0-30mph miss

[blackgn1]

I have been working on a customer car for a few weeks. Came here in bad shape. 100% stock!:biggrin: 46,000 miles. Ran like a turd. Fuel pump went out in the driveway!:biggrin: Here's the new parts list....Fuel pump(walbro) and hot wire kit, fuel filter, new 42lb injetors, RJC power plate, LT1 MAF sensor with translator, new crank sensor, new 02 sensor, scanmaster, 3" up pipe, 3" maf pipe with K&N filter, new vac lines, new plugs and wires, TT chip burned for the setup. Car runs like crap till the boost comes in. When the boost comes in it clears up and pulls well. Scanmaster numbers all in check. Drives on the highway like a new caddy. Fuel pressure regulator is stock. 38psi line off. Stock boost control but is at 14psi WOT. Knock is inconsistant. 02's 774 no knock....02's 824 4.2 knock.....02's 800.....no knock. Not enogh data there to say. I took out 2 degrees of timing out WOT and added 10% then 20% of fuel and knock is present then not. Put timing back to where Eric had it burned with the 20% fuel and the same occurs. Only thing I haven't check is cam sensor. Any ideas?? Every run is different so data is inconclusive.

 

[blackgn1]

Anyone got any suggestions. We are on a budget and money has run out. If it were mine I would tear into it. We don't have that option. I highly doubt this is Cam sensor. I could be wrong. Adding fuel doesn't help with the knock.

 

[XLR8]

I think the stock FPR may be an issue as the TT chip I believe calls for a FP setting of 43# line-off. Also if you are getting a part throtle low speed miss, it could be the cam sensor. A easy way to check is after the car is running, unplug the cam sensor and see if the miss goes away.

 

[BlackBandit]

What kind of oil pressure does the motor have? Also what kind of condition is the trans in? Make sure the translator is set correctly. Did you replace the sock when you did the fuel pump and have you checked to make sure that FP is rising with boost? I know you said that you did the pump and filter but that doesn't mean you got a good pump or the filter/sock didn't get plugged by a bunch of crap knocked loose from dropping the tank or something. Speaking of that, did you clean the tank while you had it down? Also, was the chip specifcally burned for a stock FP regulator? if not you could use a hammer and a socket to "add" some pressure to the spring in the regulator to get it up to 43 psi line off. Also, triple check that all of the intake/intercooler hoses are connected. If all of that checkes out I would be tempted to put a dial indicator on the rockers and make sure you're getting the movement you should out of the cam.

 

[blackgn1]

The chip is burned for 43psi line off. Tank was clean and the sock was not in a bind when installed. I checked the fitment before the tank went back under the car. New Walbro bad?:biggrin: Very possible!! Intercooler pipes tight. MAF could be set wrong. Thought about that tonight! I have bad feelings about getting such high knock at 14psi! Went out again tonight and can see knock at 4 degrees with 02's in the 770's. Going to run out to the garage and pull the translator box right now!:biggrin:

 

[blackgn1]

Translator settings are correct. on,on,on,off. I think there are a least two issues going on. #1 being a fuel issue and #2 being ????? Going to check fuel pressure as boost comes in with the gauge off my car and rule out fuel system. Also install my adjustable fuel pressure regulator. That should rule out fuel.

 

[QUIP'6']

i am confused i dont see any information that there is a miss at 30mph. i just see that it runs great on the highway. then i see where the knock is inconsistant. first of all the fuel pressure doesnt have to be at 43 line off. if your car is up to par you will then adjust fuel pressure based on blm's. a chip burner sets this 43 line off just to cover his a$$. if it was my car i would drain the fuel and put in 5 gallons of race fuel to see if you are having false knock. depending on mph and speed of the car and which gear your in if you have a loose motor because of no strap then the knock will be inconsistant. you can also try to ease into wot and see if the knock goes away. the 02's that i see would not indicate that you are lean. GOOD LUCK

 

[blackgn1]

02's suggest there is no lean condition. High 700's and 800's. Scanmaster knock counts suggest otherwise. When I added the 20% fuel it helped but was far from a cure. Engine is tight. No signs of anything hitting anywhere. No knock can be heard by ear but the scanmaster is going crazy. From idle till boost comes in it runs like crap. A non adjustable regulator may not be a fix but I think that it is a neccesary upgrade. Funny how boost clears up the motor but also causes knock. Knock increases as you stay in the throttle.