North American Turbocoupe Organization



Fluctuating/surging boost problem on 88 TC
tiresmoke69 Offline
Junior Member
#1
I have fixed all the problems on my 88 Tbird except for this boost problem. I am currently out of ideas and need some helpful input.

I am not running a boost controller. Car has a t3/t4 upgrade and frontmount. I am using binary editor with quarterhorses to tune with.

Here is a video of the problem... Watch the boost gauge it will start surging around 3000 rpm and continue until I let out.

http://s264.photobucket.com/albums/ii161...=001-1.flv
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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Pete D Offline
Administrator
#2
Are we to assume that the WGA is set for the Ford spec of 9.5 psi and, as you say, there is no boost control to alter that?
Pete Dunham


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tiresmoke69 Offline
Junior Member
#3
Correct and i have twisted the adjustable arm in a half inch thus resulting in 15psi max boost. In the video I am running a boost controller. I thought that it was the problem so i took it off and used my WG arm to adjust the peak boost. And now it does the same thing as in the video except it just goes to 15 psi and surges in between 13 and 17 psi very rapidly. I have no boost leaks (tested to 30 psi) and no vacuum leaks. The only thing i can think of now is that it is the WG diaphram is torn or something...

EDIT:I just had a thought... If i run a pressure source such as an aircompressor at 15 psi into the opening side of the WG it will open it right... well if the WG diaphram is torn then it should move back and forth a little which would indicate the cause of the surging back and forth.
Does this sound like a good idea?
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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Pete D Offline
Administrator
#4
You can apply pressure to the boost port on the WGA.
I've never used that to look for a torn diaphragm, but it may work. Let us know what happens.
Pete Dunham


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tiresmoke69 Offline
Junior Member
#5
Well i just got back from testing it and when I applied air pressure to the WGA it opened like it is suppose to and did not move back and forth under pressure like I thought it would do if the diaphram was torn, but I also noticed that my vaccum line going to it was leaking so I zip tied every single vaccum hose on the whole car just to be sure everything was good and tight. I went and drove the car and the problem is still there Sad There was no change...
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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tiresmoke69 Offline
Junior Member
#6
If anyone would like to sell me a internal wastegate acuator to try out that would be great.

I believe that mine is the same as this one here
http://www.racetep.com/tnetic/internalwg.jpg

I would like to have one like this. That way i would only have one vaccum port.
http://turbosunleashed.com/shop/images/W...tuator.jpg
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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Pete D Offline
Administrator
#7
Have you checked fuel pressure under boost. The EEC does richen up the mixture at 3K. Maybe its way rich?
Pete Dunham


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tiresmoke69 Offline
Junior Member
#8
I haven't checked the fuel pressure because I dont have a way to do that at the moment, but I do have an wideband A/F gauge and it stays between 10.3 and 11.1 right before it starts to fluctuate back and forth. The A/F goes up and down with the boost gauge as it should if the boost where changing. so I dont believe it is a rich cond., although i would like to check the fuel pressure under boost to see if the pressure regulator is fluctuating as well. Is there anyway to test the FPR to see if its working properly without a gauge?
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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tiresmoke69 Offline
Junior Member
#9
ok my fpr is working properly and i have no boost leaks or vaccum leaks anywhere i doubled checked this morning... The problem is still there. The wastegate is also functioning properly. Is there anyone that could look at my datalogs and tell me something?
1987 TC with A4LD, A234 cam, 3" turbo back exhaust, Walboro 255, Mallory AFPR, Innovate LC1, and soon to be P.I.M.P'd
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1988turbotbird Offline
Senior Member
#10
is the car 5-speed or auto?
88 TC/HX35/CAI/3" exhaust/Wilson MS2/Beanman header/Head Work/Laramee Cam/Gillis boost controller/3G alt/Walboro 255 fuel pump/BOV/CHE rear control arms/1" lowered/poly. bushings/Chuck W mounts/6 puck clutch/Pro 5.0 shifter/AEM wideband/Tuning MS..
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