Chevy & GMC Vans

I've posted about this one before... I've about had enough of 'living with it' ..

problem 1

my 99 has pretty much been this way since the day I bought it .. probably getting more noticeable in the last few months

it's got a lack of power. when you accelerate hard it seems like it's not getting fuel or flooding itself. there's no other way i can describe it. it idles smooth, under light or 'normal' driving conditions it's perfect. I often think twice before pulling out to pass simply due to the chance of it falling flat on it's face, needless to say, I won't make the pass. Merging on the hwy, I can only accelerate slowly and smoothly until I get up to speed, if I punch the pedal to the floor it just kind of bogs. this is not intermittent, it will do it almost 98% of the time.

I have no codes (not even stored), I have changed the plugs wires cap & rotor (with AC) twice in the past year, air filter oil & filter as well as serviced the transmission fluid & filter. .. oh and let's not forget changed the fuel pump and sending unit as well as the fuel filter twice within the past 14 months, and installed a new ignition coil. I've also ran the AC fuel treatment plus (aka poppet cleaner) through twice. It passes the emissions testing no problem, and the poppet cleaner only seemed to help temporarily, or this could have been simply hope making me think it did anything.

problem 2

Now that I have my AC fixed, when I have AC on or the heater control to dash (for defogging windshield) the AC compressor cycles as it should but it's also putting what I believe is a more than normal drain on the system, making the motor work even harder than what it has been just to pull itself. when the AC cycles and the van is in gear at a set of lights, it almost feels like the idle drops so low it's going to stall, then it corrects itself and is okay..... until I accelerate

really, I think I might have at least two problems, or one than makes the second occur worse than it should... the AC putting too much of a load on the system.. and/or this seems worse than it actually is with the bogging under hard acceleration.

I'm seriously at my wits end with this thing... please help .. before I slap a for sale sign on it... thanks

I think your 2nd problem is def related to the 1st issue, anytime I hear of a lack of quick power or power on hills I always hear folks recommend you check your cat to see if she's plugged up/fallen apart, you seem to have checked all the other standard items.

Clean your Mass Air Flow sensor with a little bit of carb & choke cleaner & a q-tip. See what that does for you.

thanks guys .... and this is why James is a 'master mechanic'

in the past I'd cleaned the MAF sensor as best i could without removing it or sprayed cleaner into the intake. that was like

this time I took it right out and right apart. used a few q-tips and some air intake clean that doesn't leave a residue. took a fair amount of carbon off the backside of the 3 tiny little wires (for lack of the right term). it actually took going over them a few times to remove all of the blackness. still, in my head i thought there's no way this is going to make that much of a difference. well.. what a difference!!!!!!!

i took it for a speed run on the semi-deserted road behind my place. not a single stutter or hesitation or bog or anything. i even went as far as two dead stop and hammering the pedal to the floor wouldn't you know it .. it actually left a black mark both times from the right rear tire .. this van has NEVER been able to do that ... James, once again

Pics would have been nice ;)

LOL.. yes Jim, I did think of that when I was typing out the reply. didn't think of it while I was doing the job because I was running out of time as I was being beckoned to figure out what was for dinner and walk the dog and get the garbage and recycling together for the morning and cut the lawn and rake the leaves.... well, you get the idea. lol

no worries though, it only took about 2min to remove the mass air flow sensor and about 2min to take the 4 allen bolts out and about 3min to clean the wires. i'm sure as long as the weather holds i can take it apart again in a couple of days to take some pics. tomorrow I'm in london at university hospital most of the day

Been there, done that.

I love it when a simple (ie:cheap) repair has outstanding results...don't you?

PS: I loved the

After doing the alternator I got an engine code . . . P0102 mass air flow sensor. I'm too tired to look right now, but maybe tomorrow. I know the wires were reconnected, but I will have a look.

Just curious so I can go in and do this... Where is the mass airflow sensor located?

something like this is what you're looking for... it's inline with the air intake between the air filter housing and throttle body

you separate the outer alum bread in the samwich .. the black part is the meat



once separated .. this is what you're looking at

Awesome! So I just need to pull my air filter housing out and lift up on the throttle body and this will be down there?

Thanks again!

Derek

it should be directly behind the air filter housing.

That is on OBD II's only,right??.Not on a OBD I like my CPI 1994 Astro.My OBD I still uses a MAP sensor??.

Derek939,

Since your van is a '91, you will not have a mass air flow sensor on your van. These vans started to have mass air flow sensors on them in the '96 version.