Idle surge and slow to rev down?

[wilkinshc]

Hi,


This is a new motor in a 63 impala with a casper wiring harness and turbotweak chip. Have 50lb injectors, stock maf, no map, stroker motor, ta ported heads, match ported intake, roller cam, te54 turbo. Surges when cold and much better when warm but still surges a little. Tap the idle and let off immediately and it will rev to 2500 and stay there for a full 4 seconds before returning to idle. It has 160 thermostat with a good radiator so I have not seen it go over 170 yet. Have a couple of power logs to review. Would appreciate any help.

Chuck

 

[pacecarta]

vac leak or iac valve sluggish

 

[TURBOELKY]

Sounds like your IAC needs adjustment.

 

[TURBOELKY]

And post a pic of the impala hybrid

 

[mikestertwo]

Your O2's are reading strange...showing extremely lean .000v? There are very little cross counts. Check your wiring and grounds. Bad O2 sensor?

 

[wilkinshc]

Attached is a couple pics, I shows the plugs, which are tan. If it was running super lean shouldn't they be white? I have been going over this with Eric a turbotweak. He thinks it is running super lean, so I bought new injectors 80lbs and chip. Still the same. Thought maybe the maf, so I borrowed 2 mafs from GNs that are running fine. One no change, the other still showed lean but it seem to get better anything over idle (see data log). Eric thought that indicated vacuum leak since it cleared up above idle which a vacuum leak would have more effect at idle. So I blocked off all vacuum at throttle body, no difference. I then used a garden hose and water the intake, intercooler, doghouse, and throttle body figuring if water was to enter in a vacuum leak the engine would stumble but no stumble. If I unhook the MAF the idle smooth's out, don't know what that means. On the O2's, I have tried new O2's denso, ac, and bosch but no difference. The wiring is a new Casper. The headers are stock but have been ceramic coated, start to wonder if the maybe I need to run a tap through the threads were the O2 goes, maybe not getting a ground? Really at a loss to figure it out. Considering pulling the TA motor and selling it and going ls3

 

[wilkinshc]

Have tried 2 IAC and reset them. If you look at on data log it shows at one point the IAC is at 0 counts. Still no difference.

 

[wilkinshc]

Have tried 2 IAC and reset them. If you look at on data log it shows at one point the IAC is at 0 counts. Still no difference.

 

[dank GN]

Are you setting it correctly ? Get the motor up to temp and Close the throttle blade till you see the IAC number raise . You are shooting for 15-20 at idle . Then readjust your TPS to .42-.46 . IAC numbers will raise when throttle blade is closed and reduce when you open the throttle Blade .

 

[wilkinshc]

Yes been setting IAC--- getting up to temp, adjust up or down keeping the tps with in .38 to .46, turn off adjusting again. If I unhook the maf it will idle smoothly, not sure what that means but I thought I would put it out there in case it does to someone else.

 

[haywire4130]

Do you have a way to check fuel pressure? What fuel lines/pump/regulator etc did you use on your build?

 

[wilkinshc]

walbro 340, ricks Stainless Steel tank, 1/2 feed line, 3/8 return and have monitored with 2 different fuel gauges to be safe. Started at stock 38psi with vacuum line off then went up to 43psi, and have gone has high as 50psi. All at Idle and it show lean at all setting with blm going to 142. Drive down the road the fuel pressure goes up and down in line with the vacuum and boost levels. sorry adjustable billet fuel pressure regulator.

 

[TurboBuRick]

Looks like the TPS is sticking. No? If it doesn't return to .46 or less, the ecm thinks your foot is still on the pedal.

BTW that's a sweet ride.

 

[bpman1234]

Inthe pic the vac line is off from the fpr ?

 

[bpman1234]

Also don't see any hoses going to your wastegate for a turbo

 

[wilkinshc]

Pic was when I was testing for vacuum leaks, unhooked the regulator. The wastegate has the RaceJace boost device that goes from nipple on the turbo inlet housing through RaceJace valve and to wastegate.

 

[bpman1234]

So after you reset the tps and iac did you reset the ecm?

 

[wilkinshc]

Yes, disconnected the battery, waited at least 5 minutes and reconnected. Going to try a Maf translator and ls maf from a buddy.

 

[JAMCAR223]

Don't give up!! That is an awesome hybrid!! The LS will make your car a dime a dozen. No matter what you find, get rid of that plastic vacuum block on the top of the intake. That is a vacuum leak waiting to happen.