Car not running right.

mrspeedy69 · Apr 6, 2008

Well today i ran seafoam through the car and sprayed their deep creap and cleaned the throttle body. Went and ran it all out and it seemed fine. Then i changed the plugs to NGK Platinums, the car started fine and everything so i thought it was all good. Also i was going to replace the fuel filter, and a buddy of mine and i tried to take it off but couldn't get it off for some reason. So we just hooked it back up and left it alone.

Well later tonight i went and drove it and when i hit about 4k it just falls on it's face like its cutting out. Seems like if i ease into it, it will go over 4k but when i push on the gas hard it just cuts out...anybody have any clue what to check? Oh and it's a 98 Cobra.

94Pro-5.0 · Apr 6, 2008

so does it run normal until 4k? my car did something similar and it came down to the dizzy being worn out.

you could also clean your maf, TB, IAC, and TPS.

thats a start

realitygt · Apr 6, 2008

94Pro-5.0 said:
so does it run normal until 4k? my car did something similar and it came down to the dizzy being worn out.

you could also clean your maf, TB, IAC, and TPS.

thats a start

whats a dizzy?

rgs · Apr 6, 2008

distributor

mrspeedy69 · Apr 7, 2008

Yeah the car runs fine, but if i hammer it, it cuts out at 4k. Now if i ease into the gas it will go past 4k until i mash on it again and it just falls on it's face.

Asylum938 · Apr 7, 2008

hmmm did you gap the plugs correctly?

mrspeedy69 · Apr 7, 2008

Yes i check all the plugs and they were gapped right. Here's a link to another forum that i posted this on. It may have a little more information about what happened too. http://www.svtperformance.com/forums/showthread.php?t=476934

94Pro-5.0 · Apr 7, 2008

i still think its the distributor

rick focks · Apr 7, 2008

ISN'T THis the same problem trey had?

mrspeedy69 · Apr 7, 2008

I don't have a distributor, i have the coil packs on the car. It has the 4.6 DOHC Cobra motor.

2slo95fiveoh · Apr 8, 2008

what type of plug came factory in the 96-98 DOHC cobra motors? i know it's not directly related, but
a friend of mine put platinums in his 5.0 (original copper i believe) and it ran fine for a while, then it missed
and ran like shit. he swapped to a copper style plug and then never had the problem again. maybe it's the wrong
style plugs?

mrspeedy69 · Apr 8, 2008

Well the check engine light came on this morning. Had the code ran at lunch and it came back as p1516, the guy said it was the idle air control valve but 1516 is suppose to be and IMRC problem? Anybody else had this code, thing the IMRC's need to be cleaned or do you think the controller might be out?

94Pro-5.0 · Apr 8, 2008

mrspeedy69 said:
I don't have a distributor, i have the coil packs on the car. It has the 4.6 DOHC Cobra motor.

lol, shows how much i was paying attention

mrspeedy69 · Apr 8, 2008

Haha it's cool man i have those moments alot. But anyway i pulled the IAC off and cleaned it, still no luck. It maybe just bad tho.

mrspeedy69 · Apr 11, 2008

I believe the stock plugs were Autolite 764's and i've heard they are the best for the 4.6. But does anybody have any other thoughts? I've changed my IAC, cleaned my MAF and my throttle body and still no change. The car runs fine still upper RPM's then it feels like it loses power and cuts out.

Someone said maybe plug wires so i'm gonna change them today and see if that helps any. I can hear the IMRC's kicking in and can feel the power increase so i think they're working ok. Just not sure what else to check.