Well ive found gobs of useful info on this site but I still have a few questions im hoping you guys can help me with.This is what im dealing with: Ive got a pre-86 SBC 383 with dart iron eagle heads and ive got 2 complete intake setups,one is the early sytle with cold start injector and the other is a later style but still MAF style.Ive also got a good complete 1991-1992 harness with the map sensor and the 730 ECU.I cant figure out where to plumb the MAP sensor in the plenum.IM gonna block off the cold start injector and use the early style plenum,runners,and base.Is this a problem with the throtttle body having the extra idle air passage?One more question,will the sensors on this early style setup physically fit the later style harness or do I need to get the same model year sensors?Also can i delete the vats and vss in the ecu?Thanks in advance for your help.

 

just in case you were wondering this is what its going into....

 

When I had a crappy setup, err I mean TPI I tapped a hose fitting on the back of the intake for the MAP sensor.

Think I use 1/8" NPT if I recall.

-- Joe

 

You can get rid of the VATS in the ECU, and you can compensate for a lack of a VSS, but it isn't the same as running one. Essentially you will pre-program the ECU to think that certain things are happening so that it thinks that its getting a VSS signal. This obviously isn't as good as real input from a functional VSS, but for your application it should work fine.

You can eliminate the cold start injector with very few repurcussions, even without doing any reprogramming. Later model ECUs don't use the cold start injector, and instead enrich each injector with cold startup enrichment logic. You can program older ECUs to do the same thing. Right now I'm not running cold start, and it seems to make very little difference, even when its cold outside.

The MAP sensor just needs to be tied into the intake system. Tapping the plenum for a nipple is the simplest way.

The sensors are all basically the same for TPI cars, and even TBI cars. Knock sensors are different from 305s to 350s, so make sure that you have a 350 style sensor. If you've got roller rockers or a geardrive you don't want to run the knock sensor, plus your engine isn't a 350, its a 383, and the frequency of detonation is different engine to engine. You can take the knock sensor out of the engine, plug it in, and ground the body so that the ECU gets the right reference signal and doesn't throw a code, or just eliminate the knock sensor in the ECU. I've got a geardrive in my car now, and am running my knock sensor in a small bracket on the framerail. I don't get a code, but I've got to be careful and listen for detonation, because the sensor doesn't really work.

 

Thanks for your help.......Ive got a few more questions though.Does the speed density harness use an oil pressure fuel pump cutoff switch?ALso does the wiring from the coil for the distributor go directly from coil to dist with no other attachments?Ive got my harness in place and im missing a plug to go on the coil and 1 plug on the dist.I dont have an aldl either.Ive got a plug that is routed right next to the ecu and im assuming thats it but it doesnt have the blacl cover on it that attaches under the dash.Does anyone have a source for these type of wiring issues?Like an ALDL or the wiring or plugs for the coil/dist and the wiring or plugs for the MAT sensor to harness?Thanks for your help and sorry for all the questions....

 

You can usually buy wiring pigtails directly from GM. I've purchased several ove the years, most recently for my T56 swap. Just go in and tell them you need a pigtail and plug for the application and they will be able to get you one. Just splice it into the harness and you're good to go. I highly recommend soldering all connections and either shrink wrapping them or using self adheering tape like the stuff from Edelbrock.

The speed density and MAF cars should have the same style coil connection. The break year is '87. Before '87 the cars used a big cap HEI with the coil in the cap. After '87 they went to a divorced coil and a small cap HEI. The systems are not any different in operation, and one can be converted to the other with simple wiring changes. Your later model SD harness is probably a divorced coil setup. The coil takes two plugs with two terminals each. There will be a thick pink wire that is hot keyed power from the ignition (positive side of the coil). There is a thin pink wire that runs into the distributor harness (positive side too). There will probably be a white wire that runs the tach (negative side of the coil).

One of the best things you can do is to get a wiring diagram or schematic. There are schematics available on this site that are very good. I printed out a complete set for myself and they have come in very handy when troubleshooting electrical problems,which all 3rd gens seem to suffer after nearly 20 years on the road.