Build Thread: Customizing My 87' GT (Page 15/23)
mitchjl22 JAN 16, 02:33 AM
Yes, I think I want a chin spoiler and some side scoops. I know I need to get the side scoops on if I am going to have the car painted, hopefully after I firgure out the engine bugs, that will be next on my to-do list.

Right now I'm having some pretty bad running issues.

When I got the car back from the exhaust shop, it ran good. I topped off the coolant, and drove it home. I did a few what i thought were "Hard Pulls" where I started at a stand still, and really romped it. The motor doesn't really need any "breaking in" since it was pulled from a 105,000 mile car. It pulled good, with consistent boost up to 6k rpm. After some pulls like that, I started getting mis-fires at WOT around 4k rpm. I thought initially, my Junkyard Fuel pressure regulator could be the culprit, but upon further investigation, the codes read High MAF and Low MAF, and engine Misfire on 2 coil packs.

I put the car up on the lift, and immediately found out why I was having misfires.




In order to prevent the wiring loom from rubbing on the belts, I stupidly pulled the loom tight against the supercharger, instead of routing that wiring on the firewall. This caused the loom to pull tight directly against the exposed end of the PLOG.
After cutting out the burned up sections of wires, re-soldering, heat shrinking, taping, and wrapping, the loom was routed and ZIP TIED to the firewall to prevent any further issues.


To address the MAF, I hooked up the scanner, and sure enough, the MAF was at 22,200hz (supposed to be between 2500-11,500) I ordered a new replacement from eBay. The new one was $40 and looked reasonable, with good feedback and good reviews. Upon further investigation my stumblings at WOT above 4k rpm could be one of many related issues.

  1. The car needs new spark plugs (which i forgot to change out when the cradle was dropped. stupid I know)
  2. The car needs new plug wires
  3. The car needs a real intake tube, (Not a filter directly off the TB)
  4. The car needs the ECM reset
  5. The car needs tuned (Has the tune from FieroFlyer)
  6. The car needs a new MAF


I installed this new MAF, and started the car and took it for a test drive. Stumbling still, and this time a new code
P0171 Oxygen sensor lean bank 1 sensor 1

What this means to me, is not to replace the sensor, but to check for Vacuum leaks. So, I got out the ole smoke machine, and hooked it up to the line for the Boost Bypass valve on the Tree on top of the supercharger. I got a couple of pretty good leaks right off the bat.

  1. The TPS was leaking (no gasket, easyish fix) - Fixed
  2. The vacuum tree was leaking (New O-Ring) - Fixed
  3. The Throttle body was leaking, (Pulled it off, and check mating surface, re-polished, and re-installed) - Fixed


Now, I ordered an new intake tube, an inline heater core adapter, and a new battery hold down (mine is shot).

Stay tuned for more interesting and annoying engine faults.

mitchjl22 JAN 17, 01:01 AM
I ordered one of these, thanks to a tip from MstangsBware


Ordered an intake tube, and I bought a new battery hold down.

Next is plugs and wires.

[This message has been edited by mitchjl22 (edited 01-17-2014).]

bmac JAN 19, 11:22 PM
Let us know if those purchases solve your issues. Those fried wires are pretty crazy/scary man! I'm glad your getting things sorted out. Also, I'd love to hear more of your opinion on the 3800sc once you get it running well.
mitchjl22 JAN 22, 01:05 AM
Hmmmmm....
Neils88 JAN 22, 05:41 PM
Running a bit lean.... May want to take care of that...
mitchjl22 JAN 22, 05:43 PM

quote
Originally posted by Neils88:

Running a bit lean.... May want to take care of that...



Are you referring to the size of the electrode? What exactly gives that indication? I think white is preignition right (pinging)?
mitchjl22 JAN 29, 02:05 AM
Just ordered a 3/4" NPT Tap, and bought a 3/4" Barbed copper fitting at lowes. Is this the right one?

http://www.lowes.com/pd_825...e%3D1&facetInfo=Barb
Neils88 JAN 29, 08:08 PM

quote
Originally posted by mitchjl22:


Are you referring to the size of the electrode? What exactly gives that indication? I think white is preignition right (pinging)?



You are right, it could be preignition, or a lean condition. They can often have a similar effect on a spark plug. If you aren't getting a code for lean, then you are probably right that it is knocking.
mitchjl22 JAN 30, 12:14 PM
Neils88, you're right. the code was lean. Do you think it was because the plugs were bad, those don't look very good to me. They were the tapered kind to begin with, I replaced them with autolite 104s gapped to .055" . I also got my 3/4" npt tap today. That is what I read is the right size for the passage under the SC snout.
kevin JAN 30, 01:11 PM
Outstanding work! I will say might offer to say you have patience and dilligence. I have been reading your post since the beginning
Cordially,
kevin