Tx_94vette

so I changed opti because car wouldn't start, it starts now but at high rpm, iac is good, so do you guys think a new opti (duralast ) could cause this, I have 94 lt1 102k on the clock, hoping not a bad ecm, car also dies after warm up

aklim

I would check out whether you have an air leak. Hook up a scanner and see if it tells you what the desired idle is and after it is at stable operating temp, what the idle is and what the IAC count is. If it is 0, you probably have an air leak somewhere.

Tx_94vette

ok thank you, will do some more looking for air leaks, just wondering if you knew if all the sensors all tied together for their grounding point, got like 5 black wires tied together on the passenger side at valve cover

aklim

I don't have an LT1 engine but often, it is an air leak that does this. When doing this job, it is hard to say if you knocked something off or connected a hose here when it should have been there. Unless you want to screw with the Opti by getting another unit in to test, I would start with checking what the sensors are reporting to the ECM.

Tx_94vette

ok will do some more digging, car has been broke for 2 months now just cant seem to find the demon, just work on her when I get some free time

aklim

You say the car idles at 1500 and dies? Can you keep it running after it starts to appear like it is dying? If you don't, I'd get a factory shop manual, often refereed to as FSM and a scanner that can work with the car or we end up throwing parts at it. I'm not sure who makes a good Opti since they are all reman and they don't all have the Mitsubishi sensor which is supposed to be good. Duralast, IIRC is a Private Label brand for Autozone. What their QC is, IDK but I don't use them except in an emergency.

Other use of the name Duralast based on an internet search is for guys who want to last longer during sex.

billschroeder5842

Air leak for sure, IAC issue probably and you need to double check your TPS

aklim

Hard to say without checking if the IAC passages are gummed up. When I clean injectors every 3 years, the car is down for a couple days so I buy new gaskets and clean the TB by taking out the IAC solenoid and the IAC housing and the top plate, flush it out with brake cleaner and reassemble.

whalepirot

Check the vacuum reading. Is it dying about when it warms up (goes into closed loop)? that's when the ECM relies on all those sensors, which usually leans the mixture, which would kill the engine. the computer will add fuel to optimize air/fuel ratio, so if there's unmetered air getting in, it'll idle fast, as if the throttle is open more than the sensor indicates.

You may get lucky and find a vacuum hose left off, or have to dig around and find a cracked hose or something else not properly sealed. Listen for hiss and search the web for how to isolate such leaks. Basics, before all that computer crap.

aklim

IF the IAC reads 0 counts even when you screw the valve close, you know you have a leak. After which you can go hunting. Otherwise, you are hoping it is a loose hose that you can see or hear some noise over the engine. Before I go that route, I'd like to know if it is leak induced or what. Just my $0.02

MatthewMiller

I agree with it likely being an air leak. Are you sure you connected the vent hoses from the opti back to the correct nipple? One goes to a port on the intake manifold to supply vacuum, and the other goes to the bellows upstream of the throttle body to supply fresh, filtered air to the opti.
https://www.corvetteforum.com/forums...e-routing.html

Tx_94vette

So after warm up and car dies I have 12volts out of new ignition coil, and no restart I have no fire to plug wires, rigged a jump wire to a plug wire and I have nothing, let car sit overnight cranks right up at 1500 rpm, goes to warm up dies, got to be new opti or my coil wire going from ignition coil to it

Tx_94vette

disconnected battery today, ran car tii it died after warm up, still getting a code 36, and a code 97 which is vss output circuit, I checked voltage going into opti, high res is good, input is good, ground is good, but getting nothing on the pink and black which I believe is my low resolution signal, hoping its the opti and not the pcm

Tx_94vette

So the latest on my 94, Happy Day for me and my 23 year old car, Day started car would not shift and drove like crap and had a high idle, Decided to disconnect the black wire on tps sensor, car purrs like a kitten, but still wouldn't shift right and get asr light and check engine light, all this after 2 optis, iac, ignition coil, new battery, countless hours searching the net, I`m thinking this is just another dead end, how can it just be this simple low voltage on tps = bad tps, on my car tps controls the shifting points and can cause rough idle, there isn't a tv cable it all controlled by tps and ccm, anyway went to autozone bought a $75 tps and all codes are gone as well as all issues. maybe I had a bad opti and a bad tps who knows, car has been broke since November anyway hope all this helps someone else someday