supermo26

I have a 95 LT1 383 Stroker with a cam that is a little bigger than the Comp 306. Heads are AFR Comp Ported LT4 matched up to a LT4 Intake. Injectors are Green SVO 42's. Computer is programmed by PCM For Less.

I seam to be having a little trouble. I know I have a few exhaust leaks with the Mufflex Y pipe and back. I plan on welding them up soon. The Hooker LT show NO sign of leaking at the heads or Y pipe.
My car started running kind of crappy after I got the Front end Aligned. I know they test drove the car. Hummm. I noticed on the ScannMaster when I picked it up the the reading on the Left side no longer mirrored the Right side when it comes to the Injector pulse width and Integrator. One of the values is reading 140 on the left and 160 on the right.???
The O2 Left and right are constantly dropping to double digits for as long as a second or two and it seams to be getting worse.
I looked under the hood to check things out and it smelled like fuel especially on the Passenger side.
The car Idles ok with no knock and other times it will pick up a little here and there or when cold. Usually it stay at 0.0 when driving, but now it is jumping up to 7.0 at time under acceleration.
The spark advance is between 23-40.
I am looking for some advice on where I should start to get this car to run right. It still has some power to it when I step on the gas but not a much as it did before the Alignment. I checked the headers for damage and they looked fine. O2 bungs looked ok as well. O2 sensors have less than 3,000 miles on the as with all the other sensor on this motor. I even changed the oil last week.

With that being said where should I start???

WS6T3RROR

I'm not going to pretend i know what 140 means but from what i've read before that means its adding fuel? anyway you might try and verify proper fuel psi. just a shot in the dark, i thought i'd try since nobody else is chiming in. the knock retard would seem to me that it might be from running super lean and not being able to correct for it? i had a fuel pump problem in the past and let me tell you an lt1 is flat sick at 24psi. hope that helps but if it doesnt maybe somebody else will see it and chime in. Good Luck

Injuneer

Under what conditions does this occur:

"The O2 Left and right are constantly dropping to double digits for as long as a second or two and it seams to be getting worse."

Idle, part load, WOT???

supermo26

O2 reading will drop down to double digits for as long as 4 seconds when at Idle as well as part throttle while driving around. I have even seen thoes values drop to 2 digits while accelerating at a pretty good rate.
Fuel pump is Racetronix kit with low miles. Fuel pressure regolator is stock.

Live for TAs

I don't have any experience with the scanmaster, so I will defer to the others mentioned.

OT, you did bring up a good point about the alignment- when I put the new front end parts on my car the front tires were like \ / , so I went to a Tire Kingdom (closest place to me) and left the car there. I gave them alignment specs, and they did a terrible job- steering wheel is now off center, pulls to the right, etc. While it could be a "coinky-dink" that your car developed a problem after being left at the alignment shop, I would wonder about it. I found a better shop to deal with and I now stay with the car while it is being serviced.

Injuneer

How are you reading the values in closed loop..... they are changing almost 10 times per second? Are you saying they drop to 0XX and actually stay there, constant for 4 seconds?

Same question regarding the BLM's.... when are they 140/160? .... which Cells?

supermo26

ok I ran the car today as well as took it for a drive to write down what I see. I wrote down all the reading about4 times 3 at Idle and one at 2,000RPM. The 2,000 RPM run was after the 10 min road trip and 5 min Idle run. I'll list times to give you an idea how long the car has been running.

ENG Start 1:24 hard to crank. Fired up with gas pedal input only.
MAF 14
SP 19-23
LP 01.4
RP 01.8
DTC --
MPH 00
Lbl 129
Rbl 160
cel 16
Lin 128
Rin 128
O2L
O2R
ATS 81
CIT 106
TPS 0.82
TPP 00
rpm 950
IAC 128
BAT 14.0
EGR 0.0
MAP 18.2-18.9
BAR 30.4 Florida
ACP 024
CCP 00

Car Idled for a few min Left drive was at 1:28 and got home at 1:46 that was a 22 min drive. Reading during the drive were not as erratic as yesterday but still not running good. O2's fell as low an 045-050 for only a few second and then they would increas to a hundred or so before getting back to the 700+ range. Would drop down 2 or 3 times a min.

1:46 Idle in drive way after drive
MAF 9-10
SP 25-29
LP 01.1
RP 01.6
DTC --
MPH 00
Lbl 130
Rbl 160
Cel 16
Lin 129
Rin 157
O2L
o2R
ATS 110
CLT 184
TPS .82
TPP 00
r 925-950
IAC 52
BAT 13.4
EGR 00
MAP 17.3
BAR 30.4
ACP.28
CCP 00

At 1:49 I added gas pedal till the car was stable at 2,000 RPM and took last reading

MAF 22
SP 41
LP 01.1
RP 01.2
DTC --
MPH 00
Lbl 131
Rbl 147
CEL 18
Lin 124-135
Rin 121-135
O2L
O2R
ATS 123
CLT 187
TPS .94
TPP 03
R 2,075
IAC 53
BAT 13.3
EGR 00
MAP 10.7
BAR 30.4
ACP.28
CCP 00

Car ran at idle for a min or to then took this reading at 1:51

MAF 09
SP 26-29
LP 01.1
RP 01.6
DTC--
MPH 00
Lbl 130
Rbl 160
CEL 16
Lin 128
Rin 152
O2L
O2r
ATS 132
Cit 193
TPS .82
TPP 00
R 900-925
IAC 49
BAT 13.2
EGR 00
MAP 17.8
BAR 30.4
ACP .30
CCP 00

There is no EGR valve. CCP will read a value when driving as well as under accel.


O2 reading were all over the place as expected until it would drop to 048-058 for part of a second and sometimes as long a a second or two.

Mikey97Z

Looks just like a vacuum leak on one side. I've been having this problem for a while. The ported intake manifold I bought from Racenet was WARPED and kept eating intake gaskets. It was an internal vacuum leak so there was no way I could see it until I removed the intake and saw the gaskets. I tried installing it with silicone on the gaskets and it worked perfectly ... until the first time I romped on it. After winding the engine up to 6000 rpm and then letting off the gas, the throttle blades closed, but the pistons were pumpin, so it made crazy vacuum and blew the seal. That caused split BLMs at idle and decel. I'll be replacing the manifold soon. I've had it machined twice and it still leaks.

If you haven't driven your car really hard since the rebuild, they may have been the first to expose a vacuum leak.

supermo26

Something that was kind of funny. When I would manually put the car in 3rd or 4th gear the O2 level would drop to 007 until the RPM dropped down below 2,000 or so.
I may have an injector seal leaking air as well now that you mentioned it could be a vaccume leak.

rskrause

I vote for some sort of leak allowing air to get in where it shouldn't.

Rich Krause