On the struggle bus

Mnt86SS

Member
Been fighting a stalling condition of of idle in gear. I smoke machined it and found vacuum leaks at the vacuum block and throttle blade shaft bushings. Replaced plenum gasket, TB Shaft bushings, vacuum block gasket, IAC block gasket, TB gasket and all the little rubber lines at the block.

Still have a stalling condition of of idle in drive. It'll idle all day in drive with your foot on the brake, but when you let off the brake and let the car start rolling, the idle dips super low and dies.

Mods:
Turbotweek chip
50lb injectors
LT1 Maf with translator
TA49 turbo
3" cat-less down pipe
External Turbonetics waste gate
Adjustable FPR set at 30psi idle, 40psi line removed
Wlabro 255 pump
Boost set @17psi


Scanmaster:

Millivolts Idle 550-85]
AF 04
L8 33
Bat 13.8
INT 128
BL 117
CLT 180
ATS 123
RPM 800
TPS .44
IAC 00 (Was 15-20 at idle until warmed up)
CCs counting
CEL 00


I'm thinking I'm still fighting a vacuum leak somewhere. In park it'll cough for a split second when you rev it before it revs up. It's also slow to return to idle.

Any ideas? I'm gonna smoke machine it again and really crawl all over it, but anything else I should be looking for?
 

TurboWh1

Well-Known Member
Had a similar issue..... How old is your Accufab regulator? Check with a mightyvac. Will it hold pressure and or is the seal at the jam nut sealing?
 

Mnt86SS

Member
Ok, reset the IAC and TPS again and got it at:
TPS .44
IAC in park 06-07

Have MAF translator set at 10% lean at idle. Millivolts hover around 200-400 for a minute, but pegs at 800-850 after idling in gear for a minute.

CCs not moving at idle, giving it throttle in park it'll move but only a few numbers before freezing again.
 

Mnt86SS

Member
Forget to add, CCs aren't super responsive at all with O2 plugged in, but for whatever reason the CCs move pretty fast from 0-255 with it unplugged.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Eric chip requires you set the fuel pressure line off at 43-44 PSI...engine warmed up in Park. He gives you instructions for a reason. Install a new Denso 02 sensor.
 

Mnt86SS

Member
Eric chip requires you set the fuel pressure line off at 43-44 PSI...engine warmed up in Park. He gives you instructions for a reason. Install a new Denso 02 sensor.

It has a new Denso in it. I still have the old Delco purple wire O2 that I can swap back in to confirm if there's any difference.

I'll check the diaphragm on the FPR and reset the pressure.
 

salvageV6

Daily Driver
The car exhaust has to be hot enough for the sensor to light up, hold it at 1500 rpms for 30 seconds and you should see the crosscounts move normally. Assuming the car is already at 160 degrees (or more) and idling first.
Delco sensor that is, densos may be self heating I don't use them myself.
 

Mnt86SS

Member
The car exhaust has to be hot enough for the sensor to light up, hold it at 1500 rpms for 30 seconds and you should see the crosscounts move normally. Assuming the car is already at 160 degrees (or more) and idling first.
Delco sensor that is, densos may be self heating I don't use them myself.

The numbers were pull while the car was at 180 degrees. The CCs seemed to be dead when the Denso was plugged in, both at idle and 2000rpm. Oddly enough they move around perfectly with it unplugged.

I'll throw the old Delco back in and see what it does.

Question: I thought most chips use open loop at idle. Would readings like millivolts and CCs move at idle while in open loop? I figured they'd be locked in
 

salvageV6

Daily Driver
The O2's are from the sensor I believe on the scanmaster mine move with open loop idle selected on my extender extreme chip. What version turbotweak chp do you have?
 

Mnt86SS

Member
The O2's are from the sensor I believe on the scanmaster mine move with open loop idle selected on my extender extreme chip. What version turbotweak chp do you have?

It's an oldie. Here's a pic of the chip:

Screenshot_20220903-122404_Gallery.jpg


I put the old purple wire Delco O2 in, and reset the fuel pressure to 43psi line off 33 line on. I put a vacuum pump on the regulator and it's holding steady, not leaking down.

At cold idle the millivolts are hovering around 300-350. CCs not moving at idle, but move immediately when given throttle.

Scanmaster readings at operating temperature:

Millivolts: 350-400
AF: 04
L8: 33
BAT: 14.0
INT: 128
BL: 128
CLT: 182
ATS: 81
RPM: 775-825
TPS: .44
IAC: 06
CCs: Moving rapidly from 0-255
MAL: 00


I unplugged the computer to get a pic of the chip, which is why the INT and BL are both at 128
 

salvageV6

Daily Driver
Sounds normal to me. I doubt the chip is your problem but that one doesn't have open loop idle I don't think...
 

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Mnt86SS

Member
Alright, so I might have found the issue.

After exhausting all options, I unplugged the converter lockup plug on the side of the trans. The car no longer wants to stumble and die from a stop. Seems to run great.

So, now it's time to see if it's the actuator in the trans that's screwing up, or potentially it's in the converter? I was planning on a PTC converter over the winter, so it's not the end of the world if the current converter is acting up.
 

hensleyt

Well-Known Member
did it help? and did you plug the converter back in?
my car likes it around 20 @140* + looks like it jumps around in D 18 -25 Water temp no AC. but all cars are different.
 

Mnt86SS

Member
did it help? and did you plug the converter back in?
my car likes it around 20 @140* + looks like it jumps around in D 18 -25 Water temp no AC. but all cars are different.

Unplugging the torque converter lockup solved it. No more stalling when transitioning from stopped to rolling.


Right now the IAC is 18 in park at hot idle. TPS at .44 and seems to like it.


I have noticed at WOT every now and then the millivolts will read low (.200-.350) for a split second, and will pull 2-3 degrees of timing. It doesn't do it every time though. Most WOT pulls show O2 voltage between .750-850


Should I mess around with the MAF translator and see if I can richen it up a little under boost?
 
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