd spray a **** ton of degreaser, let it sit, and then blast it with a pressure washer. I'd do that until it comes clean. Possibly hit it with an orbit sander to get the rest off. Spray it with rattle can primer or your gun and paint it. With all of those nice parts you are putting under there you should be proud to show them off without people constantly asking you about why your car is so dirty.
I am sorry to beat a dead horse, but you have the worst looking under carriage I've ever seen. With the lift I'd spray a **** ton of degreaser, let it sit, and then blast it with a pressure washer. I'd do that until it comes clean. Possibly hit it with an orbit sander to get the rest off. Spray it with rattle can primer or your gun and paint it. With all of those nice parts you are putting under there you should be proud to show them off without people constantly asking you about why your car is so dirty.
