PDA

View Full Version : runs but lost boost



ronl@ihsnet.com
05-08-2009, 08:06 AM
Went on a road trip to Cleveland from Pittsburgh. Ran perfect on the way there. Car has 112k miles. On the trip back it rained like cats and dogs. Early in the trip the car lost all boost. Pulling out from a toll booth, it would just creep until it got up to speed. Every time I gave it hard gas it just bogged until I got off of it. The car did 70 most of the way home, there was just no boost. It starts, but there is still no boost. I took the air silencer off, have never replaced the cam sensor, crank sensor, or the DIS. Took it to a good mechanic, he thinks it's the computer or the MAF. He's looking for used parts.

I kind of gave the car to my 20 Y.O. son. He loves the Tbird, I do too, but don't want to spend a fortune (4 kids, bad economy . . . )

Please -> any ideas ?

Thanks and a thousand blessings for your help.

Ron
Latrobe, PA

RedSC93
05-08-2009, 09:00 AM
Whats the boost gauge read at idle? Could be a vac. leak its pretty common.

Jerry

kenewagner
05-08-2009, 09:39 AM
By Pass stuck open would be my first guess. Second would something sheared in the front head of the supercharger keeping the rotors from spinning

Ken

old_coot
05-08-2009, 09:49 AM
I'm with Ken---Dan

S_Mazza
05-08-2009, 10:14 AM
I agree, it sounds like a supercharger or bypass problem to me.

There's nothing electrical about the supercharger, so an electrical problem would not be able to take out your boost. Unless it just prevented the engine from pulling hard enough to drive the supercharger and create boost, but you didn't say it was running badly. So I am thinking it is a problem in the supercharger or the bypass.

I wouldn't worry too much - although it sounds intimidating, it is not too hard to remove & replace the supercharger. And if you know where to look, repair services are not very expensive.

Scott Long
05-08-2009, 11:22 AM
What about plugs/wires. He said it bogs if you give it too much gas. Could the bogging be bucking?

I'd look at the belt for the jackshaft, the belt for te SC, the bypass valve on the back on the supercharger, and then maybe take the supercharger off (takes about 25 minutes) and spin it by hand and see if the rotors turn. If they turn freely, then the supercharger isn't the problem.

ronl@ihsnet.com
05-09-2009, 09:09 AM
Thanks for the input all - Blessings.

Picked it up from the garage. The mechanic still says MAF or computer, and that these
are a pain. $45 for him to look. At idle it has, what, -15 (about 9 clock on the dial)

Noticed that it didn't mind hitting zero vacuum. Took it for a 5 mile ride, it was like nothing was ever wrong. 10-12 pounds of boost, pulled strong - just like before ???

Still doing the “hard to start, need a cam sensor thing”, and that’s on the list.
Have spark plugs and wires, but I’m intimidated ever time I lift the hood. Have a quart of Exxon turbo/supercharger oil from the airport, $15.00 - that I’m going to figure out out to remove and replace our sc’s oil.

Could a soaked air filter have done something ? Reduce the air flow and freaked out the MAF or something ? It pulled MAF codes the mechanic said.

I love this car. It was a cool wet morning, the tank was half full of hi-test, and it ran like a big block Ford from my younger years . . . Wow this thing P U L L S . . . just like a 390.

Again, thanks for the input all, blessings on you, and now on to some R & D for the T-Bird. Attached a few after body work photo's. It's the T-Bird with the christmas tree on it from last year.

Ron

Latrobe, PA
:)

frdlvr30
05-10-2009, 03:22 PM
Needs a Maf sensor or a fuel pump. Problem is either fuel supply or fuel control. Im sure your mechanic checked fuel supply(Pressure). That would have left fuel control (MAF)...Buy a MAF sensor...They will come and go like that. All it is, is a frequency meter. It has nothing to do with mechanical boost. It has to do with the engines lack of ability to produce enough power to create the boost. Due to lack of fuel...This is a common problem. I have seen it many times. On all makes, not just Ford's

merkur
05-11-2009, 08:53 PM
My first thought when you said "ran great, then on the way back it rained like cats and dogs"was that the belt was wet. Maybe it had some gunk built up on it, and the water made it like ice. On my Buick GN when I would go through a puddle I would loose brakes and steering at the same time. Not until I steam cleaned the engine, and put a nice clean belt on the power steering/brake boost pump was it safe to drive in the rain. You could try wetting the belt to see if the problem returns. Danny

S_Mazza
05-12-2009, 10:38 AM
Needs a Maf sensor or a fuel pump. Problem is either fuel supply or fuel control. Im sure your mechanic checked fuel supply(Pressure). That would have left fuel control (MAF)...Buy a MAF sensor...They will come and go like that. All it is, is a frequency meter. It has nothing to do with mechanical boost. It has to do with the engines lack of ability to produce enough power to create the boost. Due to lack of fuel...This is a common problem. I have seen it many times. On all makes, not just Ford's

That's a good thought. I would suggest checking that out with a scanner or emissions dyno before replacing parts. If the fuel-air mixture seems right, then the problem is somewhere else.

Maybe a failed harmonic balancer has the timing off?

Scott Long
05-12-2009, 04:38 PM
Maybe a failed harmonic balancer has the timing off?

Been there, but it cracked the balancer all the way around and it slipped timing so bad eventually it wouldn't even run.

Matter of fact, one of my SC's is like that right now, so I need to get a BHJ when I rebuild that shortblock thats in it. My other 90 SC has a BHJ balancer because the stock one broke. I had to drill into broken pieces to remove it, talk about a pain in the ~~~.

ronl@ihsnet.com
05-13-2009, 08:07 AM
Thanks all, many blessings for your input.
It's running OK now - 2 weeks after.
Running OK as it was -> I need to do a cam sensor and plugs and wires.

Any thoughts on the soaked air filter ?
What could case it to be bad for a few days then go back to how it was ?

:-)

frdlvr30
05-16-2009, 02:55 PM
Thanks all, many blessings for your input.
It's running OK now - 2 weeks after.
Running OK as it was -> I need to do a cam sensor and plugs and wires.

Any thoughts on the soaked air filter ?
What could case it to be bad for a few days then go back to how it was ?

:-)

Soaked airfilter can also cause Maf problems. Especially an oiled K&N filter. You better put a MAF on it. It will be back. Did you not read my previous post?