so lately, i've noticed over the last few weeks that my car doesn't seem to hold its tune. it will do fine if its completely cooled down, but once its hotlapped, it seems like the ecu is pulling timing in the upper rpm range. like it will run around 11.0 and just drop down to under 10.0. you can feel it stop making power too like it's hesitating. my guess is that the knock sensor is triggering? before, timing was pulled 2 degrees, but i changed it a couple of weeks to 4, but still no difference.

also, i've noticed at idle when the car is warmed up, it will sort of "hiccup". you can hear sort of a "surge" like the car misfires or something and wants to die but the antistall makes it jump back up.

just yesterday, i swapped out my one step colder ngk's, to two step colder ngk's. i noticed no difference except that the hiccups at idle seemed to have gotten worse.

any advice?

 

how much boost are you running? what is the ambient air temp. a heat-soaked motor will pull timing up to a point. when you pulled the plugs how did they look. plugs will tell the true story.

i would go back to your orignial settings and start from there. back the boost down 2-3psi and see what is going on. check the the oil and coolant as well. make sure all systems are running up to par.

how long has this being going on? a bad tank of gas can cause all sorts of driveability issues.

 

im still at stock boost settings ~8.5 psi.

i'm in hawaii so ambient is around 70-75 but humidity level is high here in the islands.

i'll try to get a pic of the old plugs. there was the usual carbon buildup with some white residue.

this has been going on for a few weeks, the idle things been going on for a couple of weeks. i'm gonna try fill up at a different gas station today.

 

Is it possible the injectors or the clips (if you have them) are bad? I wouldn't have the first clue how to check them, but if you're running really rich, that'd be the first place I'd look. Either there, or at the ECU/Piggyback.

 

Check all your piping. Both hot side and cold. Sounds to me like you may have a pipe leak somewhere.

 

I say call dezod, because you may need this device:

http://www.dezod.com/pd_dezod_motorsports_partial.cfm

 

i actually have the first batch of black boxes. my afr is under control for the most part, its not running lean.

hey jrod, can you explain how pipe leaks would cause my problems? at idle, i have a normal 20 in.hg vac reading.

 

Well, I had a hot side pipe come out of the coupler and it idled like garbage. Freaked me out in thinking I had blown something. And when i'd rev it, the car would just stumble terribly and most of the time die. What was happening was the MAF was reading the air coming in thru the intake, but that "metered" air was not reaching the motor since it was leaking out the pipe, so i was dumping fuel and bogging out my motor. It was even worse when i would drive it. I would give it gas and it would hesitate badly. Once I found the issue, fixed it and car ran perfect again. I was just thinking maybe you have a leak somewhere too. It seems its always the last thing we think it is. Plz keep me posted as to your findings. Just trying to lend a helping hand.

 

thanks, i'll take a look at that but it doesn't seem like a pipe leak issue. when driving normally, it's just that: normal. my problems deal with the upper rpm range and idle.

 

you able to record any logs?

 

unfortunately, no...i don't have any logging program except for on the greddy emanage support tool. however, the blue can only log one thing at a time. right now, its hooked up to the pressure sensor.

 

PMed

 

alright, im not so worried about the pulling of timing in the upper rpm range as its during WOT.

however, my idle is getting worse. it sounds like its backfiring (?) or popping during idle. as far as what it feels like, the little surges feel like when you turn the ac on. so you can definitly feel every "pop"

this is worrying me as it seems to be getting worse. anybody have any idea what it is? i just changed plugs (running two steps colder ) and i filled up at a different gas station but these didn't do anything.

 

What gap on the plugs Ryan?

 

NGK BKR8EIX .030 gap

from sparkplugs.com. funny, garage1217.com says its .035 gap.

is this too small of a gap?

 

errr, if it's .30 it's not really too tight. but for 8psi you don't need that tight of a gap. also you really don't even need 2 steps colder for 8psi. there is alot to consider when choosing a plug.

if the plug is too hot your going to get possible pre-ignition or detenation. if it's too cold your not going to be in the correct operating range and your flame kernel/propagation is going to suffer.

 

well, turns out the gap was too small. i regapped my old 1 step colder plug from .030 to about .040 and the idle is now fixed.

im going to try the same with the two step colder plugs and see if it makes any difference at WOT.

 

So ALL of your issues were due to the gap in your plugs?

 

no, only the idle issues...

well, im going to try the two step plugs at the new gap i used to see if it fixes my WOT problem. that problem seems to be due to the fact that the ecu is pulling timing in the upper rpm range when the engine is hotlapped.