420A Hard Start Issue. NEED HELP!!

[2GNT_RS-T]

Having a hard start issue thats starting to get really annoying. Heres some of the things ive just recently done to it to try an fix the issue. Spark plugs are brand new bkr7es gapped at .32 Has a new fuel pump an fuel tank cause the old one had rust all in it, it was so bad the pump wouldnt last a month. Has new oem wires an coil. Just did fuel filter too But the issue im having is when the cars been sitting overnight or for a long period of time it has a hard time starting especially on the first crank, it just falls on its face and on the second crank i have to keep giving it gas for a good 6 seconds an it will finally start. Sometimes it takes more then 2 cranks. But When its warmed up, it starts right up an when it starts i have to let it idle for abit cause if i start driving it will start to violently buck an sputter an sometimes it stalls out an this only happens when its warmed up. If it sits more then 45 mins it gets hard to start. Ive definitely noticed a power loss too especially in the acceleration an occasionally while cruising it randomly does aquick sputter out of know where, its not bad, you can barely feel it. But any help would be greatly appreciated

 

[85Entropy]

Have you tried cleaning out the fuel system? You said the old tank had a bunch of rust in it, so any of that debris floating around wouldn't help your case.... I would run some Seafoam through it, probably replace that fuel filter again after that, and I would probably also have your fuel injectors flow tested and cleaned.

 

[DogWhistle]

You should check for correct operation of the throttle body ISC, and the FIAV. Both of these will operate differently when the car is cold vs. when it is hot.

 

[2GNT_RS-T]

Have you tried cleaning out the fuel system? You said the old tank had a bunch of rust in it, so any of that debris floating around wouldn't help your case.... I would run some Seafoam through it, probably replace that fuel filter again after that, and I would probably also have your fuel injectors flow tested and cleaned.

I always thought that the fuel system could still be dirty. So I actually put a full can of seafoam in about 5 days ago an i haven't really noticed a difference at all for the hard start or performance. Ill try checking the injectors an see how that goes

 

[2GNT_RS-T]

You should check for correct operation of the throttle body ISC, and the FIAV. Both of these will operate differently when the car is cold vs. when it is hot.

The ISC is the idle air control valve right? An the FIAV is located under the TB?

 

[85Entropy]

Definitely check the fuel filter again, too.... If it's clogged with crap, that could explain part of your problem.

 

[2GNT_RS-T]

Definitely check the fuel filter again, too.... If it's clogged with crap, that could explain part of your problem.

I literally just put a new fuel filter in like 3 days ago an i put seafoam in about acouple days before i put the filter in. You think its possible it couldve gotten clogged up again still?

 

[85Entropy]

Depends on the amount of rust and things in the fuel, but if the Seafoam dislodged more, it might be worth a check. Just take it off and make sure there's flow, that's all.

 

[2GNT_RS-T]

Depends on the amount of rust and things in the fuel, but if the Seafoam dislodged more, it might be worth a check. Just take it off and make sure there's flow, that's all.

Ok ill check it out an see how it goes. Appreciate the help

 

[DogWhistle]

You should check for correct operation of the throttle body ISC, and the FIAV. Both of these will operate differently when the car is cold vs. when it is hot.

The ISC is the idle air control valve right? An the FIAV is located under the TB?

Yes. There are several great articles on here to help you diagnose whether they are functioning correctly.

 

[2GNT_RS-T]

Yes. There are several great articles on here to help you diagnose whether they are functioning correctly.

I just realized my FIAV has been deleted so that could be part of my starting issue. Ill go looking around an see if i can come across those articles

 

[jinscho]

I just realized my FIAV has been deleted so that could be part of my starting issue. Ill go looking around an see if i can come across those articles

If the FIAV has been deleted a cold start is always going to be a little rough. I recently deleted my FIAV and ISC as I couldn't justify spending 250+ on a new one when I could just take some scrap sheet metal and make a block off plate for free. I adjusted the throttle plate set screw to give a nice smooth 750rpm idle when warmed up, but a cold start always requires a little help on the throttle. After 10-15 seconds I can let off the throttle and it'll come down to around 600 rpm until the car hits operating temps.

 

[2GNT_RS-T]

If the FIAV has been deleted a cold start is always going to be a little rough. I recently deleted my FIAV and ISC as I couldn't justify spending 250+ on a new one when I could just take some scrap sheet metal and make a block off plate for free. I adjusted the throttle plate set screw to give a nice smooth 750rpm idle when warmed up, but a cold start always requires a little help on the throttle. After 10-15 seconds I can let off the throttle and it'll come down to around 600 rpm until the car hits operating temps.

Nice so that could explain my cold start issue but once the car is warm an i shut it off an wait like 20 mins an start it again an go to drive the car bogs an bucks really bad an i have to let it sit for like other minute. Could the FAIV cause that or could it be something else? Also while just cruising it random sputters for a second an just stops. I noticed my boost gauge hose is closed shut so idk if that has anything to do with it

 

[jinscho]

Nice so that could explain my cold start issue but once the car is warm an i shut it off an wait like 20 mins an start it again an go to drive the car bogs an bucks really bad an i have to let it sit for like other minute. Could the FAIV cause that or could it be something else? Also while just cruising it random sputters for a second an just stops. I noticed my boost gauge hose is closed shut so idk if that has anything to do with it

I can't say whether or not the boost gauge has anything to do with it as I'm still fairly new to the dsm community and have primarily been looking into 4G64 issues. As for the FIAV, the main reason I decided to delete mine is because once the car reached operating temps if I would come to a stop the idle would be erratic or the car would just flat out stall. I read through numerous posts about it where people would close off the FIAV but keep the ISC. I wanted to just delete the entire lower half of the throttle body and remove any potential electronics related failures in that area moving forward. I made sure to thoroughly clean the throttle plate before manually setting the idle so I knew there would be no potential hiccups moving forward. Car has been running perfect ever since.

 

[2GNT_RS-T]

I can't say whether or not the boost gauge has anything to do with it as I'm still fairly new to the dsm community and have primarily been looking into 4G64 issues. As for the FIAV, the main reason I decided to delete mine is because once the car reached operating temps if I would come to a stop the idle would be erratic or the car would just flat out stall. I read through numerous posts about it where people would close off the FIAV but keep the ISC. I wanted to just delete the entire lower half of the throttle body and remove any potential electronics related failures in that area moving forward. I made sure to thoroughly clean the throttle plate before manually setting the idle so I knew there would be no potential hiccups moving forward. Car has been running perfect ever since.

Oh ok. I appreciate your input. I definitely think the FIAV is part of my starting issue. But i definitely got something else going on cause it never starts on the first crank. On the first crank it sounds like it trys to start but it just immediately stalls out an of course i got the performance issue an the acceleration sucks an like i said before it randomly bogs for a second alnost like the power wants to come back. Idk its weird