car losing power at 4,000rpm
03-31-2009, 09:33 PM
#21
12 Second Club
iTrader: (21)
Join Date: Jun 2007
Location: Muskegon, MI
Posts: 1,102
Likes: 0
Received 0 Likes
on
0 Posts
Well mine's fixed. I'm guessing yours is the MAF. Although mine was screwed up it was MAF related. A piece of foam from the bottem side of the lid used to seal agaisnt the air filter and come half lose. It was stuck right to the side of one of the wires in there. Took it off and it's fine. Sounds stupid as **** and I can't believe I was seconds away from ordering a fuel pump and dropping the tank for nothing.
04-01-2009, 05:08 PM
#22
On The Tree
Thread Starter
iTrader: (5)
Join Date: Sep 2006
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
ok so I put a new maf on and it still runs like crap in the upper rpm's but seems to be fine in the lower rpm's. Anymore ideas what it could be? Could it be the fuel pressure regulator? I read the check engine light and it said the front o2's had low voltage so I replaced them with new o2's and it still says the front o2's have low voltage? What could be causing that?
04-01-2009, 08:57 PM
#23
12 Second Club
iTrader: (21)
Join Date: Jun 2007
Location: Muskegon, MI
Posts: 1,102
Likes: 0
Received 0 Likes
on
0 Posts
If you did a fuel pressure test and everything checked out then I doubt it is the regulator. Seeing as though we had the exact same problem and the exact same codes I'm still guessing your's os MAF related. Maybe wiring or something but like Frost said, the MAF takes of fueling at 4000 RPM's. Right where ours was messing up.
04-01-2009, 09:12 PM
#24
On The Tree
Thread Starter
iTrader: (5)
Join Date: Sep 2006
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
ok hooked up a fuel pressure gauge and my fuel pressure goes to zero as soon as I turn the car off. When I turn the key to the on position it takes a second to build pressure then goes right back to zero. When I first start the car the pressure is about 70-75 lbs. Once it warms up seems to go down to about 55 lbs. I drove it down the road wacting the gauge and at wide open throttle the pressure drops to about 25-30 lbs. So im guessing the regulator is bad. Isn't the regulator what is suppose to keep the line pressurized when you turn it off?
04-02-2009, 09:25 PM
#26
12 Second Club
iTrader: (12)
Join Date: Mar 2007
Location: fruitport mi
Posts: 193
Likes: 0
Received 0 Likes
on
0 Posts
when we had the fuel pressure gauge on short chevys it was 59 idleing/cruising. wot dropped only a few pounds like 56 if any. and i checked mine and my car was the exact same 59 pounds so yes your problem is fueling i think its more likely your pump but swap the regulator first thats a cheaper/ easyer start. let us know what u find
04-02-2009, 11:27 PM
#27
On The Tree
Thread Starter
iTrader: (5)
Join Date: Sep 2006
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
I think I figured out the problem. The inside of my gas tank is rusty. I took a flash light and looked down in the tank and the gas looks orange. Pulled the fuel filter off and it poured rusty fuel out. So I need a new tank and fuel pump. Only problem is I can only find a tank at autozone and it's $330. Is there anywhere that sells a gas tank for a 98 Z28 cheaper? Will any other year of tank fit? Will a 98 v6 tank work?
04-03-2009, 04:20 PM
#28
12 Second Club
iTrader: (12)
Join Date: Mar 2007
Location: fruitport mi
Posts: 193
Likes: 0
Received 0 Likes
on
0 Posts
hmm i wonder how u got water in ur tank? i would assume the tanks are the same but i dont know, i think the newer ones like mine are bigger and plastic. i would check a few junk yards maybe the one on here that has a sticky in the parts for sale. good luck
04-03-2009, 05:02 PM
#29
On The Tree
Thread Starter
iTrader: (5)
Join Date: Sep 2006
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
The guy I bought it from didn't have a gas cap on it. yea 99-up are plastic I don't think they will work without a lot of fab work. I will check out the sticky. Thanks I need some luck lol.
02-04-2011, 07:57 PM
#30
Registered User
Join Date: Feb 2011
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Hey, thought I would let you know it is for sure your catalytic converter, you should get it checked out some mom and pop auto shops will do it for free. I would just check eBay for a high flow cat converter and replace it, I just did that and it fixed the problem.
02-04-2011, 08:05 PM
#31
Registered User
Join Date: Feb 2011
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
If just for comparison purposes dsm cars stock run 34-40 psi fuel pressure, and so when our cars seem to get stuck around 4,000 rpm it's because out cat converters are a little clogged.. When you out the peddle to the floor there is not enough open space for all the exhaust to escape a's fast a's it needs to so try changing the cat converter you can find a high flow cat for like 50 on ebay
02-04-2011, 08:47 PM
#32
TECH Regular
iTrader: (5)
Join Date: Jun 2006
Location: lakeland floirda
Posts: 457
Likes: 0
Received 0 Likes
on
0 Posts
e be On the tps the purple wire I think is the signal wire, it will sholwclose to 1 at closed and close to 5 open.. and yes if you unpluged your maf it would be in speed density mode and you would know if it was faulty.
Man its its losing power its most likely fuel, duct tape a gauge to your window and run wot a few times to see. If that is ok its either a air restriction via the intake side or clogged exhaust some how. Its not misfireing right? No broken valve springs or anything from a big cam or something?
Man its its losing power its most likely fuel, duct tape a gauge to your window and run wot a few times to see. If that is ok its either a air restriction via the intake side or clogged exhaust some how. Its not misfireing right? No broken valve springs or anything from a big cam or something?
