Dropping MAP at constant TPS -> Scan & pix inside
Thread Starter
TECH Fanatic
iTrader: (6)
Joined: Jan 2002
Posts: 1,193
Likes: 0
From: Springfield, IL
Dropping MAP at constant TPS -> Scan & pix inside Okay, here's the skinny on the situation. The idle on this car is hit or miss, sometimes it seems to idle okay, then when the car is shut off and a new scanner config is used, the car idles erratically after restart. The scanner also hasn't been picking up accurate data for idle tuning. LTIT's stay zero'd out the majority of the time, and seem to randomly wake up and start working (but not very often). According to the STIT's, the car is asking for a RAF around 6.XXX while warm on a 408 (much lower than expected). After raising the RAF a couple points, against what the scanner showed that the car wanted, it idled better... at least this time.
I'm about 90% sure there's a hardware issue, but its been very difficult for the owner to find. I'm just helping over e-mail, so I don't have first hand knowledge of exactly how problems have been checked and rechecked.
Here's a couple scanner screenshots of a probable indicator of the problem, but I'd like for some other people to give me their opinion on it. I'll give my thoughts on the issue after I've heard a few other opinions.
Scanner file: http://www.unrealhp.com/408currentnew02drive.hpl
This car is a 408 with FAST intake, NW 90mm TB and all bolt-ons. The oxygen sensors were just replaced due to some very lazy operation. The scan above was done in SD with the MAF turned off.
I'm about 90% sure there's a hardware issue, but its been very difficult for the owner to find. I'm just helping over e-mail, so I don't have first hand knowledge of exactly how problems have been checked and rechecked.
Here's a couple scanner screenshots of a probable indicator of the problem, but I'd like for some other people to give me their opinion on it. I'll give my thoughts on the issue after I've heard a few other opinions.
Scanner file: http://www.unrealhp.com/408currentnew02drive.hpl
This car is a 408 with FAST intake, NW 90mm TB and all bolt-ons. The oxygen sensors were just replaced due to some very lazy operation. The scan above was done in SD with the MAF turned off.
This is my car. Ive been having issues with the idle for a while now. The car did have a vacuum leak after the FAST install, the LTFT's were set at 25 and wouldnt budge. I pulled everything apart and didnt see any signs of gasket failure or etc. Cleaned everything then reinstalled everything carefully. After a restart and fuel trim reset the LTFT's went down to 10 and below, so I was assuming the leak was gone. The only thing I can think of that would be leaking would be the intake inlet gaskets, beings they have been off an on now maybe 4 times. Ill order a new set tommorow, and Ill pull the intake off today to find out if any of the gaskets are bad. Ill check then inner gasket of the FAST also. I was going to try the carb cleaner method before I went pulling everything apart to see if I could spot the leak like that. Any other suggestions?
Thanks!
Thanks!
Anybody have any clues or ideas? I pulled the intake to look for a vaccum leak and cant find anything. The gasket that goes in the middle of the FAST intake was slightly torn on the back intake. I pulled the top half of the intake off and used some gasket sealer all the way around the intake, let it sit over night and still having the same issue. The MAP seems to be decreasing as you give it more throttle. Im up for tryin anything, as my last resort is soon to be a match!
Also what are some things to look for that would skew my RAF results? They still seem to be extremely low, and the idle wants to jump up and down fron 1350rpm or so down to 300rpm. Ive got logs, tunes and all with me if anybody could take a look at them to see if maybe we're over looking something. Anybody?
Thanks!
Also what are some things to look for that would skew my RAF results? They still seem to be extremely low, and the idle wants to jump up and down fron 1350rpm or so down to 300rpm. Ive got logs, tunes and all with me if anybody could take a look at them to see if maybe we're over looking something. Anybody?
Thanks!
