themack56

iTrader: (70)

mods are asa cam. lpe 853 heads. fast intake. long tubes with cats


story

when i punch it in 2nd+ gears it hesitates to accelarate when it reaces 3200 rpms all the time, i have no engine lights on, car has 120 000 miles, any idea on what it could be, it kinda burps back and forth snaping my head back and forth like a bobble head doll, its real anoying when im trying to get on the highway, this just started to happen to me please help

jester ls1

Fuel pump going out?

themack56

iTrader: (70)

u think?

i already have a racetronix kit for my car, but i didnt want to put it in until i had my new engine in sometime nxt year, any more ideas?

wssix99

iTrader: (5)

Lemme guess - you also have a K&N filter, right? If so, you should try cleaning the oil off of your MAF with MAF cleaner.

If that works, you can throw away the K&N and go back to paper. It will make your MAF much happier...

themack56

iTrader: (70)

Actualy i have a Vararam c5 intake with the green filter, and i havent cleaned it in 3 months


u think it can be maf?

wssix99

iTrader: (5)

Yea - with the consistent problem, it sounds like your engine is either being choked for air or fuel. (Air is usually not an issue as we have a mechanical linkage to the throttle body.) So, something is tricking your engine to cutting fuel or something is constricting the fuel supply. If you don't have any other symptoms, like wild coolant temperature fluctuations, then the two likely culprits would be the fuel filter and MAF. (When the MAF gets dirty and fouled, it can't sense the air flowing to the engine and the PCM cuts fuel to compensate.)

Like the K&N filter, your filter is oiled. That oil sheds off the filter over time and the heating element on the MAF is not hot enough to burn it off like other contaminants.

I made my life easier and better by switching to paper, but if you keep an oiled filter, you should probably include a MAF cleaning in your regular maintenance schedule. (I know K&N also warns against over-oiling the filter.)

joblo1978

iTrader: (14)

You could get some MAF cleaner, that may help, they get pretty dirty. Oiled filters are not a problem, just don't over oil them. Clean the filter, don't go back to paper, lightly oil it.

If that doesn't work, I would start looking at plugs and wires. Sounds like you're due for a tune up.

Do a fuel filter while you're at it.

themack56

iTrader: (70)

ok, i also noticed that when the car is cold, barely turned on, and i go for a drive the same thing happens it jumps back and forth, i cleaned the maf and i turned the car on and went for a drive as soon as i turned it on, and it didnt hesitate, i didnt go above 3000 cause i checked my oil and it was low, so im going for an oil change and i will post results tomorrow for when i go above 3000

LS6427

iTrader: (2)

Correct me if I'm wrong....but the MAF is only used for cold start up and then after the temp reaches operating temp (I think 122* and higher) the 02 sensors take over the gig. Then from that point on the MAF is only in play when you go WOT after warmed up.

So, make sure you get it up to temp, then go WOT to check if cleaning the MAF worked.

If you still have trouble I would think you have a bad spark plug wire or possibly even a failing 02 sensor(s). And NO, you will not always get an SES light when an 02 sensor is failing or when a cylinder is misfiring. Our PCM's are funny like that.

Unless I have that all wrong....then disregard it

themack56

iTrader: (70)

i will try that tomorrow, the thing is my car dosnt reach a normal fbody temp cause i have my fans turn on early

themack56

iTrader: (70)

i also that the maf is used 4000 rpms and below

LS6427

iTrader: (2)

I don't remember that exact temp the MAF switches over to 02 sensors, but even with a 160 t-stat, your temps get well above whatever it is. I think its 122* F. If not, its 176* F.

LS6427

iTrader: (2)

Maybe, but I'm pretty sure its a temp thing, not an rpm.

LS6427

iTrader: (2)

"1987firechicken" can tell you about the MAF and 02 sensors better. Here's what he told me once.

Cold starts and WOT: Are run with the MAF
Warmed-up engine, non-aggressive driving: Your other sensors take over, O2's and MAP.

1987firechicken

Somewhat correct. Our cars always rely on the MAF if it is dirty then it will mess with your closed loop fueling. Our cars are a blend of a MAF and SD tune. Reason I worded it that way is on cold starts and WOT the PCM ignores the VE table (SD part) and uses readings primarily from the MAF. On a warm, 4000rpm, and below non-WOT conditions it's a mix as they act as a sanity check on each other. So if the MAF is dirty it could cause issues but your saying "punch" it so I'm assuming WOT which is MAF areas as well as your IAT sensor and MAP.

A way to check it on a stock car would be to simply unplug it and see what it does. You can try that but it may be dangerous to do if whoever tuned the car didn't tune the VE table properly. I'd give him a ring and ask if he modified the VE table at all. A very short burst at the RPM area giving you the issue shouldn't hurt anything though but it's your car.

I say clean the MAF and IAT and see if it gets any better. Also do you notice any smoke out of the exhaust?

brian.moritz

themack56, I'm experiencing a similar issue. You ever find the fix? I'll give cleaning the MAF a shot and see if that works. I hope it's that easy!

brian.moritz

I cleaned the MAF and wow what a difference! It made a significant difference in the car. The MAF was definitely dirty and not only is the hesitation gone but throttle response is much better.

LS1nut377

iTrader: (16)

yea clean the maf,your air filter. other issues, plugs , wires ,coils, fuel pump is a key thing to do this also. and i would look into getting a good tune....good luck