always faster

iTrader: (6)

Well im in the last stretch.The car is running and is running pretty strongth but i got one small problem.

At a dead stop(red light or stop)when the motor is cold or not in is operating range, if i want start quickly(wot) the car seems to hesitate a bit but its hardly noticeable.

But when its warm(normal operating range) at a dead stop and same thing,if i wanna start quickly,the car hesitate kinda bad until 1000/1200rpm and then pull really hard to 6k.

MOTOR/IGNITION:
-Brand new 96 LT4 GM crate motor with plastic valve cover
-New GM lt1 oil pan
-96 LT4 GM intake
-New Delphi 32lbs injectors
-New Delco optispark distributor
-New msd blaster coil
-New taylor spiro wire otvc side mount
-New tr55 ngk plug
-Moroso CAI
-Brand new crank hub
-Brand new ASP crank pulley
-New rebuilt and ported(52mm) stock throttle body to avoid sticking blade with ported air foil
-New knock sensor
-New oxygen sensor(on both side with new pass side O2 extension)
-New coolant sensor(both: on head to gauge and on water pump to ecm)
-New oil pressure sensor with new angle fitting
-New throttle cable(no traction control)
-New rebuilt stock water pump
-New power steering pump
-New poly motor mount(2)
-New A/C delete pulley
-New dipstick tube and dipstick
-New pcv
-New IAC
-ALL NEW gasket for everything(water pump,intake,steam pipe,TB,etc...)

-Ive tried 4 opti(2 msd/2delco);
-I ve clean my maf and also swicth with another one;
-The idle seems a little rough
-The only thing i didnt change is the MAP and the TPS


So what could it be?

C5042081

iTrader: (5)

did you check the fuel pressure, dp you still have the egr?

mack

iTrader: (2)

Double check your plug wires. Make sure you have the correct firing order, routed properly, no burn marks and seated properly at the plug and opti. Did you cut the wires yourself and put on the ends? Could be a broken insulator in the wire where you had to crimp the connector. I had a hesitation before after changing my wires and even though I was sure I had the correct firing order, after checking a second time, found I had crossed the 6 & 8 plug wires and that I had a cracked the insulator (internal braided wire) on one of the wires. Doesn't cost anything but time to double check yourself. Also check the connections of the wiring harness to opti and at the PCM and your vacume lines/connections. Hope you find the problem.

always faster

iTrader: (6)

Fuel pressure is perfect and yeah im running the egr valve and it work properly.

always faster

iTrader: (6)

This problem was there with 4 different new opti and 4 set of wire also brand new and 2 coils so its not the problem.

But i will check the shape of the plugs

C5042081

iTrader: (5)

did you check every vacume line?

always faster

iTrader: (6)

Yep me ,my friends and a mechanic guy.

No leaks

C5042081

iTrader: (5)

just wondering if your using a LT4 KM

always faster

iTrader: (6)

Yes sir

mack

iTrader: (2)

Hopefully it will be a bad plug and then you'll be set. Finding the causes of a slight hesitation is frustrating because it can be so many different things. If it isn't a plug problem, check your TPS w a multi meter. No leaks at header gaskets? Sorry man, I know these sugestions are all mechanics 101 and I mean no disrespect by suggesting them. Maybe a vacum leak in the EGR plunger? You said you had the TB redone. Is the blade movement and linkage consistant with one another? I'm running out of suggestions. Anybody else have any ideas?
Keep us posted and hope you find the problem.

always faster

iTrader: (6)

There is no such thing has disrespectfull suggestion,if im aksing its because i need help and all help is accepted

My plug are ok.Today i logged the car with datamaster and some weird thing came by:

Those are the number when the idle seems to be fine:
Rpm: between 700 and 800
-Map Kpa: 33.2
-Fuel trim cell: 16
-LT term count: 150 148
-Sterm count: 128 128
-BPW MS: 2.73 2.73
-Inj Dc: 1.7 1.7
-O2 mv: .53 .102
-AFGS: 6.66
-TPS: 0%
-TPS: 0.67 volts
-Spark adv: 26.00degree
-Ia temp : 47.8
-IAC pos: 13

But when i first start it the idle was stuck to 1500rpm.I then stop it and reset the IAC.I start it and it stuck to 1200rpm.I again reset the IAC and the rpm goes back to 750rpm.

I the took some log while driving part throttle in town with a lot of stop and go.I also log a WOT 1-2-3-4 run.The motor takes back 3.5/4 degree of timing in wot but the thing that i found wierd was the idle.

With the motor cold or warm,during all the log test the idle didnt want to drop under 1000rpm at idle.Some times it was a 1000 some times it was at 1300rpm.The only thing that i found on the log was that the tps was at .67volts wich is correct nut it also read 3% open when the tb blade are fully closed.

mack

iTrader: (2)

67 volts sounds about right. Mine is at 71, but IMO 67 to 71 is fine. I've had idle issues before after a new tune w the idle being at 1000 sometimes and at 800 other times. My problem was related to a dirty spring in the IAC. You have a new, so.... I would check the condition of the spring. Make sure it didn't get kinked during assemble or for maybe a burr on the shaft of the unit that the spring goes on that is causing the spring to bind. Is the spring length on the new unit the same as the old? Timing could be off by +1 and causing the knock.

dhdenney

iTrader: (53)

Don't mean to sound dumb or spur argument but I thought TPS voltage at idle was .55?

always faster

iTrader: (6)

There is a free mod call the "TPS MODS" wich bring the voltage to .67volts.This is supposed to be the best set up.Mine is not modify and it dead on .67v

dhdenney

iTrader: (53)

You mentioned that at one point it was showing 3% open when it was closed. Are the issues related?

infinitebird

iTrader: (11)

Anytime a problem is "only happening when warm" you want to look at o2 sensors as that's often the cause but they often get overlooked.

What do your o2 values do in datamaster at idle? Do they fluctuate a lot or just stay mostly the same?

FAD2BLK93

I thought the tps target was .50 to 55...when I had my chip first done my idle would be high also about 900, and when I would try to come to a stop the idle would drag the car along...So I called Alvin and he said some cars would not accept the program he used, so I sent it back and he sent me another one and all was good.

always faster

iTrader: (6)

Yeah only for the 93 model.

always faster

iTrader: (6)

Im putting this thread back on the map since im having too much problem with the car and need help.

-I set the idle at 750rpm but it doenst want to stay there,it fluctuate between 700 and 800.And this is only when it want to stay there;
-The idle can stick at 1000rpm or 1300rpm or even 1500rpm;
-It lack power in the low range and it seems to have some hesitation when slapping the gas from a dead stop;
-It knock all the way thru the rpm,the pcm take back 3 to 5 degree of timing advance;
-From the datamaster files,the motor seems to run lean and the pcm is trying to compensate but make it run rich.


I got datamaster files to send to anyone that need them to help me.

Thanks