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T-rex Tunning Emergency Help!!!!!

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Old Feb 22, 2005 | 03:32 PM
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Default T-rex Tunning Graph inside 2nd page

Ok here is the deal. I was having problems when in the lower rpms with the car kind of sputtering and almost dying. Well the guys at Mc Racing tell me that it is kind of like it drops a cylinder. I am not real sure how to explain it.
But this is what the dyno Graph is looking like

It pulls to 5800 at 377 horses then flat lines and stays there until 6500 and then noses off. The dyno #'s that they are showing is 377/346 before this cam I put down 346/340. There is obviously a problem. But what is it.

They tuned this cam before with a car and it made over 430 on the same stuff that I have.


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Old Feb 22, 2005 | 03:37 PM
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Who did the install? They have any problems?
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Old Feb 22, 2005 | 03:39 PM
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whats your valvetrain? and post the graph.

and aren't you the same guy the other day saying how streetable your car was
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Old Feb 22, 2005 | 04:19 PM
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i need way more info, what timing, need to see a graph, getting any kr?
i dont know much about them springs, whats the lift and pressrue ratings on them, you may be getting vavle float? cam could be a notch off on the install, ive seen it before, who installed it
fyi, i put down about 430/380 at 5800rpms so you have a problem
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Old Feb 22, 2005 | 05:18 PM
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Might want to have your injectors tested.
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Old Feb 22, 2005 | 05:43 PM
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Originally Posted by SMOKIN01TA
i need way more info, what timing, need to see a graph, getting any kr?
i dont know much about them springs, whats the lift and pressrue ratings on them, you may be getting vavle float? cam could be a notch off on the install, ive seen it before, who installed it
fyi, i put down about 430/380 at 5800rpms so you have a problem

I am getting the graph faxed to me now I will try to get it online in a few mins. As far as KR i am not sure to tell you the truth I am not the one doing the tunning but I am gong to try to find out. I don't think that the graph is going to show valve float but again this will be the first time I see it to. The springs are rated to .650 lift and I am using 7.4 pushrods

We installed the cam so as far as a notch off that could be very possible. Can you let me know how I might be able to fix that or some guidence on how to correctly install it.

JPR.....Yeah the cam was driving fine untill I fixed a problem that we were having with the o2 extension. Then all of a sudden is does not run like it was. I asked them if that would have something to do with it but they said that the o2's were reading fine.

Last edited by sevanseriesta; Feb 22, 2005 at 05:57 PM.
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Old Feb 22, 2005 | 05:48 PM
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also the car is running rich so I am not to sure that the injectors are bad. I called and talked to them and they said that the injectors seem to be flowing properly
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Old Feb 22, 2005 | 06:17 PM
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Originally Posted by sevanseriesta
I am getting the graph faxed to me now I will try to get it online in a few mins. As far as KR i am not sure to tell you the truth I am not the one doing the tunning but I am gong to try to find out. I don't think that the graph is going to show valve float but again this will be the first time I see it to. The springs are rated to .650 lift and I am using 7.4 pushrods

We installed the cam so as far as a notch off that could be very possible. Can you let me know how I might be able to fix that or some guidence on how to correctly install it.

JPR.....Yeah the cam was driving fine untill I fixed a problem that we were having with the o2 extension. Then all of a sudden is does not run like it was. I asked them if that would have something to do with it but they said that the o2's were reading fine.
first off, stock 26lb injectors wont cut it so if you are still on 26's your screwed already, my 28.8's are bout maxed out. i forget what came on the 98's stock? if it was running fine before you "fixed" the sensors and all of a sudden runs like crap than you might wanna backtrack what you did.

i have my springs shimmed for additional seat pressure cause i think mine are only rated for .650 also. but i jacked up the pressure a lil on them.

if none of the easy fixes work, pull the front cover off and make 100percent dam sure you are installed dot to dot on the cam.

and lastly, check your plugs and wire, i didnt notice i had some bad wires till we tried to make a pull right after putting the cam in and it ran like ****, only make like about what your making, 2 bad wires later i was up to 420's make sure they all ohm out to be ok and that you have good plugs, preferably tr6's
and last, i had this problem also, make sure your tb is opening 100% i had those adjustable tcs cables and it wasnt adjusted right to where it hit the stopper
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Old Feb 22, 2005 | 06:22 PM
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Thanks for the insight I will check on all of these. But these sound like things that would effect top end right or would this affect the way that the car runs in the lower rpms. I am damn sure that dot to dot is lined up correctly but I may take it off just to make sure. They changed the wires and that did not fix the problem. They were telling me that they were going to change the plugs to. We will have to see. I am so con fused the car runs fine after 3000 rpms but that is not going to get me very far if I am sitting at a light next to a cop.
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Old Feb 22, 2005 | 06:23 PM
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98's have 28.6# injectors. which springs are you running, like rodney said the cranes need to be shimmed for more seat pressure, that will reduce the lift rating. what was wrong with the o2 extensions? did you check the wires for frays or burns maybe caused by touching a header primary? what was your a/f?
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Old Feb 22, 2005 | 06:42 PM
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Originally Posted by jrp
98's have 28.6# injectors. which springs are you running, like rodney said the cranes need to be shimmed for more seat pressure, that will reduce the lift rating. what was wrong with the o2 extensions? did you check the wires for frays or burns maybe caused by touching a header primary? what was your a/f?
Somehow on the o2 extension 2 of the four wires were cut. They were not conected at all. When they went to tune the car before they said that they were not getting a reading and that I needed find the problem before they could tune it. I know that the wire is not on the header I routed them very carefully when I reconected those 2 wires, and yes I did connect the right wires together. This have a lift rating of .650 to so should I do shims on these if so, where would I get them and how big should I get.

I am not sure what the A/F ratio was I am waiting on the fax but it does not look like I am going to get it today.
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Old Feb 23, 2005 | 08:43 AM
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The cranes get .090 shim
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Old Feb 23, 2005 | 09:33 AM
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Ok, if the cranes get .90 shims then should i do the same on the Patriots Performance Duals. I have not heard anything from MC yet so I am not sure if they have found anythng. Where do I get shims from and where would I install them.
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Old Feb 23, 2005 | 11:34 AM
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Install them under the springs.

You can get them from anywhere, sponsors, summit etc
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Old Feb 23, 2005 | 11:38 AM
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Thanks I will see if I can find them....from someone.
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Old Feb 23, 2005 | 11:44 AM
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you dont need to shim the associated springs (PP/PRC), they both have ~140# on the seat @ 1.800
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Old Feb 23, 2005 | 01:22 PM
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Originally Posted by 93LS1RX7
The cranes get .090 shim
cranes on the trex get .030 shims
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Old Feb 23, 2005 | 01:25 PM
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Originally Posted by SMOKIN01TA
cranes on the trex get .030 shims
whats a .030 shim put the seat pressure at?
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Old Feb 23, 2005 | 01:27 PM
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Originally Posted by jrp
whats a .030 shim put the seat pressure at?
jerami, i honestly dont remember. its been so long. we basically shimed them as much as possible without risking coil bind at max lift. used the computerized spring compressor to measure it all
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Old Feb 23, 2005 | 01:40 PM
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Thanks, Jerami.......Well they got the bottom end sputtering fixed it does not do that anymore. Ended up just being a bad 02 sensor. But as far as power it is not getting any better then 377 and 358.

It starts out at 23 degrees timing and got highest #'s at 25 degrees by 2800 rpms. A/f was straight at about 13 I think that is where the line was. He adjust timing up and down and that was the best he could get. He adjusted the a/f up and down and this was the out come. He is telling me there is obviously a problem he tuned a car that had less done on the g5x cam that made 410/389 so what is wrong
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