Pensfan11

Hi I have a mpfi 2.8 V6. It runs terrible though. RPMs go from 1k to 500 at idle, sometimes it even stalls out(usually when i come to a stop sign). It will randomly drop 1k rpms for about half a second while im driving and car feels like im stomping on the breaks. Also when im driving and I'm semi heavy on the gass it starts cutting out at around 3000 RPMS but if I floor it it will sometimes power through it without cutting out, but it will drop into a lower gear at way higher rpms. I have brought it to several shops, but it only has an error code every once in a while and they tell me they won't be able to tell unless it comes up with a code. Any suggestions would be appreciated, thanks.

Pensfan11

I also forgot to mention that when the weather is hot, all of these problems intensify.

Maverick H1L

iTrader: (8)

If you have a tach, watch it as you're launching. If it drops down to near 0, your ignition module is basically telling you it's time to replace it. Most ignition problems intensify with heat. Most shops haven't had to deal with pretty much being stranded by a dead module. (actually, my car was in the shop "being diagnosed" for the above until the module finally kicked the bucket and they were still scratching their heads... I replaced the module in 10 minutes and drove it out)

Pensfan11

It sometimes drops to about 100 then will surge up past 1000. I will look into the advice that you gave me. Thanks

evilemokid94

iTrader: (6)

What are some other sympotums? Reason I ask is becUse of my cars sitting still, in drive or park the rpms surge, like the rpms will drop then come back up and my car dies after iv driven it for a second till I restart it( turning most times) and right after I start it, it drives really sluggish till it warms up alittle.

Pensfan11

It does serge like that, but its more random. I might be able to drive it one day fine. Then reandomly ill drive it and it will be terrible.

Pensfan11

Does anyone think that the cutting out might be a vss sensor? Whats happening is at 3000 rpms in certain gears it seems like it wants to shift but it doesnt really, it just kind of stops.

Maverick H1L

iTrader: (8)

VSS has NOTHING to do with the trans shifting except for the torque converter clutch above 45 MPH. It's not electronically shifted (1993). If it's not shifting right, you have trans issues as well, or the TV valve cable needs to be readjusted (the green cable on the throttle body).

Pensfan11

Ok thanks. Just found out car is showing code 30 and 34. (Low voltage at manifold absolute pressure sensor OR Fuel injector OR Park or neutral switch OR CAM, Low voltage (high vacuum) at mass air flow sensor (or MAP sensor)). Could this be the casue of my problems and how would I go about troubleshooting it?

Maverick H1L

iTrader: (8)

Double check your codes... No such animal as a code 30.

Take one of the relays by the brake booster and swap out the one behind the passenger's side headlight with it. Disconnect the battery for a moment and reconnect it. Start the engine and check to see if code 34 pops back up. No MAP sensor on a V6 before 1990 and after 1984.

Pensfan11

Yeah my bad was 33 and 34 wrote it down wrong, thank you. Does this mean that I need a new maf sensor? I unplugged the maf sensor and it idled good. Then pugged it back in and it did what it was doing before.

Maverick H1L

iTrader: (8)

Did you swap the relays yet? More than likely, with a code 33, your MAF has taken a dump. However, you need to make sure there is power to it to get rid of the code 34.

Pensfan11

No i havn't, I spaced it :O. I will try that now, thanks .

Maverick H1L

iTrader: (8)

When you're done swapping relays, check to make sure you have 12V on the orange wire at the MAF connector, otherwise the code 34 will come back to bite you :P .

Pensfan11

I am having trouble finding the relays that you are talking about. What do they look like?

Maverick H1L

iTrader: (8)

They're the 3 black boxes bolted to a bracket to the right of the brake booster (may be only 2 if you don't have A/C) with wires plugging into the bottom.

Pensfan11

Found it(hiding behind intake) thank you very much. Bought new relay put it in and the 34 went away. It does run like 10 times better now, but does this mean I need a new MAF sensor? I went and checked at a local parts store and they were $300 bucks new or $80 to referbish the one I have now.

Maverick H1L

iTrader: (8)

I will say this much: STAY AWAY FROM THE REMAN MAF SENSOR. I went through 2 of them in 2 years because the Chinese that remade them didn't make them right.

Let the car run for a while as it is and then post back if the code 33 comes back. Replace the MAF relay that you swapped (the one mounted behind the headlight, not the one from by the booster as that's obviously good).

If the code 33 comes back, you probably need another MAF. If you have a Camaro, I might have a good one (I haven't exactly looked at it yet to determine anything other than it's a V6 sensor). Other than that, you may get lucky on eBay, but, again, STAY AWAY FROM THE REMAN MAF SENSORS.

Pensfan11

I ran it for a while and the 33 is back, but I have a firebird . Do you think it is a good idea to buy one used one off of ebay?

Maverick H1L

iTrader: (8)

If you're lucky, you MAY find a NEW GM on eBay for cheap... I got mine there for the Bird back in 2010 for $50, new in box. I don't know if she has any more, though (dealer parts buyout from closing dealer, I suppose). You're taking your chances with used, but anything's better than the one you have now, I guess.

Before you go and buy one, take it out and look in the engine side at the film in the middle of the board. It should be clean and flat. If it's dirty, clean it. If it's wavy, the MAF is toast.

Pensfan11

Just cleaned MAF and it was very clean when i put it back it no problems on the inside or out still came up with 33. Found sensor on amazon for about $60. Thanks alot for your help, I know it must be kind of annoying helping someone like me. I've taken my car to several different shops and they just ignore what I ask them to look at and find other problems that they can take my money with.

project89

iTrader: (1)

check ur local jy for a v6 camaro or firebird and grab the maf off that, should only cost u 10 bucks

Pensfan11

I live in a very small town. Its slim pickins.