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Discussion Starter #1
1990 LX AOD stock computer, 340 hp Ford crate engine, Edel intake, 65 mm tb, egr, 76 mm C&L,Ford 24# inj, BBk fuel pump, new fuel filter, Accel adj FPR, 1 5/8 SVT shorty headers.
Now for the problem, the car has a lot of lope which cleans up off idle. The cars drives ok until you hit it. It jumps about 5 feet then starts moaning while falling on its face. It will occassionally backfire as it tries to rev. I started with the fuel pressure at 36#. I hooked up the gauge and taped it to the windshield, but the pressure stayed up throughout the bog. I double checked the timing. I've stayed around 10 and 12 degrees. With the wheels in the air and in gear I am getting advance with engine revs. I remove and re install the spout connector, each adjustment.
My thoughts are I am starving for fuel, but have only checked up to the fuel rail as I don't know of a feasible way to check the injectors. I have removed plug wires individual without detecting a noticeably weak cylinder. Everything is new, no fire jumping. I am leaning toward an injector or injectors being the problem. If something jumps out please advise, I need some help.
Thanks,

PS
Engine is grounded and no vacuum leaks.
 

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If the engine is boging then most likely it is too rich, and if this happens only at WOT then i would say your mass air and injectors are not matched correctly. What started everything and what do your plugs look like immediately after you have the bog.
 

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The couple of times I have pulled a plug it looks normal, not sooty. This is a new set up I am trying to get all the bugs worked out. The computer finally go used to everything and it will start and idle decent, but have the bog problem left.
 

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my guesses:

1) You are running too lean. (messed up Mass air meter/injectors etc etc..)

2) Your rocker arms were installed/adj. wrong

3) You have one nasty vacume leak. (maybe where the head meets the lower intake?)

try this. crank up the fuel pressure to like 50psi..then go get on it (WOT) if it runs better (but still not perfect) then that's proof you're running lean. If that doesn't help I would think the rocker arms arent adj correctly.
 

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The crate engine came with bolt down rockers. I have had the intake off 2 times. I could not detect any areas on the gaskets that looked like they might leak. I even sprayed the engine hoses down with starting fluid while running. If the leak is on the intake to head on the bottom side I should be pulling some oil and without cats should smoke, I think. Anyway no smoke. I will add this, which might help some recognize the culprit. The drivers side valve cover is being tapped every so lightly by one of the rocker arms. I pull the upper intake to remove the valve cover. I could not see a mark on the inside, re install, same noise, loosened the exposed valve cover bolts, tighten in a diff sequence, noise stopped for a while, now it is ever so faint. I talked to someone on the svt hot line and mentioned it to them in the event someone else has the same problem. Maybe I should hit them up for another valve cover gasket to lift the cover off the rockers.
Anyway, I will run up the fuel pressure tomorrow, say 50#.
Thanks
 

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when you say you remove/put back the spout with each adjustment, do you mean you adjust it, then unplug/re-plug?

long shot on you doing that, but jic, unplug the spout, set to 10-14, replug spout idle will read ~20
 

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How's the condition of the ignition system? I had similar symptoms to yours the other day and found a lose connection.
 

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Discussion Starter #9
Got home today and cranked up the fuel pressure to the big 50. Put the gauge back on the windshield just in case. Some improvement, but no means a cure. It ran up to 2000 rpm, nothing to write home about, then like I was in deep sand up to 4000 then the pull improved like Dad's 87 Grand Marquis. Just to try something I backed it down to about 45#, still no good. I drove it back home at 50# and pulled the plugs. Like the day they were born, white. I was afraid an inj or two may be bad, plugged or not getting a good signal, but it looks like they are all lean. I checked the mass air unit with an ohm meter. I was just searching since I did not have any specs on it. The wires are intact, and two of the tangs showed continuity and two did not. Does the tps signal have a lot of input on the fuel rpm relationship? I have a decent idle, it even handled the 50# fuel pressure. I can't believe it is the supply side of the fuel system with the pressure staying up and never falling. I quess I will quit talking to myself and see if you guys have any more suggestions.
Thanks,
 

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Discussion Starter #10
I talked with SVT Ford people and got a few suggestions on testing. I am still coming up 0. While scratching my head internally, I remembered the SVT tech saying the injectors are ground cycled from the computer. I have visually checked the ground on back of the engine and firewall, but at this point it will be an easy try. I am still waiting on a second mass sensor to swap out. I had one from a 4.6. The screws and spacing was the same, but the plug was different. One thing I forgot to ask the SVT tech was about the sensor on the speedo cable. Does the computer have to sense driveshaft rotation to richen the injectors? If anyone has any Ideas don't hesistate to post I am feeling something between possessed and depressed.
Thanks,
 

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back to the top for ya man. I know how you feel. grab a local stang lover, with the same mass air meter and ask to borrow it for 5 mins..I'm really curious to see how that makes it run..I had the exact same problem, and it was my mass air meter..I still have NO clue how it went bad..It worked fine, took the motor apart (got new heads) and ever since I got the motor back together it would barely run like you are saying..after talking to some guys on here, I cranked the fuel psi up..and it made it slighty better. Then I borrowed someone's mass air meter and "presto" car runs like a raped ape. I even put my meter on his car and his car ran the same as mine did! good luck buddy.
 

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Discussion Starter #12
Loosened and re tightened the ground 1st. It seemed to help the idle a little. Talked to SVT and C & L's Lee Bender today. Lee stands by his recommendation of 24# injectors and MA meter. Ford's younger guys want me to thow on $500 of 30# injectors and new Mass air. Jeff Dunn is the fuel system guru. He said I should not have a lean condition because of the 24# ers. I checked the mass air sensors voltage output in relation to rpm per some figures Jeff gave me. The sensor checked out Ok. My #1 son came by and let me swap sensors. I checked the voltage after the swap, both read the same. Lee at C & L sort of hinted the meter is sensitive to changes in tube sizes. I am trying to run a Cervini Mach I hood with fresh air scoops. Cervini has a filter box lid that holds a 9" K & N conical filter. The filter mouth is 2 7/8" in diameter. The filter mouth goes inside another tube which may reduce the I D even more. Anyway I think this small opening to a 3 1/2 tube 4" later into the mass air meter might have been throwing the C & L meter a curve. I did try rotating it, no luck. I finally plumbed the 3 1/2 tubing all the way to the stock filter box with a flat K & N filter. Big improvement. I think this might be OK. I now get a fair jump from idle to about 2300 rpm, then some fall off of power. This may be where the TCI converter is up to stall and the engine cannot pull the car at that rpm. At 3000 rpm it starts to pull again and much better than before. I have the timing up to 14 degrees and the fuel to 38 #. Maybe I was expecting too much from this engine. It is supposed to be 340hp. That is more than my 99 Cobra, but it sure doesn't feel like. I did talk to a local Mustang racer, tuner who said take the loss on the C & L and buy a PRO M. He showed me one. It comes with a calibrated sensor and according to this guy will handle any air flow direction. The metering tube has a funnel mouth on the inlet side. I might try it. I'm still open to suggestions, you can never know enough,.
Thanks,
 
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