Fox No Boost And Stumped

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by TWEECD, Aug 12, 2017.

  1. OK folks, need to get some insight here. This not your typical thread. I've been working on getting my car going for a few years now. Have some tuning help, but not clear why the car will not boost. By not boost, I mean it will never go over atmospheric either in Tunerstudio or on the Autometer mechanical boost gauge. I'm really running out of the drive to get this car going. It's causing a lot of pain and aggravation in my household. Wife would love to see it gone frankly. Some details...

    It's a 93 Cobra with twin turbo built 347 and 5 speed and of course MS ECU. Specifically, I bought the MegaSquirt-II V3.57 plug and play and have full version of Tuner Studio and Mega Log Viewer installed on my laptop. I have been working with someone experienced with MS remotely over the past few years, but just seem to be having the same issue no matter what we do. I mean, I've literally done just about everything imaginable to this car to figure it out and it continues to run poorly. By that I mean, it lays over under load, misses and will not build boost at all. It starts up and idles steady aside from some slight miss here and there. I recently starting working with a tuner on this forum and some things have certainly improved, but it still will not build boost. Idle fuel pressure is around 42 psi. Off the top of my head, this is what I've been through...

    * Engine was freshly built before install (has minimal test miles on it perhaps 10-20 miles at most over the last few years)
    * Thought I washed the rings out after a number of attempted starts before determining fuel constant was way off for my injectors (I honestly thought that was pre-set in the tune since I gave them my injector size- thinking back to my days of running an AFM PMS, doh)
    * Have since verified I have consistent cranking compression (120-130psi warm which seems lower than I'd expect but all cylinders are extremely close to one another) and low (<5%) leakdown. Cannot check a couple cylinders simply because it's impossible to feed the test hose into the spark plug holes, but can't believe it would result in no boost even IF they were both dead (which I can't believe or else I'd be pumping raw fuel out the exhaust)
    * Thought maybe cam was retarded (FTI custom ground for my setup), but verified it's correctly installed straight up
    * Correctly set crank timing using piston stop (was off a few degrees initially)
    * Replaced spark plug wires (Livewires) although even though they're new if they lay too close to exhaust, they will arc (I've had to tie strap them away from the manifold)
    * Replaced spark plugs (3-4 times now)
    * Car has historically run rich since initial tune, but is much improved lately with new tuner
    * Calibrated Wideband (twice)
    * Smoke tested and boost leak tested entire induction path multiple times (there are no leaks)
    * Turbos are clearly moving air - you can hear excess air being vented through the intakes at idle and if you pull the pipe off at the throttle body and rev the engine with your hand over the intercooler outlet it will blow your hand off
    * Turbos definitely spool up - I can hear boost venting when throttle slams shut
    * Blow off valve is not leaking - I removed it temporarily to verify
    * Wired wastegates shut just to verify they were not opening for some reason and dumping boost. Double/triple checked they are fully closed.
    * I have a Magnaflow catted X-pipe. I watched vacuum stay steady while free revving the engine around 2000 rpm to verify they are not clogged. I even pulled the factory O2 sensors once to let the exhaust leak there just to be sure.
    * There is no PCV system on the car - PCV hole at rear of intake is plugged and I have two catches cans with a -12 line from each valve cover to each can
    * There's no MAF of course as it's a speed density setup
    * It makes 12 inches or so of vacuum at idle

    I run 93 octane, no methanol.

    * I just finished capping off one turbo inlet to the intercooler at a time to see if perhaps one turbo was bad and the good turbo was leaking boost through it. I did each side and no change.
    * I ran the car without the intercooler outlet connected to the T-body... so the turbos were just blowing straight to the atmosphere and the engine was running in N/A mode. The car was noticeably slower when I test drove it. It's clear that the turbos are doing something.

    It seems as if the engine cannot make use of the boost. When I lay into it, the boost gauge will go to essentially zero vacuum/zero boost and I can hear and feel the turbos working... the car wants to move quickly, but it starts to break up and feels like it's suffocating.

    Some more details about the setup. Everything here was installed brand new aside from the turbo kit which is no longer available.

    Engine: 347 Sportsman, 4340 rotating assy, TFS SFI balancer, 7 qt oil pan and HV pump with ARP shaft, FTI 185cc CNC Twisted Wedge heads with spring package to match custom FTI cam installed straight up, billet timing chain, all new lifters and correct length pushrods, ported and extrude honed upper/lower Holley Intake, Accufab 75mm TBody

    Fuel System: In tank pick-up feeding -10 line to Aeromotive inline filter, -8 line to Y-block to -8 line to twin T-Rex pumps feeding billet fuel rails, billet Aeromotive regulator, -6 line back to tank. 72 lb low imped injectors

    Ignition system: MSD digital 6AL, Screamin Deamon coil, Livewires, Summit billet distributor and the plugs are Autolite 3923's @ 0.035" - they were the recommended heat range and gap for this setup based on input from others running a similar combo with the same turbos.

    Power adder:
    Used Incon 800TT Twin Turbo setup. Setup was removed in working order. Turbos spun freely before install. Have recently verified they still spin freely and are not crashing.

    Exhaust: 2.5" Magnaflow x-pipe with high flow cats. 2.5" stainless catback with 2 chamber flowmasters.

    Cooling System:
    Aluminum dual row radiator, Flex a lite electric fan/shroud, Weiand polished water pump, New T-stat (180F IIRC)

    Trans/Driveline: MMR TKO 900, Spec Stg 3+ Clutch, Billet steel flywheel, FRP Aluminum driveshaft, Moser 31 spline 5 lug axles, Auburn Pro Diff, 3.55 gears, big brakes, etc
  2. How does it run if you remove the Turbos from the equation? (essentially just make it NA temporarily)
  3. Yep, I know I wrote a lot, but that was one of the steps I mentioned above...

    "* I ran the car without the intercooler outlet connected to the T-body... so the turbos were just blowing straight to the atmosphere and the engine was running in N/A mode. The car was noticeably slower when I test drove it. It's clear that the turbos are doing something."

    Basically, it runs, but a lot slower.
  4. If there is no boost you may have 1 or more cylinders not firing. Turbos work on exhaust heat and if the exhaust doesn't get really hot, nothing happens.

    It is time to do a temp check on the header pipes with an infrared thermometer or rub colored chalk on a cold stack and then run the engine at high power settings. The stacks where the chalk marks change color are the ones that are getting hot from the exhaust heat.
    a91what and 90sickfox like this.
  5. I feel like it should have more power in N/A mode, but tough to say with no good reference. I wasn't totally ripping through the gears though, just some quick test runs to get a feel for it. I could always take it out again for another N/A run. I want to say it still felt a little stifled when I got on it in N/A mode, but again tough to say.
  6. Have you tries it without the MSD hooked up? I'm not an MSD basher...I have msd6al and 7al2.

    Electronic boost controller brand ?

    Turbo brand and sizes ?

    If waste gate and blow off valve are both shut car should go into boost. Where are the vacuum lines for MS and the boost gauge connected ? I'm sure these questions have been asked from you a hundred times....along with vacuum leak questions.

    Something is not right. How is your BOV plumbed ? What size spring ?

    Its got to be something super simple. I've got a turbo car and MSPNP2
  7. That's a neat trick with the chalk. I do have an infrared temp gun so can do that pretty easily. I'll do that. Assume an idle check should show an issue if there is one.
  8. No boost controller. This is strictly a manually adjusted actuator arm setup. That said, I have the driver side wastegate vacuum line disconnected and the actuator arm is fully closed... I disconnected the actuator to verify the flapper door is closed the reconnected it. So, that turbo should boost all day long. The passenger side wastegate had a vac leak so I pulled it and tied the actuator shut with safety wire - I've been over this a few times and it's fully shut.

    This is an Incon Twin Turbo setup. Company was around in the late 90's/early 2000 era. The turbos are GT2871's. Little to no shaft play and spun freely when installed.

    MS MAP sensor and boost gauge are tied into the same hose which leads to the intake manifold. I've also verified the MS MAP sensor responds to compressed air as expected so it works. It's also in sync with the Autometer mech boost gauge.

    I've pulled the BOV a couple times to verify it was not the issue. It's a Tial Q BOV with 8 psi spring.

    You would think it's something simple, but I've been racking my brain. I've been waiting for the mice to come out or the rag to show up in the intake, etc... nothing.
  9. 90sickfox likes this.
  10. This stuff sucks sometimes. I've been working on my set up for a couple years and have made some embarrassing mistakes. ( I'm no genius )

    I assume you've had a91what try to help you out. madmike1157 is also a turbo guy that my give some ideas. Just one thing....if he tries to have you put a cat in front of your radiator and cut the fans on or put a box on your head...just do it. ( don't ask :nonono:...and take pics )

    There are a few guys that'll also chime in.

    The temp gun is a good idea... that's something I do often.

    You've got to drive the car to see boost. Free revving won't do it. ( I'm sure you know that already ).

    Do you rum a PCV valve ?
  11. I've definitely been driving it to make boost... I know the engine needs load. I actually have two other heavily modded turbo cars and they run great. I've modded at least 10 Fox body mustangs over the last twenty some odd years from all motor, to nitrous to turbo to blower cars and never had such a problem. I recall one time where I left tape on my lower intake manifold and car wouldn't run - took me a while to find that. Point is stupid things happen, but I'm really digging to find what I screwed up on this one. Appreciate all the feedback - keep it coming. I do plan to check the manifold temps next.
  12. No PCV valve by the way. It's closed off on the intake. Both valve covers are vented... there's a -12 AN line from each VC to a remote catch can with a breather (one for each VC).
  13. There's only been one other instance on here where the person claimed that he was unable to get boost. He found that the gasket on his BOV was compromised and leaking.

    Although it sounds like you've been all over it it has to come down to a few different things here.
    #1 you have defective equipment.
    #2 your gate has some gonzo spring in it
    #3. You have a leak.

    Have you put a regulated air source on the waste gate nipple to see where the gate starts opening, and what air pressure is required to hold it fully open?

    I know that you said that you smoked the system, and that it doesn't leak,..but what about what might get past the gate internally through worn out WG valve stems?

    Here's my particular circumstance:

    I have a dual WG system on a twin scroll turbo. The first version of my set up had Chinese waste gates.

    The gates were brand new, and both from the same, junk, supplier.

    They were supposed to have 5 pound springs in them, but a pressure test on the lower port revealed that they were'nt opening until almost 13 p.s.i. All of the air I was applying to that dome was slipping past the valve guide and going straight out the exhaust, and it took 15 p.s.i to hold a 5 pound spring fully open.

    But even with the leaks, my combination made boost,...It just made more than I wanted.
    I fixed that w/ New name brand gates that opened exactly at rated pressure. Turbo smart gates w/ 7 pound springs. Now, 7 p.s.i applied to the lower port opens that gate fully.

    What is your pressure circumstance? Do you know what the spring is rated at in that gate? If you have a compressor, rig up a regulator w/ a large scale dial gauge so that you can see what air pressure is opening that gate. Since you can actually see the actuator arm move on an internal gate, I'd be curious to know.

    The other instance was another guy's problem,..the gasket under his BOV had shifted, and it was letting boost vent. But despite that he was still making plenty,..He wanted 16, he was only getting like half that..

    Other than that, The turbo's aren't gonna make boost unloaded,..and they'll certainly spin as a byproduct of the exhaust gasses spinning the turbine,...gotta be something w/ the gates.
  14. I like the dead cylinders theory, that would explain the idle issues I had to tune out.
  15. If you're running it NA and feel like it's underpowered then I'd agree with a91what and say you need to check the heat on all the cylinders at the header primary tubes. I also recommend disconnecting the MSD stuff and making things as simple as possible as timing issues can be a huge PITA, especially on the MS ECU's.
    90sickfox likes this.
  16. I fired it up, let it idle for maybe 5 minutes and started checking each log and they were all within 10-15 deg of each other (~400 F) so it would appear all cylinders are lit.

    As for ignition, I recall dealing with the guys at DIY Auto shortly after I purchased the MS ECU... we were having trouble getting the MSD to fire off the TFI mod so we ended up bypassing the TFI mod all together and it ran fine. It's been like that ever since.
  17. madmike - I've been through all of that many times. The driver side gate is safety wired shut. The passenger gate is shut and there's no vac line connected. I also know it works as I previously supplied pressure and it opened at the set pressure (10 psi or thereabouts as I recall). Even still, I've isolated one turbo at a time and cannot get boost that way. If there was a vac leak this big, I would hear it in my mind. I cannot get any boost on the gauges.... absolutely zero best case, but I know the turbos are making boost as I can feel the difference when they are connected (intercooler pipe is connected to t body that is) and I can hear the boost blow off when the throttle slams shut. It feels ignition/timing/fuel related to me, but I would think ignition or fuel problems would show up in the logs (no?) and timing has been verified multiple times and I even ripped the front of the engine apart over the Winter to confirm the cam was installed properly and set TDC with a piston stop.
  18. And I've had massive boost leaks on my other turbo cars and they are very audible and I still get some boost.
  19. I just went through my old emails with Matt Cramer over at DIY Auto (few years back) and it appears that I wasn't able to adjust timing properly when the TFI module was firing the MSD so I wired the MSD white wire direct to pin #36 and it worked. It's been like this since. This has me wondering now if the distributor (Summit Billet distributor) could be faulty leading to no boost? Seems like a stretch to me, but throwing that one out there.