KA-t acting strange....

green_machine

green_machine

Gay_machine
Driver
I just replaced my head gasket, put arp head studs and a koyo radiator in my car and I cant get it to run right. When the car is cold it works perfect but when the car warms up, as i get in to higher rpms with the throttle from about 50% to 100% floored the engine breaks up and pops and backfires. But doesn't always happen at the same rpm or boost level or throttle level. I cant figure it out. And after the car sits and cools for a while it runs fine and doesn't break up even at full throttle til redline.

Things I've done to try to get it to work....

- put in walbro fuel pump
- changed coil
- checked all my grounds and added extra grounds
- checked the battery and cleaned all the terminals and added grounds to the neg side
- checked the timing like a million times (although I doubt that's it)
- put new spark plugs in
- checked compression
- checked for vaccum leaks

and now i'm stumped. Also, I have an safc2 so i know that the mafs, tps, knock are working. So please if anyone has had this problem HELP!!!
 
Sounds like it could be a timeing issue.. What retard are you running?

Also did you check your FPR?? Injectors?
 
I thought about all those things but it runs really good for like the first 2 minutes and then it craps out but runs perfect with partial throttle and under boost. I believe it is electrical. It is similar to when I had a loose ground.

...lol this is off topic but i'm watching the daily show and - lance from nsync came out of the closet...
 
changed coil to what? ive seen some pretty crappy s13 coils. What plugs and gap are you running? Are you blowing out spark?

do you have a wideband? is it going stupid rich or lean when you start to get into boost?

Is the fpr raising the fp as manifold pressure increases?

Is the vac line on the fuel pressure regulator?
 
I just pulled a coil from another 240, It's not good odds that i pulled another coil that works half the time like mine. I'm only running 7-8 psi, I dont thing i would be blowing out the plugs but it's possible. No wide band :( . All the vaccum lines are good. My car was running good (except for the blown headgasket) before I put a cometic and the studs in, so that's why i'm stumped. I only let the car sit for about 2 weeks.
 
green_machine said:
...lol this is off topic but i'm watching the daily show and - lance from nsync came out of the closet...
Click to expand...

Really?? hahaha OMFG ROFL... that made my night dude!

Hmm... bad case of heatsoak?

maybe sparkplug wires or the coil?.. you might be heating your plugwires to the point where it is causeing a problem..
 
haha check your Coolant Tempature Sensor!!! and if you havent bought a Factory Service Manual yet, BUY ONE!! or steal it from NICO. The CTS are only like 20 bucks at Nissan...
 
I would not doubt for a second that you could blow out spark at 7-8 psi at .44" of gap (spec). If you have it down to about 27 or 28 then i would rule that out.

try putting a vicegrip on the fuel return line and see if it breaks ups\runs fine\bogs because of too much fuel. This will tell you if its a lean condition if you have not already determined that. <---- easiest way for me to know if your rich lean or okay.


pull the spark plugs after it happens. what do you see? what do you see after regular driving? are you running colder plugs?
 
I changed the temp sensors and nothing happened. I just saw that my valve cover gasket is leaking into the spark plug holes and there's like a crapload of oil all over 2 of the spark plugs... that's probably it. It might screw with the electrical connections between the plug and wire at higher rpms. Ill proabably not get to check anything this weekend because of work but ill update on monday. Thanks guys! I really appreciate the help and i'll do a smaller gap on monday too and check the fuel return line.
 
how old are your injectors? sounds like it could be a fuel delivery problem. but im not a mechanic so dont quote me on it.
 
240sicknessx and Dori THANK YOU VERY MUCH!!! I tried a .25'' gap on some crappy plugs and the car runs fine. I'll now do them on the irridium ones. I would have never thought that the gap was too large. THANKS!
 
I was kind of joking around but not at the same time... .44" would be huge as would .25" I'm thinking you mean .025" ;)
 
i know what this is, but i have to ask a friend, he was telling me a guy came in to service a car at his shop and it was the exact same problem, i will PM
 
^it's fixed bro. I put the good plugs i had gapped to .025'' and it runs a million times better! I have alot of car knowlege but this is the first time I have turbocharged a car, I guess this is just stuff that comes with the territory. Again thanks guys, I was running out of things to try
 
Yeah dude, colder plugs and a smaller gap are a must for boosted application and always keep a spare set of plugs with you if you are running copper (which you should be).
 
i have another question for you guys, should my iacv be under boost? because i dont have it like that but it still runs fine. does the iacv leak if it's like this?
 
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