Engine light causing car to run rough and miss

Hey guys, I had a question and wanted to see if you guys could help me out. I have a '89 gt with a powerdyne supercharger on it with about 9k invested into the motor. It seems like after I run the car for about 15 minutes the check engine light will come on and cause the car to run very rough, and the car will not have a constant idle when I come to a stop. I think it's some sort of sensor on the car, maybe even an o2 sensor? I checked if both of them were getting power and they were. But, let me know what else to could be. Thanks

Is the tune in open or closed loop?

cody, run KOEO and KOER tests!

RTW0223 wrote:cody, run KOEO and KOER tests!

This is the first thing to do before anyhing else is done, assumed or asked

TT_05_Stang wrote:Is the tune in open or closed loop?

open, no cats

RTW0223 wrote:cody, run KOEO and KOER tests!

Idk if that actually works, I try it out I guess. But it has something to do with a sensor of somesort. Someone said it could even be a MAF. But, the car needs retuned I know that much. The guy before me had it tuned in at the dyno, but then car basically sat for two years and was barely ran. He said I could buy a chip and take it to a dyno and have it tuned in. Which I'm probably going to do whenever i get the $$$. I mean that could be the biggest part of it. The car loads up really bad sometimes and surges from 300rpm all the way up to 1000 and sometimes settles down to a constant 900 where I have it at. But, it didn't act this way until it got colder out. So I'm not sure if the cold weather could have something to do with it as well??

If its open loop your sensors are doing nothing. So you can rule that out, thats why I asked.

Where are you referencing vac/boost?
What are you using to reference boost/fuel? FMIC?

What MAF are you using? blow thru or draw thru?

More info the more we can narrow it down.

TT_05_Stang wrote:If its open loop your sensors are doing nothing. So you can rule that out, thats why I asked.

Where are you referencing vac/boost?
What are you using to reference boost/fuel? FMIC?

What MAF are you using? blow thru or draw thru?

More info the more we can narrow it down.

If by FMIC you mean Frontmount intercooler, I dont have one. It's not a turbo charger, it's a Powerdyne Supercharger and I don't need an inercooler. All I have in the car to tell how much boost im running is a boost gauge. Then I have my boost retard knob which is numbered 0,1,2,3. i just know the boost retard has to do with the timing of everything so I dont screw with it too much. As for the MAF its a blow thru.

Nope I meant to write FMU.. somehow I wrote that...

TT_05_Stang wrote:Nope I meant to write FMU.. somehow I wrote that...

To be honest I'm not sure what FMC stands for, is it like Fuel Management something? I know it has to do with the fuel regulator and fuel to air ratio or something like that?

http://www.vortechsuperchargers.com/product.php?p=31

it ramps up fuel pressure as boost increases.

pull the codes, and find out what the ecu is bitchin about, and go from there.

TT_05_Stang wrote:http://www.vortechsuperchargers.com/product.php?p=31

it ramps up fuel pressure as boost increases.

pull the codes, and find out what the ecu is bitchin about, and go from there.

Yeah alright I got you now! And I'll have to go get an adaptor for my scanner to pull some codes.... Damn technology! I'll try to get one tomorrow and let you know what it's saying.

use a paperclip cody

dont have time for that crap lol... i'd rather just use my scanner and have the exact code that i can just look up. TT_05 I'm just really confused on what is happening because when I'm driving the light will all of sudden just come on. but as soon as i shut the car off n turn it back on it goes off? then it will come back a few minutes later. I'm just trying to figure out what is happening. It seems to start acting up after the car warms up a little bit.

I wish I knew off hand, but it could be anything. If its in open loop I dont think it could be the o2 sensors.

You can test for codes vie a multimeter as well

http://www.corral.net/tech/maintenance/eecivtest.html

This could be actually helpfull I'll check it out here in a little bit. What about my EGR valve. I still have it on there, and I dont know if that could cause any malfunctioning problems or not.

weese8991 wrote:This could be actually helpfull I'll check it out here in a little bit. What about my EGR valve. I still have it on there, and I dont know if that could cause any malfunctioning problems or not.

for the second time, run a koeo/koer test, no reason to make assumptions until the test is run koer runs egr test so if it's malfunctioning it'll pick it up

i know that. im running test tomorrow on it. but im doing it with a scanner not with a paper clip lol.

weese8991 wrote:i know that. im running test tomorrow on it. but im doing it with a scanner not with a paper clip lol.

I have multiple scanners and for quickness I often use them but sometimes the paper clip deal or accessing the the koer test manually will reveal codes the scanner won't pick up, if you doubt it, you need to speak with one of the premier diagnosticians of the eec iv, he can be found on sbftech.com by the screen name of joel5.0.......either way I'd do the scanner methood first good luck.

mjr46 wrote:

weese8991 wrote:i know that. im running test tomorrow on it. but im doing it with a scanner not with a paper clip lol.

I have multiple scanners and for quickness I often use them but sometimes the paper clip deal or accessing the the koer test manually will reveal codes the scanner won't pick up, if you doubt it, you need to speak with one of the premier diagnosticians of the eec iv, he can be found on sbftech.com by the screen name of joel5.0.......either way I'd do the scanner methood first good luck.

Thanks for the information. Its just I have never seen it done or even heard of it before. and yes im doing the scanner within a few days actually. But I ran the car yesterday for a while and it didnt act up at all actually. I was quite surpised. Car is like a damn woman lol