I've rebuilt more than my fair share of Qjets, but never a 'Feedback' or 'Computer Controlled' version. Always junked them instead.

However, I'm in a budget crunch and am swapping a 1985 Chevy Van Motor into a non-computer car. I have a non-computer HEI but no goood Qjet.

1) What does the computer control inside the Qjet, if anything?
2) Are the electronics 'feedback only' for the computer, meaning that they send info to the computer only but the computer does not actually adjust the carb at all?
3) What happens if you just unplug the damn thing? Will it still function? This is no show vehicle and the motor isn't great anyway, so if it runs at all I'll be happy until I can find a good Qjet to replace it with. I just need it running ASAP even if it doesn't run 'Good'...

Thanks!!!
Scott

 

It will run as good as the carb is. the sensors are for the happiness of the computer.

 

It will run. But gas mileage will be horrible and you'll be running in full rich mode. There are only 2 sensors on the carb, the throttle position sensor (self explanatory) and the mixture control solenoid. The MCS receives pulses from the ECM to determine fuel mixture of the primaries. With it disconnected, it will run the primaries full rich. The car will still run, but not well.

 

This is the same problem I face. Any feedback on which one of these answers is right?

 

Go disconnect your carb and drive it. Then you tell us

 

That's an excellent idea..except my car isn't registered or insured right now. Trying to get it ready for the road, and am wondering about installing the Edelbrock Performer intake and Carb I just bought, that doesn't have the connectors the Q-jet has.

 

That's a whole different matter completely. Your Edelbrock carb is not CC controlled, so it will function properly. However your distributor and torque converter (if equipped) will not. Do a search on this topic.

 

Hey, im thinking of getting a edlebrock performer carb this weekend. I already got a non computer distributor, so am I ok to go for it? I cant stand my computer controlled q jet. It's all screwed up, I can tell. It was rebuilt once before before i bought it, and its just really dirty and what not.

 

If you have an automatic transmission the torque converter will not lockup. You will need to buy an aftermarket wiring kit for it. You can make your own, but I'd suggest buying a kit. Painless Wiring makes an excellent kit.

One other thing to note: Your CHECK ENGINE light will stay illuminated. Just remove the bulb.

 

Oh ok. Is this wiring kit easy to install? Thanks Marc.

Marc, I will look for a wiring kit too, but just in case, could you tell me how to make my own? Thanks again.

 

It's much easier than DIY. That's why they call it "Painless Wiring" But, if you insist on at least learning what's involved, do a search on TCC lockup both here and over at www.thirdgen.org There are several threads on this, and I've seen at least 3 entirely different methods of doing it. Electrically external from the trans, electrically internal to the trans, and via vacuum.

I've seen the Painless kit. And although I'm pretty adept at wiring, I think I'll go with the Painless kit when I rid myself of the CC QJet. Don't get me wrong, the CC QJet has served me very well. Power, driveabiltiy, and gas mileage are on par with any other fuel injection or carb setup I've encountered. It's just the ECM can't cope with large cams, and the XE274 I've got now is borderline at best. I want bigger

 

Marc is right about the E4ME. If you disconnect it, you'll run pig-rich and wash down your cylinder rings and get accelerated wear of the cylinder walls, among other things. The other wire to the carb is the electric choke. Dont overlook it or you will have a terrible idle, rich mixture, and no secondaries.

Marc, I still run my factory Qjet, even with a big cam. I recently switched to a T56 transmission, and imagine my surprise when my 20 year old, 138,000 mile Feeble305 with the big XE274 cam turned in 26 MPG on the highway. Around town / mixed highway was 20 MPG.

Trust the computer to hold the air/fuel mix to stoic. Under wide-open throttle, the computer goes open loop, holds the primary rods wide-open and you get a manually controlled quadrajet that responds to secondary metering rods just like the old ones!

 

ws6transam - No problems with the same XE274 in a 305? That's a big cam for a 305, much less for the carbed ECM. What kind of vacuum are you pulling? With tuning my car runs great. Highway mileage is superior to any similar power output V8 I've come across, with maybe the exception of the new LS1/LS6 cars. City driving nets me only about 10-12mpg at best, but cruising in OD at 70 and I'll knock down 26-28mpg no problem. I'm looking to go up to a XE284 with some better heads in the near future. I don't think my ECM will like the over 240* duration of the cam lobes

 

Actually, I double-checked the cam card and it's an XE268H, with 224/230 duration @ .050. The cam has troubles idling at less than 900 RPM, especially when the engine is cold and the ECM isnt in closed loop. When it goes closed loop, it idles rather smoothly at 1000 rpm, but when it's cold, idle is very lopey at 650 to 700 rpm. It also idles rich when cold, but cleans up when the computer gets ahold of the MCS. I could probably fix it with some fiddling but I'm going fuel-injected soon.

Vacuum is around 12-14 inches, if memory serves me correctly. The ECM doesn't throw any codes except when it's really cold outside and I'm idling a long time. I suspect the non-heated oxygen sensor is cooling off. However, that only really happens when it's 38 degrees outside, windy, and I'm sitting in the staging lanes of the dragstrip in late October. I discovered that the '84 E4ME ECM doesn't have any feedback associated with air pump, transmission, or EGR. Those functions have been eliminated, and the ECM is none the wiser. I still have functional coolant, knock, BARO(barometer), oxygen, and throttle position sensors.

 

cant find this wiring harness nowhere for the torque converter, cans someone help me out again? i dont want to mess this up.