Stumble before boost??

[D16z6TurboCivic]

Just got my new engine in the car and it runs o.k. It seems to be missing on idle but not at anything above 1500 rpm. Its not a constant miss either just comes and goes. From 1500 up ....no miss. When I stab the throttle, the engine stumbles for a split second and takes off like a Champ.
I'm puzzled ... any ideas????

[SleeperCivicEX]

What are you using for fuel management?

[D16z6TurboCivic]

I have the greddy Black box, 310cc inj, FMU, and 255lph walboro.....this was never a problem with my z6, but it seems to be a problem with the ZC VTEC.

[Rexinre]

Mine does the same thing It has to do with the timing and fuel maps. I havn't profected it yet, but still messing with it.

[Likklekilla]

I know exactly what you are talking about. I am not sure what i did to stop it but i say try.

1. Different plugs
2. Plug Wires.

and if u luck try another set of injectors or try to get your injectors cleaned. I had that prob but sine i went to 345's i have not had that prob as yet so i guess your injectors could be dirty. Not sure but check it out and tell me.

[Rexinre]

What kind of plugs are you using?
What kind of wires are you using?
:D

[D16z6TurboCivic]

The wires a MSD wires and the plugs are Autozone bought
Denso's gapped at .038"

[Rexinre]

I got MSD and champion (its what edelbrock suguested) I want to get NGK, but don't know what number is the 2 colder then stock ones!

[SleeperCivicEX]

I got MSD and champion (its what edelbrock suguested) I want to get NGK, but don't know what number is the 2 colder then stock ones!

Don't waste your money on the NGKs, I ran Champion 344 series plugs from AutoZone for a LONG time without any problems and switched to NGKs to see if what the difference is - there is none. Felt exactly the same and burned the same.

[D16z6TurboCivic]

I have looked and i'm noticing Fuel pressure drops from 100psi flutuating down to 40psi and back up associated with the stumble. After more than 4 constnat seconds of boost there is a check engine light coming on.

[Rexinre]

Thanks for the tip Sleeper.

I also don't have an ignition system yet, that might be part of the problem! Not a hot engough spark at low rpm with too much fuel. Yes No?

[D16z6TurboCivic]

I have the MSD Cao and Blaster SS coil also.

[SleeperCivicEX]

I also don't have an ignition system yet, that might be part of the problem! Not a hot engough spark at low rpm with too much fuel. Yes No?

I wouldn't think of an aftermarket system, the factory ignition is very efficient and works great, even with boosted setups. I bought a MSD 6AL and never installed it. I did get some wires, but they made no difference - just replaced the dry, cracked originals.

Also, if you're having problems with boost, ensure that your plugs are gapped down to .032-.034 so that the boost won't blow the spark out. :wink:

[Rexinre]

I dono? I am clueless! I just thought it was normal until you said something! Maybe a stand alone will fix it, or hondata!

[D16z6TurboCivic]

my car sounding like an AK 47 during boost has never seemed normal

[D16z6TurboCivic]

You should see the people duck though while walking down the street....lol

[Rexinre]

wow, thats bad

[D16z6TurboCivic]

Found problem ....broken purge solenoid....Thanks for your help.