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Idle surge causes?

G

GTPChristopher

New member
Finally got around to "finishing" my winter build. Turned key today and have this strange idle surge. Didn't do it right away, but after about a minute the idle surges (up and down). No vacuum leaks, STFT's are -/+3%, this is very strange. When I unplugged the MAF, it seemed to get a tad better. I already did a cam/crank relearn on it, so timing should be dead nuts. Only code it's throwing is a P0300. It isn't dead hole misfiring, just a little blip here and there, and it's on every cylinder. Which maybe makes me think it is a MAF? Idk. All I know is I spent way too much time on the car this weekend and my brain is effin' fried! 2000 L67 bottom end, L67 ported heads, dual timing chain, 136# springs, ST1 cam, LS7 lifters, 6.95 pushrods, L26 upper/lower mani, 42 lb injectors, Precision 6262 T3 turbo, etc. Any thought or suggestions would be greatly appreciated. Thanks guys!
 


What are the long term trims like?

Computer tuned for injector change?

It's going to need a MAF tune anyway with all the work done and I'd disable the P0300 code because of the aftermarket camshaft.

If no real tune is done yet, I wouldn't expect it to run really nice yet.
 
The PCM is ZZP-tuned for my current injectors, cam, turbo build, everything. I wasn't planning on driving it on that tune, but I was hoping that atleast it wouldn't idle all sorts of fukked up. The P0300 code doesn't throw a check engine light, it's just there when I scan it. Could this just need to be tuned?
 
The stock O2 is cycling as it should, and I also have a wideband. It's staying in the middle for the most part. Fuel seems to be doing what it's supposed to.
 


It's a PLX wideband setup. 14-15 AFR at idle, and when I bring it up to 2k+ RPMs, it goes to the 11-12 range. When I bring it off of idle the surge goes away.
 
Starts off at 800-1200, then after a couple minutes it swings 600-1400. Talked to the guy that's going to be dyno-tuning it and he said a tune should be able to fix that. Even though the ST1 cam isn't supposed to be "lopey", the PCM still needs a tune to learn what to do with it.
 
Wondering because I get a cold start surge with my s1x cam that I thought was "tuned" out. Now with the Is3 cam it's back until it warms up
 
if your tuner touches your car before fixing what ever is wrong with it, hes a hack and should be avoided. a tune wont fix a surging idle.

your cam should run fine on a stock tune. the tune makes the best of it.
 


CrazyGuy03 said:
Hey now I don't know what you're implying but I don't think I like it lmao
Click to expand...


lol ^^^^

other then his timing needed to be changed for wot, iirc hes na with a added turbo. it should run fine right now at idle and cruising out of boost, unless theres a issue hiding. surging on a little cam is not normal. dont think a p0300 is normal for a small cam either.

ive already told one guy no to tuning his car cause he told me its high idling. tune cant fix stuff like that.

post a vid or some pics, maybe someone can see something not set up right.
 
I would disable the P0300 and find someone else to tune it other than zzp. with it going rich in park with only a bit of a rev it wouldn't surprise me if the tune was way too rich. you can change the idle, but like the other people said that probably isn't your issue. I bet a maf tune will help a lot.
 


Thank you SgtMarshal! I appreciate your input on the MAF table. I posted this looking for tips/suggestions and advice. Not criticism. I'm not going to waste time "posting a video or pics so maybe someone can see something not set up right". I spent 7 months on my winter build. I'm here looking for answers, not to have my mechanic skills questioned. Just because I don't live on this site everyday for years doesn't mean I don't know my sh!t.
 
I would suggest investing in your own tuner, like an hp tuner, and start tuning it yourself. Having scan logs will help isolate the problem
 
hey dick head, if you dont post pics or a vid your over sight can stay there forever. zzp tunes leave the maf pretty much stock. fyi.


and no one has criticized you. unless you think trying to help by asking for pics is wrong, pics are worth 10,000 words, you clearly have no clue how often someone spots something not right. happens weekly here, your not special or exempt from f ing up something. (clearly)

or maybe your build is a sloppy mess and your to embarrassed to show it. coin toss, dont care either way.

7 month build, what were you doing for 7 months?
 
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