Im having issues with poor fuel milage and starting the SUV...
When i go to start the truck it winds over for abit then starts and revs really high?!?!? I did a complete tuneup, plugs, filter, fuel filter, oil and filter... I changed the fuel pump which has the fuel regulator built into it. I have no codes on the dash. Also if i am at a red light and i put it to the floor I MEAN TO THE FLOOR!!! the truck bogs then drives off NO POWER!!!

Im stumped! I dont know what to do and dont want to keep replacing expensive parts... fuel pump was $430 on a friends account at cost! i can just guess at my cost what it would have been... LOL

Thanks Mike

 

I would check the MAF for dirt on the wires. If the MAF goes bad, it will cause hesitation when accelerating. You can disconnect the MAF for testing purposes, and the computer will assume 'reasonable' values based on throttle position{i think} sensor input, and add fuel accordingly. If you get improved performance, I would take the MAF apart and clean the wires. They are *DELICATE*, and will break{expensive..} if messed with too severely.
I would not have replaced the fuel pump unless the pressures had checked out as bad.
If you had a leaking intake manifold, or a large vacuum leak, it could be hard to start, and would idle high, within limits. If the IAC was jammed wide open, the idle would also be high. You can test that a bit by putting the transmission in gear, while watching the tachometer. If the engine is idling at ~750, it should stay at 750 with the tiniest of changes as you put it in neutral - gear - neutral. Or, turn on the A/C, while watching the tach. The idle should not change significantly if the IAC is functional.
If it will not idle down at all, check for throttle cables being damaged or binding, the cruise control cable being jammed, damaged, or binding, and the operation of the throttle itself in the throttle body. If all those check out, look for manifold leaks and the IAC. Your order of preference is your choice.
tom

 

i hear some air being sucked in around the engine and i sprayed WD40 on all the vacuum lines and no engine RPM gain or anything... I think it is an intake issue. Are these engines known for that?

It has been like this for a long while now and when i replaced the spark plugs you have to remove the plenum to get at the rear plugs, the gasket and o-rings looked fine so i put it back together and tightened it with my hand as close to the ratched head as possible due to i dont have a torque stick.

 

You absolutely should have replaced the gaskets when changing the plugs.

 

Intake gaskets are a known failure point on these engines, and the MAF sensor is definitely worth looking at early on.

And not to sound rude, but for all of the money you are throwing at this you could have had a mechanic diagnose it and tell you what's wrong with it. I work at a dealership, and even there we only charge an hour of labor to diagnose EEC concerns, and especially these days we have a lot of people that want to do their own work but lack the expensive tools sometimes needed for diagnosis. We diagnose, give them an estimate, they do the repairs, and even let them come back to clear the codes and check their work.

 

@ FireMe, I had it at Ford Dealership in Cornwall ON Canada when the computer fried... They wanted around 1000$ for computer and programing...
I purchased a computer online installed it and got them to flash it. Im not getting work done there if i can help it! I would deff go to your shop if you guys diagnose and let them do there own work, that must be nice! But dont dealerships rely on mechanical work to make money?!?!
Anyway... Im thinking its an intake leak im working on it today ill let everyone know what i find, IF i find it.

 

Well, if you don't want to check the MAF/[or MAP], then how about checking fuel pressure and regulator? Pressure should change in response to throttle position and manifold vacuum.
tom

 

I did try the MAF as soon as i unplugged it the truck starting stalling and dieing. The fuelpump houses the regulator and I changed it. The only thing left that i can think of is TPS or vacuum leak.

 

To bypass the MAF, unplug it with the key off, then turn the key from "off" to "run" at least three times, pausing for a few seconds each time. Then start it. The PCM needs to see the failure several times before it begins using default values.

 

It may be a problem with ignition cutoff switch or faulty starter motor .

 

I'd get a new set of intake manifold gaskets and install them. The old ones take a 'set', and compress to oval cross section. They then don't seal as well as original, when their natural circular shape was deformed by contact to the oval.
It's cheaper than a lot of other things...

A faulty starter motor would not enable the engine to start, much less run.
An ignition cutoff would make the engine die, not rev high.

tom

 

Hey guys! I am back! after months of trying to figure this out i gave up and drove it as is. Now im trying to figure it out again as it gets worse. I pulled all the coils and they look fine no water or cracks. I then REPLACED the 6 oval gaskets and while assembly i looked for cracked hoses or anything bad. NOTHING I CAN SEE!!! I start the vehicle SAME PROBLEM whined whined whined then start HIGH REV then slowly comes down.

Im driving it and when i get to a stop light i have to put it in neutral because the vehicle (i dont know how to explain it) shutters? rough idle? vroom vroom vroom none stop untill i hit the gas again.

Im ready to light it on fire and walk away. Its too bad because its the limited edition with all leather and sunroof........

 

I don't know the exact vintage this applies to, but some have both a MAF and a MAP. Also, the fuel pressure is regulated by pulsing voltage to the pump. The regulator sensor is mounted on the fuel line, near the fuel rail. I think it has a vacuum line attached.
Did you do the rpm test? Did you measure fuel pressure with the vacuum line attached & detached? Installing the intake without using a torque WRENCH is not a good idea. Torque sticks are for use in limiting the maximum torque that can be applied to lug nuts by impact wrenches. Their numbers are in the 10-12X the torque used on the intake, which is not much more torque than one can generate using a large screwdriver or nutdriver. You may have distorted the intake, and caused a leak.... or not. Put a vacuum gauge on it and watch what happens. If the fuel pressure or FLOW is low, you will get poor power, and flaky acceleration.
tom

 

i torqued useing a torque wrench and proper specs
how do i cheque fuel pressure and pulse thing your talking about? also where do i test the vacuum which hose?

Does anyone have readings that i can go off of?
Thanks Alot!!! I really appreciate it!
Mike

 

The fuel pressure sensor sends a signal to the computer. The computer decides what pressure it wants in the fuel rail. It then sends power, pulsed or solidly on, to the fuel pump.
If you disconnect the pressure sensor, on the passenger side, near the left end of the intake manifold. It has a vacuum line connected to manifold vacuum, and is connected to the fuel lines, and has a few electrical connectors. If you attach a fuel pressure gauge to the system, and with the engine running, disconnect the vacuum line, the pressure in the system should rise. Under load, the vacuum falls in the intake, and the fuel pressure is increased to make the engine run better under the load. Some auto parts stores will lend you a fuel pressure gauge. You can also check delivery volume by using some gauges that have a fitting and attached hose to collect delivered fuel. You measure how much can be passed in a timed manner, i.e. 10oz in 10 seconds.. not that 10 is a good number...
tom