Digital Tuning Good Power Sometimes

Discussion in '1994 - 1995 Specific Tech' started by JonezySN95, Jun 19, 2012.


  1. JonezySN95

    JonezySN95 Member

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    What do you all think. In my sig is my setup. Recently I've been having an issue of loss of significant power. I found a plug wire arking and fixed that but still no power (cant break tires loose from a stop no power). I dont have a tune, stock injectors, stock MAF, and stock fuel pump so I know those are contributing factors (if not the problem by itself). I mixed 3 gallons of e85 with 10 gallons of 93 octain and walla. Tons of power after that. I got excited until the next morning... no power. That afternoon after work the power was back. I checked all plug wires and electrical plugs but all was ok. this morning again, no power. Im thinking when its cool out (morning) a sensor somewhwere is hurting it somehow because when is hot out (like 96 yesterday) I have a hard time getting traction. What do you all think? New motor and tuner coming soon, but I still like to troubleshoot things for my library later on.
  2. 95Vert383AOD

    95Vert383AOD Active Member

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    Hows the Cap and rotor look? Is the timing correct?
  3. toyman

    toyman Active Member

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    What gear ratio is in the differential? With the AODE I can tell you from experience that with 4:10's and a shift kit you can light the tires in first and second if the car is running as it should. Pull the codes and see if that leads you to a solution. If you haven't done a basic tune up (plugs, wires, cap, rotor, cleaned the MAF and change the air and fuel filters). This will give you a baseline upon which you can logically address issues as they arise.
  4. JonezySN95

    JonezySN95 Member

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    Ok so the rotor, cap, and wires are fairly new (about 1000 miles old). Yesterday I changed the plugs, coil (msd), and cleaned the maf with maf cleaner. Also found that cruddy old vac line that dryrots easily and goes to some smog plug component was broke. I unplugged it and caped off the vac line. The car then runs horrible (sounds like timing) I triple check my plug wires and all is good. I plug the smog deal back in (vac still disconnected) and its better but not 100%. hooked the vac lines back up to it and it didnt change anything. I went to fill up with gas and when I took off the gas cap it sucked in tons of air, way more than usual. left the gas station and the car runs great again. On the way home it started acting up a little but its better than it has been. Tomorrow I am double checking the actual timing just to make sure, but more importantly I am going to do some fuel pump checks. It seems pretty suspect to me.

    Question: Say it is the fuel pump. Can I buy a 300 lph with the little mods I have? I would assume the FPR, injectors, MAF, and computer all control amount of fuel going into the engine and the pump just insure enough volume gets up the line correct? I just dont want to go overkill if it will hurt anything, but if it wont then I will go big because I only want to buy it once and they are close in price range. beside when I get Blackvert's 408 finally I will need something big enough to feed it.
  5. JonezySN95

    JonezySN95 Member

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    Oh sorry I forgot to answer your questions lol. I know its geared cause the speedo is off, but the other owner swears it's not. I believe it's 3:73's by the way it feels but I could be wrong. remember it used to be a 6 cyl so unless the 6 cyl comes with a gt rearend (idk what it comes with) then who knows whats in it. Ive been too busy and lazy to spin the wheel and check. I ill also be pulling codes tomorrow. thats east though, I just hooked a toggle swith up to the jumper and I can just sit in the car, flip the switch, and get my codes :) sad I know lol.
  6. toyman

    toyman Active Member

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    The gas tank is vented back through the charcoal canister which is controlled by the vacuum purge solenoid. So, if the gas tank is under vacuum something is wrong with the venting of tank. The size of the fuel pump won't matter as the excess fuel is redirected back into the gas tank or at least is supposed to. Since it's going into vacuum means that the pump is working and in fact is working overtime to compensate for the vacuum created in the tank. You really need to sort this out as it will affect how the engine runs. If the differential is still from the V6 it's completely different than what comes with the GT and will have 2:73 gears. You will need to confirm both the diff and gears. How long have you had the car and did these issues just start?
  7. JonezySN95

    JonezySN95 Member

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    I have had the car for about a year now. It has always had some issues running a little lean but I did put H/C/I on it so I just shrugged it off as that being the issue and I was going to get a Tweecer until I got the engine deal from Blackvert and there is one that comes with everything he is selling me so i've been patiently waiting for that one. The spitting and stutering issue has just statred. I pulled codes and came up with both o2's running lean, ecu at limits for richening fuel, egr, and fuel pump codes. I removed the egr due to the gt40p heads not having the holes to hook it all back up but the sensor is still plugged in. I had just recently cleaned the maf and then my problems statred so I just replaced it. It helped tons but its still hard to start and stutteres under a load. I pulled the codes again and got right bank lean and egr. The vacuume lines are a nightmare but I rerouted the one from the tank around the charcoal canister and tossed the canister cause it was messed up. All the vac lines are tight now and it all looks good but now my options are 3 things i believe. 1) replace fuel pump 2) get a Tweecer to shut off egr and calibrate the maf or 3) Check the fuel injectors and or replace them for some 24#'s. I may be wrong though...

    And the rear end is an 8.8. Not sure but I believe when they put a 5.0 in the car they also switched the rear end.
  8. JonezySN95

    JonezySN95 Member

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    I just pulled codes 172 (left side lean), 181(Adaptive fuel rich limit reached at part throttle, system lean, right side
    ), and 332(EGR valve opening not detected).

    These are pulled from other forums as to what the codes are. Any idea where i can get a list of all/most codes so I dont have to search each and every code?

    Thanks
  9. JonezySN95

    JonezySN95 Member

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    Ok I checked the timing today. Origionally I had it set at 13* (about 9 months ago). When I checked today it was at 5*. I put it at 12* and drove it(yes I took out the spout). It is alot more responsive and got some power back but it still has a thump (best way to explain it) while cruising. It kindafeels like a miss but its not as bad with the timing set back now. On acceleration it feels rough like a dead cyclinder or off balance. I guess my next step is checking the fuel injectors. If those check out ok then I am still leaning towards the fuel pump.

    Any ideas to why the timing changed by itself? I jusr recently changed the seal and gasket on the timing cover due to it leaking but didnt touch the timing chain and didnt think to chck it because the problem started right after that (the same day). I appreciate the help.
  10. 94stangfan

    94stangfan Member

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    I had a similar problem with timing and the cause was that I did not tighten the bolt enough when I set it. Once I set it and made sure it was tight, I haven't had any problems since.

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