Extremely rough idle. Then Stall

[Jon89LE]

Just needed to add something else. Although the cars battery has been disconnected quite a few times doing all the work, how fast will the ECM throw a code IF the ECM was bad? I had the car running for about 2minutes while running a scantool and it came back with no codes. Im not sure if thats enough time to actually throw a code though.

[gpse3400]

It won't throw a code asap. If you want to see what the computer thinks wait a while with it idling and eventually it'll throw a code....it'll take a while but it'll happen,and you can start your troubleshoot from there. Surprisingly.... it's not ignition, so it has to be fuel.If your pressure is good I'd think about the injectors. It's either that or your valvetrain is compromised or out of adjustment. If you have a scan tool you can what the computer sees. I have one. If you need me to run up I'd be happy to.

[Jon89LE]

Im in Delaware so itd be a bit of a drive. I scanned the computer with a scan tool i borrowed and nothing came up. I can try scanning the computer again with the car running longer. Im just not sure on the injectors though bc all the plugs were black and smelt like fuel. Not to mention the smell of fuel out the exhaust. Im off tomorrow for the holiday so I will take a better video of the way it sounds exactly. If it were an injector, it would have had to have failed electrically. Is the impedence at the connection the only thing to check for on them or is there a reading from the scan tool i should look out for? IIRC there was a data reading for injector pulse on the scan tool but im not 100% sure.

[gpse3400]

Well if all the plugs were black and all smelled like fuel...Fuel pressure is good...Ignition is good... TPS, MAP, and coolant temp sensor are the only other things that can cause that.... If you borrow your friend's MAP real quick

[Jon89LE]

Ive got a brand new MAP that to put in. Ill try that along with reading the codes tomorrow. I'll also check the output readings of those sensors from the scan tool with what they should be reading according to the service manual. Did i mention already I love OBD1?

[Jon89LE]

Yup, broken valve spring on front cyl #4. I went ahead and ordered a pair straight from Crane for $10 and they'll be here UPS ground by Friday. Jegs wasnt shipping for 2wks and Summit until 12/8.

[gpse3400]

Wow... Yeah well like I said it's either one or the other. If you want to go with LS1 springs which arent a bad idea and would be a perfect match for your setup, you'll need a set of 12 springs, and a set of 12 3100 spring retainers and a set of 3100 valve locks, and lastly a set of 12 LS1 spring seats/shims.You might want to get some 3.1 valve seals and rocker cover gaskets while you are at it since you need to remove them to replace the seats/shims. You'll need a hose with a sparkplug fitting(valve holder tool) and some air to hold the valve in place. These parts wont set you back alot. If you got a dealership that give you a discount go for it. Otherwise I recommend www.GMOTORS.com, dealership in florida, thet give a discount on parts and are good at mail orders.They don't hit you hard on shipping ether.

[gpse3400]

Wow you edited while i was typing! In that case i guess your fine!

[Jon89LE]

Haha. I was thinking about going the LS1 route but for $10 i cant go wrong. Plus the motor isnt staying in the car long enough to cover the expense of a new LS1 valvetrain. The spring actually broke in two places. Im wondering if the spring was broken for a while and when the second break came is when my issue now arose. Because ive always had a random dead spot in my midrange as well as random stalling and idle problems. Moreso when cold. Im hoping none in the back are broken.

[gpse3400]

Cool then.. Yeah check the back half when just to be sure.