Ok guys need some feed back, My 93 black vert has been in the shop almost two weeks local reputible shop having issues with determination of problem car wont start but turns over and WONT continue to run IT JUST DIES. No codes present tried two different ECM`S nothing. Before I spend thousands making it run { going to dealer tommorrow} for diagnostics how and has anyone converted one of these. I do know a good bit about doing it but just want some feed back from you who have been there. I have spent $435.00 so far in labor and ECM. Heres my list
1. distributor
2. intake
3. fuel pump , or regulator not sure if it has a block plate for manual pump.
4. gaskets
5. harness`s
6. CARB
7. plug wires
I think thats probably most of what I need. let me know if I have missed somthing


No opti spark. No fuel injection, no computer,no issues I have a local Mechanic a quadrajett GURU been working w/ chevys for 40+ years that can sell me the parts I need for less than $350.00 and will help me do it he has done these before. FEEDBACK PLEASE

 

I would not convert to a carb. You will loose power, fuel economy, cold start is usually more of a pain (remember pumping the accelerator pump and choke adjustments).

If your local mechanic is so good - I can't believe he has charged you so much in labor and a new computer to no avail. He should have been able to verify the computer and definetly should not be charging you for a new one that did not fix the problem. Has he verified that you have good fuel flow to the cylinders, proper throttle/throttle body setting. I assume you have no spark. Has he pulled the plugs to verify they are wet from unburnt fuel.
Do you have ignition power to the opti? I assume he has checked this. My guess is the opti system is your problem.

There are very few things that will actually keep a car from cranking/running. It may run rough w/ a lot of other problems but it will crank if you have:
Fuel, air, spark, compression on even a few cylinders.

 

Car has spark opti appears normal fuel pressure normal ECM 1ST ONE WORKED UNTIL YOU TAPPED IT WITH YOUR FINGER AND DIED. 2ND one didnt work and would not communicate w/ scanner.

 

1st ECM I assume was your original one. It is bad.
Second one was a purchased replacement. Send it back for your money back and get another one.
Sounds like you just have a bad ECM. Why would he be charging you all that labor when you have a bad ECM and you both know this.

 

1st ECM not original failed tapptest 2nd failed to communicate 220for ecm 65 battery 150 labor cant get a good ECM

 

Mine would not communicate with the scanner either and all kinds of weird things were happening. Turned out that battery acid had gone through the battery cable and corroded the fuse box and fuses and one of the fused links. I'm talking about the fuse box under the hood with the big fuses. One of them is for the ECM, one for the fuel pump, etc. Replaced all that and communication was restored to the ECM and car runs fine.

 

This really sounds like an opti-spark issue. No start - no codes... I've seen this a few times with the opti-spark. Have you had it checked out to determine difinitively it's good?

GUSTO

 

You have spark at the plugs. You have fuel pressure. Obviously you don't have fuel injectors firing. Or your EGR valve is stuck wide open allowing exhaust straight back in. It should crank w/ EGR bad but just won't run worth a crap and takes a lot of throttle to keep it runing.
All you can do is keep trying to get a good ECM. Should not be costing you anything to keep swaping until the mechanic gets a good one.

 

Its not but damn I havent been able to enjoy it since I bought it.

 

I'd suggest you take a very close look at the connections to the ECM. An intermittent contact could cause every symptom you've seen with this fault, including failing the "tap test".

Be well,

SJW

 

"lose"

I converted to carb.... wanna race?

 

What year is it

 

The 93 has a chip inside the ECM looks sort like a computer memory slot.There is a cover on the bottom take it off and remove the chip and reseat it.May be all that is wrong.Did you put the chip in the new module? If it came without it it definately will not work till it has one in it.Get a new mechanic or DIY.Do you have any codes?That might help.

Do you have the Helm manual?Forget about conversion unless you want real trouble. There is no way for an LT1 to work with out the ECM and Opti.Your problem is probably something minor you just have to find it and the Factory Service Manual is what you need to work on your car.

 

I have no idea of what you are running but am willing to bet you get no gas mileage. I may not have the fastest car on the planet, it will certainly hold it's own, but I still got 27 MPG on both of my last two trips. I converted my 84 to a carb and have since learned quite a bit about working on fuel injected cars and will never go back and would never even consider slapping a carb on a LT1.

 

I agree that I would not do it but you can buy a conventional intake for the LT1 and slap a carb and a standard GM HIE type distributor on it.

http://www.sdpc2000.com/catalog/738/...e-SB-Chevy.htm

 

I know about the intake but I have never read that you can put a HEI on it.Where are the gears for the distributor at? They certainly did not make the engine for it.It is a dumb thing to do IMHO and asking for all kinds of trouble and additional cost for tuning a lot more than taking the car to someone who knows Corvette LT1 engines to diagnose it correctly.Take a deep breath and fix it the right way.

 

[QUOTE=FD2BLK]I have no idea of what you are running but am willing to bet you get no gas mileage. I may not have the fastest car on the planet, it will certainly hold it's own, but I still got 27 MPG.. QUOTE]

Fuel economy? I was disputing the part where the guy said switching to carb would result in a loss of power. What does fuel economy have to do with that? People with slow cars try to change the subject from power to fuel economy or maybe even trunk/passenger space. If I want fuel economy I'll go drive my wife's Saturn, thanks. Oh, it has pretty good trunk space too.

Now, I'm not recommending someone convert to carb because they are frustrated w/ FE*, especially if they hope to merely change out the intake and put a carb on top of it. It's much more complicated than that.

*IMHO FE is much better for DD's and it's no slouch on HP either. my point is that I'm not knocking fuel injection.

 

An LT1 is the same as any other SBC as far as the cam gear goes, same hole in the block and same cam gear. The only difernce is the LT1 uses a gear and plate to turn the oil pump and there is no hole in the intake but if you pull the plate out you can drop a standard Gm distributor into it and it will work fine as long as the intake has the hole for the distributor. Some of the F-body guys have modified the LT1 intake and installed a MSD crab style distributor to repace the Opti high voltage side. They take the coil output and run it to tyhe cap simmilar to a conventional distributor but stil use the optical side of the Opti spark.

 

I don't think a mid 11 second car, soon to be 10's , is a slow car and I wasn't changing the subject just pointing out that you sacrifice a lot of tuning ability and drivability going to a carb. Call me silly I wan’t 400+ RWHP 400+ RWTQ and a daily driver that I can tune throughout the entire RPM range and Load conditions not just WOT and still get great gas mileage. I have no desire to drive another car for a daily driver and I think I make fairly good power for the way I designed and built my motor. I agree that if someone wants to make a race car and never drive it on the street that a carb may be the way to get great power cheap without having to go through the time and effort of learning how to tune a fuel injected system. Now with that said there are plenty of fuel injected cars, a couple on this forum, that run mid to low 10's on all motor.

 

Converting to a carb would be a big mistake at this point. It's a huge step back and it shows that you have little faith in your mechanic to throw 1500.00 in a conversion that will only make your car fail any future emissions tests.

1) Check the coil, coil wire and ignition module. 93jetjockey had a ton of problems with his 93 regarding the harness at the ignition module.

2) The optispark might be the problem, but it's rare when they fail in this manner. If the electronics side of the opti were bad, I would expect to see codes. As soon as the engine starts, even for a few seconds, I would expect some codes to be left.

3) Check all the harnesses... all you need is a single loose contact.

4) As suggested, make sure the MEM/CAL is installed completely and correctly.

5) Try to pull codes from the ECM. If you get a code 12, I would bet the ECM is ok. When you don't thats a big time indicator things are bad.

6) I assume you spark and fuel pressure? Then the problem is fuel injection related.

Modern fuel injection (I put emphasis on "modern") is leaps and bounds ahead of the carb. It's a crude method of delivering fuel. The one area where a carb excells is at WOT... but when drivability is the key, MFI is a great device that is very reliable.

I would suggest investigating the LTCC (www.bailey-eng.com) or the DelTeq system (oops, forgot the link. sorry )

Both systems use the optispark for low resolution signal but use either 8 LS1 coil packs (LTCC, I personally have this system and like it very much) or a Cadillac Northstar lost spark system (DelTeq).

just some options.