new problem
 

finally got my car running. i got a new problem though. the only thing i changed is the fuel pump. the problem happens after driving it for a while. it doesn't get all the power and hesitates when i gas it, all the way through accelleration. it goes away at the upper RPM's, about 2500 and above. when the problem happens, it's running at like 80% power. you can feel the difference in the butt dyno. what might be the problem? underperforming fuel pump?

What fuel pump did you put in it?

Also did you change the fuel filter?

stock replacement.

yes i did.



my car's check engine light also flashed too. on-off-on-off-on-off-on-off until it quit. i am gonna look at my plugs Sunday, and make sure all the connections are tight on the fuel lines.

when i revved it to 3000 RPM, i could hear a seperate *pop* kinda like it was misfiring. the engine is off balance, it shakes more when it falls into the hesitation. it's fine for about 10 minutes, then it starts happening. it doesn't start as soon as i start the car...which is wierd.

Where did the pump come from, dealer or autoparts store?

Try this, unhook neg cable and turn on headlights. Let the car sit overnight. Reconnect everything in the morning and start the car without touching the gas, let it run for 20 minutes (dont touch the gas) and see if that will help it any.

i've debated on doing that actually. resetting the ECU might fix it.

Flashing check engine light means there is a missfire. You need to pull the plugs at the least and see how they look. If its been any kind of time since they were changed, just go get new ones and swap them out.

it's only been 2/3 of a year since i changed my plugs. i will look at them anyway, thanks.


EDIT: the plugs still looked like new, but there was oil inside the spark plug holes. also, my car is not throwing any kind of codes, but a cylinder is not firing at all. why the fuck is it not throwing a goddamn code?

sorry to double post, but BUMP!

Are you sure that one cylinder isn't firing period? Did you already reset the ECU because that might clear the codes (don't quote me on that I'm not positive)

And if you haven't reset the ECU yet maybe you should.

And if you're positive it's continuously misfiring you might want to take a look inside

I would recommend resetting the ECU. Its very likely that the old fuel pump was pushing a lower pressure before it quit. Therefore your computer adjusted its A/F maps to compensate. Reset the ECU, let the car idle for like 10-20 min., then take it out and see how she feels.

just to make sure, do you let it sit for 5 minutes or overnight when trying to reset the ECU (negative battery cable off, headlights on)? cause i tried it sitting for 5 minutes, then let it idle for 20 minutes, didn't work.


EDIT: let it sit for about 2 hours. didn't work. i did do some data logging of my car though, i will show the information here.

RPM average: 656 rpm
load: 0.155
long ft: .980 (whatever this means)
MAF counts: 160.000 on idle
MAF Voltage: 0.000
spark: between 13.000 and 20.000, averaged at 15.000
TP voltage: 193.000

when revving the engine to about 1500 RPM, the MAF voltage didn't move an inch, meanwhile the spark went from -1.000 to 31.000 when i revved it.

so am i safe in guessing my MAF meter quit?

sorry to bump this, but i want to find out what the hell is going on. i'm running out of ideas, short of the ECU being bad, but why that would be, i have no idea.

sounds like she might be running in a "limp-home" mode. Stangs will run with the MAF dis-connected, just not well. check the connector at the MAF, clean the MAF, and try again.
Although, if you pulled a data-stream and NEVER saw MAF voltage, then its either not connected, or its toast. Sorry to hear that man.
If I'm not mistaken, your MAF and IAT are seperate, correct? If so, I've got an MAF sitting in the garage that should work in your car. Got it from r3dn3ck when I bought his Steeda CAI.
Anyway, its yours for the cost of shipping if you want it. Other than that, if you decide to get another one, DON'T, PLEASE DON'T buy one from Autozone. Go to NAPA, Advanced Auto, Ford, anywhere but Autozone. I used to work there, and learned to NEVER trust their electronics. Just some advice.

how much is shipping? i really can't fork up 200+ that is required for a new MAF, right after buying a fuel pump. i can give you my address in a PM.

and yes, i drove it while it was datalogging, i never saw MAF voltage at all.

Before paying for ANYTHING check your connections. If they look good then detach them and the plug them back together. You'd be surprised how often electrical problems in general are caused by things not being connected properly.

PM sent, and yes, please check your connections underhood.

did that, twice. also reset my ECU 3 times. still didn't work. i had a friend that had an extra one, the new MAF got rid of most of the issue, but it's still kinda there. it's not as pronounced as it was. does the ECU "get used to" the new MAF, or is there something else? (GOD FORBID.)


EDIT: drove it some more. NOTHING FUCKING FIXED. FUCK THIS SHIT. what the fuck is going on?!

Test the TPS and see if its giving the correct voltage. Should be .99 or under at idle and 4.5-5volts at WOT.

what's it listed under in the SCT Xcalibrator 3? TPS_V?

No idea what name its under in that. Common sense would tell me that if it says that then most likely it is. What is the voltage readings? and PS you can do this with the car off and just have the key in the ON position.

my meter said that the TP_V was at 195.000. whatever that was. it doesn't say if it's in volts or not. but i found a sensor, i unplugged it, and nothing happened to the engine. i will take a pic of it tomorrow.