3fourty6

iTrader: (2)

This has me stumped. I've got a 00 TA with 77,000 miles and the only mod being LM exhaust and no cats. The car starts up fine and will drive great for about 2-3 minutes and then it will start to hesitate and cuts out under light load till around 2500 RPM's, it then smoothes out and runs hard. Even under WOT it doesn't run right till 2500 and then takes off. Sometimes the idle will even fall to around 500 RPM's.

It did this once in the past but it was almost out of fuel so I stopped and filled it up and it ran fine. Now it seems to do this all the time. I can rev it up and it will come out of it for a minute or two, then it goes right back to running like crap. I just don't get why it comes out of it at 2500-2800 RPM's?? It seems like the problem is from 1500 to 2500


I've cleaned the MAF and it seemed pretty clean. I've tried unhooking one plug at time and when I do that raw fuel spits out the tail pipe when I rev it but none does when they are all hooked up. So I believe it's firing on all 8. I just don't want to dump money into parts that I really don't need. Any help or imput is appreciated. Thanks

blkbird

iTrader: (28)

Have you tried changing out the fuel filter. Its a start.

3fourty6

iTrader: (2)

I'm going to give that a shot in the morning

Bandit28

iTrader: (28)

if you have a mobil scope check your afr

00firebird

iTrader: (3)

hmm.. it could be a transmission problem.

Y2K Z28

iTrader: (1)

if it's an auto car then the idle should be at 500 once warm. If it's not throwing a code check your fuel filter if that ain't it check the fuel pressure and see if your getting fuel. If that ain't it check over your plug wires and what but if you weren't getting spark it should throw a code i think. If all that checks out it could be a tranny issue if its an automatic. Have you checked the fuild? Check that too. By throwing a code i mean your service engine soon light comeing on. If that is on have it scanned and that will tell you the issue. When you ran the car out of gas you have picked up some trash in the tank. I'd check the fuel system first. Also if you want people to answer you they need to know what kinda car it is? What tranny? The mileage if it is high mileage? things like that help also if it's been driven in harsh weather alot that can cause mad issues in an f-body.

3fourty6

iTrader: (2)

It's a 6 speed. I just filled it up and noticed my fuel mileage is down to 15 mpg. I just checked last week and got 21 mpg and that's with 9 passes down the 1/8th and a lot of idleing.

It's now cutting out and hesitating all the time. I can rev it up and then accelerate to 2000 rpm's fine and if I hold it there for about 5 seconds the rpm's will drop 300-400. It then starts to run crappy. I have taken my cats off and I am in the process of getting sims to get rid of the ses light that's been on for a while now. So I'm not sure if it's throwing a code or not.

Can a O2 sensor slowly go bad and cause these symptons. I just don't understand why it comes out of it and seems to run good towards top end??

cantdrv65

iTrader: (3)

Does it only do it under load or all the time?

Full-Force

iTrader: (11)

My car started doing that when I put new plugs in. I put NGK TR55 plugs in right out of the box. It doesnt rev up snappy anymore and when Im crusing under 2000 it misses. I think the gap on the TR55 plugs is too big out of the box.

cantdrv65

iTrader: (3)

Yours certainly sounds like A) bad Plug or B) bad wire....

PS. I recently had a bad TR55 right out of the box myself, gap was fine.

Swicthed to the NGK Iridiums and havent had a single plug issue.

3fourty6

iTrader: (2)

I filled it up last night and drove around for a couple of hours. It was getting worse and worse. I noticed it was cutting out all the way through the rpm's but it was less noticeable above 2500. I then took it out of town and got on it pretty hard and after that it ran great for about 20 min. I shut it off and let it sit a few minutes then restarted it and it was back to the same old crap.

I just got done changing the fuel filter and noticed when I turned it upside down when I removed it black dirt and grit was coming out. I've changed several fuel filters in vehicles and never seen one have that black of stuff run out. Hopefully this solves it but if it doesn't it sure did need it. I guess I will find out.

zackls1

try replacing the spark plugs. ive seen this many times were there is a crack in a plug and the car wont miss while its cold but when the motor heats up it expands the crack enough for the car to miss under certain load ranges. sometimes the crack is very hard to spot by eye. i would also recomend replacing with factory delco.

pla-tym

I use Iridiums also... Troublefree performance

RevGTO

iTrader: (12)

Definitely run a can of BG 44K or other quality fuel injector cleaner through your system. If crap was pouring out of your filter like that, God knows what has gotten into your fuel system.

bjamick

iTrader: (31)

well when you gutted your cats the computer is prob making the motor run lean which def. will make the car run very crappy and not want to pull threw the lower rpms i have just put the true duals on my 99 trans am and the cats were taken off but my car is running fine for now but im planning on getting the hypertech programmer which u can delete the o2 sensors which might possibly fix the problem your having it will cost you bout $436 but its still a good investment anyway.

JMBLOWNWS6

iTrader: (17)

COT= Cat overtemp protection is enabled. You need a tune or your own software to tune!

3fourty6

iTrader: (2)

Well I pulled both front O2's and the passenger side one was black. I replaced it with one of the rear's that I took off and now it is running great. I don't know if there is another problem that slowly caused the O2 to go completely bad, like a bad plug, wire, or fuel injector?? The first time it started this was a good month and a half ago and then was fine till a week or so ago. The symptons would come and go and then at the end it did it all the time. Plus I don't think it is running as hard as it should. I guess we'll see if it does it again.

Thanks for the help and suggestions, As I will be trying some good injector cleaner and change the plugs and wires.

JMBLOWNWS6

iTrader: (17)

Its dumping fuel to protect the cats that dont exist! Its going to end up doing the same thing.

drohm6

also, clean your tb, if you are running a k&n (or simm) that oil and carb. will make your tb dirty as hell and make it run like **** till your rpms get up there.

(easy thing that people forget about)

ringram

I recon its crap till 2500 because thats when you go into open loop under PE mode and o2 feedback is ignored.
Under 2500 you are in closed loop with o2 feedback and your O2 shat itself causing crap fueling. You fixed that so now it should be ok.

However that said you will want to check your fuel trims and pcm codes to make sure its not just put a plaster on something else.

That would be my guess.