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| MikeG | New Member - 93 Running Poorly | ||
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Guru
 
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Greetings Guru"s. My name is Mike and I have been reading this forum for about 2 years, gathering all the know how that is available. I am 57 , retired from a coal fired power plant where I was an engineer for 32 years. I HAVE A 76 that I am currently rebuilding from the ground up. Plans for it are an Auto LS3. now for my other dilemma. I also own a 93 coupe, black on black. Recently its been running like crap. No codes whats so ever. Feels like it is running out of gas. I can peddle it a little and it will then pick back up and run fine for maybe 5 to 10 miles and then we start the whole thing over again. I have replaced the fuel sock, fuel pump, fuel filter, fuel pressure regulator and also added bosch 3 injectors from FIC. Now I am at a loss as to what to look for. Any thoughts on the matter would be helpful. Thanks Mike
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Posted on: 2010/4/25 22:09
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| TommyT-Bone | Re: New Member | ||
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Hello Mike. Welcome to CORVETTE-GURU. Hang tight and I'm sure some valuable responses will be posted. Glad to have you aboard.
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Posted on: 2010/4/25 22:14
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| Matatk | Re: New Member | ||
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Welcome, Mike.
If you feel this is fuel related and you have changed parts, next step is to hook up a fuel gauge to the schrader valve on the fuel rail and monitor it while driving. This could be unrelated to fuel, though, so how are your spark plugs, wires, vacuum lines, etc along with basic maintenance items? Also, how many miles? Opti can cause rough running problems, Matthew |
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Posted on: 2010/4/25 23:28
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| uxb101 | Re: New Member | ||
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welcome to the madness Mike
opti (code 36) heat soaked coil icm does the rpm tach jump all over the place, if so its the opti |
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Posted on: 2010/4/26 0:17
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| BrianCunningham | Re: New Member | ||
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welcome to the forum
no codes has me thinking it's the opti as well or the coil getting hot. does it run ok when it's cold? did you ever wash the front of the engine? is the waterpump leaking out the weephole? |
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Posted on: 2010/4/26 0:19
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| MikeG | Re: New Member | ||
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Opti has less than 20k on it, no leaking water pump,never washed the engine , runs like a scalded rabbit when cold. Thanks for the welcome .
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Posted on: 2010/4/26 0:24
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| MikeG | Re: New Member | ||
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Also plugs, and wires have less than 20k on them. Have checked every vacuum line I can find. I feel its fuel related but I am open to suggestions. If the dang thing would just throw a code I would have a starting point to go from .
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Posted on: 2010/4/26 0:27
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| 1Fast04Vert | Re: New Member | ||
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Elite Guru
 
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Here is my first stupid question - Is the digital temp gauge working correctly? Reasoning is that the same sender sends the readings to the ECM. Your analog gauge gets it's reading from a different sender. Intermittent or faulty readings at the ECM can cause some odd behavior.
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Posted on: 2010/4/26 0:37
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2004 Vert. 475hp. Built by Vengeance Racing |
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| uxb101 | Re: New Member | ||
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unplug your crank sensor wire to see if it sends a code (ses light burnt out)
was the opti a msd? what spark plugs are in it? what size injectors.......24s bad gas burnt plug wire ohms on injectors? could be a bad ground wire |
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Posted on: 2010/4/26 0:40
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| bogus | Re: New Member | ||
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I am betting on the coil or coil wire at this point.
Let's step back and analyze the LT1 ignition for a moment. The OptiSpark is the distributor. It is the modern interpretation of the conventional distributor. It has an optical pickup that the computer uses to set timing and a more or less conventional high voltage side. If there is something wrong with the high voltage, it will more than likely NOT leave a code. If there is something wrong with the Optical side, there are two codes, 16 (lo res - fuel) or 36 (high res - timing). Since you aren't getting those, I am betting on the high voltage side. Check the coil wire. It runs from the coil (right head, behind PS pump reservour) to the opti (below throttle body). It can chaffe against the pump... It will then ground out and kill power. Check the condition of the wires to the coil. There are a couple of separate harnesses that plug into the coil and to and from the ignition module. These connectors age and get worn to the point they won't stay connected. Finally, the Ignition Control Module could be over heating. Hit it with cold spray and see if the problem eases. The ICM is between the coil and the head, right side. I have seen this happen in the past and troubleshooting it was a real bitch. Good luck and Welcome aboard!!! |
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Posted on: 2010/4/26 0:47
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| X-FIRE | Re: New Member | ||
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Want to welcome you to the forum...there are some great guys on here. I can't help with your problem, but it looks like you are getting some good starting points on it. Good luck with the troubleshooting and again Welcome to the forum..
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Posted on: 2010/4/26 1:49
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| Durango_Boy | Re: New Member | ||
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Welcome to the forum.
Start a different thread about your '76. I'm a C3 guy so seeing that project would be very cool. You mentioned something about your symptoms that makes me think of something other than Opti. Your O2 sensors. Curt's '95 had very similar symptoms. Cold it ran fairly good. Warm though it got crappy fast and didn't sound all that different than how you described it. When was the last time the O2 sensors were changed? |
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Posted on: 2010/4/26 2:23
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| bogus | Re: New Member | ||
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First off, 92 and 93 LT1's don't have crank sensors.
I am not a fan of the O2 sensors being the problem, but its not a bad place to start. I am a fan of Denso O2s. Hate Bosch. Junk. I am not betting on a bad ground wire. If so, it would run poorly all the time. I agree with checking temps, however, if the temp sensor on the waterpump fails, it throws a code, H15. Which leads to the final question: Does the SES light come on at startup? If not, then the bulb may be blown. |
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Posted on: 2010/4/26 4:16
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| uxb101 | Re: New Member | ||
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Quote:
1990-1995 Chevrolet Corvette Crank Position Sensor - Replacement http://www.corvette-guru.com/cache/2371_4bd57b96136b4.jpg Attach file:  repo311801updated.jpg (22.40 KB) |
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Posted on: 2010/4/26 11:40
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| Trae1976 | Re: New Member - 93 Running Poorly | ||
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2012 Memorial Day Car Show Winner!
 
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Welcome Mike!
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Posted on: 2010/4/26 12:38
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| BillH | Re: New Member | ||
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Quote:
Yep, no crank sensor. Ya know, the 92 FSM says that if the O2 on an LT5 has low readings, the ECM will go back into open loop (and throw codes). But that's not mentioned for the LT1 (doesn't mean it won't happen). Almost sounds like the car runs fine in open loop, crappy in closed, goes back to open and runs OK for 5 min. But again, no codes. Mike, are you pulling codes on the dash or with a scanner? Peddling- is that crusing at 1/4 throttle? And how long until it goes back to running OK? When it starts running bad, no missing, bucking or monentary engine shutoff, right? I do think the fuel pressure should be checked while driving, if nothing else, you will eliminate that as part of the problem. |
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Posted on: 2010/4/26 13:36
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Every man dies but not every man lives. |
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| bogus | Re: New Member | ||
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Grand Imperial Pooh-Bah
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Bill is absolutely right... no crank sensor on the 92-93 Vette. Trust me on this one; I had the engine out on my 92, with the timing cover off and beleive me, there is no crank sensor! |
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Posted on: 2010/4/26 14:02
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| biggrizzly | Re: New Member - 93 Running Poorly | ||
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2011 Memorial Day Car Show Winner!
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No Crank Sensor on my 94 either.
OH - BTW -- Welcome Mike! |
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Posted on: 2010/4/26 15:12
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Don Haller Corvette Club of America 94Coupe, 383Stroka, PeteK Trans, 3000stall, 3.54rear, Konis and bigger sways. |
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| MikeG | Re: New Member - 93 Running Poorly | ||
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I'm checking everyone"s suggestions and I'll post back when I am done with the list Y'all gave me. I did unplug the digital temp sensor and the SES light does work, gave me a H15 code. Bill H. I have been pulling codes from the dash and also with a scanner, everything from the scanner looks to be in the norm. Wish it would throw me a code !!!
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Posted on: 2010/4/26 16:29
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| uxb101 | Re: New Member - 93 Running Poorly | ||
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vin j is a zr1 and they have them,i was using as an example to test the ses light
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Posted on: 2010/4/26 16:35
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| 1Fast04Vert | Re: New Member - 93 Running Poorly | ||
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[quote]
MikeG wrote: I'm checking everyone"s suggestions and I'll post back when I am done with the list Y'all gave me. I did unplug the digital temp sensor quote] That is the sensor on the water pump. With it unplugged the car should never go into closed loop. My suggestion was to leave it alone and watch the digital gauge whne it was acting up. If the gauge acts erratic then you know where the problem is. |
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Posted on: 2010/4/26 17:57
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2004 Vert. 475hp. Built by Vengeance Racing |
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| BillH | Re: New Member - 93 Running Poorly | ||
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Only reason I asked Mike, is because I've seen one or two crappy scanners give false codes or none, looks like you have that covered. Good luck. |
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Posted on: 2010/4/26 19:10
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Every man dies but not every man lives. |
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| dan0617 | Re: New Member - 93 Running Poorly | ||
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Senior Guru
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Unplug the 02 sensor and see how it runs. If it runs better, you need an 02 sensor. They can go bad but not bad enough to throw a code. There are many many things it could be, don't just start throwing parts at it. Go one step at a time. Welcome to the forum!
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Posted on: 2010/4/26 22:49
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ยด89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| MikeG | Re: New Member - 93 Running Poorly | ||
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Well I had a code 15 ( low coolant temp) when I checked the codes. Never paid much attention to the digital gauges until it was brought up. Drove the car today and watched the digital temp and as suggested it was very erratic. Came home changed the sensor and no the digital is stuck at 142 degrees, doesn;t increase or decrease. before I started the car after changing the sensor I unhooked the battery to clear all the codes. Now I have the SES light at all times, checked the codes and still have the code 15. What did I do wrong ???
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Posted on: 2010/4/26 22:53
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| Matatk | Re: New Member - 93 Running Poorly | ||
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Is that a one wire sensor? Did you use teflon tape, etc on it? Perhaps it's not getting a proper ground.
Matthew |
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Posted on: 2010/4/26 23:06
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| BillH | Re: New Member - 93 Running Poorly | ||
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The Stig Moderator
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No Matt, 2 wire, yellow is signal, black is ground (in the ECM). But the tape would make sense if it was a one wire.
Mike the SES is on because of the 15, the 15 is a signal voltage problem. IIRC, the 142 will show when the sensor is unhooked. Ck the connection and look at the harness for chaffing, shorting to ground. May be why it's erratic The clear the code. I'd suggest that you clear the codes with the dash buttons, it's a little easier. You can clear them in modules 1.7, 4.7 and 9.7. Also, there should be 5 v. at the sensor connector, yellow wire. |
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Posted on: 2010/4/26 23:16
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Every man dies but not every man lives. |
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| bogus | Re: New Member - 93 Running Poorly | ||
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Grand Imperial Pooh-Bah
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Mike, you really need to read this:
http://www.corvette-guru.com/modules/ ... ection/visit.php?fileid=3 That will show you how to read the codes from the CCM. I had a run on bad temp sensors... don't exlude that from your potential diagnostics. Also, the connector should only go in one way, but, if it's backwards, it could look ok, but not actually be making connection. A bad temp sensor will cause issues, but its rather transitory. Once the sensor hits the failure point, the car starts to run like crap, hell it will even quit! I found if you floor it, the car will then run in closed loop and do ok. In other words, it doesn't sound like your entire problem. |
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Posted on: 2010/4/27 13:59
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| pr0zac | Re: New Member - 93 Running Poorly | ||
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Elite Guru
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Quote:
it will show the lowest value if you unhook the coolant sensor. i worked on a 94 box van last month that needed a new connector for the coolant sensor. it ran like shit all the time until you pressed on the connector and it would smooth right out. you need to plug a scan tool in and see what the computer is seeing. not the dash. |
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Posted on: 2010/4/27 14:01
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| bogus | Re: New Member - 93 Running Poorly | ||
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Grand Imperial Pooh-Bah
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A little clarification:
The IP has 2 temp displays. The Analog dial gets its feed from the cylinder head and that's it. The digital display on the speedo is from the sensor on the water pump and the same source used by the ECM. The digital display is usually quite accurate and what the ECM is seeing. If this display gets erratic, then the engine will start running poorly. |
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Posted on: 2010/4/27 14:06
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| MikeG | Re: New Member - 93 Running Poorly | ||
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Thanks for that link Andy. I looked for that about a week ago but couldn't find it.
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Posted on: 2010/4/27 15:16
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| 1Fast04Vert | Re: New Member - 93 Running Poorly | ||
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Reread my response #21 in this thread. You really didn't need to look very far. |
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Posted on: 2010/4/27 16:33
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2004 Vert. 475hp. Built by Vengeance Racing |
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| MikeG | Re: New Member - 93 Running Poorly | ||
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Sorry I must have overlooked your post, but hats off to you. You were right on track !
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Posted on: 2010/4/28 14:57
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| 1Fast04Vert | Re: New Member - 93 Running Poorly | ||
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No problem, I am very used to it, my wife ignores any and every thing I say. Glad you have it fixed now. |
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Posted on: 2010/4/28 17:05
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2004 Vert. 475hp. Built by Vengeance Racing |
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