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350 TPI New engine High blm's on throttle

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Old May 25, 2016 | 01:59 PM
  #51  
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Car: 1987 Trans Am
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Re: 350 TPI New engine High blm's on throttle

Here is a recording of the sensors from the snap on computer. Any ideas will be great.

Thanks

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Old May 27, 2016 | 10:28 AM
  #52  
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Re: 350 TPI New engine High blm's on throttle

It looks to me like your BLMS go out of whack every time the EGR comes on, then when it shuts off the BLM and integrator start settling back to normal.....
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Old May 27, 2016 | 11:59 AM
  #53  
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Re: 350 TPI New engine High blm's on throttle

I see what you are saying, I did not notice that before. But the egr is supposed to open while cruising, is it not??
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Old May 28, 2016 | 10:56 AM
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Car: 1992 T/A convertible
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Axle/Gears: 4.11
Re: 350 TPI New engine High blm's on throttle

Im not entirely familiar with its operation i usually shut it off in the bin. Could be there is an issue with it? I'm just theorizing here but if it is stuck closed and the engine thinks it should be open it may be increasing fuel to compensate for the extra air it thinks its getting through the EGR (but really isnt) causing it to go rich.
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Old May 28, 2016 | 02:42 PM
  #55  
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Re: 350 TPI New engine High blm's on throttle

Yeah, the EGR vs BLM is the only thing I see as well...

MAybe there's a vacuum leak downstream of the EGR soleoind. I.e., when the EGR solenoid activates, the engine is then exposed to the vacuum leak.

How is the EGR valve diaphragm? Hoses between solenoid and EGR valve?
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Old May 28, 2016 | 07:36 PM
  #56  
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Re: 350 TPI New engine High blm's on throttle

Got it, this week I will remove the EGR valve and put a plate over it. I will do the recordings and post them here. Let's see what happens.



The vacuum lines are all new, either way.
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Old May 28, 2016 | 07:43 PM
  #57  
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Car: 1987 Trans Am
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Re: 350 TPI New engine High blm's on throttle

One question I have is that there is no back pressure since the cat is hollowed out would this EGR valve even open?
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Old May 28, 2016 | 10:43 PM
  #58  
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Car: 1992 T/A convertible
Engine: LB9 TFS175heads Ebase/accel runners
Transmission: T5 5spd
Axle/Gears: 4.11
Re: 350 TPI New engine High blm's on throttle

I cant imagine why that would make any difference, the EGR valve is vacuum actuated isnt it?
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Old May 29, 2016 | 07:42 AM
  #59  
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Re: 350 TPI New engine High blm's on throttle

I thought that it works with back pressure as well on this engine?
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Old May 29, 2016 | 06:02 PM
  #60  
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Re: 350 TPI New engine High blm's on throttle

Originally Posted by nikom1
Got it, this week I will remove the EGR valve and put a plate over it. I will do the recordings and post them here. Let's see what happens.



The vacuum lines are all new, either way.
No, it's even simpler than that. Just take the vacuum line off the solenoid vacuum input port and cap it off (the vacuum line to the engine that the solenoid routes to the EGR valve). Solenoid should have two vacuum ports, an input and an output. Output connects to the EGR valve. Take the input off and cap off the line.

Leave the electrical connection on the solenoid so as to avoid the ECM throwing a code. But just take the vacuum input off of it. That will disconnect everything downstream of the solenoid (the vacuum lines, EGR valve, etc). No need to remove the valve itself.
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Old May 29, 2016 | 07:17 PM
  #61  
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Car: 1992 T/A convertible
Engine: LB9 TFS175heads Ebase/accel runners
Transmission: T5 5spd
Axle/Gears: 4.11
Re: 350 TPI New engine High blm's on throttle

But if the EGR valve is carbon-ed up and physically stuck pulling the vacuum lines isn't going to change anything is it?
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Old Jun 1, 2016 | 03:05 PM
  #62  
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Car: 1987 Trans Am
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Re: 350 TPI New engine High blm's on throttle

Hi guys,

Well here is the recording from todays quick run with the car. I had the EGR Vacuum plugged. The only thing that I noticed a little different was the BLM's go lower at idle, lets say around 120 or so.


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Old Jun 7, 2016 | 11:28 AM
  #63  
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Re: 350 TPI New engine High blm's on throttle

Anyone??
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Old Jun 9, 2016 | 10:09 AM
  #64  
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Car: 1987 Trans Am
Engine: 5.7L 350
Transmission: Automatic
Re: 350 TPI New engine High blm's on throttle

THis is the latest recording with some adjustment on the throttle, still though under load the numbers go out of place.
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Old Jun 29, 2016 | 10:52 AM
  #65  
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Re: 350 TPI New engine High blm's on throttle

Have ever performed a leak down test on the engine? What conditions are you recording your mileage numbers?
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Old Jun 29, 2016 | 04:44 PM
  #66  
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From: Boston, MA
Car: 1987 Trans Am
Engine: 5.7L 350
Transmission: Automatic
Re: 350 TPI New engine High blm's on throttle

No I have not done a leak down test. Just a compression test.
I did not understand your second question about the mileage numbers?
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Old Jun 30, 2016 | 07:12 AM
  #67  
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Re: 350 TPI New engine High blm's on throttle

Originally Posted by nikom1
No I have not done a leak down test. Just a compression test.
I did not understand your second question about the mileage numbers?

A leak down test would let you know how well your rings and valve are sealing and is way more revealing than a compression test. At this point I would begin to suspect something may have gone wrong during the rebuild. A nice set of cheapo "rebuild" pistons might lower the compression to 7.5/1.

Its hard to see on my monitor but your data looks pretty good. Your high BL numbers seem to only happen when you give the throttle a jab which isn't all that surprising. If you want a real picture of what is going on the car has to be under load and a fairly steady throttle state. Take it on a drive and log some data. Mind you I did only look at the latest vid.

How are you driving when you are getting 10mpg? City driving with lots of stops, steady highway, etc? My 305 tpi get 11mpg city with 24 on the highway. Why? Cause I spend most of my time in the city idling in traffic.
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