E4ME Carb replacement

[PMartin]

Once again my 81 is running way to rich. :confused This carb is driving me nuts. What would be the side effects if I moved to a different Carb than the E4ME? Please advise...

 

[GerryLP]

If you must, you can switch the distributor to a standard HEI distributor, and use a number of carburetors available; however, I would highly recommend you get the E4ME carb overhauled, and then tune it on your vette. Once they are set right, they work like a charm, and it will be less maintenance than a standard carburetor.

Holley could still have available their replaceable carburetors that work with the 81 Corvettes. The Holley model number 4175 was available for computer controlled GM vehicles, and one of their part numbers (they call them "List numbers") is the List 0-80073. I would recommend you call Holley, and ask them if there is one that will work with the 1981 Corvette.

With the E4ME, a rich condition is moderately tedious to determine the cause, for there are some many situations that could cause them. But the basic checks you must do is for the O2 sensor to be in working order, the water temperature sensor in working order, and the air valve adjusted appropriately.

GerryLP:cool

 

[LannyL81]

I know all about the E4ME carb running rich....been fighting mine for two months!!!
Do you check the dwell? Is it varying? If not, then that is why it is rich. The O2 sensor has to be working for the computer to take control, otherwise it runs it rich to avoid damage to the engine by going lean.

Lots of help here....tell us more what you have checked and found out.

 

[Sensei]

Once again my 81 is running way to rich.

Several things can cause this. Try the simple stuff first. Get a can of Caig Labs Deoxit (you can find it on ebay). Use it to clean all those 28 year old Computer Command Control electrical connections. This is a good thing to do even if it does not fix the problem you are having right now (but it very well may)

God bless, Sensei

 

[PMartin]

I found out that the previous owner unplugged the ECM and when I plug it in the car just dies and will not start. Any ideas where I should start? Do I go ahead and replace the ECM? I found out that NAPA has them rebuilt for around 100 bucks. Does anyone know what sensors commonly go bad?

 

[minifridge1138]

So the ECM has been unplugged the entire time you've owned the car?

 

[Sensei]

You need a 1981 GM Corvette service manual. You can find them on Ebay.

eBay Motors: 1981 Corvette GM Shop and Service Manual (item 260316678124 end time Dec-15-08 19:12:12 PST)

This one is a bit pricey, but I found mine for $9 missing the front cover. I saw others go for around $30.

This will take you step by step through all the diagnostics you need to locate the problem (or any other problem you may experience in the future). You need this book, it will save you money in the long run.

God bless, Sensei

 

[LannyL81]

Once again my 81 is running way to rich. :confused This carb is driving me nuts. What would be the side effects if I moved to a different Carb than the E4ME? Please advise...

Many have replaced the E4ME carb. No real side effects. Have to replace the carb, and the distributor and go with a vacuum advance one. The EGR will not work since you have to unplug the computer.

As far as the engine dieing when you plug the ECM in, could be a dead ECM, or a PROM, or a short in the wiring somewhere. Engine should not run very well without the PCM, unless the distributor has been replaced. Before replacing the PCM, need to check a few things. With the ECM plugged-in, check for 12 volts at the green test connector or at the mixture solenoid connector. If not there, then probably the PCM needs replaced. But like Sensei suggested...get the manual for all of the troubleshooting steps...far too many to try to type out.

 

[PMartin]

I've had the car for a year and just got it road worthy last weekend (it had no interior but ran when i bought it). So i go out for about a 15 mile ride and everything is good. Then turn around to make the trip home and it just started missing and running really rough. I new it was running rich so I figured I fould out a plug or 2 maybe. Thats when i discovered the ECM was never hooked up. I remember reading that it will run with the ECM unplugged but will run rich. So the plan for the weekend is to replace the plugs, plug wires and get the old voltmeter out and start testing everything associated with the igintion system. Sensei I took your advice and bought a shop manual. Dad always said bought lessons are taught lessons. Thanks for the advice guys!