When I did my 454 tbi swap, I put the o2 inthe 454 manifold in the same location as the 350 manifold.
The problem i am having is that engine shows signs of being lean (surge, good mpg) and blm is ranging from 100 to 120.
02 datastream looks normal. Sure looks like o2 voltage is showing richer than actual. Could my placement cause this.
I unhooked the o2 and drove it in open loop, and it is much smoother.
Rich can also cause surge.
What do you mean by "same placement as 350"? Not all of us use Chevy engines, some just use their electronics. ;)
The man who says something is impossible, is usually interrupted by the man doing it.
Basically in the collector of the manifold.
Sounds like a good spot to me, but some pictures would also help.
Is this a known good O2 sensor?
The man who says something is impossible, is usually interrupted by the man doing it.
Not known good, but was new when i did the swap. I will replace it in the morning, sure looks like its voltage doesnt reflect actual a/f ratio.
Well, replaced the 02, and same thing. Then I remembered that I had replaced the fuel pressure regulator diaphram, and didnt have time to check and adjust fuel pressure. Pressure was down to 10.5. Cranked it back up to 13.5, and made it better, but after awhile of messing with it with the scan tool on it I finally got it to where it was surging pretty badly. What I found was that when coolant temp was exactly 190, the cts reading would bounce back and forth between around 135-140-190 degrees. As soon as coolant temp was above or below 190 it was (the engine) much smoother.
It is funny how you can mislead yourself sometimes. When this problem was the worst, was real light throttle in low gears (crawling around in the hills), and more throttle would make it better as would less.
It sounds like placement of CTS is the issue? Like it is loosing contact with flow or air?
I like to here answers to strange issues! Never saw a CTS be intermittent!
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
cts is in the same location it would be on the stock 454 manifold. I am hoping it is just an intermittent cts.
I had an intermittent fast idle a month ago, and I replaced the cts with a used one that I had laying around, and it did fix it.
I will get a new one this time, and see how it goes. With my luck it is probably a wire issue.
Back to my original question....
this thing even when it is running good, has a slight surge to it (light throttle in low gears) that I am sure if I put a graphing meter on the o2, would match the 02 voltage as it was swinging rich-lean-rich-lean.
Does the ecm expect a certain amount of time before the o2 reacts to the pulse width change? The stock 454 stuff has the o2 a little ways down the pipe (almost next to the trans) and I have wondered if maybe having it in the manifold is doing anything.
also has a borderline obnoxious surge during decel at lower rpms (that I am sure would mirror fuel control).
Yes, there is an expected delay before the O2 reacts, but I haven't noticed any huge side effects from moving the O2 sensor along the exhaust, unless it's a huge change, like several feet in change of distance.
The man who says something is impossible, is usually interrupted by the man doing it.
INT Delay Vs Airflow is the adjustment if the O2 sensor is moved further downstream. If it is closer it should not be an issue. The fueling change would already be past the O2 sensor so it is reading exhaust that has been adjusted. Problem is moving the O2 sensor further, then as INT/STFT makes and adjustment the O2 sensor reads to soon = wrong exhaust! That does cause surging, it's like a yo-yo effect to fueling.
You should not be having any surge issues with a stock motor... but you've never said what is done to motor?
Also never said what chip BCC?
The Prop Gains on BB chips is ridicules high which is always a problem when surging is happening. Along with Open Loop idle, after it enters closed loop then comes back to idle their is a delay then POOF, Open Loop again. Not a big issue when fueling is dialed in. But I have not seen a stock BB and stock chip have fueling dialed in.
But none of that is going to help if the CTS keeps changing temperatures? And if it's a rock Crawler and you want a good stable idle you do need VSS.
If you post ypur bin file and a data log I could find the issue?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
No it wouldn't, they all swing, then there is a O2 Error measured from that swing which effects Proportional Gains. This is what causes the surging.this thing even when it is running good, has a slight surge to it (light throttle in low gears) that I am sure if I put a graphing meter on the o2, would match the 02 voltage as it was swinging rich-lean-rich-lean.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Motor is very mild, but it does need tuning to be correct. I do have vss. Cant remember bcc offhand.
I would love to get into tuning, the problem is that I would not have the time to put into it to get stuff working to the point that I would be satisfied.
It actually works pretty good, but if I ever had the time I would just let somebody have it for however long it would take to make it perfect.
I did get the cts and pigtail changed, and so far so good. One interesting thing though, is that the old cts wouldnt show over 192 deg.
bin is arpa. I have noticed on the scan tool, that it will stay closed loop WOT and idle for several seconds, like it is on a timer.
Bring it over for a day and I'll tune it right!Originally Posted by black dawg
WOT is PE and it has a 5 second delay! It also sounds like an Open Loop Idle bin, but it is $4F 1227787 ECM and that mask does not have all the parameters that I have in $42 which shows the OP Idle RPM settings. Most C3 ECM BB I've seen are all OL idle. I just make a bin so it can idle CL and steady always.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
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