Help, my car is missing....

[Slobra]

ok, long story short.. I put a new ported plenum and TB from amazon on my car, reset the pcm.. took the car out and hit the rev limiter which blew my fuel pressure sensor. Car started to miss bad at a stop light, it would dip down to about 400 rpm, then back up, back down, etc, etc. I changed the plugs after it started missing thinking I had a bad plug but found out it was the fuel pressure sensor.. So I then got a new sensor, installed that, changed oil, reset the pcm and it's still missing. It's fine when I first start the car but after it runs for a few minutes, it will start missing when stopped at a light. I'm going to try and put new plugs in this week to see if that will fix it.. Any other ideas?

Thanks
John

 

[Slobra]

up

 

[2814v]

bump

 

[Slobra]

up again

 

[n0xlf]

You sure it's actually missing and then dropping in RPM, or is the RPM dropping so low that it can't idle any more?

Don't know why the RPM limiter would affect the IAC or TPS, but you could check the voltage on the TPS and remove the IAC and tape over the hole to see what happens...

Also, when you are resetting your PCM, make sure that you turn the lights on if you are pulling the battery cable to do it...That seems to be the fastest way to actually get it to reset...You will know that it actually reset when the next start takes a little longer than normal and all of the gauges peg...I've left the battery cable off for quite a while in the past, and without turning on the lights, enough power was still being stored in some capacitor somewhere...

 

[Slobra]

Originally posted by n0xlf
You sure it's actually missing and then dropping in RPM, or is the RPM dropping so low that it can't idle any more?

Don't know why the RPM limiter would affect the IAC or TPS, but you could check the voltage on the TPS and remove the IAC and tape over the hole to see what happens...

Also, when you are resetting your PCM, make sure that you turn the lights on if you are pulling the battery cable to do it...That seems to be the fastest way to actually get it to reset...You will know that it actually reset when the next start takes a little longer than normal and all of the gauges peg...I've left the battery cable off for quite a while in the past, and without turning on the lights, enough power was still being stored in some capacitor somewhere...

Yea it's missing.. The engine shakes a bit, as does the car when it drops. I leave the battery unplugged for a few hours then go back.. all the gauges peg then go back. I am going to try to clean the MAF and put in new plugs to see if that fixes it.

 

[CobraBob]

ttt

 

[Slobra]

up again.....

 

[AmazonTuning]

check the TPS..voltage should be at .98
what are your plugs gapped at? are they fouled?what kind are you using?

 

[SNAKEYE]

Originally posted by Slobra
ok, long story short.. I put a new ported plenum and TB from amazon on my car, reset the pcm.. took the car out and hit the rev limiter which blew my fuel pressure sensor. Car started to miss bad at a stop light, it would dip down to about 400 rpm, then back up, back down, etc, etc. I changed the plugs after it started missing thinking I had a bad plug but found out it was the fuel pressure sensor.. So I then got a new sensor, installed that, changed oil, reset the pcm and it's still missing. It's fine when I first start the car but after it runs for a few minutes, it will start missing when stopped at a light. I'm going to try and put new plugs in this week to see if that will fix it.. Any other ideas?

Thanks
John

Have you checked for a vacuum leak?

 

[coleman]

Slobra, does it idle any better with the A/C off?

 

[Slobra]

Plugs are ngk tr6's. I'll check the voltage tonight of the TPS. When I took the first set out, they all were fine. I'm going to pull out the current ones out tonight to see how they look. They are all gapped at .035.

Everything is turned off while it's idling, I dont understand why it only misses once it's warmed up, when I first start the car, it will idle normal (around 1000 rpm)

 

[AmazonTuning]

if your FPR needed to be replaced you will also need to change the oil because there might be gas in the oil..all the gas probably fouled the plugs...

 

[Slobra]

Here are some pics of the plugs on the driver side.. I'm going to pull the passenger side tonight.

 

[Slobra]

I tried to check the voltage on the TPS but it kept reading 0??

 

[2814v]

Plugs look very clean. I had the #4 coil pack on my old 99 5.4 F150 go out causing a very bad miss.

Hope you got it fixed.

 

[HISSMAN]

Looks like you have a lean condition. :shrug:

 

[Slobra]

Those plugs were only in the car for about 3-4 miles.. The miss only starts once the car heats up too. I'm going to try and swap out a stock tb for my ported one tomorrow to see if that fixes it. Can a TPS go bad? I'm curious why the voltage on it was reading 0.

 

[Pred_mech]

This may sound dumb but when I hooked up my accufab t/b I forgot to hook up the vaccum hose on the back of it and it did the same thing youre talking about. Not that its that hose but it could be a vaccum leak...