Any i deas of what this could be?

[SUICIDAL™]

Any i deas of what this could be?
Stock 99 Z28 with a whisper lid, If i launch the car off a foot brake, at about four grand the engine is still pullin RPM's but the car falls on its face...The car will rev to 6 grand all day but after 4 grand the front end drops and goes nowhere till it hits second and there on after... But it is inconsistent. Doent always do it sometimes it feels strong..
THING IVE ALREADY REPLACED OR DONE
-Brand new GM performance parts 4L560E (warranty)
-Fuel filter
-fuel pump
-Brand new converter (warranty)
-Cleaned mass air
Also have had the computer scanned several times, and nothin comes up
ANY IDEA"S

[Damone]

Bad Grounds !!!

[SUICIDAL™]

what should i check or where im not an ls1 guy ya know

[Damone]

www.ls1tech.com
Or at your work have a mech. run a search on the problems you are having. It will give you a run down of things to check. It sounds like 1st gear shifting solenoid ????

[SUICIDAL™]

Yea tried that too.. they looked at it for 2 hours and couldnt figure out a thing... Thats why i came to chitown

[Damone]

:thinking: I can give ya $500 for it then

[runningta]

does it do that in park or neutral? if it does check the O2s

[LilSlo1]

does it do that in park or neutral? if it does check the O2s

what ? the trans slips after 4500 rpms in first gear all the way up to 6000. It only appears to be slipping at WOT, when you are makin a pass. Could it be a line pressure problem with in computer ?

[yellowsrt]

Could it be an ignition problem that doesn't set any codes? Maybe you are having a cylinder misfire problem that only happens when you put a load on the engine. will it do it if you feed it gas slow from 4-6k rpms??

[SUICIDAL™]

No it wont do it if i roll into it but even soemtimes when i hit second i noticed today the engine does not want to rev it will stay at 3 grand and then kick in like it hovers and you hear the sound of the exhaust like its flooded

[xpndbl3]

sounds ignition related, check out wires, plugs, etc

[Damone]

... spray it :nxsmile:

[BAD GN]

Junk that shit box

[SUICIDAL™]

Hmmmmmmm?

[BAD GN]

or buy a ford

[danielcrmstr]

gm mass air flow sensors typically dont get dirty like the ford ones do. GM mass airflow sensors crap out electronically, so disconnect the mass airflow sensor and drive it. If it runs like a raped ape, you've found it. If that doesn't fix it (but it probably will) take the exhaust down and drive it. If it runs good, find the restriction in the exhaust, which could be in either the cat or the muffler. I can almost guarantee that it's the MAF.

[LilSlo1]

the trans feels like it is slippin to me, the motor feels as if it is free reving between 4500 and 6000 the car quits pullin. The motor runs fine.

[danielcrmstr]

then the trans is slipping

[SUICIDAL™]

maybe 05 huhhhhh? Its not the trans cause like i stated when i grab second the r's drop to like 3500 rpm and stay ther and the car goes nowere and you can actually here through the exhaust that it sounds like its flooded. Then it clears up and feels like i hit the shit and just rides

[LilSlo1]

im almost 100 percent sure the trans is slipping. the car got a new trans and converter from GM and its doing the same thing again... to me that says the problem is else where.

[danielcrmstr]

humor me and drive it with the MAF disconnected, see what it does.

[1fast97gsx]

If the trans isn't really slipping it's a fuel problem most likely. My turd gen did the same thing but in my case it was only a fuel filter. Check fuel pressure at the rail under those conditions you have these problems in. If it drops norrow it down from there since you then know it's a fuel system problem. Could be as simple as a bad regulator even altough unlikely. If fuel pressure stays up under wot and injector resistances check out then check ignition components. There's only so much it could be, don't waste your time with O2 sensors and other stupid shit like that since the car is in open loop under wot anyways.

[SUICIDAL™]

I ordered plugs and wires just to be on the safe side so ill go from there.. Its buggin the fuck out of me cause untill i get it right its not dependable to race with...

[lt1camaroman93]

put a fuel pressure guage on it and go romp and it and see if your fuel pressure is falling off. Do you know anyone with autotap? the efilive data logs a lot of usefull information you can use to diagnos with.

[SUICIDAL™]

Thats my prob,i know anyone with an autotap im gonna order my hp tuners soon but this this is buggen me, now.

[1fast97gsx]

well an ls1 most likely has a port to hook up a fuel pressure guage without needing any real tools or anything. Keep an eye on it while you experience this problem. Worst case you can even stall up the car and have someone watch the guage for you to see if the needle moves, although you really want to watch it during the times you have the problem.

[danielcrmstr]

disconnecting the maf will take all of 2 seconds. Disconnect and drive, I think you'll be suprised.

[1fast97gsx]

disconnecting the maf will take all of 2 seconds. Disconnect and drive, I think you'll be suprised.

Just curious what the purpose of that would be? I'm not an ls1 expert so I'm just interested in your theory.

[LilSlo1]

i don't understand it either. why would a tune up of fuel problem make the trans slip ? Just doesn't make sense. there must be something that i don't know or understand about this fuel injections shit.

[nate91gst]

if the motor still bogs w/ the mass air disconnected its not the mass air..but if it runs fine then the problem is in the mass air sensor if the motor doesnt think its getting ne air it will cut fuel pressure drop in power

[mzoomora]

If the maf gets dirty it will make the trans act weird. There was a service bulletin on this from GM regarding reuaseable oiled filters. I also reccomend trying the car with the MAF disconected just to see what it does.

[LilSlo1]

i see.

[1fast97gsx]

if the motor still bogs w/ the mass air disconnected its not the mass air..but if it runs fine then the problem is in the mass air sensor if the motor doesnt think its getting ne air it will cut fuel pressure drop in power


If the computer thinks it's NOT getting air it doesn't drop fuel pressure. It might keep the injectors open for a much shorted amount of time, but pressure should remain constant, hence the reason for a regulator .. which is why I told him to check rail pressure and see if it remains constant under load. With the maf disconnected the computer will base fuel delivery soley on TPS value and a map sensor from my understanding and of course O2 voltage unless the car is in open loop.

I don't see how a maf could cause a trans to "act wierd", so I would appreciate if someone could further explain this. An automatic transmission is to a point electronically controlled, but I wasn't aware that the MAF has that type of control over it.

[mzoomora]

Here you go.

Bulletin number 04-07-30-013a

Info - Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter #04-07-30-013A - (Jan 25, 2005)

2005 and Prior GM Cars and Light Duty Trucks

2005 and Prior Saturn Models

2003-2005 HUMMER H2

This bulletin is being revised to add additional model years and to clarify warranty coverage. Please discard Corporate Bulletin Number 04-07-30-013 (Section 07 -- Transmission/Transaxle).

DO THIS DON'T DO THIS

First, Inspect the vehicle for a DO NOT repair MAF sensors under
reusable aftermarket excessively warranty if concerns result from the use
over- oiled air filter of an excessively/over-oiled aftermarket,
reusable air filter.

The use of an excessively/over-oiled aftermarket, reusable air filter may result in:

• Service Engine Soon (SES) Light On
• Transmission shift concerns, slipping and damaged clutch(es) or band(s)
• Engine driveability concerns, poor acceleration from a stop, limited engine RPM range

The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur.

When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over- oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern.

The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.

If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs.

Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items.

[mzoomora]

The air isnt metered properly so the load isnt read properly. The line pressure in the trans which is copntrolled by the computer is too low which causes driveability issues. Its more complicated than that, but that is the basic part.

[LilSlo1]

The SES light doesn't come on when the problem happens, or after it happens.

[danielcrmstr]

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine (low voltage) indicates a deceleration or idle condition. A large quantity of air entering the engine (5 volts) indicates an acceleration or high load condition. When the MAF sees low voltage, it keeps the injectors open for a shorter period of time. When the MAF sees high voltage (5 volts) it keeps the injectors open longer. When the MAF malfuntions electronically, the computer has no idea of what the engine load is, so it uses the oxygen sensors to monitor the amount of oxygen in the exhaust, and tries to compensate fuel pulse width (the injector on time) to make the upstream oxygen sensor(s) switch around 0 volts. When you disconnect the MAF, the reading that the PCM sees is 5 volts at all times, eliminating any false readings between 0-5 volts, which puts all of the MAF readings to the test, and makes the pcm deliver one large dose of fuel, instead of varying amounts. Does that make sense? Disconnecting the maf is a quick and easy test that will rule it either in or out. By the way, if you brake torque the car to the floor for about five seconds, does it fall on its face? If so, disconnect the MAF and do it again. If it doesn't fall on its face, replace the MAF.

[SUICIDAL™]

No it does not fall on its face durin a brake torque. but it does occasionall through the ses light for a few miles and than shuts off.
Im in the middle of replacing the maf waitin on some parts. i will update as soon as weather is nice enough to make a rip.. thanks guys i get more help here than i did on ls1tech or the guys at SPEED INC.and it is definitly appriciated

[danielcrmstr]

does the light come on while at a cruise above 40mph?

[SUICIDAL™]

no not

[jakes4321]

Where are you located??

If your close (evergreen park) I will throw my efilive on there and read the code.

[1badbird]

Where are you located??

If your close (evergreen park) I will throw my efilive on there and read the code.
way to jump in on a 2 year old fuckn thread

[jakes4321]

guess i shouldnt drink................whoops

[slogn]

Thats my prob,i know anyone with an autotap im gonna order my hp tuners soon but this this is buggen me, now.i have an idea pay people what u owe them than kill urself ...there prob solved :finger:

[danielcrmstr]

way to jump in on a 2 year old fuckn thread
now thats some funny shit right there!

[danielcrmstr]

i wonder what fixed this car.

[rocketman19851985]

Sorry i have to have so many post to list my car for sale. If shift kit was installed; My freind had the same problem. The guy put grease in the brain to make it shift harder and fucked it up and had same problems. Dont know if that's what you did but it's another post for me.

[rocketman19851985]

The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The powertrain control module (PCM) uses the MAF sensor signal to provide the correct fuel delivery for all engine speeds and loads. A small quantity of air entering the engine (low voltage) indicates a deceleration or idle condition. A large quantity of air entering the engine (5 volts) indicates an acceleration or high load condition. When the MAF sees low voltage, it keeps the injectors open for a shorter period of time. When the MAF sees high voltage (5 volts) it keeps the injectors open longer. When the MAF malfuntions electronically, the computer has no idea of what the engine load is, so it uses the oxygen sensors to monitor the amount of oxygen in the exhaust, and tries to compensate fuel pulse width (the injector on time) to make the upstream oxygen sensor(s) switch around 0 volts. When you disconnect the MAF, the reading that the PCM sees is 5 volts at all times, eliminating any false readings between 0-5 volts, which puts all of the MAF readings to the test, and makes the pcm deliver one large dose of fuel, instead of varying amounts. Does that make sense? Disconnecting the maf is a quick and easy test that will rule it either in or out. By the way, if you brake torque the car to the floor for about five seconds, does it fall on its face? If so, disconnect the MAF and do it again. If it doesn't fall on its face, replace the MAF.


This guy knows his shit.

[slogn]

i wonder what fixed this car.
a 9mm to the owners head.......lol

[stimpy66]

a 9mm to the owners head.......lol

he missed ... now what ...:finger:

[1dayminewillwoopurass]

chech wires