Idle/Miss

[SwivelSawvel]

Hey, Im having a miss issue. I have had a slight miss (as I mean slight like barly noticeable) but it got alot worse after I installed some mods. I have been to my buddies shop and had him do a quick look over and he couldnt find a vacuum leak. What are the most common leak areas and what else could cause a miss at idle.

Mods are

Metco 4lb lower with 3.2 alt pulley
60lb injectors
2.76 upper
BA2600
JLT Ram Intake.
PPRV delete.
Boost bypass mod found in the DIY thread.
BBK O/R H
Flowmaster CB
Amazon racing tune (curently working with rick on this issue as well.)

While driving the car after its up to temp it feels like it hits a wall. No low end power and in between gears shifting the rpms drop super fast and sometimes stalls before I can shift. The IAC will sometimes catch it but rpms are very erratic going from 300-1500 then stalling.

I have double checked and triple checked for leaks do to feeling every vacuum line by hand to spraying cab/choke cleaner (while engine is cold) to find leaks and got nothing. My plans are to change all coils and the IAC valve. Any help would be usefull! Im banging my head against the wall tryin to figure this out!

 

[jetmech]

I wouldn't start changing parts just yet. My method to finding vac. leaks are isopropal alcohol if it picks up rpm while spraying in small direct spots(fittings and lines), you found the leak. If no leak just take IAC off and clean with carb. cleaner. I might next look at the tune, try just loading the stock tune back in, or pull the chip all together to eliminate a problem with the tune. I'm not a 100% sure though by pulling the chip that it would act like it would in stock form, maybe someone else who knows for sure can comment on that. Also check the contacts on the chip it could be dirty or loose. When did the slight miss start happening? all of a sudden or did you change something and it started happening after that? What rpm were you idling at before the mods?

 

[AmazonTuning]

if you have a chip and remove it the PCM reverts back to the factory setting

also if you have a Preditor and put the stock tune in the vehicle you will lose your custom tune so make sure you have it backed up somewhere

if you have a preditor and a revision was sent make sure that the file downloaded completely and did not get corrupted

otherwise it is just going to be a process of elimination to find the issue
Rick is very good at giving suggestions to single out the issue so dont hesitate to contact us

 

[SwivelSawvel]

Sorry forgot to mention I dont have a chip, just a tune(SCT X3). I have always had a miss but not nearly this bad (got worse after put more mods on). All I had done was Upper pulley intake pprv and exhaust. I just added the lower injectors and maf. Installed the new tune from rick and the miss got worse. The tune runs great a WOT pulls like a beast just an issue with drivability.

Lynn thanks for the response, I just hate bothering people on the weekends and I know at a performance shop you guys are really busy.

I was thinking of disconnecting the battery to see if I could get the pcm to relearn its settings. Maybe thats could be the issuse due to the BAP I had installed was bad. Im just looking for any ideas to tinker on over the weekend before I break into it and start changing parts on payday.

 

[SwivelSawvel]

Bump. Any help would be great!

 

[jetmech]

Did you throw the stock tune back in yet? Try that first, to check the idle. If it goes away then it's in the tune. Don't go doing power runs driving it with a stock tune. Do you still have the stock MAF? Might not hurt to put it back on to see if it's related to the MAF. It sounds to me that without a load it's searching for MAF info or TPS info.

 

[01Jes]

Bad plugs, coils could also cause a engine to miss

 

[jetmech]

If it had bad plugs or coils it would not run like a raped ape under WOT as the OP has said then idle search from 300-1500 then stall. It would run like crap all the time.

 

[04screamingvert]

What plugs are you using? I also had small miss at around 1500 rpm after a plug and 3.1 pulley TR6 gaped at .032. I put my stock plugs back in gap at .045 and it made a big change in the miss trouble. Good luck

 

[SwivelSawvel]

I have changed the plugs multiple times. From stock ford motocraft to auto light platnum to tr6 iridium to what im currently using autolight iridium. I have another terminator owner helping me today doing 1 for 1 swaps on most parts (coils iac frps exc..) for finding a fix.

 

[SwivelSawvel]

Well after I took the 4lb lower , maf and injectors off. Put it back to stock it still had a miss on it. Went out for a drive everything seemed normal until a dida WOT pull and had a bad hesitation. I ordered up some new COP and blammo probem fixed. Now I have to decide to put back on all the parts I JUST took off. :shrug: