Real Fiero Tech

Sounds lumpy. Keep the driving light till you are confident things won't go awry, and stay close to home for a little while too

Shaun41178(2) wrote:Sounds lumpy. Keep the driving light till you are confident things won't go awry, and stay close to home for a little while too

definitely plan on staying close to home. All things considered, the car is very tame, I was expecting it to be much harder to drive with the big cam, ported heads, big TB, stage 5 clutch ect... but even with the rough tune, it's a cake walk. definitely needs idle tune worked on, and throttle response is poor at best, but with time I'll get it.

ok, so not much of an update, but I've been slowly working on the tune, and slowly been making progress. I threw down the other night, and bought wire and connectors to remake my engine harness with, as I've just been severely disappointed with how it looks, it looks very sloppy, and thrown together. since I was going in this deep though, I figured I may as well see if my coil per cylinder upgrade will work.

The plan:

after much research, I found the LX5 V6(shortstar) uses coil per cylinder ignition in a manner extremely similar to the LSx setup, using a PCM that carries an interchange with the 3400 PCM I am running, but it uses a different crankshaft position sensor arrangement. after a little more digging, I found a flag for "engine type" and "crankshaft position resolution" if I can input the 7x crankshaft position signal directly to the PCM removing the ICM altogether,I might possibly be able to drive LSx ignition coils with my PCM.



how:

first step was to find a hall effect sensor to replace the inductive sensor currently installed on the car. this has taken me a while, but I think I finally have found a winner.



this sensor is from an 02 N*(left). it's a little too long, but it's smaller in diameter, so I can make a sleeve/spacer combination to obtain the correct offset compared to the stock crank sensor(right).

next step, run signal wires from the PCM to the LSx coils and try to fire it.


I am fairly confident this will work. Many of you are probably asking yourselves "why all the work for coil per cylinder? DIS works fine" while DIS does work, the ignition modules are another failure point, and under the decklid of a fiero with a turbo, I don't think it'll fair very well long term. I also believe the LSx coils will provide s much hotter spark than the DIS coils. I also feel like I could clean up the engine bay quite a bit by removing the DIS module. if this works, it would be a viable upgrade for anyone running an OBD II 60v6. 3.4 DOHC owners might be able to run shortstar, vortec 4200 or ecotec coils as well, and have the coil directly on the plug.

I've had a oil leak since the startup that I've been trying to track down, I've traced it back to a fitting I used in my oil filter relocation setup. the PCM has been intermittently throwing a CEL for the camshaft position sensor, and I've been having several odd issues with the CEL not coming on, along with other lights on the dashboard and my oil pressure gauge. Now, along with the engine/PCM harness, I am going to look into the body side harness as well.that being said, if you have a stock '85 cabin harness, I'm interested in buying one, preferably with cruise and a/c, but no power windows or locks.

well, nothing like full retard... the new harness is about 60% done right now. I went to the junkyard and picked up a relay center to mount in the engine bay. I also ordered a set of LS6 ignition coils, and some crank trigger parts for the coil per cylinder ignition setup. it looks like I'll have to get a custom wheel made though. the PCM gets it's crank position signal from the ignition module, and the ignition module outputs a 3x signal to the PCM. so I think I'll have to make a 3x wheel to replace the current 7x wheel.

Did the Shortstar use a single sensor?
What wheel did it use? 24x LS1 or 32X Northstar?

The Dark Side of Will wrote:Did the Shortstar use a single sensor?
What wheel did it use? 24x LS1 or 32X Northstar?

it used a wheel similar to the LS1 wheel, all I know about it, is that it is a dual pattern 24x wheel, with each side inverse of the other. I do not know if the wheel is the same as the LS1 wheel or not.

Made a good bit of progress on the new harness today, I also got the old harness completely removed. I'm moving all of the wiring the enters the bay from behind the console to the passenger side where my PCM is mounted, and replacing my C500 with newer metri/micro pack connectors. most of it will be hidden out of the way. Between ditching the junky C500 and adding the fuse/relay center, my engine bay will look way better, and hopefully function better as well.


here is the C500 pinout for pins F through J for an '85 V6 automatic, I couldn't find it anywhere else, so if you need it:

F6-tan- servo position input hi
f7-brn- taillights
F8-grn/wht- trunk ajar
F9-lt grn- backup lights
F0-blk- ground

G6-lt blu/blk- servo position input lo

h6-dk blu- cruise vent valve control
H7-dk grn- right turn flash
H8-brn- trunk blower fused power
H9-orn- trunk light

j6-lt grn- cruise vac valve control
J7-lt grn/blk and ppl- brake switch
J8-yel- left turn flash
J9-dk grn/wht- blower fan

Rock and Roll.

Steven converted his wiring to use relays for the high current loads.

I've been thinking about setting up front and rear fuse/relay centers for that purpose as well. The stock high current wiring then becomes the control circuits for the relays.

The Dark Side of Will wrote:Rock and Roll.

Steven converted his wiring to use relays for the high current loads.

I've been thinking about setting up front and rear fuse/relay centers for that purpose as well. The stock high current wiring then becomes the control circuits for the relays.

I'm getting ready to set up a forward one as well, but it won't be ready for a little while longer.

I've made lots of progress on the new harness, but it's taking a bit longer than I would like, mainly because I've been working very long hours here lately, the other day, I was at work for over 17 hours straight, not including drive time...

You still at Prototype?

The Dark Side of Will wrote:You still at Prototype?

Yeah, it can be brutal at times.I'm regularly working 14-16 hour days.

Yeah, the fleet eats its young.

The Dark Side of Will wrote:Yeah, the fleet eats its young.

well, lucky for me, I'm one of the older junior enlisted anywhere I go...

not much to report, but I got the new fuse center mounted...



Please excuse the mess of wires underneath it, it's a work in progress still. I hope to finish the new harness tomorrow.

Found out what was wrong with my cam position sensor... on older 3x00's, pins a and c are power and ground. on 3500(LX9) power and ground are a and b. I'm using the 3500 sensor, but I had it wired as a 3x00, so the signal was aligned to ground, and the PCM was just seeing a ground the whole time.

That's a pretty significant finding.

Emc209i wrote:That's a pretty significant finding.

it surprised me how well it ran without the cam position sensor. I hoping now that it's fixed, it'll run even better.

not much to report, but I did discover (after several hours of frustration) the GM installed the 2 speed fan wiring in single speed fan optioned cars, but only from the C500 to the C100...

I thought the 2 speed fan wiring was only for the '88's?