zdalunatic

99 si GSR swap
9.1 pistons, eagle rods, sleaved blocked, built head. boosted.

the car was recently tuned, and even on the dyno it felt like a misfire after letting off in 4th gear. it goes through the gears fine, but if i punch it in anygear and go to shift to another it seems like it drops 2 cylinders until the idle drops to 1000 and then its fine! lookin at the dyno graph, and all the sensors everything is correct, theres proper fuel and spark. let me kno if yo need more info

4dohs4mohoes

Check your head studs/bolts. Sounds like the head may be lifting off the block under WOT.
I know it sounds like a terrible place to start.... but it seems you or your tuner has already checked the basics.

zdalunatic

if it was lifting under wot conditions would i have a missfire all the time?? the tuner advised me to get a new coil and or distributor from honda and have my injectors checked.

4dohs4mohoes

Well now after reading your OP again, it's kinda confusing. So it feels like a misfire while the clutch is in and your shifting? Or it feels like a misfire after WOT and letting it get back to idle? Or it feels like a misfire while "getting on it in any gear"?

zdalunatic

ok, well i havent WOT and let off in the same gear ima have to do that tomorrow. but say if you get on it WOT and change gears it will feel like its missin till u press in the clutch n let the rpms drop to idle and then u can get bak into it. i thought it could b a crank walk, but theres very little/no play in the crankshaft.

4dohs4mohoes

the way you talk is soooo confusing. I still cant figure out when you feel it? Sheesh

zdalunatic

lol. your in 2nd gear and you punch it "WOT" and change into 3rd you will feel the missfire till you slow down to where idle is back down to normal idle or you press in the clutch till the rpms drop down to 1000.

4dohs4mohoes

LOL.... ok. So how much boost are you running? What tune on what octane? What ignition set up? Did this happen before the dyno pulls? And did the tuner change anything?

I guess we do need to get back to the basics

zdalunatic

15lbs (at 15 lbs i was at 90% duty cycle, and at 17lbs maxing out stock fuel lines and single 255 walbro fuel pump), 93 pump gas, stock/oem ignition. before the dyno pulls it would barley idle (it ran fine 2 months ago before i put som work in) naw, he threw in a set of new plugs, temporally installed a msd ignition set up and see if it made a difference n it didnt. (it did it on each pull regardless of how much boost)

4dohs4mohoes

Ok... You may be having an issue with spark. After the tech put new plugs in, did you pull them afterward? Or are the still in the motor. Did he/you pull the plugs to see what they look/looked like? i.e. white/black? But it sounds like a restriction somewhere when under a very light load.

zdalunatic

thats exactly wat both me and the tuner said, aswell as matt keller and bryan fisher. i pulled the plugs out after the dyno pulls and they were fine, burning fuel properly judging by the way they looked. like i said we went back through the data list and checked for proper air fuel ratios, spark and timing. They were all in spec in every curve of the chart. He, the tuner says it could be something electrical as in the motor torquing back could be pullin on a connector/terminal causing it to lose continuity between 2 connectors!

4dohs4mohoes

One last stupid question... are you getting a check engine light at any time?

zdalunatic

no check engine light at all

4dohs4mohoes

Have you done the visual "look over"? Make sure all your gounds and connectors are tight. I doubt it's an issue with the motor torquing because I'm sure you dont have stock mounts in it.

Also another somewhat simple thing to try... lower the boost. If possible.

zdalunatic

not only a visual check over, i made sure every connection was secure wit enough wiring for it b able to stretch wit no problem. removed all ground connections cleaned up the area (meaning removed paint/rust from under ground connections) double checked the engine harness to see if there was a broken wire of anysort, checked connections at the ecu and even bought a new jumper harness to make sure it wasnt the problem. Lowering the boost did not do anythin, cuz it seemed to do it any lbs of boost.