engine running rich MAP QUESTIONS??

[Gaspo]

hey guys I haven't been around here much. been working on the car a lot and have been really busy with work. I've been google searching and troubleshooting for over a week and i'm finally breaking down and posting.. please help!

I have a 99 Camaro ss. 5.3 bored to a 5.7 with forged rods/pistons, ported heads, custom cam, meth injection, 76mm turbo, ls6 intake and its SD tuned. the other day it started misfiring badly and would hardly stay running. it's not throwing any codes. the car doesn't have any 02's. I swapped plugs and it ran ok for a couple miles then started misfiring badly. I checked the plugs and all 8 are fouled out. I know its dumping way too much fuel. the two things I could think of was a bad ground (checked them all) and bad map. the car supposedly has a 3bar map sensor. with key on engine off I tested the volts it was reading and I only got .79v when I tested the green and gray wires (iirc) in the MAP pigtail. and with my handheld scanner I got from autozone it reads 29.9. with the engine running it reads between 17-18.8 but my boost gage only reads 11 (like it always has).

my MAP doesnt have a part number on it and the ONLY 3 bar GM map sensor I could find was the wrong style that doesn't fit in the back of an ls6 intake. so I thought maybe I got the 3.3bar MAP was what I had so I bought it and installed it and the car starts up, then dies.

SOMEONE PLEASE HELP! what other causes might there be? am I testing the MAP incorrectly? is it reading correctly? the FPR is set at 60lbs at idle like it always has. gage seems to read accurately.

thanks so much in advance!

[OIF1VET]

I can tell you when I had a MAP issue, the car would fire and idle like a champ for 3-5 seconds.. Then it would dump fuel and run like shit, had to play with the throttle to keep it going.. Just something to check, might help confirm MAP is bad.. My isue was a wire had pulled out of the harness at the MAP, had to re-pin it.

[hoogiesngrinderz]

got any way to datalog it?

[Gaspo]

got any way to datalog it?

no but all of my sensors are reading correctly today. drove it today. it sputters sometimes under slight load and sometimes it doesn't. and it never sputters under boost.

[hoogiesngrinderz]

I have EFIlive for the time being (I've borrowed it for WAY too long from the owner) but maybe I can scan it during a ride-along. I can datalog a LONG time with this thing!

[SOPES]

leaking injectors ?

[Gaspo]

leaking injectors ?

all 8 plugs fouled out. I doubt all 8 would get leaky all of a sudden.. mike, when are you available?

[hoogiesngrinderz]

booked up until Monday or Tuesday

[SOPES]

all 8 plugs fouled out. I doubt all 8 would get leaky all of a sudden.. mike, when are you available?

I agree, just throwing it out because working in service for the last 12 years nothing suprises me anymore lol

[kammi10]

I have EFIlive for the time being (I've borrowed it for WAY too long from the owner) but maybe I can scan it during a ride-along. I can datalog a LONG time with this thing!

you havent given that back to darius yet>?

[1999Black_Z28]

Jeremy, my guess is that you have the wrong MAP sensor. There is an old style GM 3-bar sensor (block style), there is the new ZR1/LS9 3-bar (which I assume is the first one you tried but it didn't fit), and there's the most common one for LS1's which is the 2.5 bar sensor. It won't read past 2.5 bars but works fine with the 3-bar custom operating system.

I believe the 3.3 bar sensor you have is from a duramax.

It's very possible the person that sold you the car was confued b/c the 2.5bar sensor uses the 3-bar operating system. Just a guess but seems to make sense with what you are experiencing...

Another option is to have the car re-tuned with the current sensor you have (3.3bar)

[hoogiesngrinderz]

I wasn't able to road tune it due to the trans setback and the shock fiascle. He said I could keep tuning with it now that the car is finally able to go down the road. WB should be hooked up this weekend so I can get WOT tuning done, been waiting on a db9 null modem to show up.

He's getting a couple cases of beer, that's for sure!

[1999Black_Z28]

One more thought...

Do you know anyone with HPtuners? They can download your tune for free and check to see what your MAP sensor settings are. For example, if linear=256 and offset=10 than you had a 2.5Bar MAP. If linear=329ish and offest=-6ish you had a 3 Bar MAP.

Even if your numbers dont match these you could still figure out which MAP you need to run with the numbers in your tune.

If you don't know anyone with HPtuners I could likely help out sometime this weekend.

[Gaspo]

I checked my map again and it was getting 4.8 volts and the signal wire was reading 1.81 with key on engine off. so its reading right. and then the car ran fine for a couple days. went to the Michigan mile yesterday and it ran like shit the whole way there and back. so it's gotta be a wiring issue right? if the car runs good sometimes and not others?

[hoogiesngrinderz]

Very well could be. I was reading the other day about a guy who was having a horrible time with sensor outputs, turned out his ECM wasn't getting a good ground.