i'm seriously gonna burn this muther down!!

[camlisonfire]

hey guys. i recently picked up a '87 crown vic 2-door as a winter/dd.
first a little background on the car:
Ford racing 4.10 rear gears with track lock. 5.0l HO motor swapped from a similar year mark 7. BBK shorty headers into true duals, no cats with flowmasters
real ghetto cold air intake that i plan to return to stock.

since i bought the car it has had a surging idle that i've been chasing but just recently within the last month it has become more than just at idle. it will start bucking and jerking while driving in ANY gear at cruising speeds. under hard accel its ok. its also TERRIBLE on gas. i've owned an '87 grand marquis and a '91 crown vic and both were no where near this bad. its really starting to piss me off so i've come to you guys for some advice.


so far i've done the following:

motorcraft plugs, cap and rotor. Ford Racing plug wires. motorcraft fuel filter. changed oil/filter. cleaned IAC (no change). inspected for cracked/broken vacuum lines (all look ok). inspect PCV valve (moves freely)

so any other ideas would be awesome before i burn this fucker to the ground! thanks guys!

heres a shity pick of the new vic next to the marauder.

[85crownHPP]

Id suspect the MAP sensor. Have you checked any codes?
I like those wheels!

[camlisonfire]

no lights on but i had planned on trying to pull codes early this week.

thanks, the rear wheels are ranger wheels with 295's. i'm still looking for a matching set for the front

[87gtVIC]

The light in the dash is not a check engine light that shows codes.

[marquisman]

my old 88 wagon did that but never found the problem, usally its the MAP sensor tho...does the car seem to run/smell rich? and before you burn it to the ground, call me lol

[BigT]

I'll tell you what helped me. Disconnect the EGR vacuum hose and plug it with a golf T. If the car runs good after that...you need a new, or clean the old EGR valve.

Big T

[ald872000]

if its happening on all gears, (the bucking an jerking) it could be the fuel pump and or the regulator, I have had experienced the bucking an jerking while the fuel pump was on its way out.

[gadget73]

When the HO swap was done, was the ECM and injectors changed as well? They won't run worth a crap if the computer and injectors didn't get moved over. Msssive vacuum leaks also cause this same symptom, but so does a map thats shit the bed. Stupidly, the last car I worked on that had a bad MAP idled perfectly with the MAP unhooked from the vacuum line.

Also, if you get a code about insufficient vss input, you have an 88+ ECM. The 88+ ecm uses vss input to control stuff with the egr valve, and 87 and older cars don't have vss wiring. It causes an off-idle hesitation, but thats really about it. Easy fixes are disconnecting the egr vacuum line, or adding the vss wiring to the ecm connector. I had a problem somewhat related to this, but in my case it was a combination of the EGR valve opening right off idle, and the regulator not working properly so it opened to 100% as soon as I touched the gas. I fixed it by spraying oil into the egr regulator to un-stick it, and then later added the vss wiring to really fix it.

[Smokestacklightnin]

Check the connection at the Throttle Position Sensor. I had a similar problem and it turned out to be a bad connection where the harness connects to Throttle Position Sensor. With the car running wiggle the wires and see what happens, mine would actually kill the engine. Check connections at other sensors, if that doesnt turn anything up then have the codes checked.

[camlisonfire]

...

it wasn't just the HO swap, it was the entire engine from the mark 7 that was swapped so i would assume the injectors and computer went with it. unfortunatly it was done by the previous owner so i'm not 100% sure.

if i pull the map vacuum line the car dies immediatly but if i pull the connector from the map sensor it really doesn't change very much. i also pulled the connector from the iac to check and see if it would keep running (valve stuck) but it also dies right away. i don't have a vacuum gun to check for proper vacuum but i've been over most of the lines and i haven't found anything cracked or broken.

i'm gonna try and get to the junk yard and throw a MAP/IAC/TPS at it and see if it does anything. Maybe even a TFI.

the reason i don't suspect the fuel pump (and i could be wrong) is that under WOT it performs flawlessly.

i'll get back to you after i try and get codes from it

When the HO swap was done, was the ECM and injectors changed as well? They won't run worth a crap if the computer and injectors didn't get moved over. Msssive vacuum leaks also cause this same symptom, but so does a map thats shit the bed. Stupidly, the last car I worked on that had a bad MAP idled perfectly with the MAP unhooked from the vacuum line.

Also, if you get a code about insufficient vss input, you have an 88+ ECM. The 88+ ecm uses vss input to control stuff with the egr valve, and 87 and older cars don't have vss wiring. It causes an off-idle hesitation, but thats really about it. Easy fixes are disconnecting the egr vacuum line, or adding the vss wiring to the ecm connector. I had a problem somewhat related to this, but in my case it was a combination of the EGR valve opening right off idle, and the regulator not working properly so it opened to 100% as soon as I touched the gas. I fixed it by spraying oil into the egr regulator to un-stick it, and then later added the vss wiring to really fix it.

[mrltd]

I suggest finding out if the ECM is correct. It's ot the left of the steering column under the dash. Also look at he injectors and see if they are orangish or grey.

Then get the codes.

[gadget73]

The fuel rail for the Mark VII does not fit a Panther, so its a very good possibility that they used the original injectors instead of the HO ones. HO injectors have orange or yellow tops, stockers have a grey top. Also possible the ECM was not swapped since you don't have to pull that to switch the engine. The ecm is where mrltd mentioned. You'll want the 3 digit catch code on the sticker. Probably you're looking for a D9S or DY3 if its the Mark ECM. I don't know what the stock catch codes are offhand but they're listed at fordfuelinjection.com

[zoomie]

if you decide top get rid of it make sure to get ahold of me i would love a 2 door....

i know it sucks but take down the gas tank and drain it into a bucket and see what you have in there , i noticed my linc does not like ethanol in the gas much it likes reg gas alot better,also might be a vac leak somewhere i know when i did my smog pump removal that i had to plug a few lines and stuff
im not sure how 4.10 would ac but i suspect they are part of your gas issue though

[camlisonfire]

well just an update for ya. i got ahold of a free coil and TFI module. i replace both at the same time and the bucking has stopped. i dont' no which one solved the problem but i don't care. i'm just glad its fixed...altho the idle still surges but i can live with that for now

[moneypit]

My money is on the fuel pressure regulator. Yank the vacuum line at idle and see if fuel sprays out. Hint: it's not supposed to.