warmeck

Okay well i replaced every ignition part including wires cleaned and got new grounds etc. found out that it is the ECM. now could i just go to my local dealership with my old ecm and have them reprogram it? or do i have to buy another one and give it to them? how exactly does that work. i have a 94 camaro z28 manual 5.7l.

Injuneer

How did you "find out that it is the ECM"? Do you mean the PCM (last year for "ECM" was 93) failed?

What problem were you having?

warmeck

well upon trying to start it kinda stutters, the mechanic told me it was my computer and that i should take it to the dealership.

shoebox

Highly doubtful. The computers are quite robust. Sounds like he did not want to work on it and you need some better diagnosis. Ask for particulars that lead him to his suggestion.

warmeck

im on the phone with him as we speak he said because of how it sounds and that its getting fuel it has spark compression is good. so he replaced, ingiton switch,optispark 3 times, brand new icm, brand new igniton coil, grounds correct, brand new wires coming from the optispark to the spark plugs. so he determined that it had to be that. he did say i should take it to the dealership to get it re-programmed? i honestly am leaning towards taking it to the dealership if this is not an easy fix.

Injuneer

Did "him" ever attempt to pull codes? Was he successful?

The PCM controls the spark and fuel, and you indicate it has spark and fuel - did he verify injectors are firing by using a 'noid light at the injectors. That would verify the PCM is providing the required ground.

warmeck

i dont even think he did any of this.. hes just guessing i feel like. im going to take it to the dealership and have whatever it needs to have done professionally.

Injuneer

Why don't you try to pull codes? Free software download available (Scan9495). Dealers may know even less than the person who was trying to help you, and continue to spend your money playing "parts replacement roulette".

Not Dave

Warmeck, LT1 cars can be a nightmare sometimes. There aren't many people that properly know how to diagnose problems. The first thing you need to do is check for codes. If the Check Engine Light (CEL) a.k.a. Service Engine Soon (SES) comes on then you can scan for the codes and it'll tell you what the problem is for the most part.

Get a free scan from someone, even AutoZone, before dropping it off at a dealership expecting them to expertly diagnose and fix the problem the first time. Even dealership mechanics get things wrong frequently or purposely replace perfectly working parts to charge you more. Go the cheap route first.

warmeck

ok how do i run the scan on it. i have it for a week, until my appointment at the dealership.

Fatdog2

Does the engine run ok after it's warmed up?If so then just turn the screw on the throttle body that adjusts the accelerator position.It's on the right side of the throttle body where the accelerator stops at.My 02.(makes the engine rev higher.).Hope this helps.Hope somebody chimes in with more detail.

shoebox

You really don't want to do that. The throttle stop should never have to be touched. It can really get things out of whack (like TPS position). The IAC valve controls the idle speed via computer commands. So, adjusting the throttle stop will only have a slightly temporary effect until the IAC regains control and puts the idle back to where it was. If you move the stop too much, the IAC may not be able to compensate.

Injuneer

To clarify:

The SES light does not have to be on in order to scan for codes. An SES light indicates an active code. But past codes could be stored based for an intermittent problem that set a code in the recent past, and stored codes can be recovered.

There are codes that do NOT turn on the SES light.

You should do a code scan any time the engine or transmission is acting up.

Generally, the auto parts stores can only scan OBD-2 systems - 96 and up for the 4th Gens. If you are lucky enough to find a shop that can scan OBD-1, be sure to write down the exact numerical code. Their scanners will often provide a very generic description of the code, that can be misleading. Shoebox has a list of codes that are specific to the LT1. Some of us have shop manuals that can expand on the description.

And I agree totally with Shoebox.... do NOT play with the throttle blade stop screw. All that does is screw up the ability of the PCM to control the idle speed using the IAC motor.

What is the EXACT problem you are experiencing?

Describe in detail what happens when you turn the key to start the engine. How long does is crank before it tries to start? Does it "sputter" and not start at all? Does it start but then "sputter"? Does the sputtering go away after the engine warms up?

The problem could be as simple as a fualty coolant temp sensor, for example.

At any point has he checked the fuel pressure?

Injuneer

Go to this thread. Download the latest version of Scan9495. If you encounter any problems, send a "Private Message" to GaryDoug. He is very responsive to problems downloading or installing the software.

https://www.camaroz28.com/forums/com...95-lt1-874306/


You will need a cable to connect the 12-pin ALDL connector under the dash to your PC. A ready-made cable from a reliable source is the best bet. You can get parts to make your own, but it seems like the quality and features of the cheap parts, particularly those from China, change frequently.

If you run the data log of the engine trying to start - or running if it runs - I can review the data log for you. I've been doing it for 15 years.

warmeck

the parts that i need are going to be here in 1-2 weeks